An Ecological Land Survey for Fort Richardson, Alaska

Abstract
An ecological land survey (ELS) of Fort Richardson land was conducted to map ecosystems at three spatial scales to aid in the management of natural resources. In an ELS, an attempt is made to view landscapes not just as aggregations of separate biological and earth resources, but as ecological systems with functionally related parts that can provide a consistent conceptual framework for ecological applications. Field surveys at 132 plots along 16 toposequences and at 99 other plots were used to identify relationships among physiography, geomorphology, soils, hydrology, and vegetation. The relationships revealed that the various ecosystem components were closely related to fire effects and geomorphic processes, such as floodplain development, landslide and slope instability, and coastal flooding. Associations among vegetation structures and geomorphic units were used to identify 51 ecotypes (local-scale ecosystems) that were effective at differentiating dominant species and plant associations. Ecosystem maps were developed at three spatial scales. Forty-six ecotypes (1:20,000 scale), derived from the integrated terrain unit (ITU) mapping, differentiated areas with homogeneous topography, terrain, soil, surface form, hydrology, and vegetation. Vegetation (structure and composition) and environmental (elevation. organic matter accumulation, depth to rock, water depths, pH, and electrical conductivity) characteristics of ecotypes were summarized using data obtained from field surveys. Sixteen ecosections (1:100,000 scale) were aggregated from the ecotypes to differentiate areas that are homogeneous with respect to geomorphic features and soil texture, and thus have recurring patterns of soils and vegetation at various successional stages. Four ecodistricts and eight ecosubdistricts (1:250,000) were developed from separate mapping of Landsat imagery to differentiate broader areas with similar physiography, geology, and geomorphology.