The Ecological Survey of Central Arizona (ESCA) is an extensive field survey and integrated inventory designed to capture key ecological indicators of the CAP LTER study area consisting of the urbanized, suburbanized, and agricultural areas of metropolitan Phoenix, and the surrounding Sonoran desert. The survey is conducted every five years at approximately 200 sample plots (30m x 30m) that were located randomly using a tessellation-stratified dual-density sampling design. Study plots cover habitats throughout the CAP LTER study area ranging from native Sonoran desert sites to residential yards to an airport tarmac. Measurements include an inventory of all plants (identified to the lowest possible taxonomic unit, typically species), plant biovolume, soil coring for physicochemical properties, arthropod sweep-net sampling, photo documentation, and a visual survey of site and area characteristics. The objectives of the survey are to (1) characterize patches in terms of key biotic, physical, and chemical variables, and (2) examine relationships among land use, general plant diversity, native plant diversity, plant biovolume, soil nutrient status, and social-economic indices along an indirect urban gradient.

Survey 200 was the original name of the project, and it was renamed to ESCA following the survey conducted in 2015. The data set here includes a subset of information from the Survey200/ESCA focusing exclusively on annuals in the survey plots. Investigators interested in more recent survey data, or other variables measured as part of ESCA should search the data catalog for 'ecological survey of central arizona' or 'survey 200'.