Analyzing ecological land units to improve understanding of landscape composition
The relatively fine resolution (250m) of the Ecological Land Units (ELUs) dataset recently published by the USGS and Esri make it possible for analysts to make comparisons between areas such as countries, watersheds, or landscapes. The basis for comparison is the composition of four ecological components represented within ELUs: bioclimate, landform, lithology, and land cover. By understanding the composition of these four components, analysts may compare two or more landscapes to understand the heterogeneity and diversity. For instance, two landscapes may be mostly composed of plains and grasslands that overlay carbonate sedimentary lithology, but differ slightly with respect to the proportions. The basis for these differences includes site and situation relative to nearby landscape features such as mountain ranges, fragmentation of ecological character within the landscape, and observations of species or other field research. The introduction of additional themes of data such as proximity to human population, landscape disturbance estimates, and changes in biomass or land cover can further explain or inform the basis for differences or similarities of these landscapes.
This talk will include a demonstration of how ArcGIS produces compositional assessments of landscapes using Python script tools. The assessments are initially database tables that inventory, summarize, and rank ecological characteristics. These tables are human interpreted and the interpretations along with the significant aspects of the summary are stored in a spreadsheet template. Collections of such compositional assessments are the basis for comparing the characteristics of landscapes, physiographic provinces, watersheds, or political units. This technique was used, in part, to document areas of high ecological diversity to produce an online story map with the purpose of introducing the concepts of the ELU research and work.