Ecosystem Management (EM) and Historical Range of Variability (HRV)

Transcription

1 Geog 4430 Ecosystem Management (EM) and Historical Range of Variability (HRV) Brief introduction to general concepts

2 Ecosystem Management (EM) Ecosystem management is management that acknowledges the importance of human needs while at the same time confronting the reality that the capacity of our world to meet those needs in perpetuity has limits and depends on the functioning of ecosystems. Christensen et al Ecol. Applications 6: Ecosystem management means managing forests as a whole, integrated systems rather than the frequently fragmented and uncoordinated management for individual ecosystem components and values trees, wildlife, water, aesthetics, and so on. --- J.P. Kimmins, Forest Ecology. Prentice Hall.

3 Guiding Principles of Ecosystem Management (Christensen et al. 1996) 1. Intergenerational sustainability 2. Explicit goals 3. Sound ecological models and understanding 4. Ecosystem complexity and connectedness 5. Recognition of the dynamic character of ecosystems 6. Context and scale 7. Humans as ecosystem components 8. Adaptability and accountability

4 Adaptive management Retain management flexibility Monitor outcomes and compare with expected (hypothesized) outcomes Incorporate new knowledge (research) Forecast future scenarios using multiple values, multiple scales, and incorporating effects of disturbance and climatic variation.

5 Multiple Use Zoning Spatial and/or temporal separation of certain forest values (e.g. timber vs. recreation) Percentages of area dedicated to different forest values are strongly influenced by social and political factors. Design of zonation systems requires sound understanding of dynamics of natural dynamics as well as social interactions (e.g. cycling, hiking, hunting, etc.).

6 Emulation of natural forest disturbance (ENFD) Maintenance of the historical (natural) range of ecosystem conditions. Consistent with a coarse filter rather than a fine filter approach to sustain biodiversity and ecosystem function. Incorporating natural disturbance (exploiting it, sometimes guiding it) is usually more cost effective than suppressing it. Use of ENFD implies an understanding of Historical Range of Variability (HRV) of ecosystems.

7 Historic Range of Variability (HRV) of Ecosystems What is HRV and what is its role in ecosystem-based management? For resource managers, it is important to know the range of critical ecological processes and conditions that have characterized particular ecosystems over specified time periods and under varying degrees of human influences. An understanding of how ecosystems functioned and sustained themselves in the absence of major human modification of ecological patterns and processes provides a concrete model of ecosystem integrity.

8 Why are HRV studies needed? -- An ecological perspective: Human-generated changes must be constrained because nature has functional, historical, and evolutionary limits. Nature has a range of ways to be, but there is a limit to those ways, and therefore, human changes must be within those limits. Pickett et al The new paradigm in ecology.

9 Why are HRV studies needed? -- A resource management perspective: Awareness and understanding of disturbance ecology and the role disturbance plays in ecosystem dynamics...is essential in understanding the consequences of management choices. The more we attempt to maintain an ecosystem in a static condition, the less likely we are to achieve what we intended. Averill et al

10 Challenges and limitations to ENFD and HRV approaches Zonation not compatible with all values. Large infrequent disturbances (LIDs) pose special problems (Mt. St. Helens, YNP 1988). What is the appropriate historical period? Knowledge of HRV is often inadequate. Equilibrium models (perceptions) tend to bias expectations. Climatic variation in the recent past is often poorly known and future climate variation may change everything.

11 How is ecological restoration related to ENDF and HRV? Object oriented restoration Tries to recreate a static model of the past Stresses patch size, percentage cover, tree density, percentage of landscape in different seral stages. Process-oriented restoration Allows the processes (fire, insect outbreaks) that shaped the landscape to continue. Identifies processes that create habitats for sensitive wildlife species. Which approach is more likely to attain a set of management goals in a cost effective way?

12 HRV Assessments in Northern Colorado since 1999: AR, PSI, GM, RWR Principal Research Projects: Fire history Fire effects Spruce & mtn pine beetle Spruce budworm Blowdown Disturbance interactions Aspen ecology/extent

13 Goals and Uses of HRV Assessments: Synthesize the records of natural (climate-related) and anthropogenic disturbances and changes in forest conditions Identify the ecological processes that have shaped modern forest landscape---but not a template for objectoriented restoration Evaluate precedents of scales and severities of recent fires, blowdowns, droughts, and insect outbreaks Inform public discussion of management issues (e.g. fuels reduction vs ecological restoration) Identify uncertainties and research needs

14 Brief Introduction to Major Forest Types in Colorado

15 Variation in Forest Types Along the Eastern Slope of the Front Range 9,300 7,700 5,600 Ponderosa, Douglas-fir <5500 Lodgepole, spruce, fir

16 Subalpine forests: Moffat Rd

17 Lodgepole pine

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19 Lodgepole pine Serotinous cones Closed Open

20 MRS-4 Lodgpole pine mixed Engelmann spruce and subalpine fir

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23 Marvine Lakes

24 Limber pine

25 Limber pine above Rainbow Lakes

26 Routt, 2004 Lodgepole, spruce-fir, aspen

27 West from Peak-to-Peak: aspen

28 Quaking aspen

29 Aspen is often, but not always, successional to conifers

30 Mixed conifer type in the Upper Montane zone: Crozier Mtn.

31 Montane zone: importance of aspect

32 Montane zone: Ponderosa pine and Douglas-fir

33 Dense even-aged Douglas-fir

34 Ponderosa pine: open woodland

35 Dense ponderosa pine. High fire hazard...why?