PARENT SESSION
Poster Session #38: Landscape Ecology.
Thursday, August 9, 2001. Presentation from 10:30 AM to 12:00 PM. Exhibition Hall

Prairie species diversity along a connectivity gradient.

WESTHUS, ERIC ¹, CAMILO, GERARDO¹, ¹

ABSTRACT- The critical threshold theory of landscape connectivity states that in a randomly fragmented landscape, which consists of at least 60% good habitat, there is enough connectivity to allow movement of organisms across the landscape without having to cross a section of bad habitat. We restored native prairie in an abandoned agricultural field in 1998, at the Lay Field Station, Louisiana, MO. A one ha plot was divided into 10m x 10m subplots. We used a stratified random design to generate a fragmentation gradient of 0% to 90% good habitat by selective mowing. Diversity and distribution of plant species in the unmowed plots, as well as the abiotic soil parameters (pH, compaction, temperature, and humidity) were analyzed using Mantel analysis of spatial data and canonical correspondence analysis. Pollen movement was tracked with the use of florescent powder. If pollen or seed dispersal is affected by fragmentation, the critical threshold theory of landscape connectivity states that there should be a change in diversity and distribution of species at the 60% connectivity. Diversity and distribution of species within the experimental plot was independent of connectivity during the first three growing seasons. Responses to connectivity were linear, thus not supporting predictions of the critical threshold hypothesis.

KEY WORDS: Fragmentation, Restoration, Prairie, Connectivity