Ecological Sites and Ecological Site Descriptions (ESDs)
An ecological site is a distinctive kind of land with specific soil and physical characteristics that differs from other kinds of land in its ability to produce distinctive kinds and amounts of vegetation, and in its ability to respond similarly to management actions and natural disturbances.
Unlike vegetation classification, ecological site classification uses climate, soil, geomorphology, hydrology, and vegetation information to describe the ecological potential of land areas. A particular ecological site may feature several plant communities (described by vegetation classification) that occur over time and/or in response to management actions.
Ecological sites comprise a land classification system that describes ecological potential and ecosystem dynamics of land areas. They are used to stratify the landscape and organize ecological information for purposes of monitoring, assessment, and management.
Ecological Site Concept
The concept of an Ecological Site is defined based on reference conditions representing natural states. The state changes and transitions are subsequently estimated based on our understanding of succession and ecological thresholds. Reference states and their component community phases represent the historical range of variability due to successional dynamics following disturbances. Within this natural, historical, or reference state, the community phase used to define an ecological site is termed the reference community phase. See Interagency Ecological Site and Ecological Site Descriptions, Handbook for Rangelands, 2012. Caudle, Dan; Jeff DiBenedetto; Michael Karl; Homer Sanchez, Curtis Talbot. 108 pages.
Ecological Site Content
- Physiographic features
- Climatic features
- Influencing water features
- Representative soil features
- States and Community phases
- Supporting information
- Site description approval
What Ecological Sites Provide
Resource information includes site characteristics: physiographic, climate, soil, hydrologic, and plant community features for describing interactions among soils, vegetation, and land management.
Framework to address condition of current resources, monitor changes, identify and transfer knowledge gaps in vegetation dynamics, and communicate among disciplines and organizations.
Supporting information such as site interpretation for use and management, includes plant community dynamics, growth curves, associated wildlife communities.
Ecological Site Descriptions (ESDs)
ESDs are used to predict how vegetation and site conditions may respond to change and how soil and plant indicators are tied to land health. ESDs and associated information are used primarily to stratify the landscape for monitoring and assessment, interpretation of resource hazards and opportunities, and to prioritize and select management actions. ESDs are developed and housed by the U.S. Department of Agriculture (USDA) Natural Resources Conservation Service (NRCS) and its partners, and used by the Bureau of Land Management (BLM), and others. The Interagency Ecological Site on Ecological Site Descriptions Handbook for Rangelands establishes national standards and protocols for ESD development.
ESD’s are reports that describe:
- Biophysical properties of ecological sites,
- Vegetation and surface soil properties of reference conditions that represent either
- pre-European vegetation and historical range of variation or
- proper functioning condition or potential natural vegetation,
- State-and-transition model graphics and text, and
- A description of ecosystem services provided by the ecological site and other interpretations.
ESDs contain information about ecological dynamics of each site and are used as a standard or reference for resource evaluations and assessments such as trend, growth-production, and rangeland health. They help synthesize much scientific information concerning soils, hydrology, ecology, management, etc., and serve as a clearinghouse of that information for each ecological site. ESD’s assist in management decisions for a landscape based on ecological principles that help the land manager:
Improve rangeland health by determining site specific management;
Distinguish a Cause versus a Symptom—for example, invasive annual grasses may be symptoms of either natural or human caused disturbances to achieve sustainable rangeland; and
Provide decision support tools to get positive results for effective land management.
ESD’s are a Step by Step Process
Differentiation between Ecological Sites
Ecological sites can be distinguished by differences in environmental factors, such as climate, topography, plants/animals, soil, and parent material. Such differences result in significant differences in the species that are in the characteristic plant community, relative proportion of species in the characteristic plant community, and total annual production of the characteristic plant community. Below is an example of four sites with relatively similar parent material, soil textures, soil depths, and slopes. However, they have distinctive differences in elevation, amount of precipitation, and specific types of dominant plant species. For example the four ecological site types shown below all have alluvium, eolian, sandstone/shale; sandy loam-loam soils; however, they have various differences in soil depths, slopes, precipitation, and elevation, resulting in different dominant species.
|Soil Depths:||20–60" |
|Precipitation:||< 8" / year|
|Dominant Plant:||Shadscale (indicating salt in the soil)|
|Precipitation:||8-12" / year|
|Dominant Plant:||Wyoming Big Sagebrush|
|Precipitation:||12-16" / year|
|Dominant Plant:||Mountain Big Sagebrush|
|Soil Depths:||> 60"|
|Precipitation:||< 8–16" / year + flooding|
|Dominant Plant:||Basin Big Sagebrush|
Additional Information Sources
To view reports of approved rangeland and forest land ESDs, see the Ecological Site Description (ESD) System for Rangeland and Forest.
Ecologically-based invasive plant management (EBIPM) website discusses ecological processes, vegetation changes, ecological principles, management tools, rangeland health assessments, practical perspectives on adaptive management.
Jornada Experimental Range website provides excellent material on ESD’s including tools and literature pertaining to their development.
New Tools for Conservation: Ecological Site Descriptions and Their Role in Conservation Planning