National Ecological Framework (4 of 23)

Introduction

This attribute database replaces the earlier version released on diskette in 1996 (Selby and Santry, 1996). Project resources, availability of national data sets, and time limited the scope of the earlier 1996 database. The intervening years have allowed for revisions and access to new sources of data. The supporting attribute database has been substantially expanded to include over 16 new attributes, covering climate, elevation and surficial geology. In addition, a draft ecoprovince level of generalization, which falls between ecozone and ecoregion in the hierarchical ecological framework, has been added to the database (Marshall et al. 1999).  A complete description, list of source documents and methods of compilation are provided for each attribute. The collection of abiotic, biotic and socio-economic data on a consistent, standardized basis to characterize ecosystems on a national level is difficult to achieve. However, new characterizing attributes will be added, as they become available.

Conventions

There are 26 attributes included in the database, covering five general categories, including: area of each ecological unit (2); climate (14); physical landscape characteristics (8): land cover (1); and population (1). For each attribute, there is a separate data table for each level of the ecological framework: ecozone (zn), ecoprovince (pr), ecoregion (rg), and ecodistrict (dt). The following example for elevation illustrates the four types of tables:

Only two of the climate attributes provide data at all four levels of the of the framework (temperature and precipitation) and two at the ecodistrict and ecoregion levels ( growing degree days and effective growing degree days). The remaining climate attributes are compiled only at the ecodistrict  level.  Data was not available for population at the ecodistrict level.  A "directory of codes" (files starting with "c") is provided for eight of the attributes, which have several components defined. They include: landform; surface form; surface material;  texture; soil development; surficial geology; and land cover.  The correspondence table (zprd.dbf) relates the unique map unit numbers from one level in the ecological framework to the next.