Credit River Watershed Natural Heritage System Strategy Final Technical Report. Credit Valley Conservation 1255 Old Derry Road Mississauga ON L5N 6R4

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3 Credit River Watershed Natural Heritage System Strategy Final Technical Report Credit Valley Conservation 1255 Old Derry Road Mississauga ON L5N 6R4 September 2015

4 Report prepared by: Aviva Patel. Maps by Kamal Paudel. For Further inquiries regarding this report please contact: Dr. Aviva Patel Credit Valley Conservation 1255 Old Derry Road Mississauga, Ontario L5N 6R4 To be cited as: CVC (Credit Valley Conservation) Credit Valley Conservation Natural Heritage System Strategy. Phase 3: Credit River Watershed Natural Heritage System. Final technical report, September 2015.

5 Resolution #59/15: Approval of CVC Natural Heritage System Strategy Date: October 16, 2015 Moved by: Bob Inglis Seconded by: Don MacIver THAT the report entitled, CVC Natural Heritage System Strategy Phases 1-4 be received and appended to the minutes of this meeting as Schedule C ; and THAT the CVC Natural Heritage System Strategy (herein the strategy ) be approved; and THAT staff make council presentations, develop materials, and offer conduct workshops or information sessions to inform provincial ministries, municipal staff and stakeholders about the strategy tools and science to assist in land use planning in an advisory capacity; and THAT staff be directed to promote the use of the science and tools in the strategy to local and regional municipalities as appropriate to assist them in developing, refining or defending systems to achieve local natural heritage protection and restoration goals in their official plans and to provide support as requested to interpret or apply the strategy in development review/official plans and site specific plans; and THAT staff use the strategy for CVC activities including watershed and subwatershed planning, land planning and securement, environmental management, restoration, stewardship and education; and further THAT staff monitor and periodically report on progress toward achieving the natural cover targets for the CRWNHS, and continue research and monitoring to provide leadership in advancing the science in sustainable ecosystem management. CARRIED

6 Acknowledgements Credit Valley Conservation (CVC) thanks all those who have contributed to this report: past and present members of the Technical Advisory Committee, the Municipal Advisory Committee, technical peer reviewers, Internal Steering Committee and CVC staff. CVC would also like to thank the many external stakeholders and partners who took the time to provide feedback on this project. CVC would like to acknowledge Beacon Environmental and Lake Simcoe Region Conservation Authority for the Big Woods concept, and North-South Environmental Inc. and Halton Region for the Centres for Biodiversity concept. Authors of this report would particularly like to thank the CVC core team particularly Scott Sampson, Liam Marray, Yvette Roy and Bob Morris for their dedication to this project. Their input greatly helped in developing the Credit River Watershed Natural Heritage System. Municipal Advisory Committee Ministry of Energy and Infrastructure Ministry of Natural Resources and Forestry Ministry of Municipal Affairs and Housing Halton Region Region of Peel County of Dufferin County of Wellington City of Brampton City of Mississauga City of Mississauga Town of Oakville Town of Caledon Town of Erin Town of Halton Hills Town of Mono Town of Orangeville Township of Amaranth/East Garafraxa Credit Valley Conservation Technical Advisory Committee Environment Canada Fisheries and Oceans Canada Ministry of Natural Resources and Forestry Natural Heritage Information Centre Niagara Escarpment Commission Grand River Conservation Authority Halton Region Conservation Authority Nottawasaga Valley Conservation Authority Toronto and Region Conservation Authority Credit Valley Conservation

7 Table of Contents TABLE OF CONTENTS... I LIST OF FIGURES... VII LIST OF TABLES... VIII EXECUTIVE SUMMARY... IX 1.0 INTRODUCTION PLANNING AND POLICY CONTEXT FOR NATURAL HERITAGE SYSTEMS DEVELOPMENT USES OF THE NHS NATURAL HERITAGE SYSTEM STRATEGY PHASES AND TIMELINES SYSTEMS APPROACH TO NATURAL HERITAGE PLANNING IN ONTARIO THE IMPORTANCE OF WATERSHED SCALE NATURAL HERITAGE SYSTEMS FOR HUMAN SURVIVAL, HEALTH, AND WELL-BEING ECOSYSTEM GOODS AND SERVICES THE IMPORTANCE OF ECOSYSTEM RESILIENCE TO HUMANS STRESSES AFFECTING THE CREDIT RIVER WATERSHED S ECOSYSTEMS AND NEED FOR A WATERSHED NATURAL HERITAGE SYSTEM LAND USE CHANGE Unsustainable development Unsustainable agricultural practices Unsustainable recreation practices Aggregate extraction Infrastructure PATHOGENS, PESTS, AND INVASIVE SPECIES i

8 4.3 CLIMATE CHANGE GUIDING PRINCIPLES, GOALS AND OBJECTIVES FOR THE NHS GUIDING PRINCIPLES IN DEVELOPING THE NHS GOALS AND OBJECTIVES FOR THE NHS Goals for the NHS Objectives for the NHS TARGETS INFORM DEVELOPMENT AND IMPLEMENTATION OF THE NHS THE IMPORTANCE OF OVERALL NATURAL COVER PHYSIOGRAPHY AND NATURAL COVER IN THE CREDIT RIVER WATERSHED INFORM NATURAL HERITAGE SYSTEMS PLANNING CLASSIFICATION OF LANDSCAPES INTO ECOZONES AND ECODISTRICTS PHYSIOGRAPHIC ZONES OF THE CREDIT RIVER WATERSHED The Upper Watershed The Middle Watershed The Lower Watershed DISTRIBUTION OF NATURAL COVER IN THE CREDIT RIVER WATERSHED USE OF PHYSIOGRAPHY AND NATURAL COVER TO INFORM THRESHOLDS PROCESS FOR DEVELOPING THE NHS SCALE AND RESOLUTION OF NHS MAPPING INCORPORATING CLIMATE CHANGE IN NHS DEVELOPMENT RECOMMENDATIONS FOR NATURAL HERITAGE SYSTEMS DESIGN IN THE FACE OF CLIMATE CHANGE DESIGNING THE NHS TO ADAPT TO CLIMATE CHANGE ii

9 10.0 COMPONENTS OF THE NHS NATURAL HERITAGE FEATURES Categorization of natural heritage features BUFFERS NATURAL HERITAGE AREAS Centres for Biodiversity VALLEYLANDS WHAT ARE VALLEYLANDS? Definition of valleylands WHY ARE VALLEYLANDS IMPORTANT? EXISTING CONDITIONS AND IMPLICATIONS FOR THE NHS VALLEYLANDS IN THE NHS High Functioning valleylands Supporting valleylands WETLANDS IN THE NHS WHAT ARE WETLANDS? Definition of wetlands WHY ARE WETLANDS IMPORTANT? EXISTING CONDITIONS AND IMPLICATIONS FOR THE NHS SCIENCE SUPPORTING WETLAND CRITERIA Wetland size or area Wetland proximity Wetland role in surface water quality and quantity WETLANDS IN THE NHS Wetland size iii

10 Wetland proximity Wetland role in surface water quality and quantity, multifunctional linkage WOODLANDS WHAT ARE WOODLANDS? Definition of Woodlands WHY ARE WOODLANDS IMPORTANT? EXISTING CONDITIONS AND IMPLICATIONS FOR THE NHS SCIENCE SUPPORTING WOODLAND CRITERIA Woodland size Woodland interior Woodland proximity Woodland role in surface water quality and quantity WOODLANDS IN THE NHS Mapping of woodlands for the NHS Woodland size Woodland interior Woodland proximity Woodlands and surface water quality and quantity, multifunctional linkage AQUATIC HABITAT AND LAKE ONTARIO SHORELINE WHAT ARE AQUATIC HABITAT AND THE LAKE ONTARIO SHORELINE? Definition of aquatic habitat and Lake Ontario shoreline WHY ARE AQUATIC HABITAT AND THE LAKE ONTARIO SHORELINE IMPORTANT? EXISTING CONDITIONS AND IMPLICATIONS FOR THE NHS iv

11 14.4 AQUATIC HABITAT AND THE LAKE ONTARIO SHORELINE IN THE NHS Aquatic habitat - watercourses Aquatic habitat - water bodies Lake Ontario shoreline SIGNIFICANT WILDLIFE HABITAT WHAT IS SIGNIFICANT WILDLIFE HABITAT? Definition of significant wildlife habitat WHY IS SIGNIFICANT WILDLIFE HABITAT IMPORTANT? EXISTING CONDITIONS AND IMPLICATIONS FOR THE NHS SIGNIFICANT WILDLIFE HABITAT IN THE NHS HABITAT OF ENDANGERED SPECIES AND THREATENED SPECIES WHAT IS HABITAT OF ENDANGERED SPECIES AND THREATENED SPECIES? WHY IS HABITAT OF ENDANGERED SPECIES AND THREATENED SPECIES IMPORTANT? EXISTING CONDITIONS AND IMPLICATIONS FOR THE NHS HABITAT OF ENDANGERED SPECIES AND THREATENED SPECIES IN THE NHS BUFFERS WHAT ARE BUFFERS? WHY ARE BUFFERS IMPORTANT? SCIENCE RELATING TO BUFFER WIDTHS PRACTICE RELATING TO BUFFER WIDTHS BUFFERS IN THE NHS CENTRES FOR BIODIVERSITY v

12 18.1 WHAT ARE CENTRES FOR BIODIVERSITY? WHY ARE CENTRES FOR BIODIVERSITY IMPORTANT? SCIENCE SUPPORTING THE CONCEPT OF CENTRES FOR BIODIVERSITY CENTRES FOR BIODIVERSITY IN THE NHS CREDIT RIVER WATERSHED NATURAL HERITAGE SYSTEM MERGED NHS RELATIONSHIP OF DESIGNATED FEATURES AND AREAS TO THE NHS Overlays of NHS with designated features and areas RELATING THE NHS TO A PPS FRAMEWORK CONNECTIVITY WITHIN THE SYSTEM AND TO ADJOINING NATURAL HERITAGE SYSTEMS AND FEATURES ASSESSMENT OF THE NHS AGAINST TARGETS AND EXISTING CONDITIONS NEXT STEPS GLOSSARY REFERENCES APPENDIX A: MAP FIGURES APPENDIX B vi

13 List of Figures Figure 3-1 A representation of strong sustainability demonstrating the view that economy and society are constrained by environmental limits Figure 7-1 Land cover and land use in the Credit River watershed and its three physiographic zones Figure 10-1 Schematic showing the Credit River Watershed Natural Heritage System and its components Figure 12-1 Distribution of wetland size classes in Northern and Southern zones, Credit River watershed Figure 13-1 Size classes of woodlands in Northern and Southern zones of the Credit River watershed Figure 13-2 Woodland interior area represents woodland area that is 100 m in from a woodland edge Figure 18-1 A section of a Centre for Biodiversity, a natural heritage area, showing natural heritage features as well as other land cover and land use included within it (left) and an air photo of the same area (right) vii

14 List of Tables Table 3-1 Goods and services provided by ecosystems (from de Groot et al. 2002) Table 6-1 CVC targets for achieving natural heritage system objectives Table 10-1 Components of the Credit River Watershed Natural Heritage System Table 11-1 Valleylands in the NHS Table 12-1 Wetlands in the NHS Table 13-1 Woodlands in the NHS Table 14-1 Aquatic habitat and the Lake Ontario shoreline in the NHS Table 17-1 Ranges of buffer widths to natural heritage features based on current science (from Beacon Environmental Limited 2012) Table Buffer widths for natural heritage features in the NHS Table 19-1 Components of NHS Table 19-2 Statistics relating to the land cover and land use in the mapped NHS Table 19-3 A comparison of some provincially designated features and areas and the mapped NHS boundary Table 20-1 Comparison of features and areas of the Provincial Policy Statement and of the NHS Table 22-1 Ecological assessment of CVC watershed targets under a scenario of full NHS implementation viii

15 Executive Summary Credit Valley Conservation (CVC) is undertaking a project to develop a Natural Heritage System Strategy for the Credit River watershed. The project was formerly called the Terrestrial Ecosystem Enhancement Model or TEEM, with four phases as follows: Phase 1: Characterize and assess existing conditions for the watershed using geographic information systems (GIS), based on existing terrestrial and hydrologic data. Use this Landscape Scale Analysis to assess and rank existing natural cover in terms of its watershed importance. Phase 2: Gather data and conduct research as needed to develop a natural heritage system that integrates aquatic and terrestrial functions. Consult with stakeholders on Phases 1 and 2. Phase 3: Develop methodology for identifying a Credit River Watershed Natural Heritage System (CRWNHS, abbreviated to NHS for the purposes of this report) integrating terrestrial and aquatic components. Prepare data layers for input into the NHS. Conduct quality assurance and quality control on data prior to mapping. Ensure that the NHS captures the best of the Credit River watershed s existing natural cover and adds other lands strategically to improve connectivity and resilience. Incorporate climate change science as appropriate. Consult with stakeholders including neighbouring conservation authorities and municipal planning staff, and conduct technical peer review of NHS methodology. Phase 4: Develop recommendations for implementation of the NHS including consideration of stakeholder comments through consultation. Ongoing beyond Phase 4: Implement the NHS in municipal Official Plans by engaging municipal partners, plan input and plan review. Use the NHS to highlight the watershed importance of existing natural heritage features being protected by municipalities. Provide information to assist in updating existing natural heritage system protection strategies within the context of watershed health. Implement the CVC Natural Heritage System Strategy through CVC watershed management programs such as the Greenlands Securement Strategy and the Integrated Watershed Restoration Strategy; through restoration, stewardship, and education activities with interested landowners; through continued inventory or monitoring of important watershed features and functions; and through CVC s advisory role in municipal natural heritage planning. Monitor and refine the NHS at appropriate time intervals, and update as required to integrate with provincial policies, Official Plans, and new science. The NHS is a science-based, integrated system based on CVC s extensive natural heritage data and technical expertise. This technical report provides a detailed methodology for identification of the NHS and represents Phase 3 of the CVC Natural Heritage System Strategy. ix

16 The term Credit River watershed is used in this document as a convenient term to refer to the entire CVC jurisdiction which encompasses the watershed of the Credit River and also the watersheds of several smaller creeks that flow directly into Lake Ontario. A systems approach was used to develop the NHS, recognizing the long term ecological and human health and well-being benefits that arise from ecosystems that are healthy, connected, and resilient. The primary goals for the NHS are to protect, restore, or enhance the ecological integrity of the Credit River watershed s natural features, functions and systems; and to protect or enhance the quantity and quality of surface and ground water for environmental and human uses. A watershed is recognized by the province of Ontario as the ecologically meaningful scale for planning to protect, improve, or restore the quality and quantity of water; hence the CVC focus on the watershed as the scale for natural heritage system planning. The CVC Natural Heritage System Strategy will also help identify connections between provincial natural heritage systems and features such as the Greenbelt Natural Heritage System, Oak Ridges Moraine and Niagara Escarpment, municipal natural heritage systems and surrounding watersheds. The components of the NHS consist of natural heritage features and their buffers, and natural heritage areas. Within this system there are multiple types of land cover and land use including: natural or naturalizing ecological communities as defined by the provincial Ecological Land Classification, aquatic features consisting of watercourses and water bodies, and lands such as agriculture, manicured open space, or urban which are associated with and contribute to the form and function of the NHS. The criteria for the system components and thresholds for criteria were based on well-established scientific principles, federal or provincial guidelines, best practices, professional judgment of technical committees or external peer reviewers, and CVC data. The system is designed to be compatible with the natural heritage policies of the Provincial Policy Statement and follows well-established landscape ecology and conservation biology principles included in the scientific literature and the province s Natural Heritage Reference Manual. This document represents a technical report for identifying the NHS. Recommendations relating to the implementation of the NHS will be addressed in Phase 4 of the CVC Natural Heritage System Strategy. x

17 Credit River Watershed Natural Heritage System components: Natural heritage features Valleylands High Functioning and Supporting Wetlands - High Functioning and Supporting Woodlands High Functioning and Supporting Aquatic habitat - High Functioning and Supporting Lake Ontario shoreline High Functioning Significant wildlife habitat High Functioning Habitat of endangered species and threatened species High Functioning Buffers Buffers on natural heritage features to protect the features and their functions from adjoining land uses Natural heritage areas Centres for Biodiversity Natural heritage features The Natural heritage features component includes ecological features in the Credit River watershed that collectively are important for maintenance of biodiversity and ecological function in the watershed. It includes features that collectively provide lifesustaining ecological functions such as flow moderation, climate moderation, nutrient regulation, disturbance regulation, soil formation, and pollination. It includes but is not limited to ecological features listed in provincial policy and guidelines (Provincial Policy Statement and the Natural Heritage Reference Manual, respectively) for protection of natural heritage. Natural heritage features included in the NHS consist of valleylands, wetlands, woodlands, aquatic habitat and the Lake Ontario shoreline, significant wildlife habitat and habitat of endangered species and threatened species. Natural heritage features are classified into three major categories to reflect relative differences in function at the watershed scale: High Functioning, Supporting, and Contributing. Many natural heritage features have multiple roles and functions. For example, treed wetlands or swamps meet the definition of both woodlands and wetlands; and wetlands may also function as aquatic habitat. A natural heritage feature may also fall under two different relative importance categories (for example, a treed swamp may classify as a Supporting woodland but also as a High Functioning wetland, based on ecological criteria for inclusion in the NHS). In such cases, it is recognized that the feature provides multiple functions and management, restoration or protection of the feature should consider all the functions provided by the feature. xi

18 High Functioning features High Functioning natural heritage features represent key natural heritage features from a watershed and/or provincial perspective that are essential for maintaining biodiversity and ecological function within the watershed over the long term. Collectively these features are essential for ensuring the integrity and resilience of the NHS. Some of these features are of provincial significance (e.g. Provincially Significant Wetlands or Areas of Natural and Scientific Interest). Others may be deemed significant by planning authorities according to the Provincial Policy Statement (e.g. valleylands, woodlands, or significant wildlife habitat). Cumulative impacts to these features are likely to have a significant impact on the resilience and self-sustainability of the NHS. High Functioning features are comprised of High Functioning valleylands, High Functioning wetlands, High Functioning woodlands, High Functioning aquatic habitat, High Functioning Lake Ontario shoreline, High Functioning significant wildlife habitat and High Functioning habitat of endangered species and threatened species, and are included in the NHS. Supporting features Supporting features represent features that play a supporting role within the watershed. These features enhance the quality and function of High Functioning features and collectively are highly likely to improve the resilience of the NHS. These features contribute to meeting science-based and federal guidelines for overall natural cover within the watershed, help maintain the abundance of common species in the landscape, and improve connectivity by providing stepping stone habitat or tableland linkages. The cumulative loss of these features will have some impact on overall levels of natural cover in the watershed. Supporting features are comprised of Supporting valleylands, Supporting wetlands, Supporting woodlands, and Supporting aquatic habitat and are included in the NHS. Contributing features Contributing features are features that play a contributing role within the watershed. These features may contribute to connectivity across the landscape. They are typically very small and may also be relatively isolated from other natural heritage features. In urban areas they may be especially valued for their social function. Contributing features are comprised of Contributing wetlands, Contributing woodlands, Contributing aquatic habitat, and headwater drainage features contributing to valleylands. Contributing features are not generally included in the NHS, unless they are part of a more important feature or area (for example, a small woodland located in the floodplain of the Credit River would be included, but is primarily classified as a valleyland natural heritage feature; or a small wetland located in a natural heritage area would be included in the NHS due to its classification as a Centre for Biodiversity). xii

19 Buffers Buffers represent minimum areas around natural heritage features that protect or mitigate impacts on their functions from existing or future adjacent land uses. Minimum buffer widths have been mapped in the NHS around specific features, including valleylands, wetlands, woodlands and aquatic habitat. The widths specified represent minimums, and all natural heritage features need to be further evaluated through the planning process on site. An evaluation should consider the function and sensitivity of the feature in order to evaluate appropriate buffer width and composition. Natural heritage areas Centres for Biodiversity Centres for Biodiversity are defined for the purposes of the NHS as landscapes with a concentration of natural heritage features representative of physiographic regions in the watershed, which collectively represent important ecological features and functions capable of supporting native biodiversity over the long term. Centres for Biodiversity contain the best representative aggregations of natural features such as woodlands, wetlands, and aquatic habitat. They may also contain other habitat that contributes to diversity or connectivity of ecosystems on the landscape, such as tableland successional areas, agriculture, open space, or urban land use. In the Credit River watershed, there are a total of 11 Centres for Biodiversity, associated with the watershed s eight major physiographic regions, one inland lake and one estuarine area in the Credit River watershed. Because these natural heritage areas are large, each Centre for Biodiversity may cover more than one physiographic region. One large Centre for Biodiversity was divided into two due to its overall size, and to foster stewardship efforts within local communities (i.e. Inglewood and Forks of the Credit). All components of the NHS cannot be mapped. While every effort has been made to ensure data quality and currency, some minor mapping errors may exist and will be corrected as appropriate. Therefore the intent of this report is that the text of the criteria for identifying the NHS supersedes the mapping. The system will be updated at the appropriate planning scale (e.g. site, subwatershed, secondary plan) when land use changes occur, as official plans are updated, or as new site level information is obtained. The mapped NHS occupies 39% of watershed area, with 29% occupied by natural or naturalizing cover and 10% occupied by other land uses such as agriculture, open space, or urban. xiii

20 Many of the components of the NHS are compatible with existing planning policies and various regulations (e.g. the Conservation Authorities Act). Many of the features and areas are also already designated under provincial legislation (e.g. Greenbelt Plan) or in municipal Official Plans. It is intended that the NHS be viewed as a single system and implemented using a systems approach. It is also recognized that not all features and areas of the system have the same level of ecological importance and different parts of the system may be subject to different policies during implementation by municipalities. The NHS provides a common watershed context for CVC to provide sound, sciencebased natural resource management information to municipalities and key stakeholders, provides efficiencies for plan input and plan review at provincial, regional or municipal scales, and lessens uncertainty to watershed stakeholders. The NHS is intended to be provided to municipal planning authorities in an advisory capacity as a tool to review existing natural heritage systems policies and strategies at the municipal scale and to enhance the protection and restoration of natural heritage features and functions within their area of jurisdiction over the long term. The NHS is not intended to limit the ability of municipalities to develop their own science-based natural heritage systems using systems approaches within their own land cover and land use context. Future work in Phase 4 of the CVC Natural Heritage System Strategy will focus on strategies for implementation of the NHS. The system will be examined in the context of future potential land use changes and recommendations will be provided relating to protection, land securement, restoration, and stewardship. Components of NHS with criteria, thresholds and categories. NHS criteria and thresholds Category Natural heritage features 1. Valleylands 1a) Credit River and its major tributaries, and major watercourses draining to Lake Ontario Northern and Southern zone: i) Valleylands of the Credit River and major tributaries, namely those having direct confluence with the Credit River; and ii) Valleylands of major watercourses (Sheridan Creek and Cooksville Creek) having direct drainage to Lake Ontario, from their outlet to the farthest upstream extent of their defined valley landform 1b) Valleylands supporting surface water functions (conveyance, attenuation, storage and release), productivity, and linkage High Functioning High Functioning xiv

21 NHS criteria and thresholds functions Northern zone and Southern zone: All other valleylands associated with watercourses Category Supporting 2. Wetlands 2a) Size Northern and Southern zone: i) All wetlands >2 ha ii) All wetlands >0.5 ha and <2 ha 2b) Proximity Northern and Southern zone: All wetlands >0.5 ha and <2 ha within 30 m of a High Functioning woodland, High Functioning wetland, or High Functioning valleyland 2c) Surface water quality and quantity, multifunctional linkage Northern and Southern zone: All wetlands >0.1 ha and <2 ha located within or adjoining a valleyland 3. Woodlands 3a) Size i) Northern zone: All woodlands >16 ha ii) Southern zone: All woodlands >4 ha iii) Northern zone: All woodlands >4 ha and <16 ha iv) Southern zone: All woodlands >2 ha and <4 ha 3b) Interior i) Northern zone: All woodlands <16 ha containing >0.5 ha interior habitat (100 m from woodland edge) ii) Southern zone: n/a (no woodlands <4 ha have interior) 3c) Proximity i) Northern zone: All woodlands >2 ha and <16 ha within 30 m of a High Functioning woodland, High Functioning wetland, or High Functioning valleyland High Functioning Supporting Supporting Supporting High Functioning High Functioning Supporting Supporting Supporting Supporting Supporting xv

22 4. Aquatic habitat NHS criteria and thresholds ii) Southern zone: All woodlands >0.5 ha and <4 ha within 30 m of a High Functioning woodland, High Functioning wetland, or High Functioning valleyland 3d) Surface water quality and quantity, multifunctional linkage i) Northern zone: All woodlands >0.5 ha and <16 ha within or adjoining a valleyland ii) Southern zone: All woodlands >0.5 ha and <4 ha within or adjoining a valleyland 4a) Watercourses Northern and Southern zone: i) All watercourses containing or linking habitat for top predators associated with the following aquatic communities: a) Coldwater Brook Trout Fish Community; b) Coldwater Brown Trout/Rainbow Trout/Atlantic Salmon Fish Community; c) Large Warmwater and Migratory Coolwater Fish Community; and d) Estuarine Fish Community ii) All other watercourses 4b) Water bodies Northern and Southern zone: i) Lake Ontario within CVC jurisdiction ii) All lakes that a) are not created and maintained by human infrastructure such as a dam; and b) are of aggregate origin whose aggregate license has been surrendered and show evidence of naturalization iii) All lakes that are created and maintained by human infrastructure such as a dam iv) All water bodies >2 ha of aggregate origin whose aggregate license has recently been surrendered (text criterion) 1 v) All water bodies >0.5 ha and <2 ha within 30 m of a High Functioning valleyland, High Category Supporting Supporting Supporting High Functioning Supporting High Functioning A High Functioning A High Functioning B Supporting Supporting xvi

23 5. Lake Ontario shoreline 6. Significant wildlife habitat 7. Habitat of endangered species and threatened species Buffers 8. Buffers on natural heritage features NHS criteria and thresholds Functioning wetland, or High Functioning woodland All areas within Lake Ontario shoreline defined by Lake Ontario Flood Hazard, Lake Ontario Erosion Hazard, and Lake Ontario Dynamic Beach Hazard Northern and Southern zone: All habitat identified as significant wildlife habitat (text criterion) Northern and Southern zone: All habitat identified for protection as habitat of endangered species and threatened species (text criterion) High Functioning valleylands: Crest of slope or meander belt - minimum 30 m plus evaluation High Functioning wetlands: Minimum 30 m plus evaluation High Functioning woodlands: Minimum 30 m plus evaluation High Functioning aquatic habitat (water bodies): Minimum 30 m plus evaluation Supporting aquatic habitat (water bodies): minimum 30 m if it adjoins a High Functioning wetland plus evaluation Supporting wetlands: Minimum 10 m plus evaluation Supporting woodlands: Minimum 10 m plus evaluation Supporting aquatic habitat (water bodies): Minimum 10 m unless it adjoins a High Functioning wetland plus evaluation All other natural heritage features: To be evaluated Category High Functioning High Functioning High Functioning n/a xvii

24 NHS criteria and thresholds Category Natural heritage areas 9. Centres for Biodiversity Landscapes with a concentration of natural heritage features, encompassing the top 5% of habitat patches by area within Northern and Southern zones, representative of the eight major watershed physiographic regions, an inland lake and an estuarine area, that collectively represent important ecological features and functions capable of supporting native biodiversity in the long term 1 Text criterion: means the feature is not mapped as such but if it meets this criterion it is included in the NHS. n/a xviii

25 Mapped Credit River Watershed Natural Heritage System. xix

26 1.0 INTRODUCTION Human health is tightly linked to the health of the natural environment. Healthy ecosystems are adaptable, resilient, self-sustaining, and support diverse native flora and fauna and associated ecological functions. Functions provided by ecosystems include provision of habitat for wildlife and regulation of water, climate, gases, nutrients and disturbance. Ecosystems are also valued for the services or benefits they provide that are essential for human health and well-being such as flood moderation, water purification, waste and pollutant mitigation, temperature moderation, erosion prevention, soil formation, crop pollination, biological pest control, aesthetics and recreation. Ecosystems also provide goods such as water, food, raw materials, genetic resources, and models for design and engineering (biomimicry). In 2002, the Ontario Ministry of Natural Resources and Forestry (OMNRF) and Credit Valley Conservation (CVC) developed a comprehensive plan to protect and enhance the fisheries resources of the Credit River watershed (OMNR and CVC 2002). In 2007, CVC released the Credit River Water Management Strategy Update (CRWMSU) (CVC 2007); this strategy provided clear evidence that business as usual development practices would result in continued declines in water quality and quantity across the watershed, and called for an increase in watershed natural cover to slow or reverse these declines. At around the same time, based on the results of the CRWMSU, Credit Valley Conservation Authority (CVC) recognized the need to develop a watershed scale natural heritage system to determine the most efficient and effective location for the increased natural cover recommended by the CRWMSU. Together, these strategies are intended to sustain biodiversity and healthy ecological function, to maintain water quality and regulate water quantity in the watershed, and to ensure continued provision of ecosystem benefits for present and future generations. Consequently the CVC Board of Directors approved the Terms of Reference for developing a watershed scale CVC Natural Heritage System Strategy through a project that was then termed the Terrestrial Ecosystem Enhancement Model or TEEM. This term has been replaced by more standard terminology and the project is now known as the CVC Natural Heritage System Strategy. The goal of this project was to establish a strategy for the Credit River watershed to protect biodiversity and ecosystem functions of the watershed in perpetuity (CVC 2006b), through a) development of a Credit River Watershed Natural Heritage System (CRWNHS, abbreviated to NHS) and b) recommendations for management and implementation of the system. This project builds on the detailed direction for fisheries and aquatic resources provided in previous studies and follows through on recommendations from those studies to increase terrestrial natural cover in strategic locations of the watershed. Through the project, CVC committed to the development of an integrated natural heritage system that would maintain, enhance, and restore both aquatic and terrestrial functions of the watershed. 1

27 A watershed is defined as a region draining into a river, river system, or body of water. In this report, the term watershed or Credit River watershed is used for convenience to refer to the Credit Valley Conservation jurisdiction, and includes the watershed of the Credit River, watersheds of creeks draining into Lake Ontario, Lake Ontario shoreline and the portion of Lake Ontario within CVC jurisdiction. Water and land functions in a watershed are tightly linked. Water quality and quantity in a watershed are strongly dependent on the amount and quality of natural land cover in the watershed for example, the number, area and distribution of wetlands are important in moderating the flow and quality of water in the watershed. Terrestrial natural cover, biodiversity and functions are strongly dependent on available water resources for example, the water balance in forests influences nutrient cycling, soil formation, and the types of flora, fauna and ecological communities found in forests. As defined under the Provincial Policy Statement (PPS), a natural heritage system is defined as; a system made up of natural heritage features and areas, and linkages intended to provide connectivity (at the regional or site level) and support natural processes which are necessary to maintain biological and geological diversity, natural functions, viable populations of indigenous species, and ecosystems. These systems can include natural heritage features and areas, federal and provincial parks and conservation reserves, other natural heritage features, lands that have been restored or have the potential to be restored to a natural state, areas that support hydrologic functions, and working landscapes that enable ecological functions to continue. The Province has a recommended approach for identifying natural heritage systems, but municipal approaches that achieve or exceed the same objective may also be used (OMMAH 2014). Lands with the potential to be restored to a natural state means lands that currently do not hold natural cover but have the capacity to be restored or rehabilitated to a natural state. Agricultural lands within a natural heritage system that have no or limited natural cover still provide natural functions such as infiltration, groundwater recharge, and habitat for species movement, feeding, or migration. A natural heritage system could also include specific urban areas, such as urban areas in floodplains, that would benefit from management practices to improve ecological function of the natural heritage system, or that could be used to enhance ecological function under future redevelopment. In heavily human-modified environments such as the Credit River watershed, certain natural features are not large enough or diverse enough, or lack sufficient 2

28 connectivity to meet the daily, seasonal and long term life cycle requirements of species. When species survival is compromised, ecosystem functions within a feature may be impaired or lost. Land use change from rural to urban and the impacts of climate change result in significant impacts to natural areas and increased human dependence on dwindling natural features and functions. A natural heritage system that improves the functioning of natural features through improvements to their size, connectivity, and hydrological functioning will help mitigate to some extent the impacts of current and future land uses within the watershed. 1.1 Planning and policy context for natural heritage systems development There is a strong established provincial framework for the development of natural heritage systems in Ontario. Section of the PPS (OMMAH 2014), a policy document under the Planning Act, states: The diversity and connectivity of natural features in an area, and the longterm ecological function and biodiversity of natural heritage systems, should be maintained, restored or, where possible, improved, recognizing linkages between and among natural heritage features and areas, surface water features and ground water features. Natural heritage protection is also mentioned in section 2.2 of the Provincial Policy Statement on Water, particularly policies 2.2.1a, 2.2.1c and 2.2.1d: Planning authorities shall protect, improve or restore the quality and quantity of water by: a) using the watershed as the ecologically meaningful scale for planning; c) identifying water resource systems consisting of ground water features, hydrologic functions, natural heritage features and areas, and surface water features including shoreline areas, which are necessary for the ecological and hydrological integrity of the watershed; d) maintaining linkages and related functions among ground water features, hydrologic functions, natural heritage features and areas, and surface water features including shoreline areas; The Conservation Authorities Act is the enabling provincial legislation that provides the legal basis for the creation of conservation authorities (CAs) in Ontario. Generally, the Conservation Authorities Act directs CAs to perform a number of functions regarding watershed planning and management including the prevention, elimination, or reduction of loss of life and property from flooding and erosion, as well as the protection and restoration of natural resources. Section 20 of the Conservation Authorities Act outlines the objects of conservation authorities which is to establish and undertake, in the area over which it has jurisdiction, a program designed to further the conservation, restoration, development and management of natural resources other than gas, oil, coal and minerals. 3

29 For the purpose of accomplishing this object, Section 21 of the Conservation Authorities Act establishes the powers of a conservation authority. A few key powers most applicable to watershed planning include: To study and investigate the watershed and to determine a program whereby the natural resources of the watershed may be conserved, restored, developed and managed; To collaborate and enter into agreements with ministries and agencies of government, municipal councils and local boards and other organizations; To cause research to be done; and Generally to do all such acts as are necessary for the due carrying out of any project. Whereas Sections 20 and 21 govern the objects and powers of conservation authorities, Section 28 of the Conservation Authorities Act empowers conservation authorities to make regulations in the area under its jurisdiction. In 2006, conservation authorities updated their regulations through provincial approval of the Development, Interference with Wetlands and Alterations to Shorelines and Watercourses Regulations for all conservation authorities. Through these updated regulations conservation authorities are to regulate interference with wetlands and watercourses as well as development in or adjacent to natural heritage features such as river or stream valleys, shorelines of Great Lakes and large inland lakes, watercourses, hazardous lands and wetlands. In support of managing natural heritage systems on a watershed wide basis, the regulatory responsibilities of conservation authorities help in managing risks to public health and safety including the protection of the natural hydrologic cycle and ecological functions associated with flooding, erosion, dynamic beaches, pollution and the conservation of land. There are a number of other provincial and federal Acts and strategies that additionally protect species, features, or functions that that form part of a natural heritage system. In the Province of Ontario, the Greenbelt Plan refers to a natural heritage system of core areas and connecting corridors (OMMAH 2005). The Greenbelt Plan includes land within, and builds upon the Niagara Escarpment Plan and the Oak Ridges Moraine Conservation Plan, complementing other provincial level initiatives such as the Parkway Belt West Plan and Rouge North Management Plan. The Credit River watershed contains lands that fall within the Niagara Escarpment Plan area, Oak Ridges Moraine Conservation Plan area, Parkway Belt West Plan area and Protected Countryside area of the Greenbelt Plan. The Places to Grow Growth Plan for the Greater Golden Horseshoe, implemented through the Places to Grow Act 2005 (Government of Ontario) includes the direction to protect, conserve, enhance and wisely use the valuable natural resources of land, air and water for current and future generations and also states that Planning authorities are encouraged to identify natural heritage features and areas that complement, link or enhance natural systems. 4

30 A commitment to the conservation of biodiversity has been identified as a key focus for the Ontario Ministry of Natural Resources and Forestry (OMNRF). Ontario s Biodiversity Strategy (Ontario Biodiversity Council 2011) has developed a list of key actions to protect and restore biodiversity in the Province, which includes a recommendation to adopt landscape conservation planning and comprehensive land use planning approaches at all scales. The Federal Fisheries Act protects all fish habitat, including that of threatened and endangered fish species. The Federal Species at Risk Act (SARA; Government of Canada) provides protection for federal species at risk. The Endangered Species Act in Ontario provides protection for species that are endangered or threatened, and their habitat (Government of Ontario). These species are identified in the Species at Risk in Ontario (SARO) list. Ontario s Clean Water Act (Government of Ontario) relates to protection or regulation of lands within watersheds that provide drinking water. 1.2 Uses of the NHS The NHS can or will be used in several ways: Provides an integrated system of terrestrial and aquatic features and functions to enable better management of the watershed s natural resources; Enables CVC to provide consistent and efficient plan input and plan review on provincial, regional, or area municipal initiatives as part of its technical advisory role, using a common NHS across the watershed; Supports CVC s Strategic Plan and existing watershed management programs such as the Greenlands Securement Strategy, the Credit River Fisheries Management Plan, the Credit River Water Management Strategy, the Lake Ontario Integrated Shoreline Strategy, and current and future programs, including subwatershed studies and a watershed plan; and Provides partners, including municipalities and the province with a sciencebased natural heritage system based on ecological and hydrologic principles within a watershed ecosystem context and extensive data. The resulting NHS can be used to help defend and refine existing municipal natural heritage systems, or can be adapted for development of municipal level natural heritage systems in municipalities that currently lack such systems. The NHS may be used by planning authorities and other agencies to emphasize the watershed importance of existing municipally protected natural heritage features. The NHS can also provide information to assist in updating existing natural heritage system protection strategies within the context of watershed health. The NHS is not intended to limit the ability of municipalities to develop their own science-based natural heritage systems using systems approaches within their own land cover and land use context. 5

31 1.3 Natural Heritage System Strategy phases and timelines Development of the CVC Natural Heritage System Strategy is divided into four phases (see Terms of Reference CVC 2006a): Phase 1: Review literature and relevant natural heritage models. Establish Technical and Municipal Advisory Committees. Characterize and assess existing conditions of the watershed in GIS, based on existing terrestrial and hydrologic data. Use this Landscape Scale Analysis to assess and rank existing natural cover in terms of its watershed importance in sustaining ecosystem function. Phase 2: Gather data and conduct research as needed to develop a natural heritage system that integrates aquatic and terrestrial functions. Communicate analysis of existing features and functions (results of Phase 1 and Phase 2) to stakeholders and invite stakeholder input. Phase 3: Develop methodology for identifying a Credit River Watershed Natural Heritage System (NHS) integrating terrestrial and aquatic components. Prepare data layers for input into the NHS. Conduct quality assurance and quality control on data prior to mapping. Ensure that the NHS captures the best of CVC s existing natural cover and adds other lands strategically to improve connectivity and resilience. Incorporate climate change science where possible in the natural heritage system design. Consult with stakeholders including neighbouring conservation authorities and municipal planning staff, and conduct technical peer review of NHS methodology. Phase 4: Develop recommendations for implementation of the NHS including consideration of stakeholder comments through consultation. Ongoing beyond Phase 4: Implement the NHS in Official Plans through engagement of municipal partners, plan input and plan review. Use the NHS to highlight the watershed importance of existing natural heritage features being protected by municipalities. Provide information to assist in updating existing natural heritage system protection strategies within the context of watershed health. Implement the CVC Natural Heritage System Strategy through CVC watershed management programs such as the Greenlands Securement Strategy and the Integrated Watershed Restoration Strategy; through restoration, stewardship, and education activities with interested landowners; through continued inventory or monitoring of important watershed features and functions; and through CVC s advisory role in municipal natural heritage planning. Monitor and refine the NHS at appropriate time intervals, and update as required to integrate with provincial policies, Official Plans, and new science. Documentation of the biophysical conditions of the watershed and an assessment of its natural features with respect to their ability to support biodiversity and contribute to watershed function is an essential prerequisite to developing a natural heritage system. Phases 1 and 2 of the CVC Natural Heritage System Strategy, namely, background information on the watershed and an assessment of existing features 6

32 and functions in the watershed are provided in another document (CVC 2011). Phases 1 and 2 were combined because much of the hydrologic integration was initiated during Phase 1 of the project. This report covers Phase 3 of the project. 7

33 2.0 SYSTEMS APPROACH TO NATURAL HERITAGE PLANNING IN ONTARIO Environmental planning in Ontario in the 1970s included the identification of landscape features of high biodiversity or species habitat value, hydrological value, or aesthetic or distinctive landform characteristics. These features were identified as Environmentally Significant (or Sensitive) Areas (ESAs). Provincially significant features identified under similar criteria, including contribution to ecosystem function, were identified by the Ontario Ministry of Natural Resources as Life Science Areas of Natural and Scientific Interest (ANSIs). These natural heritage features and areas lacked overall connectivity, although the location of some of these features and areas within valleyland systems likely permitted some flow of genes and species among them. Recognition of the importance of these features and functions is reflected in municipal Official Plans and policies. As the science of landscape ecology and conservation biology progressed, studies showed that landscape level planning is necessary to maintain biodiversity and ecosystem functions over the long term, because the spatial configuration of natural features can have important effects on biodiversity and the health of ecosystems (Forman and Godron 1986, Forman 1995, Hargis et al. 1998, Leitao and Ahern 2002, McGarigal and Marks 1995, McGarigal and McComb 1995, Ritters et al. 1995). For example, it is now understood that the health of a wetland is maintained not by protecting just the wetland area, but through protection of the wetland s hydrology as well. This systems approach, recognizing that the health of individual natural heritage features depends upon their placement within a functioning system, gained rapid acceptance. In 1991, OMNR released a framework for protection of natural heritage (OMNR 1991), outlining key principles for natural heritage protection. In 1996 (OMMAH 1996), the Provincial Policy Statement was released to provide direction on matters of provincial interest related to land use planning and development. Now replaced by the 2014 version, the Provincial Policy Statement contains natural heritage policies that provide protection for key natural heritage features while stressing that the diversity and connectivity of natural features in an area, and the long-term ecological function and biodiversity of natural heritage systems, should be maintained, restored, or where possible, improved (OMMAH 2014). The 1999 Natural Heritage Reference Manual updated in 2010 (OMNR 2010), intended for use in policy development, provided guidance on developing natural heritage systems, while reinforcing the importance of a systems approach in protection of individual features: A natural heritage system approach is a useful method for the protection of specific natural heritage features and areas because it reinforces an understanding that individual areas and features have strong ecological ties to other physical features and areas in the overall landscape. While the 2014 PPS requires the protection of significant natural features and areas, it also emphasizes the importance of recognizing linkages between and among natural features to maintain, restore or, where possible improve diversity, 8

34 connectivity, long term ecological function and biodiversity of the natural heritage system. This systems approach is now a generally accepted approach to developing natural heritage systems. The policy direction provided by the provincial government has resulted in the development of several natural heritage systems in Ontario that utilize a systems approach, based on sound, scientifically defensible landscape ecology and conservation biology principles examples are the Middlesex Natural Heritage Study (UTRCA 2003), Seaton Lands/Duffins-Rouge Agricultural Preserve Natural Heritage System, City of Pickering (OMNR 2005), Oxford County Natural Heritage Study (UTRCA and County of Oxford 2006), the Lake Simcoe Region Conservation Authority Natural Heritage System (Beacon Environmental and the Lake Simcoe Region Conservation Authority 2007), the Toronto and Region Terrestrial Natural Heritage System Strategy (TRCA 2007), the Halton Region natural heritage system recommended in the Sustainable Halton Phase 3 report (North-South Environmental Inc. 2009), and the Natural Heritage System of the North Oakville West Secondary Plan (Town of Oakville 2009). These natural heritage systems frequently identify cores and corridors, where cores represent large tracts of natural areas, and linkages or corridors represent other natural, naturalizing or non-natural areas (e.g. valleylands) that knit the cores into a larger, functioning system (OMNR 2004). The NHS has been developed using a systems approach. Natural heritage features and areas important for ecological and hydrological functioning of the watershed have been identified while considering the overall land use context of the regional landscape. Together, these features, areas, and associated buffers form a natural heritage system that is likely to be more resilient and easier to maintain and manage under conditions of increased urban development. A systems approach to natural heritage planning includes the development or refinement of natural heritage systems at different scales. At the provincial scale, the province of Ontario has designed connected systems (e.g. Greenbelt Natural Heritage System of the Protected Countryside Area, Oak Ridges Moraine Conservation Plan). At the watershed scale, conservation authorities have designed natural heritage systems to protect or enhance water quality and quantity and watershed scale ecosystem benefits. Subwatershed scale or local scale plans (e.g. area municipal natural heritage systems or Secondary plans) may further refine watershed natural heritage systems to achieve local objectives for biodiversity, ecological function, and benefits to local communities. Integrating watershed based systems with regional or provincial systems results in long term resilience of natural features and functions, because ecosystems and flows of energy, material and water transcend political boundaries. Provincial areas and plans such as the Greenbelt, the Niagara Escarpment Plan and the Oak Ridges Moraine Conservation Plan also integrate watershed based natural heritage systems across watershed boundaries. At local scales, the NHS can integrate subwatershed or local scale systems to achieve watershed or municipal objectives for natural cover, water quality and water quantity. The NHS considers the watershed ecosystem context, thereby helping inform municipal plans, as municipalities may not always include entire watersheds. 9

35 The value of designing systems at different scales, and the shared objectives of healthy, resilient ecosystem functioning across scales, allows for efficient and optimal land use planning at each scale. 10

36 3.0 THE IMPORTANCE OF WATERSHED SCALE NATURAL HERITAGE SYSTEMS FOR HUMAN SURVIVAL, HEALTH, AND WELL-BEING An ecosystem consists of a dynamic set of living organisms (plants, animals, and microorganisms) together with the non-living components of their environment, related ecological processes, and humans (OMNR 1999). Ecosystem functioning is a broad term that encompasses ecosystem properties and processes, ecosystem goods, and ecosystem services. Ecosystem processes involve the flows of energy and materials through ecosystems (Hooper et al. 2005). Examples of ecosystem properties and processes, also known as ecosystem functions, are biogeochemical cycling and storage, hydrologic flux and storage, nutrient and sediment cycling and transport, regulation of gases, water, and disturbances, and maintenance of biological diversity (Christensen et al. 1996). These ecosystem functions support life at all levels. 3.1 Ecosystem goods and services Ecosystem goods and services refer specifically to those components of the ecosystem that are recognized as being of direct or indirect benefit to human populations occupying ecosystems (Costanza et al. 1997, Daily 1997). Ecosystem goods have direct market value, such as food, fuel, construction materials, medicinal plants, genetic resources, tourism or recreation, and biomimicry models for engineering design (Christensen et al. 1996, Hooper et al 2005). Ecosystem services refer to ecosystem processes benefiting humans such as flood control, groundwater recharge, climate moderation, production of oxygen, generation and maintenance of biodiversity, pollination, seed dispersal, waste management, erosion and sedimentation control, natural pest control, decomposition, recreation, and aesthetic, spiritual, or scientific services (Table 3-1; Kareiva 1994, Costanza et al. 1997, Daily 1997, Daily et al. 2000, de Groot et al. 2002, Hooper et al. 2005). Environment Society Economy Figure 3-1 A representation of strong sustainability demonstrating the view that economy and society are constrained by environmental limits It is now generally accepted that it would be highly unlikely that humans could replace all critical ecosystem goods and services by technological means, and that a 11

37 minimum stock of natural capital is required for human social and economic wellbeing (Ott 2003). The province of Ontario has also recognized that natural areas and natural heritage systems form part of a green infrastructure (OMMAH 2014) that supports human health, wellbeing, public safety, and the economy. Biodiversity is the foundation of the ecosystem goods and services from which humans benefit (Kareiva 1994, Hooper et al. 2005, Duffy 2009, Haddad et al. 2009, Hargrave 2009, Srivastava and Bell 2009). Table 3-1 Goods and services provided by ecosystems (from de Groot et al. 2002) No. Ecosystem goods and services Examples Regulation functions 1. Climate regulation Mitigation of urban heat island effect; cooling through evapotranspiration 2. Gas regulation (e.g., oxygen /carbon dioxide balance, Provision of oxygen, removal of carbon dioxide; maintenance of good air quality; UVB protection by ozone ozone layer) 3. Water regulation Maintenance of water cycle (evapotranspiration and rainfall); moderation of flooding intensity Storm protection, flood moderation (coastal and inland wetlands, stream sides, and forests) 4. Disturbance regulation 5. Nutrient regulation Maintenance of healthy soils and productive ecosystems 6. Soil retention Prevention of erosion and siltation; maintenance of arable land 7. Soil formation (e.g., leaf litter decomposition) Maintenance of woodland and wetland productivity and species that support agriculture and natural systems 8. Waste treatment Pollution control/detoxification; noise abatement; filtering of dust and other particulates 9. Pollination Pollination of wild plants; pollination of crops 10. Biological control Control of pests and invasive species (e.g., mosquitoes); control of diseases and pests (e.g., spruce budworm) Habitat functions 11. Refugium function Living space for wild plants and animals 12. Nursery function Habitat for reproduction of species (e.g., for fisheries) 13. Movement function Movement corridors for migratory or resident species 12

38 Production functions 14. Fresh water Provision of water for consumption and irrigation (filtering and storage) 15. Food Provision of existing and novel food items (e.g., fish, berries) 16. Raw materials Provision of materials for building or manufacturing, biofuels and energy, fertilizer 17. Genetic resources Genetic resources for research and development of novel foods, textiles, fuels, medicines, raw materials 18. Medicinal resources Resources for pharmaceuticals, health care products 19. Ornamental resources Resources for crafts, art, gardening, worship, or souvenirs Information/Social functions 20. Science and education Use of natural areas for school or public education; scientific knowledge 21. Human health and wellbeing Livable neighborhoods and cities; sense of place; aesthetics; recreation 22. Recreation Walking, biking, canoeing, fishing, bird watching 23. Cultural, artistic, religious, historic Use of nature in art, books, painting, etc; religious significance; historic significance (e.g., heritage forests) Ecosystem goods and services have been valued at $33 trillion globally (Costanza et al. 1997), although technological fixes for many ecosystem services do not exist. A study of Ontario s Greenbelt shows that the value of ecosystem services provided by the Greenbelt surrounding the Greater Toronto Area (roughly 60% of the Credit River watershed is covered by the Greenbelt) was $2.6 billion annually (Wilson 2008). Over people are estimated to live in the Credit River watershed (based on 2001 census data; CVC 2007). A study of the Credit River watershed has shown that the watershed provides a minimum of $371 million in ecological services annually to area residents (Kennedy and Wilson 2009). Examples of the values of ecosystem services are as follows: Water quality and quantity: Technological replacements for the provision of clean, safe drinking water in one watershed (Catskill watershed, New York) were estimated at US$6-8 billion, leading municipalities to purchase the entire watershed to perform this ecosystem service for the considerably lower price of US$1-1.5 billion (Chichilnisky and Heal 1998). A study in southern Ontario showed that lands in permanent vegetative cover have been estimated to reduce the cost of filtering sediment in municipal drinking water by $5.60 per 13

39 hectare per year, and phosphorus reduction costs by $23.30 per hectare per year (Olewiler 2004). A study of the Credit River watershed (Kennedy and Wilson 2009) showed that the watershed s natural capital saves watershed taxpayers $100 million in water supply costs every year. Preserving the natural capital of the watershed and ensuring its resilience via natural heritage systems will likely provide strong returns in overall avoided costs of groundwater or surface water processing and purification, and flood control. Pollination: Agriculture and Agri-Food Canada has estimated that the value of honeybee pollination in Canada is more than $1-billion a year (Agriculture and Agri-Food Canada 2003). Research has shown that forest habitat within 1-2km of a farm can strongly stabilize and enhance pollination services, thus serving as insurance for farmers in the region (Kremen 2005). With approximately one-third of the Credit River watershed in agricultural land uses, pollination services are likely to play an important role in the watershed. Recreation: In Ontario, combined expenditures of Parks and visitors supported a gross total output of $705.4 million (Ontario Parks 2002 cited in Canadian Urban Institute 2006). The economic value of outdoor activities in Ontario was also estimated to be $807.1 million annually, that is, the value Ontarians place on recreation above and beyond the actual costs paid to engage in the activity (DuWors et al. 1999). The benefits of green space in the Credit River watershed for recreation and wellbeing are significant. A CVC study has shown that the total annual value of the Credit River fishery is estimated to be in the order of $1.2 million, which converts to a cumulative net present value of around $48 million (DSS Management Consultants Inc. 2008). Well-being and prosperity: A study has shown that natural features increase property values in south Mississauga by a total of $127,636,079 and in north Mississauga by a total of $127,810,876 (DSS Management Consultants Inc. 2009). Trees Ontario has reviewed a subset of the scientific literature showing links between green space and public health and wellbeing (Trees Ontario 2012). While several papers in this review are related to air pollution which is not necessarily bound by watershed boundaries, others more specifically link public health with green space. 3.2 The importance of ecosystem resilience to humans Ecosystems are said to be self-regulating or self-sustaining because they contain feedback mechanisms that allow them to function in one or more stable states. Ecosystems have the capacity to exist in multiple equilibrium or stable states under conditions of moderate natural disturbances to which they have adapted (such as fires or flooding) but excessive disturbance can flip a system from one state into another state (Holling 1973, Gunderson 1999, 2000). If a disturbance pushes a system beyond its capacity to adapt or self-regulate, it enters a chaotic state wherein its components are reorganized into a new equilibrium state. The flip from one state into another is at times precipitated by human activity, for example, massive tree dieback due to water stress (Breshears et al in CCSP 2009), the conversion of woodlands into grasslands through grazing and fire, or the eutrophication of lakes 14

40 (Scheffer et al. 2001). In some cases ecosystems that experience disturbance develop into completely new or novel ecosystems (Seastedt et al. 2008). Because of the complexity of ecosystems and their processes and our incomplete knowledge of how ecosystems work, it is difficult to predict the characteristics or the functioning of new ecosystem states. The impact on humans when ecosystems flip into other states can be severe and include loss of key ecosystem goods and services, impacts on human health, safety or well-being, and increase in system maintenance costs. For example, conversion of woodlands to scrub or grassland habitat could potentially increase flooding and erosion, result in greater numbers of hazard trees, cause algal growth in streams and Lake Ontario, increase local temperatures and the heat island effect, and increase costs of restoration and mitigation. Ecological resilience is defined as the capacity of an ecosystem to absorb stress yet retain essentially the same structure and functions and avoid flipping permanently to another state (Holling 1973, Gunderson 1999, 2000). Biodiversity provides for both stability (resistance) to and recovery (resilience) from disturbances that disrupt ecosystem functions and services (Christensen et al. 1996) and thereby acts as an insurance policy for ecosystems. Ecosystems with greater biodiversity are better able to handle stress and catastrophic events and are better able to provide humans with key ecosystem benefits. Biodiversity is important not just in the watershed context but also in an urban context. A recent example of the impact of limited biodiversity in urban areas is the heavy loss to southern Ontario urban tree canopy cover caused by the emerald ash borer (Agrilus planipennis). The heavy loss of street tree cover in some urban and suburban neighborhoods is directly attributed to past planting practices that limited the diversity of street trees, resulting in a high proportion of ash trees that were susceptible to this invasive pest. When the valuable ecosystem services provided by the watershed s natural areas are compromised, the lost value must ultimately be borne by taxpayers. Maintaining and restoring a resilient, self-sustaining natural heritage system is a precautionary approach that reduces the risk of impaired ecological services and is more costeffective than addressing problems after ecosystem services are lost. 15

41 4.0 STRESSES AFFECTING THE CREDIT RIVER WATERSHED S ECOSYSTEMS AND NEED FOR A WATERSHED NATURAL HERITAGE SYSTEM There are a number of stresses that affect the watershed s ecosystems, the natural areas that provide ecosystem goods and services to its inhabitants. Primary stresses, or root threats, include the following: Land use change from natural to urban or rural residential (residential, commercial, industrial), recreational (e.g. golf courses, parks, infrastructure), agriculture, aggregate (pits and quarries), infrastructure (e.g. roads, utility corridors), and water management (e.g. dams, grading, water taking); land use change is associated with secondary stressors such as increases in impervious cover, pollution, and alteration of hydrology or soils; Pathogens, pests, and invasive species (e.g. non-native invasive species, pests, diseases, modifications of the wild gene pool); Suppression of natural events (e.g. fire, flooding, erosion); Unsustainable harvesting of biological resources (e.g. illegal harvesting of plants, unsustainable logging, hunting, fishing) this is not currently a major threat in the Credit River watershed; and Climate change. Primary stresses are frequently interlinked for example, urbanization is associated with increased levels of water taking, recreation, and invasive species. A number of CVC studies have demonstrated degradation of the natural environment and the need for sound planning to direct development away from areas that provide multiple ecological benefits to the watershed. The Credit River Watershed Management Strategy Update (CVC 2007) showed unequivocally that business-as-usual patterns of urban development will result in continued declines to water quality and quantity in the watershed. Subwatershed studies have identified stressors in each subwatershed, and CVC s long term Integrated Watershed Monitoring Program has demonstrated the cumulative impacts of stresses on the watershed s aquatic and terrestrial features and functions. Development of the NHS can help lessen the impacts of these stresses on the watershed s ecosystems by guiding stressors away from sensitive ecological features and functions or by improving the resilience of ecosystems. Such a system would have the additional benefit of retaining features that provide key ecological services to the watershed and its residents and reducing maintenance or compensation costs to municipalities. It is important to note that the area of the NHS is constrained due to regard for competing land uses and socioeconomic imperatives therefore the implementation of the system alone will be insufficient to achieve watershed ecological integrity. A more holistic approach is necessary that includes both recognizing the importance of protecting a robust natural heritage system and managing the matrix (urban, 16

42 agricultural) in which the system is embedded will be necessary to maintain long term watershed health. A subset of major stresses on the Credit River watershed is described below. The list is limited to those stresses that may be somewhat alleviated by the identification and implementation of the NHS. 4.1 Land use change Land use change causes both habitat loss and habitat degradation. The landscape of southern Ontario has undergone significant change over the past 200 years. Prior to European settlement, southern Ontario including the Credit River watershed was almost completely covered by forests and swamps, with smaller open areas of successional or open country habitat as a result of natural disturbance, and small patches of prairie habitat in the south. Estimates of pre-settlement vegetation cover in southern Ontario suggest that 70% of the landscape was woodland/scrubland, primarily woodland; the percentages for the Regions of Peel, Halton, Wellington and Dufferin (Credit River watershed upper tier municipalities) ranged from 74% to 89% woodland/scrubland cover (Larson et al. 1999). Between 1850 and 1920, large tracts of land were cleared for agriculture and logging operations, resulting in severe habitat loss. An estimated 93.7% of original upland woodlands were converted to other non-forest land uses by 1920 (Larson et al. 1999). In subsequent years, extensive reforestation efforts by landowners, municipalities and other agencies have resulted in increased woodland cover over time. However, conversion of agricultural and forested land to urban development has continued apace. Wetland losses in southern Ontario have also been significant (Snell 1987, Ducks Unlimited Canada 2010). A study of wetland extent and loss in southern Ontario has shown that 76% of large (>10 ha) southern Ontario wetlands have been lost following European settlement, primarily through early conversion of land for agriculture; this number is likely greater when the loss of smaller wetlands is accounted for (Ducks Unlimited Canada 2010). Remaining wetlands in the watershed therefore gain in importance as they represent communities that have become relatively rare on the landscape. In the Credit River watershed, 80% of natural areas have been lost, first due to agriculture, logging and other extractive activities, and subsequently due to development. A study for CVC has estimated that at the time of European settlement, wetlands covered approximately 10.4% of watershed area (Dougan and Associates et al. 2009). A study of pre-settlement vegetation in the Region of Peel using surveyor records determined that wetlands including swamps, bottomlands and low lying areas covered approximately 15% of Peel Region. Upland forest (including some open treed areas and successional areas) covered approximately 85% of Peel Region and grasslands or open treed habitat covered less than 1% (Puric-Mladenovic et al. 2013). 17

43 Currently about 12% of natural upland forest and 6.7% of wetlands currently remain in the Credit River watershed. The distribution of natural cover is uneven, with a majority of natural cover in the Middle and Upper Watersheds. Land use change can also cause habitat degradation through fragmentation of natural areas, flooding, erosion, changes to flow magnitude, frequency and duration, decline in air and water quality, pollution, and the impacts of urban sponsored predators. Listed below are the major types of land use change that can cause habitat loss and/or degradation Unsustainable development Development and the associated increase in impervious cover (hard surfaces) can cause severe loss and degradation of natural habitat if not sustainably planned. Impacts of unsustainable development practices on species can include inadequate habitat for species reproduction, alteration of ecosystem water balances through grading or imperviousness, alteration of ecosystem processes and food supply, and impacts from road mortality, light, noise, contaminants, trails, direct disturbance, and predation (Faulkner 2004, Gibbs and Shriver 2005, CWP 2006, Environment Canada 2007). Rural development can have similar impacts that can be significant because such development in the Credit River watershed is typically located near natural areas of higher ecological integrity. Between 1976 and 1996 more than 150,000 acres of farmland in the GTA (or 18% of Ontario s best agricultural or Class 1 farm lands) were lost to food production (CVC 2006b). To prevent uncontrolled urban sprawl, the Greenbelt Plan and the Growth Plan for the Greater Golden Horseshoe were developed to focus urban development in the southern part of the watershed. Consequently the southern part of the watershed and urbanizing parts of the Upper Watershed (e.g. Orangeville) are facing somewhat different pressures from the more rural parts of the watershed. Approximately one-third of the watershed is urbanized, with most development focused in the Lower watershed. The total amount of impervious cover in a watershed is strongly related to surface water quality and stream health. A study of southern Ontario streams (including some in the Credit River watershed) showed that the percentage of impervious cover was a significant modifier of fish, benthos, stream temperature, stream width:depth ratio, and percent stable banks even after accounting for landscape variables (Stanfield and Kilgour 2006). Fish and benthic assemblages were clearly altered above 10% impervious cover, with no coldwater streams above that threshold. Impervious cover of 10% in the Stanfield and Kilgour study corresponded with urban cover of approximately 40-50% or agriculture cover of %, or a combination of the two. Other analyses show that benthic communities can be altered at even lower levels of impervious cover, e.g % (King et al. 2011). 18

44 The Credit River watershed has >10% impervious cover over much of the Lower Watershed, and <10% impervious cover in the Middle and Upper Watersheds (CVC 2005). Given estimated urbanization growth in the watershed, one might reasonably begin to see additional changes in the hydroperiod and flow regime of streams resulting in an impact to the structure, composition and function of streams within the watershed in the future. The NHS can help identify areas important for watershed functioning and serve to guide development and impervious cover away from such areas. Development has also contributed to pollution in the Credit River watershed. Since 1982 there have been over 6000 spills reported within the watershed s municipalities. Spills include bypasses from waste water treatment plants, vehicle accidents, sediment, and disposal of hazardous chemicals down local storm sewers (CVC 2006b). Ammonia, chloride, nitrate, and E. coli loadings have been detected in waterways as a result of degrading septic systems in some watershed communities. Other stressors relating to unsustainable development are alteration of hydrology, alteration or pollution of soils, wastewater from septic systems or municipal servicing, poor pesticide and fertilizer application practices, industrial effluent, spills, landfill/garbage leachate, and light or noise pollution. An increase in total natural cover and inclusion of areas affecting surface water quality through identification of a NHS would help mitigate or prevent pollution. In addition the implementation of a system could help guide development away from areas associated with surface water functions Unsustainable agricultural practices Agriculture can be both beneficial and detrimental to species, communities and natural heritage systems. A number of terrestrial wildlife species use agricultural land such as hayfields, meadows, or pastures for feeding or movement. Agricultural lands provide important groundwater recharge and stream flow moderation functions. Farmers have also been key stewards of natural areas and are responsible for much of the natural cover in the watershed today. The majority of streams, forests and wetlands in the Credit River watershed exist and are healthy due to the protection and stewardship of private landowners. However, in some cases, unsustainable farm practices in southern Ontario have led to declining water quality, aquatic habitat, soil erosion, and loss of habitat for species. Pollution issues observed in certain rural environments of the watershed include excess nutrients, organic pollution or agricultural effluent, landfill leachate, wastewater from septic systems or municipal servicing, overuse or misuse of pesticides, and livestock access to waterways (CVC 2006b). Some areas show evidence of groundwater contamination from fertilizer. Sustainable farm practices such as nutrient management, soil and water conservation and integrated pest management have reduced and in some cases reversed the adverse impacts of agriculture. 19

45 Agriculture occupies approximately 35% of the Credit River watershed area. The Credit River watershed now has a greater proportion of hayfields, pasture, horse and cattle farms than of row crops such as corn or wheat (based on data from Statistics Canada). Hayfields and pasture are in general more supportive of local biodiversity than row crops and represent novel ecosystems that support a suite of open country flora and fauna species in the watershed. In the Lower Watershed, agriculture also includes a number of horticultural operations and greenhouses. The NHS can identify agricultural areas that provide multiple supportive functions to existing natural areas, thereby guiding stewardship activities to the most costeffective locations for improvement of watershed ecological services Unsustainable recreation practices Like agriculture, recreation can be both beneficial and detrimental to natural heritage systems. Large recreational areas such as golf courses can impact water quality through pesticide and fertilizer application. Manicured open space (such as sports fields and lawns) also has the potential to affect water quality, particularly in urban watersheds (CWP 2003). Recreational areas can hinder the connectivity of natural areas, may have negative impacts on water quality or quantity when located within valleylands, or may introduce opportunities for degradation of natural areas through unauthorized trails or mountain biking courses, littering, garbage dumping, and predation. Structures associated with recreational areas (trails, buildings or other structures) result in some loss of habitat but also provide amenities and societal benefit. Recreational areas can also provide positive natural heritage benefits. Plants in recreational areas can support insect, bird, and small mammal populations. Manicured open space and shrubs provide a soft edge to adjoining natural areas, and can provide supportive habitat for wildlife within natural areas. Open space occupies about 4% of the Credit River watershed, or 3,700 ha. Open space within the NHS offers opportunities for stewardship to maintain existing functions and mitigate stresses or to restore to natural cover where feasible. Natural areas can provide important social benefits: mental and physical health and well-being, a sense of safety and community, local access to green space and ecosystem services, and environmental education. Sustainable recreation planning and development of the NHS will help direct the right activities to the right location in order to avoid negative impacts on important ecological functions or sensitive features Aggregate extraction Aggregate extraction can cause both habitat loss and habitat degradation. Dewatering for the purposes of extraction below the water table can alter baseflows to rivers and creeks, and alter hydrology of nearby wetlands and ponds. Altered hydrology can affect surface water quantity and/or quality, degrade natural habitat through water balance changes, or cause loss of natural habitat (e.g. loss of 20

46 coldwater fisheries). Other stressors associated with aggregate extraction include noise, dust, and increased traffic. Approximately 4% of the Credit River watershed is occupied by pits and quarries, and a number of potential future sites have been identified. Identification of the NHS is a proactive step that flags potential aggregate areas within the natural heritage system, offering opportunities for dialogue with appropriate stakeholders at an early stage Infrastructure Fragmentation by roads, rail corridors, utility corridors, dams, online ponds or other land uses results in a preponderance of smaller sized habitat patches or fragmented aquatic habitat which can, depending on species, impede the movement of flora or fauna and the flows of material or energy. Aquatic barriers create thermal and physical barriers for certain aquatic species and may also displace wetland or upland habitat. In addition fragmented areas may lack the ecological structure and composition necessary to maintain certain functional groups. In the Credit River watershed natural features have been extensively fragmented by roads and other land uses. Woodlands and wetlands once covered large tracts of land (a few remain in the Credit River watershed) but now exist as fragments on the landscape - the average size of woodlands is now 7 ha and that of wetlands is now 4 ha. About 500 dams have been documented on the Credit River; of these, approximately 35 are major dams, with minor dams concentrated in headwater areas (CVC unpublished data). 4.2 Pathogens, pests, and invasive species A number of tree and plant species in the watershed are threatened by pathogens, pests, or invasive species that are non-native (i.e., arrive from outside Canada), spread rapidly due to lack of natural predators, and have multiple ecological impacts (Mooney and Cleland 2001). Currently emerald ash borer (A. planipennis), an introduced beetle from Asia, attacks and kills all ash species, and Asian long-horned beetle (Anoplophora glabripennis) causes crown dieback and eventual tree mortality of hardwood trees. Examples of pathogens that contribute to tree decline and mortality include Dutch elm disease (Ophiostoma ulmi) affecting elm trees, beech bark disease (Nectria coccinea) affecting beech trees, and non-native invasive earthworms that affect entire ecosystems (Addison 2009). Invasive species (non-native species that spread rapidly) are a significant and growing threat to natural areas within the watershed (e.g. in wetlands) (CVC 2010b). These species tend to be tolerant to disturbance and reproduce rapidly, often eliminating more sensitive native species locally. The effects of invasive species may be widespread as wildlife species lose the food sources on which they are dependent. Invasive species can alter ecosystems and soil, creating conditions unsuitable to sustaining native species. 21

47 Pathogens, pests, and invasive species will impact the ecological integrity of the NHS. Creation of a natural heritage system for the watershed may not fully address this watershed stress but may help in improving the resilience of natural areas. The Credit River watershed s Invasive Species Strategy (CVC 2009) has the potential to be integrated with the NHS to target areas for invasive species management. 4.3 Climate change Climate change has the potential to dramatically alter Ontario s terrestrial and aquatic ecosystems (Varrin et al. 2007). Climate projections for southern Ontario include warmer winter temperatures and mean annual temperatures. A 10% increase in precipitation is expected, along with changes to the intensity, duration and frequency of precipitation events. Data show that the warmer and wetter trends are already occurring in Canada (Insurance Bureau of Canada 2012). Predicted impacts of climate change include potential increases in insect outbreaks, fire, and tree mortality; more extreme heat days causing stress on species and habitats such as wetlands and competition for water resources; and an increase in extreme weather-related events such as ice storms, flooding, or fire (Colombo et al. 1998, 2007). There are over 1200 structures within floodplains in the CVC jurisdiction; hence natural heritage planning to minimize the impacts of climate change where feasible is important to achieve objectives of maintaining public health and safety within the watershed. The NHS can help maintain or enhance biodiversity, resilience and connectivity of natural features, and linkage of different ecological zones. 22

48 5.0 GUIDING PRINCIPLES, GOALS AND OBJECTIVES FOR THE NHS 5.1 Guiding principles in developing the NHS The following are CVC s governing principles as outlined in its Strategic Plan (CVC 2006b). These principles have guided development of the NHS methodology and provided a context for the development of the vision, goals and objectives for the system. Recognize that healthy communities require healthy ecosystems, while acknowledging the presence of other land uses in the watershed; Maintain a watershed scale perspective and consider the implications of cumulative actions on the watershed as a whole; Recognize that protection of existing natural heritage is preferable to (and more cost-effective than) restoration; Take a preventive, proactive and integrative approach and apply the Precautionary Principle to watershed management based on adaptive environmental management. The Precautionary Principle recognizes that the absence of full scientific certainty shall not be used as a reason to postpone decisions where there is a risk of serious or irreversible harm; Make decisions and take actions based on our accumulated and emerging knowledge, skills and experience. We work to continually improve our understanding of the watershed and how it functions; Subscribe to the belief that protection and restoration of watershed health is a broadly shared responsibility. We implement watershed management by working with partners and engaging clients in shared interests and objectives. We strive for excellence in those relationships; Pursue practical approaches to the management of water, other natural resources and natural heritage based on the application of sound science, creativity and innovation; Promote ecologically sustainable development and practices within urban and rural communities; and Contribute to climate change mitigation and adaptation in the Credit River watershed. In addition, CVC has taken into account the principles established by the South Central Ontario Conservation Authorities (SCOCA) Natural Heritage Discussion Group relating to Natural Heritage Systems design. Accounting for these principles in natural heritage systems design ensures that natural heritage systems planning across southern Ontario takes a common scientific systems approach, regardless of the specific methodology used. The SCOCA principles are summarized as follows; they generally apply to all natural heritage features, both terrestrial and aquatic: Approach - Ecosystems are complex entities; therefore the Precautionary Principle should apply when defining, managing and defending the Natural Heritage System. 23

49 Scale A Natural Heritage System defined at a local scale should be compatible with a system designed at a larger regional or provincial scale and with neighbouring natural heritage systems to the extent feasible. Consideration of temporal scale and recognizing the changing nature of ecosystems is also important. Cover/Distribution The more natural cover there is on a landscape, the greater its ecological health. Even distribution of natural cover ensures that ecological functions occur across the landscape. Size In general, large habitat patches are better for biodiversity conservation. Decisions about minimum patch size for inclusion in natural heritage systems should consider habitat type and total cover and distribution of natural habitat within the study area. Shape For forest habitat in a fragmented landscape, compact patch shapes are generally preferred over more convoluted shapes. More compact shapes provide some protection from edge effects and may support forest interior or prevent disturbance to sensitive species. Matrix An important determinant of habitat quality is the matrix, or land use surrounding a natural feature. Human land uses such as urbanization or agriculture have differing degrees of impact on a patch, while neighbouring natural habitat may provide additional resources or support functions to a habitat patch. Connectivity Landscape connectivity is important in maintaining species functions and life cycles. Connections among features must be determined using a functional approach where feasible. Quality/Biodiversity Conservation and restoration should be focused on native species and ecosystems. The quality of natural areas is an important consideration in natural heritage systems planning, as is the presence of special features such as excellent biodiversity representation, rare species or community types, or old growth. 5.2 Goals and Objectives for the NHS The goals and objectives for the NHS arise from an overarching vision of an environmentally healthy watershed supporting native biodiversity and self-sustaining natural features and functions. Goals and objectives from CVC s Strategic Plan (CVC 2006b) related specifically to the maintenance of biodiversity and healthy ecosystem functioning were used to develop the following goals and objectives for the NHS. These goals and objectives are listed below Goals for the NHS Terrestrial and aquatic species, communities and ecosystems: To protect, restore, and enhance the ecological integrity of the Credit River watershed s natural features, functions and systems. 24

50 Water quality and quantity: To protect and enhance the quantity and quality of surface and ground water for environmental and human uses; Natural Hazards: To protect public safety and minimize property damage from natural hazards including flooding, drought, erosion, sedimentation, wetlands and dynamic beach processes; and Social and Economic: To promote the health and sustainability of watershed communities through effective watershed management Objectives for the NHS Terrestrial and aquatic species, communities and ecosystems: Protect, restore and enhance the integrity of watershed ecosystems, through an integrated network of natural areas, connections, and linkages; Protect, restore and enhance native terrestrial and aquatic plant and animal species, community diversity and productivity; Ensure that the complete range of representative and significant natural features and functions distributed within the watershed are protected in perpetuity; Protect, restore and enhance natural ecosystems to sustain watershed functions, human uses, and build resilience to stresses such as climate change; and Promote sustainable resource management of aquatic and terrestrial systems and areas within the watershed for plant, animal and human needs. Water Quality and Quantity: Preserve, maintain and re-establish the natural hydrological cycle; Maintain, enhance and restore natural stream processes to achieve a balance of flow and sediment transport; Maintain and restore groundwater levels and baseflows (groundwater discharge to streams) to sustain watershed functions and human uses and build resilience to stresses such as climate change; Minimize risk to human life and property due to flooding and erosion; Maintain and enhance water and sediment quality to achieve ecological integrity; Protect and restore surface water quality with respect to conventional and toxic pollutants to ensure protection of ecosystem functions and water supply; Protect, restore and enhance groundwater quality to support watershed functions; and Improve water quality in streams, the Credit River, and Lake Ontario. Natural Hazards: Protect potentially hazardous river or stream valleys, flood plains and Lake Ontario shoreline; and Protect watercourses (including their meander belt) and wetlands. 25

51 Social and Economic: Promote the community benefits of the watershed s natural areas and system (recreational, educational, cultural, psychological, tourism, economic); Recognize the contribution of the matrix, i.e. other land cover and land uses such as the urban forest to the health of the watershed s natural areas and to the well-being of watershed communities; and Promote and engage in partnerships with agencies, municipalities, landowners and others to protect, enhance, and restore the health of the watershed s features and functions. The objectives of the NHS are associated with measurable targets in the following section. The above objectives will likely come closer to being achieved if the targets in the following section are met. 26

52 6.0 TARGETS INFORM DEVELOPMENT AND IMPLEMENTATION OF THE NHS Targets and thresholds can provide useful guidance for natural heritage planning and securement, stewardship and restoration prioritization. Targets are frequently used to inform conservation planning at global, regional, and local scales (Svancara et al. 2005, Carwardine et al. 2009). However, targets also have the capacity to be misused or misunderstood, through poor communication about the nature and intention of targets or the misuse of targets (Carwardine et al. 2009). Targets are also understood to be somewhat subjective by nature as they reflect human values (Tear et al. 2005, Wilhere 2008). Nevertheless a review of the scientific literature on targets suggests that use of target-based conservation planning continues to play an important role in developing protected areas systems (Carwardine et al. 2009). Targets and thresholds based on the best available science can assist in determining whether there is adequate natural cover to maintain stated objectives of minimum viable plant and animal populations or stated levels of habitat representation. Further, targets may be a useful policy or implementation tool to develop restoration or stewardship strategies and assign appropriate levels of funding. Ultimately, targets are most useful if they are considered as guidelines that can be considered along with other natural heritage planning objectives. Targets may be used to inform natural heritage system planning through measurable, science-based objectives that achieve viable plant and wildlife populations and functioning, selfsustaining ecosystems. Targets need to be regularly reviewed to ensure they capture the best available science, and must be communicated with care so that they do not become the sole driver of conservation planning. Credit Valley Conservation has developed and refined targets for terrestrial and aquatic systems that are recommended for achieving water quality and quantity objectives and improved functioning and self-sustainability of ecosystems (CVC 2007 and refined in subsequent subwatershed studies). These targets are outlined below (Table 6-1). A review by Fischer et al. (2006) identifies the top ten guiding principles to help maintain biodiversity, ecosystem function, and resilience in production landscapes (i.e. forestry and agricultural landscapes). The principles are divided into landscape pattern oriented strategies and process oriented strategies: Landscape pattern oriented strategies: Maintain and create large, structurally complex patches of native vegetation Maintain structural complexity throughout the landscape Create buffers around sensitive areas Maintain or create corridors and stepping stones Maintain landscape heterogeneity and capture environmental gradients 27

53 Process oriented strategies: Maintain key species interactions and functional diversity Apply appropriate disturbance regimes Control aggressive, over-abundant, and invasive species Minimize threatening ecosystem-specific processes Maintain species of particular concern While these strategies are not targets, they are suggested as a framework for helping to preserve biodiversity, ecosystem function, and resilience over the long term. 6.1 The importance of overall natural cover The total amount of natural cover in a landscape has a strong influence on biodiversity and ecological functions such as species movement and reproduction, although responses differ among species. Considerable research and review shows that the total amount of suitable habitat in an area is a very important explanatory variable of species distribution or abundance (Askins and Philbrick 1987, Andrén 1994, Forman 1995, Fahrig 1997, Rosenburg et al. 1999, Trzcinski et al. 1999, Austen et al. 2001, Fahrig 2001, Golet et al. 2001, Mortberg 2001, Fahrig 2002, Lee et al. 2002, Environmental Law Institute 2003). Existing scientific literature, from southern Ontario and regions similar to southern Ontario where possible, has been used by Environment Canada to develop guidelines to inform the development of comprehensive rehabilitation plans. The Environment Canada publication How much habitat is enough? A framework for guiding habitat rehabilitation in Great Lakes Areas of Concern has undergone a recent update to incorporate the best available science on landscape scale natural cover guidelines (Environment Canada 2013). The data on pre-settlement woodland and wetland cover suggest that native biodiversity has been maintained by large tracts of natural cover on the landscape. Larson et al estimated that about 90% of southern Ontario s land base was forested prior to European settlement. The substantial loss of natural cover suggests that development of a robust natural heritage system to maintain biodiversity and ecological function necessitates the inclusion of much remaining existing natural cover. Landscape, community and species scale monitoring and inventory data from CVC confirm that existing natural cover is likely insufficient for achieving terrestrial and aquatic ecosystem health and the persistence of existing species. CVC therefore used existing literature, Environment Canada guidelines, and other guidance documents (Credit River Water Management Strategy Update, CVC subwatershed studies) to develop targets relevant for the Credit River watershed (Table 6-1). These targets were used to inform development of the NHS and as a final check to ensure that the design of the NHS resulted in moving potential future watershed natural cover closer to these targets. 28

54 Monitoring of the watershed through the Integrated Watershed Monitoring Program and updated inventories will be used to report on progress towards achieving these targets. Monitoring of the NHS will be used to report on progress towards increasing natural cover in relatively more strategic and efficient locations on the landscape (namely, within the system). Table 6-1 CVC targets for achieving natural heritage system objectives Target Existing conditions Supporting evidence Forest cover: percent woodland cover in watershed Watershed woodland cover target is minimum 30% (high risk according to Environment Canada) with a preferred target of 40% (moderate risk according to Environment Canada) Watershed woodland cover is currently 23% A study from Eastern Canada identified that habitat requirement thresholds for forest breeding birds ranged from 9-29% habitat; thresholds differed for different species (Betts et al. 2007, Betts and Villard 2009). An Ontario study found 12 out of 15 forest bird species studied were responsive to either forest cover or forest configuration (Villard et al. 1999). A key study of forest generalist and area sensitive bird species in New York State by Zuckerberg and Porter (2010) found that for 22 forest bird species, the average threshold value for persistence was 61% forest cover. Research suggests that as suitable habitat falls below 20-30%, fragmentation effects are apparent and the habitat configuration or the spatial arrangement of habitat patches becomes more important in maintaining biodiversity (Freemark 1988 cited in Environment Canada 2004, Andrén 1994, Fahrig 1997) Herrmann et al. (2005) studying amphibians in the northeastern United States found that forest cover above 60% was associated with high species richness and abundant larval assemblages. Studies in Washington state, United States have shown that watersheds with at least 65% forest cover were associated with minimally impacted streams or a healthy aquatic insect community (Booth 2000, Booth et al. 2002). 29

55 Target Existing conditions Supporting evidence A study of stream health in Maryland has shown that stream health ratings of good required less than 10% impervious cover and 60% forest cover (Goetz et al. 2003). Environment Canada (2013) guidelines for forest cover relating to species persistence, and for aquatic health: 30% forest cover in a watershed represents a high risk for declines in species and aquatic health; 40% forest cover in a watershed represents a medium risk for declines in species and aquatic health; 50% forest cover in a watershed represents a low risk for declines in species and aquatic health. Forest interior: Percent of woodland interior (woodland cover 100 m in from woodland edge) in watershed Watershed woodland interior target is 10% or greater; maintain, enhance and restore existing woodland interior Watershed woodland interior cover (i.e. woodland cover that is 100 m or further in from a woodland edge) is 3.8% Forest habitat edges have a different structure and function compared to forest interior (Ewers and Didham 2006). Forest fragmentation and widespread lack of interior forest has been documented in the United States (Riitters and Wickham 2012). Edge effects have been shown to affect the abundance, and behaviour of species (Forman and Godron 1986, Forman 1995, Ries et al. 2004). The response of species to edges differs among species and at different edge distances but is generally consistent within species that is, edges affect certain species in predictable ways (Ries et al. 2004). Examples of edge effects include increased nest predation along habitat edges (Bátary and Báldi 2004), increased amphibian parasitism at edges (Schlaepfer and Gavin 2001 cited in Ries et al. 2004), active avoidance of edges by mammals (Jacob and Brown 2000 cited in Ries et al. 2004) and increased predation on plants at edges (Ries et al. 2004). 30

56 Target Existing conditions Supporting evidence Environment Canada recommends a forest interior target of greater than 10% be considered in natural heritage planning where appropriate (Environment Canada 2013). Large forest patches: area of large woodland patches Watershed target is at least one, and preferably several, 200 ha woodland patches There are currently seven large (>200 ha) woodland patches in watershed A study of migratory forest birds in Pennsylvania found that several species, particularly longdistance migrants, were more likely to occur in medium (i.e ha) and large (i.e. >1500 ha) patches during the breeding and spring-migratory seasons (Keller and Yahner 2007). Cottam et al. (2009) observed that, where forest patch sizes were 250 ha or larger, neither nest predation nor landscape matrix had an impact on nesting success of two forest breeding bird species. Environment Canada guidelines for large forest patches recommend at least one, and preferably several, 200 ha forest patches, measured as forest area that is more than 100 m from edge (Environment Canada 2013). Wetland cover: percent wetland cover in watersheds and sub-watersheds Watershed wetland coverage target is 10.4%; subwatershed target is minimum 6% of each subwatershed or 40% of historic wetland coverage Watershed wetland cover is currently 6.7% Historic wetland coverage for the Credit River watershed has been calculated at 10.4% (Dougan and Associates et al. 2009). A review by Johnston (1994) found that for flood flow and loading of suspended solids functions of wetlands, watersheds that contained less than 10% wetland cover were more sensitive to incremental loss of wetland area and suffered greater cumulative effects than those with more than 10% wetland cover. A report by Adamus and Stockwell (1983) noted that flood attenuation benefits of wetlands increase sharply with increasing wetland cover to 10% wetland cover and then level off (Adamus and Stockwell 1983 reported in OMNR 2013). A review by Mitsch and Gosselink (2000) concluded 31

57 Target Existing conditions Supporting evidence that the optimal amount of wetlands in temperate zone watersheds should be 3-7% for the optimization of ecosystem values such as flood control and water quality enhancement. Environment Canada revised guidelines for wetland cover based on an updated review of the scientific literature are as follows: At a minimum the greater of (a) 10% of each major watershed and 6% of each subwatershed, or (b) 40% of the historic watershed wetland coverage, should be protected and restored (Environment Canada 2013). Riparian cover 1: width of riparian cover on streams Watershed riparian cover target is minimum 30 m natural cover on each side of streams Watershed riparian cover is currently 69% In a Toronto area study, the domain of stream degradation, i.e., a shift from good to fair biotic integrity, ranged from 75% removal of riparian forest from smaller streams at 0% urbanization, to 0% removal of riparian forest at 55% urbanization (Steedman 1987). A review of vegetated buffers and a meta-analysis of their efficiency in removing nonpoint source pollution showed that buffers of 30 m width on favourable slope conditions removed more than 85% of the pollutants studied (Zhang et al. 2010). Environment Canada revised guidelines for watershed restoration based on a review of the scientific literature are as follows: 100% of the area within a 30 m buffer on streams should be naturally vegetated (Environment Canada 2013). Riparian cover 2: percent of stream length under natural cover Watershed riparian cover target is 90% of stream length in natural vegetation Watershed riparian stream length is currently 74% under natural cover The importance of riparian cover for aquatic integrity is well established (Naiman and Decamps 1997, Wenger 1999). The Credit River Fisheries Management Plan recommends that 90% of stream banks of all tributaries be restored with natural vegetation (OMNR and CVC 2002). Environment Canada (2013) revised guidelines for 32

58 Target Existing conditions Supporting evidence watershed restoration based on a review of the scientific literature recommend that at least 75% of stream length be naturally vegetated. Multi-functional linkages: valleyland natural cover Watershed target is 90% natural cover in valleylands; maintain, enhance, and restore existing multifunctional linkages such as valleylands Percent valleyland natural cover is 74% Protection of floodplain areas in valleylands from development is recommended as a multiple benefit climate change adaptation measure that ensures human health and safety and reduces risk and costs for municipalities (Opperman et al. 2009, Seavey et al. 2009). Valleylands moderate stream flows; provide storage for floodwaters; moderate stream temperatures; provide organic and inorganic inputs to aquatic habitat; provide linkage and habitat functions; in urban contexts valleylands represent remaining green space for natural heritage that is also used for recreation or transportation (see Naiman et al on importance of riparian corridors for water and landscape planning; Naiman and Decamps 1997 and Wenger 1999 for review on riparian ecology and buffers). Target of 90% reflects similar riparian target. Aquatic habitat: various measures Aquatic targets for water quality and water quantity are as determined by subwatershed studies As reported in subwatershed studies Communities: floral and faunal communities Credit River Water Management Strategy Update (2007a) and individual subwatershed studies have studied existing conditions and provided targets. Aquatic targets are best developed at the subwatershed level, during subwatershed studies. Certain targets may be applicable at the watershed level and will be dealt with in CVC s Watershed Plan. Watershed target is to maintain the number of floral and As existing in CVC inventories and monitoring Different types of floral and faunal communities (including those occupying open country habitat and aquatic habitat) enable the existing diversity of native species and associated ecological functions to continue to be maintained in the watershed. CVC 33

59 Target Existing conditions Supporting evidence faunal communities as documented through watershed inventories and monitoring using 2013 as base year; restore or enhance where feasible Biodiversity: monitoring indicators habitat utilization reports document the species in the watershed, and the types of habitats on which they depend (CVC 2002a, 2002b, 2002c, 2002d). Watershed target is to maintain representatio n of functional guilds and species as documented through monitoring and inventory data using 2013 as base year; maintain, enhance, and restore numbers and distribution as feasible Status and trends as reported at terrestrial and aquatic monitoring sites across the watershed Biodiversity is associated with increased ecosystem resilience and stability (Christensen et al. 1996, Tilman et al. 2006). Biodiversity provides a form of insurance in the provision of ecosystem goods and services via redundancy in the ecological functions carried out by different species. Consequently maintenance of biodiversity is also recommended for climate change adaptation (Thompson et al. 2009). CVC long-term monitoring reports provide information on biodiversity status and trends in the watershed. Monitoring reports can be found on the CVC website: 34

60 7.0 PHYSIOGRAPHY AND NATURAL COVER IN THE CREDIT RIVER WATERSHED INFORM NATURAL HERITAGE SYSTEMS PLANNING 7.1 Classification of landscapes into Ecozones and Ecodistricts The Canada Committee on Ecological Land Classification was established in 1976 to delineate, classify, and describe ecologically distinct areas of the earth s surface. Between 1976 and the 1980s, a standardized, hierarchical classification framework was developed based on a previous foundation (Hills 1959) that remains in use today. The hierarchy of Ecological Land Classification units continues to describe Ontario s landscape today and allows for planning at multiple scales (Lee et al. 1998, Jalava et al. 2001). Ecozones represent very large and generalized units approximately 10,000-1,000,000km2 in area, characterized by biotic and abiotic factors. The Credit River watershed lies within the Mixedwood Plains Ecozone that encompasses all of southern Ontario. This area was once dominated by deciduous forest. Ecoregions are subdivisions of the Ecozone characterized by distinct large order landforms and are on the order of ,000km2 in area. The Credit River watershed is located within Ecoregions (also termed Site Regions) 6E and 7E. Site Region 6E occupies the northern portion of southern Ontario in what Rowe (1972) called the Great Lakes St. Lawrence Forest Region and is now called the Lake Simcoe Rideau Ecoregion (Crins 2009). It is characterized by a moist, mild climate, and a gently undulating terrain of deep ground moraine material underlain by dolomite and limestone. The diverse vegetation in this Ecoregion includes hardwood forests dominated by sugar maple (Acer saccharum), American beech (Fagus grandifolia), and white ash (Fraxinus americana), as well as lowland forests dominated by green ash (Fraxinus pennsylvanica), silver maple (Acer saccharinum), eastern white cedar (Thuja occidentalis), and yellow birch (Betula alleghaniensis). Ecoregion 7E occupies the southernmost part of southern Ontario in what Rowe (1972) termed the Deciduous Forest Region and is now called the Lake Erie Lake Ontario Ecoregion (Crins 2009). The climate in this Ecoregion is one of the mildest in Canada. Except for the Niagara Escarpment and some moraine and drumlin features, the topography is flat with substantial glaciolacustrine deposits left over from historic lakes. The flora and fauna in this Ecoregion are among the most diverse in Canada, with remnants of Carolinian species such as pawpaw (Asimina triloba),tulip tree (Liriodendron tulipifera), hackberry (Celtis sp.), oaks, and hickories, along with hardwood species found in Ecoregion 6E (Crins 2009). Ecodistricts, on the order of km 2 in area, are subdivisions of Ecoregions and are characterized by distinctive assemblages of landform, relief, surficial geologic material, soil, water bodies, vegetation, and land uses. Due to the presence of southern species, Ecoregion 7E contains a unique and diverse flora and has also been termed the Carolinian Zone. The Credit River watershed contains parts of three Ecodistricts, namely, 6E1, 6E7, and 7E4 (Figure A1, Appendix A; Figures with the prefix A refer to maps; these are all found in Appendix A accompanying this report). Brief descriptions of these Ecodistricts, including those within the Credit 35

61 River watershed, may be found in documents prepared by the Nature Conservancy of Canada (Henson et al. 2005a, 2005b). 7.2 Physiographic zones of the Credit River watershed The Credit River watershed contains a number of distinct physiographic regions. Chapman and Putnam in 1951 described eight major and two minor physiographic regions within the Credit River watershed. Mapping for these physiographic regions has been recently updated by the Ontario Geological Survey (Chapman and Putnam 2007). Physiographic regions are created when characteristic differences in glacial deposits create distinct regions with unique combinations of soils, elevation, and drainage. The major physiographic regions are described in the Credit River Water Management Strategy Update (CVC 2007). The physiographic regions are grouped into three broad physiographic zones of approximately equal area based on a combination of subwatershed boundaries and physiographic regions. These physiographic zones are termed the Upper Watershed (above the Niagara Escarpment), the Middle Watershed (Niagara Escarpment and Oak Ridges Moraine areas), and the Lower Watershed (below the Escarpment). Physiographic regions and physiographic zones are described briefly below and in greater detail elsewhere (CVC 2007). Physiographic regions and physiographic zones are shown in Figure A1 in Appendix A. For some communities (e.g. fish), the Niagara Escarpment serves as a physiographic divide The Upper Watershed The Upper Watershed includes the portion of the watershed that lies above the Niagara Escarpment and has a total area of 32,858 ha. This zone lies within the Greenbelt Plan area and contains the headwaters of the Credit River. It is generally comprised of till plains, moraines, and glacial spillways. The soils in this area are moderately to highly permeable and permit significant infiltration to the support regional groundwater, cold water streams, and drinking water supplies. The surface topography is undulating and the region is generally well drained. Base flow to rivers and streams is maintained predominantly from springs and groundwater discharge, and water quality is generally good. Dominant vegetation associations include deciduous forest and white cedar swamps. The main land use in the area has traditionally been agriculture, although in recent years this has declined somewhat, being replaced by small hobby farms. The major urban centres in the Upper Watershed include Orangeville, Erin, Alton, Caledon Village, and Hillsburgh. These towns are experiencing growth pressures due to their location within (Alton and Caledon Village) or near the Greater Toronto Area (CVC 2006b). The municipalities within the Credit River watershed are shown in Figure A2 (Appendix A). Greenbelt Plan areas within the Credit River watershed are shown in Figure A3 (Appendix A). Land cover and land use within the Credit River watershed is shown in Figure A4 (Appendix A) with greater detail on the Upper Watershed in Figure A5 (Appendix A). 36

62 7.2.2 The Middle Watershed The Middle Watershed lies within the Greenbelt Plan area. It includes the Niagara Escarpment area between Inglewood in the north and Georgetown and Norval to the south, with steep slopes, significant rock outcrops, and thin overburden. This zone with an area of 30,988 ha also contains the western edge of the Oak Ridges Moraine. Average slopes exceed 0.5 m/km and in some areas the Escarpment has sharply defined cliff faces. The topography of this area causes relatively high runoff volumes and velocities; however, the high forest cover in this zone helps to slow runoff and increase infiltration. The Middle Watershed including the Niagara Escarpment is heavily forested with mixed deciduous forest in upland areas and white cedar swamps in lowland areas (Figure A6, Appendix A). Many tributaries of the Credit River in this zone develop in massive headwater complexes that cover approximately 40% of the Escarpment plateau. East of the Escarpment, the Credit River cuts through clay till plains and is characterized by steep-walled valleys with floodplains of varying widths. The Middle Watershed represents a significant natural heritage landscape in Ontario due to the confluence of the Niagara Escarpment, Oak Ridges Moraine, Paris Moraine, and the Credit River Valley. The area is characterized by large natural areas supporting a high concentration of provincially, regionally and locally rare species and vegetation communities. Communities in the Middle watershed include Inglewood, Cheltenham, Terra Cotta, Ballinafad, Acton, Georgetown and Norval, all of which lie within the Greater Toronto Area (GTA) except for Ballinafad which lies near the GTA. Consequently these towns, like those in the Upper Watershed, are experiencing growth pressures (CVC 2006b). Opportunities for improvement of ecological health in the Upper and Middle Watersheds are to maintain, enhance or restore resilience, ecological integrity and connectivity among natural heritage features and areas, to maintain, enhance or restore fluvial processes and terrestrial-aquatic linkages, and to utilize sustainable management practices in agriculture The Lower Watershed The Lower Watershed contains a small portion of the Greenbelt Protected Countryside and covers an area of 31,045 ha; however, most of the zone lies outside the Greenbelt Plan Area. The ground surface topography of this zone is relatively flat with a gentle slope south towards Lake Ontario. Surficial soils in this zone have low infiltration rates compared to the rest of the watershed, although the Lake Iroquois Plain area within this zone has areas of higher permeability due to sandy soils. In general, runoff is greater in this zone and infiltration significantly lower than in other parts of the watershed. To prevent uncontrolled urban sprawl, the Greenbelt Plan and the Growth Plan for the Greater Golden Horseshoe were developed to focus urban development in the southern part of the watershed. This provincial direction combined with historic patterns of settlement has resulted in a highly urbanized Lower Watershed that contains 87% of the watershed s 750,000 37

63 inhabitants. Natural cover in this zone is low. Few woodlands and wetlands remain, mostly found in valleylands (Figure A7, Appendix A). This zone contains most of the City of Mississauga, the western portion of the City of Brampton and the eastern part of the City of Oakville. Several creeks originate in this zone and empty directly into Lake Ontario. Many of these creeks, and tributaries of the Credit River, have been channelized and have lost significant riparian area, and water quality in the main stem of the Credit River and its tributaries is generally low (CVC 2006b). The Lower Watershed, bordering Lake Ontario, contains an important provincial corridor, the Lake Ontario shoreline. It also contains unique natural features such as shoreline bluffs, coastal wetlands, and nearshore aquatic habitats. Despite the low levels of natural cover, there are opportunities to improve ecological health in this zone through protection and enhancement of existing remnant habitat, improvement of connectivity where feasible, management of natural heritage features to improve resilience and ecological condition, restoration of habitat through stewardship and redevelopment opportunities, and retrofitting of existing urban lands to improve perviousness. 7.3 Distribution of natural cover in the Credit River watershed Approximately one-third of the Credit River watershed remains under natural (including semi-natural) cover - that is, consists of woodland, wetland, aquatic, or successional communities, the remaining major land cover types being agriculture and urban. Watershed land cover values as a percentage of total watershed cover are as follows (based on CVC s 2012 ELC layer; Figure A4, Appendix A): Natural 35%, Agriculture and open space 35%; Urban 30% Existing natural cover is distributed unevenly among physiographic zones and Ecodistricts in the Credit River watershed. The Upper and Middle Watersheds have high levels of natural cover (42% and 45%, respectively). The Lower Watershed has low levels of natural cover at 16%. In terms of woodland cover, the Upper and Middle Watershed physiographic zones have woodland cover that might be considered moderately good for maintaining species diversity (at 27% and 36% respectively; see Figure 7-1). Woodland cover is low in the Lower Watershed zone, currently at 8%; there are indications that this may be declining in area and quality due to urbanization pressures. In terms of wetland cover, the Upper and Middle Watersheds contain much higher wetland cover (10% and 9%, respectively) than in the Lower Watershed (1%). Figure A4 (Appendix A) shows the distribution of different land use and land cover types in the watershed and its three zones. 38

64 Aquatic & other natural Cultural forest Forest Successional Wetland Urban Agriculture & open space Figure 7-1 Land cover and land use in the Credit River watershed and its three physiographic zones 39