Studying Urban Patches In Broad Spatial And Long Term Temporal Scales: A Case Example From Phoenix Metropolitans (poster)

ZHU, WEIXING*, Diane Hope, and Corinna Gries

City landscapes are composed of different patches which are all heavily affected by human activities. The structures and processes in urban patches, the interactions among patches, and the patch dynamics determine the overall urban energy budget, material input/waste production, the composition of non-human organisms, and the well being of humans. Here we outline a proposed 200 plot survey of the CAP LTER study area and report on some preliminary results. Using a tesselation-stratified sample design, we propose to sample a 900 m2 plot in each 5 km x 5 km grid overlaid on the study area. We will sample more intensively (every grid square) in the central urban "core" than the surrounding fringe and desert (3:1 ratio). Plots will be surveyed initially in spring 2000 and once every 3-5 years thereafter. Plot location and mapping will be carried out using a GPS, combined with detailed air and ground photos, and high resolution remote sensing. The plots to be surveyed comprise a broad range of patch types including residential yards, industrial sites, commercial locations, vacant lots, desert parks, roads, and waterways. Initial results from our pilot study of 20 plots showed that patches differ significantly in terms of vegetation cover and diversity, bird and insect diversity, built structure, human activity, and soil nitrogen content. The differences are related to land use type, plot location, the length of human occupation and the intensity of human activities in the plots. The results generated should contribute greatly to our understanding of urban ecosystems.