PARENT SESSION
Oral Session # 5: Biogeography I: Community Structure and Diversity.
Presiding: B Enquist
Monday, August 4. 8:00 AM to 11:30 AM, SITCC Meeting Room 104.
The relationship between pollen and extant vegetation across an arid urban ecosystem and surrounding desert.
Stuart, Glenn2, Gries, Corinna1, Hope, Diane*,1, 2 Department of Anthropology, Tempe, AZ, USA1 Center for Environmental Studies, Tempe, AZ, USA
ABSTRACT- A probability-based sample was used to determine the relationship between pollen counts in surface soil and extant perennial vegetation, across the Central Arizona - Phoenix region, including the urban area, surrounding agricultural and native Sonoran desert land. We asked whether taxa behaved as expected from known pollination characteristics (e.g. anemophilous versus zoophilous) and whether the pollen:plant relationship differed between the undeveloped desert and agro-urban regions. We mapped pollen:plant abundance across the study area and applied two statistical approaches to examine the data quantitatively. Firstly, the sum of total pollen concentration divided by total cover computed for each taxon, was used to compare pollen productivity of different taxa using a cluster analysis (K means, normalized). Secondly PC-Ord was used on a cross matrix containing the presence/absence of both pollen and plants for each taxon at each site. Both techniques produced the same broad groupings. Group I contained wind-dispersing taxa with high pollen counts relative to the amount of vegetative cover (e.g. Pinus, Cupressacea). Groups II and III were comprised of largely native taxa for which both pollen and plants were typically found at the same sites, the former having a more widespread abundance (e.g. Asteraceae, Ambrosia) than the latter (e.g. Larrea, Parkinsonia, Prosopis). Groups IV and V were comprised of taxa with relatively low pollen and plant cover across the region, taxa in Group V (e.g. Citrus) having a higher overall plant abundance than in group IV (e.g. Fraxinus, Acacia). Group VI consisting of zoophilous taxa with modest plant cover but very little pollen in samples and included most of the Cactaceae. These finding have important implications for allergy-related pollen forecasting techniques, in particular that significant variation can occur in pollen rain across a city, even for taxa with very mobile pollen.
Key words: distribution, pollen, desert, urban