Step 1 – Define spatial and temporal scales for assessment
Spatial scales for assessing ecological condition varies from individual sites to multiple sites across watersheds, landscapes, and regions. At small spatial scales evaluation might include assessing one or several target sites, sometimes comparing them to other similar sites. At broader spatial scales, all locations or areas of a vegetation type may be systematically compared across a managed area, watershed or region. Temporal scales vary from a one -time assessment to monitoring over many time periods. The temporal scale also takes into consideration the timing of data collection (e.g., summer only or year -round) and the planned duration (e.g., one time or repeated).
Step 2 – Select target resources to be assessed
Broadly speaking, DoD’s target natural resources might be grasslands, shrublands, forests, riparian areas, rivers, lakes, and coastal marine ecosystems, and/or habitats for selected species of concern where the agency should be able to report on their condition and trends.
As described above, ecological classifications and maps help managers better understand natural variability within and among types, and thus play an important role in helping to distinguish sites that differ across a gradient of conditions and stressors (Collins et al. 2006). Given the diversity of ecosystem types on a given DoD jurisdiction, and the different kinds of management questions associated with each, it is critical to organize existing knowledge about their location on the landscape, how they naturally function, and how land use decisions affect those functions. Descriptions of each classification unit are the practical starting point for conceptual modeling; and in many cases, are sufficient on their own. They typically include a characterization of the environmental setting, vegetation structure and composition, and sometimes include common natural disturbance regimes associated with the type. The summary description includes much about the typical environmental setting (elevation range, landforms, slopes, soils), vegetation structure and composition, including the primary species of tree shrub and herb one could expect to encounter. NatureServe’s Explorer, the U.S. National Vegetation Classification, LANDFIRE biophysical settings and NRCS ecological site descriptions are all useful for accessing existing descriptions for terrestrial ecosystems that may occur on DoD installations.
Step 3 – Identify key ecological attributes
A scientifically based model facilitates the identification of the key ecological attributes (KEA) of composition, structure, and function that are most crucial for ecological integrity, and which likely respond most directly to ecological stressors. For example, with a given woodland or desert shrubland occurring across the Intermountain West, we not only need to know about the vegetation structure and composition (such as the contribution from cryptobiotic soil crusts), but we also need to describe the major types of dynamic processes (succession following wildfire) and ecological functions (such as nitrogen fixation and soil stabilization) that lead to that vegetation pattern. In another example with riparian vegetation, key attributes may include the flooding regime and the expected native composition or presence of functional groups of wetland plants or animals that provide essential structural or functional roles. Therefore, conceptual models should also include ecological drivers, such as climate regimes (e.g., drought effects) or geology (e.g., chemical extremes in soil or bedrock), in addition to more direct dynamic processes (flooding and fire regime) that influence the variation in ecological components (Parrish et al. 2003, Tierney et al. 2009).
Ecological stressors, such as groundwater pumping, or invasive species, may quickly alter the riparian system and displace native species that play important functional roles. Alteration to landscape -level natural disturbance processes such as wildfire also may be identified as common stressors because they can have cascading effects on native composition and structure, and other critical natural processes.
Next Page: Determine the indicators
Author
Patrick Comer, Ph.D., Chief Ecologist
NatureServe