Document: JEN-3-40-40

Environmental gradient effects on plant community composition in a halophytic habitat.

JOHNSON, J.E.* and L.L.WALLACE

University of Oklahoma, Norman, OK 73019 USA ¹

Abstract:
We studied the effects of soil and elevational gradients on plant distribution at the Salt Plains National Wildlife Refuge to determine how plant distribution on hummocks within the refuge is regulated. Hummocks are islands that occur on the otherwise flat peneplain of the salt flats; they support the only vascular vegetation in the region. The plant species composition on these hummocks ranges from salt tolerant halophytes to intolerant glycophytes. Community composition was analyzed using Canonical Correspondence Analysis (CANOCO). The soil gradient from the bottom to the top of the hummock was decomposed into salinity, pH, calcium, iron and texture, with the strongest positive correlations for plant cover and diversity found with increasing iron, nitrogen and elevation. Salinity, calcium, silt, pH and clay were positively correlated. These gradients were negatively correlated with plant cover, species diversity and elevation above the peneplain. Given the very steep nature of these gradients, the plant communities appeared to consist of species that were either tolerant of high salt (10 ppt) and high pH (10.9) or not tolerant of these conditions. Some individual species, however, appeared to possess wider tolerance ranges including Schizachyrium scoparium and Lolium perenne .

Keywords: pH, salinity, Oklahoma, gradient analysis

This abstract is being presented at: 3:30 PM in session:
Poster Session #17: Vegetative Analysis.