PARENT SESSION
Oral Session 129: Biodiversity IX: Modeling; Theory.
Presiding: J Maerz
Friday, August 6, 8:30 AM to 12:00 PM, Meeting Room B 110.

Quantifying and qualifying dominance in vegetation.

Frieswyk, Christin ^*,1, Johnston, Carol², Zedler, Joy¹, ¹ University of Wisconsin-Madison, Madison, WI² South Dakota State University, Brookings, SD

ABSTRACT- The concept of ecological dominance lacks explicit definition. Species display dominance in different ways, and the same species can change its dominance over space and time. We quantified dominance using an index (DI) based on three attributes derived from easily collected field data (tendency for high cover [THC], mean cover [MC], and mean species suppression [MSS]). We then used DI to compare species behavior within 72 Great Lakes wetlands (1768 1-m² plots). We qualified dominance by describing seven forms, all of which occurred in Great Lakes wetlands. The most prevalent were monotype (high THC, high MC, and high MSS) and matrix forms (high THC, high MC but low MSS). Monotype characterized 18 species in 40% of the cases, and matrix form described 14 species in 27% of the cases. Invasive Typha spp. was the most common dominant taxon at all aggregation scales (wetland, lake, region). It predominantly showed the monotype form. In contrast, several native dominants followed the matrix form, co-occurring with many species, which had, on average, high coefficients of conservatism. Dominance forms differed across aggregation scales and locations; they might also shift over time. Thus, DI not only helps quantify and qualify a useful concept, but it shows promise as an indicator of vegetation change.

Key words: Great Lakes, Typha spp., wetlands, indicator