Tuesday, May 27, 2008 - 10:00 AM
149

Macroinvertebrate production and functional structure along a tallgrass prairie stream continuum

D.P. Whiting and M.R. Whiles. Department of Zoology and Center for Ecology, Southern Illinois University, Carbondale, IL 62901-6501

Conceptual models of stream continua predict that consumer functional structure changes with riparian vegetation.  In order to quantify these relationships in a prairie landscape, we examined macroinvertebrate production and functional structure along a longitudinal continuum of Kings Creek, a tallgrass prairie stream draining the Konza Prairie Biological Station in Eastern Kansas.  Riparian vegetation along the continuum ranged from grassy headwaters, to shrubby mid-reaches, to lower reaches with gallery forest.  Total habitat-weighted production ranged from 13 g ash-free dry mass (AFDM) m-2 y-1 in the headwater reach to 3.1 gAFDM m-2 y-1 in the shrubby reach, and was 8.1 gAFDM m-2 y-1 in the gallery forest reach.  Functional group contributions to production were similar, with collector-gatherers (55%-70%) and predators (20%-34% of total) dominating all reaches.  Shredders were not major contributors, and decreased from 396 (grassy headwaters) to 60 (gallery forest) mgAFDM m-2 y-1 along the continuum.  Scraper production was nearly equal (~600 mgAFDM m-2 y-1) at all sites, but taxonomic shifts were evident.  Patterns differed from systems with forested headwaters, but reflected some predicted linkages between consumers and riparian gradients.  Total production was also much lower than prior estimates from the same stream, reflecting the inherent variability of prairie systems.