Land Stewardship in the Columbia Bottomlands of Texas. A Guide for Landowners

Transcription

1 Land Stewardship in the Columbia Bottomlands of Texas A Guide for Landowners

2 the rivers flow not past, but through us. john muir At The Nature Conservancy of Texas, we believe that no matter what the conservation problem, people are the heart of the solution. As landowners, we have within our hands the collective power to shape the very future of conservation in Texas. Whether you live in the Columbia Bottomlands, the deserts of West Texas or on the lush, coastal plains, your land is a crucial piece of a larger ecological system. The rich and unique lands, waters and wildlife of Texas are connected in profound ways, and all property owners The Nature Conservancy included can help ensure their protection by being thoughtful stewards of the land, so that future generations will know the beauty and wonder of Texas in all her natural glory. table of contents The Columbia Bottomlands rivers, forests and prairies 2 The relationship of the land to the river watersheds 3 The form and function of a river 4 What is a riparian zone and how does a healthy riparian zone help my land? 5 How can I recognize a healthy bottomland? 6 How can I recognize an unhealthy or impaired bottomland? 7 How can I improve or maintain bottomland health? 8 What is instream habitat and why is it important? 9 How does instream habitat become impaired? 10 How can I improve or maintain quality instream habitat? 11 Riparian forest plant list for the Columbia Bottomlands 12 Riparian forest health checklist 14 Watershed, stream and riparian zone management resources 16 Kendal Larson 1

3 Lower Brazos River the columbia bottomlands rivers, forests and prairies the relationship of the land to the river watersheds San Bernard River Colorado River Columbia Bottomlands Conservation Area West Columbia \ Kilometers \ G u l f o f M e x i c o Miles Houston!µ!H Meandering through coastal Texas, the lower Brazos, San Bernard and Colorado rivers combine to form the Columbia Bottomlands, one of the most diverse ecosystems in the state. Bottomland ecosystems are created under the fluctuating hydrological actions of an extensive network of natural levees, oxbow lakes and floodplain wetlands. Trees found in the bottomland hardwood forests include the bald cypress, pecan, oak, elm, cottonwood and hackberry. Hardwoods, particularly old-growth trees over 150 years old, contribute to the biological diversity of the wetland system. The Columbia Bottomlands provides critical terrestrial habitat as well as varied and important aquatic habitat for fish, mollusks and crayfish. Millions of neotropical songbirds fill the bottomland forests on their migration from the Gulf of Mexico to interior Texas and beyond, while coastal prairies within the watershed provide critical habitat for grassland bird species. Despite their diversity, bottomland hardwood or riparian forest systems are one of the most endangered ecosystems in the United States. The health and survival of this valuable ecosystem ultimately depend upon the actions of landowners within the region. The amount and quality of running water in rivers and streams are determined in large measure by the characteristics of the land where the water drains, commonly referred to as a watershed. Every acre of land in Texas is within a watershed, and the land use within an individual watershed determines the amount and quality of water entering our rivers. In complex systems like the Columbia Bottomlands, land use anywhere within the watershed impacts the quality and quantity of water flowing into rivers and entering the groundwater system. Even land without river or creek frontage impacts the surface and ground waters of the Columbia Bottomlands. Proper land management at appropriate scale can slow and retain rainfall runoff. This benefits water quality, improves groundwater recharge and sustains river flows over long periods of time. Appropriate land management that seeks to retain water rather than drain water is important to the health of a river and a worthwhile endeavor for all of Texas. Krystal Murphy/TNC Jeremy Pryor/TNC

4 The entire Columbia Bottomlands ecosystem periodically connects through a web of water in extreme flooding, rejuvenating the health of plant and animal communities. the form and function of a river A river or stream has two main functions: to move water and to move sediment. A river s course and physical form are reactions to the water and sediment it has to move, which are in turn tied to conditions in the watershed, the elevation change of the land and the natural obstructions to river flow. Rivers and streams will shift course as elevations, amounts of water or amounts of sediment in the system change. The rivers in the Columbia Bottomlands meander back and forth, pushing though deep layers of sediment long ago deposited by the rivers themselves. Alterations such as denuding stream banks, constructing drainage ditches or withdrawing surface or ground water result in unnatural fluctuations of water and sediment in the system, ultimately impacting both river course and flow. The condition of the watershed, along with rainfall and groundwater influences, determine the amount of water and sediment in the river or stream. These factors, combined with land-management decisions within the watershed, influence the condition of the river s riparian zone and instream habitat. what is a riparian zone and how does a healthy riparian zone help my land? A riparian zone is the band of vegetation adjacent to a stream bank. In its natural state, a riparian zone typically includes vegetation on the edge of the stream, and shrub species and trees found throughout the floodplain. In the Columbia Bottomlands, the riparian zone includes the vegetation along abandoned channels isolated from the river s main stream by course changes. Healthy riparian zones are critically important to the bottomland ecosystems. They provide important habitat for wildlife and fish, create wildlife travel corridors, improve water quality, sustain stream flows and stabilize stream banks during flood events, among other benefits. Bottomlands are also a popular recreational region for anglers, hunters and canoeists. Bottomland forests are also vital to maintaining water quality by serving as natural filters and depositories for runoff of landuse sediments, waste and pollutants. This function ultimately enhances the bays and estuaries downstream, where rivers empty into the Gulf of Mexico. Bottomlands also serve as expansive shallow reservoirs that contain dangerous floodwaters when rivers overflow. Benefits of a healthy riparian zone Exceptional wildlife habitat for complex plant communities and unique species Attractive to birds, mammals, reptiles and amphibians Diverse and abundant insects, an important part of the food chain Critical to fish and other aquatic life Healthy and productive instream habitat Reduce velocity of flood water and reduce erosion Filter runoff and improve water quality Retain soil and sediment Store water in banks and floodplain Prolong base flow Kendal Larson Recharge alluvial aquifers 5

5 how can i recognize a healthy bottomland? A healthy bottomland normally has a diverse collection of native vegetation dominated by a mature tree canopy with shrubs, vines, grasses and young trees in the understory. Vegetation varies according to depth of water table, frequency of flooding, soil type, the nature of the hydrologic connectivity of stream systems and other site specific conditions. Forests in the Columbia Bottomlands more closely resemble the southeastern and coastal forests of other gulf states than forests common to Texas. A wide range of oak and hawthorn species as well as native pecan, ash and elm thrive in the area. Jeremy Pryor/TNC how can i recognize an unhealthy or impaired bottomland? Impaired bottomlands can be difficult to recognize. Lack of vegetation, exposed soil and sinking banks are signs of a degraded riparian area. Vegetation typical of upland, or drier, sites can also be a clue. Riparian zones dominated by exotic or introduced species, such as Chinese tallow, Bermuda grass, St. Augustine grass or similar vegetation, should also be considered impaired. Areas that have been groomed into park-like settings with non-native grass and mature trees, or areas that are continuously grazed, can generally be considered impaired. Linking riparian health in the bottomlands strictly to vegetation can be difficult, as healthy and impaired riparian zones can both be densely vegetated. A list of plants indicative of the Columbia Bottomlands can be found near the end of this booklet. Clockwise from top left: Closeup of Chinese tallow leaves Dr. Warren Conway; Closeup of orange trifoliate Ryan Smith/TNC; Chinese tallow trees and trifoliate orange are a 6 sign of impaired bottomland habitat. Ryan Smith/TNC 7

6 Common causes of degraded bottomlands how can i improve or maintain bottomland health? what is instream habitat and why is it important? Aquatic organisms are indicators of instream habitat characteristics, quantity, quality and health. Manicured landscapes encroaching into riparian zones Concentrated livestock grazing Pollution from agricultural runoff Excessive number of deer, feral hogs or other exotic or problematic species Concentrated recreational activities Introduction and spread of exotic grasses, shrubs and trees Denuded stream banks Altered stream channels Construction in the riparian zone 8 The single most effective strategy for maintaining the health of your riparian zone is creating or restoring buffer strips of appropriate native vegetation along streambanks. In many cases, this can be accomplished almost entirely through thoughtful stewardship of the land. Riparian areas within grazing lands can be fenced for protection, and alternative sources of water or dedicated watering areas away from the river can greatly reduce the impact of livestock on bottomlands. If you do not have livestock but keep your riparian zone groomed for recreation, consider growing native vegetation in the area, especially near the water s edge. If you farm up to the river s edge, or your riparian zone is dominated by introduced or exotic vegetation, consider replanting with a mixture of native grasses, shrubs and trees. Healthy bottomlands house a diversity of native wildlife, adding value for landowners and their neighbors. Instream habitat includes the water, streambed, banks and connectivity of all the waterways in a watershed. Instream habitat is strongly influenced by vegetation at the water s edge, and determines the kind and amount of fish, insects and other organisms living in the water. Instream habitat is determined by several factors, including water quality and chemistry, water quantity or flow and passing sunlight and shading of the water surface. The shape and materials composing a streambed and the presence of decaying wood and other organic matter also affect instream habitat, and temporal or seasonal fluctuations further add to their complexity. Cloudy water that is slow moving and deep that flows over a silt or sand bottom provides habitat for different organisms than shallow, fastmoving clear water running over a gravel riverbed. Rivers in the Columbia Bottomlands have a variety of interconnected instream habitat types, all of which help support the ecosystem s biological diversity. Learning more about the structure and flow of your stretch of the river can help determine what types of organisms should be found there. Timothy Bonner An abundance of adaptable species such as red shiner (top) can be indicative of lower water quality or habitat conditions, while an abundance of species like silverband shiner (bottom), found in flowing water, can indicate higher quality instream habitat. 9

7 how does instream habitat become impaired? Instream habitats are impaired by a number of factors, including many of the same ones that degrade riparian zones. These include reduced or altered flows from dams or water withdrawal, as well as excessive sediment loading and runoff from land-use practices that are not compatible with a healthy watershed. Streambed modifications, such as straightening, removal of dead wood and natural obstructions and riparian vegetation clearing can also impact instream habitats. Drastically modified instream habitats will not support the same quantity and quality of aquatic life as those that are part of a healthy river or stream system. how can i improve or maintain quality instream habitat? Two of the most important factors in healthy instream habitat are the maintenance of natural stream flow and promotion of good water quality. In many cases, stream flow and water quality are determined by land and groundwater use throughout the watershed, but they can also be impacted by nutrient runoff from agriculture and pasture lands, non-functional park-like riparian zones and excessive sediment entering the river. Limiting modifications to the streambed and stream channel can help maintain quality instream habitat. Restoring riparian zone connectivity and functionality is an excellent way to improve instream habitat along your river or creek front. Small modifications to land management across the entire Columbia Bottomland landscape can have a large impact to the health of instream habitat. Kendal Larson Jeremy Pryor/TNC

8 Krystal Murphy/TNC riparian forest plant list for the columbia bottomlands The function of a riparian zone is determined by a combination of factors, including erosion, sediment deposits, hydrology and riparian vegetation. As a streamside landowner, you can positively influence the plant community found within the riparian zone. Different plant species, or groups of plants, provide unique attributes and riparian zone functions. For example, a diversity of plants, both in species and structure, is needed to provide the best wildlife habitat. A healthy, balanced plant community is also critical to streambank stability. Stable streambanks require a mix of species including those with fine roots and those with larger, more substantial roots. In most cases, this requires a mixture of sedges or rushes, grasses and woody species. A good illustration of this concept is concrete. For concrete to be durable, it needs the proper mixture of cement, sand, gravel (fine roots) and reinforcing steel (large roots). Following is a list of plants typically found in functional riparian zones of the bottomlands. Not all plants are typical across the entire ecological region, and this list is not comprehensive. Trees coastal live oak (Quercus virginiana) cedar elm (Ulmus crassifolia) sugar hackberry (Celtis laevigata) water oak (Quercus nigra) pecan (Carya illinoinensis) American elm (Ulmus americana) green ash (Fraxinus pensylvanica) black willow (Salix nigra) Shumard oak (Quercus shumardii) water hickory (Carya aquatica) Shrubs/Small Trees Carolina laurel-cherry (Prunus caroliniana) western soapberry (Sapindus saponaria) deciduous holly (Ilex decidua) yaupon (Ilex vomitoria) dwarf palmetto (Sabal minor) roughleaf dogwood (Cornus drummondii) American beautyberry (Callicarpa americana) swamp privet (Forestiera acuminata) buttonbush (Cephalanthus occidentalis) red buckeye (Aesculus pavia) Grasses wood oats (Chasmanthium sessiliflorum) savanna panicum (Panicum gymnocarpon) rustyseed paspalum (Paspalum langei) basketgrass (Oplismenus hirtellus) Virginia wild rye (Elymus virginicus) two-flower melic (Melica mutica) creek oats (Chasmanthium latifolium) Forbs Turk s cap (Malvaviscus arboreus var. drummondii) elephant s foot (Elephantopus carolinianus) frostweed (Verbesina virginica) Canada snakeroot (Sanicula canadensis) white avens (Geum canadense) green dragon (Arisaema dracontium) Canada wild onion (Allium canadense var. canadense) Virginia jumpseed (Tovara virginica) Sedges Cherokee sedge (Carex cherokeensis) crowfoot sedge (Carex crus-corvi) hop sedge (Carex lupulina) Vines peppervine (Ampelopsis arborea) rattanvine (Berchemia scandens) trumpet creeper (Campsis radicans) poison ivy (Toxicodendron radicans) grape (Vitis spp.) Virginia creeper (Parthenocissus quinquefolia) greenbriar (Smilax spp.) Epiphytes Spanish moss (Tillandsia usneoides) resurrection fern (Polypodium polypodioides) 13

9 riparian forest health checklist (Adapted from Alberta s Cows and Fish Program s Riparian Health Checklist) Answer the following questions to determine the health of your streambank. If you are unsure of an answer, leave it blank % or more of the riparian area is covered with vegetation (of any kind). Yes No 2. More than 50% of the riparian plants are taller than knee height. Yes No 3. Shrubs and trees such as buttonbush, willow, sycamore, pecan or elm are growing along or near the stream edge, and grow without a browse line or hedged appearance. Yes No 4. There are young trees and shrubs that will replace the mature forest over time. Yes No 5. Exotic plants such as Bermuda grass, Chinese tallow, St. Augustine, dallis grass, chinaberry, ligustrum, salt cedar and Christ-thorn make up less than 15% of all the plants growing in the riparian area. In other words, native plants dominate the riparian zone. Yes No 6. Plowing or mowing is set back at least 100 feet from the stream. Yes No 7. The bank is NOT damaged by recreational use, livestock or other activities. Yes No 8. The stream bank is sloping rather than heavily undercut into the stream. There are exposed tree roots or trees recently toppled into the stream. Yes No 9. Waterways appear to naturally spread across the floodplain in rain events. Yes No 10. Water in the stream is NOT excessively cloudy, full of sediment, algae or moss during stable flow. Yes No 11. There are no retaining walls, rip-rap or other bank stabilizing structures. Yes No 12. Wildlife is often seen in the riparian area and fish live in the stream. Yes No Total YES Total NO If you answered YES to 10 or more questions, it is likely that your riparian area is healthy, functioning well and providing key riparian functions, including trapping sediment, buffering the impact of flooding, providing primary productivity and providing fish and wildlife habitat. If you answered NO to 10 or more questions it is likely that your riparian area is unhealthy and not functioning properly. Such a riparian area can show signs of erosion, absence of fish and wildlife and reduced water quality. If you answered NO to 5 or more of these questions the riparian area could be healthy but with problems. Some riparian functions may be impaired

10 watershed, stream and riparian zone management resources 16 For more information on riparian zones Alberta Riparian Habitat Management Society (403) River Systems Institute (512) Texas Parks and Wildlife Department (800) Texas Riparian Association (512) Technical assistance Local Soil and Water Conservation Districts (800) Texas AgriLife Extension (979) USDA-Natural Resources Conservation Service (254) US Fish & Wildlife Service Ecological Services (281) Assistance also available from Brazos River Authority (888) Friends of the San Bernard River (979) Gulf Coast Bird Observatory (979) Lower Colorado River Authority (800) Conservation easements are one of the most powerful, effective tools available for the permanent conservation of private lands. For more than four decades, The Nature Conservancy has been using conservation easements to protect landscapes from development, often affording them better protection than could be accomplished through outright purchase. The use of conservation easements has successfully protected millions of acres of land while keeping it in private hands and generating significant public benefits. A conservation easement is a restriction placed on a piece of property to protect its associated resources. The easement is voluntarily donated or sold by the landowner and constitutes a legally binding agreement that limits certain types of uses or prevents development from taking place on the land in perpetuity, while at the same time ensuring the land remains in private ownership. Conservation easements protect land for future generations while allowing owners to retain private property rights, live on and use their land and alleviate tax burdens. Kendal Larson For more information on conservation easements, please visit our website at nature.org/texas or contact one of our offices: Columbia Bottomlands Brazos River Office P.O. Box 1018 West Columbia, TX (979) San Antonio 200 E. Grayson, Suite 202 San Antonio, TX (210) Austin 318 Congress Avenue Austin, TX (512)

11 The Nature Conservancy of Texas is the leading conservation organization working to protect the ecologically important lands and waters in the Lone Star State for nature and people. The Nature Conservancy of Texas owns and manages more than 30 nature preserves and freshwater conservation projects. With partners including hundreds of dedicated Texas landowners the Conservancy has helped conserve more than 750,000 acres of land, water and wildlife habitat across Texas for the benefit of future generations. For more information, visit nature.org/texas. 18