Conservation planning at any scale—regional, landscape level, or local—requires an understanding of patterns of environmental variation and biological diversity. This dataset was developed as a tool for assessing the biophysical character of landscapes, and for mapping the distribution and composition of community assemblages across those landscapes. Informed decisions on where to focus conservation efforts require such tools.

Data on biological distributions are very often inadequate to a large-scale analysis of biodiversity. The close relationship of the physical environment to ecological process and biotic distributions underpins the ecological sciences, and in the absence of suitable biological datasets, conservation science has recognized that physical diversity could be an acceptable surrogate for biological diversity. Research has repeatedly demonstrated especially strong links between ecosystem pattern and process and climate, bedrock, soils, and topography. This recognition led to the development of the ecological land unit, or ELU.

The ELU is a composite of several layers of abiotic information: elevation, bedrock geology, distribution of deep glacial sediments that mask bedrock’s geochemical effects, moisture availability, and landform. An ELU grid of 30 meter cells was developed for the Lower New England-Northern Piedmont (LNE) and North Atlantic Coast (NAC) ecoregions. The ELU dataset describes the “ecological potential” of the landscape, but carries no information about actual landuse or landcover in a region where human alterations to the landscape have everywhere affected the natural vegetation. The current dataset informs ELUs with landcover data, bringing them to earth by telling us what is actually on the ground. We may use this dataset to map ecological systems, which are dynamic assemblages of communities that occur in a mosaic on the landscape, and that are linked by shared ecological processes and environmental gradients.

Ecological Land Units (ELUs) are based on elevation zones, geology, and landforms, used in The Nature Conservancy's ecoregional planning processes. - See more at: https://www.conservationgateway.org/ConservationByGeography/NorthAmerica/UnitedStates/edc/reportsdata/mapsdata/Pages/default.aspx#sthash.kanQUEwj.dpuf