PARENT SESSION
Oral Session # 80: Urban Ecology II: Soils and Streams.
Presiding: J Ehrenfeld
Thursday, August 7. 1:30 PM to 5:00 PM, SITCC Meeting Room 105.

The manmade plant communities in a desert metropolitan area.

Gries, Corinna^*,1, Hope, Diane¹, Stabler, Brooke², Martin, Chris², Briggs, John², ¹ Center for Environmental Studies, Tempe, AZ, USA² Dept. of Plant Biology, Tempe, AZ, USA

ABSTRACT- In a stratified tessellation random sampling design perennial plant abundance and richness was measured as percent cover of non-paved area within 30x30 m plots in the Phoenix, Arizona metropolitan area including surrounding natural desert. Of the 204 total plots that were investigated, 166 plots contained plant cover of a total of 188 unique genera. Average diversity was 8.4 and diversity 23 with 95% empty cells and an average total cover per plot of 35%. After eliminating rare taxa and appropriate data standardization, a cluster analysis revealed a clear division between mostly urban and mostly desert plots with only 25% information remaining. Eight urban sites were classified in the desert cluster all of which had original desert vegetation and 10 desert sites were classified as similar to urban sites. Natural desert communities are characterized by dominance of Larrea, Ambrosia or Encelia. Three of the urban sub-clusters were dominated by the genera Cynodon/Pinus/Morus, Prosopis, and Syagrus, respectively, while a fourth urban sub-cluster was highly diverse with no clear indicator genus. The last two urban sub-clusters were examples of 'desert' landscape design while the first sub-cluster represents an 'oasis' landscape design type. The Prosopis dominated and the desert landscape sub-clusters also contained highly disturbed desert sites that lacked the typical desert genera.

Key words: arid plant community, urban plant ecology