Patterns of floristic diversity in wet meadows and fens of the southern Sierra Nevada, California, USA
Date
2011
Authors
Jones, Jennifer Rains, author
Cooper, David J. (David Jonathan), 1952-, advisor
Martin, Patrick H., committee member
Schweiger, William E., committee member
Stohlgren, Thomas J., committee member
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Abstract
Wetlands are often described as important contributors to species diversity, but this contribution has seldom been quantified. In mountain regions, wetlands often occur as geographically isolated habitats in a matrix of forest, shrub, or dry meadow communities, providing important ecosystem services and increased habitat heterogeneity. The goal of this study was to quantify the contribution of wet meadows and fens to the floristic species richness of Sequoia and Kings Canyon National Parks in California, USA, and assess variables that influence species richness and composition in wetlands and broad vegetation assemblages. Park-wide inventory data were used from 687 samples to identify broad-scale vegetation assemblages and compare species richness values among assemblages. Data were grouped using an iterative clustering procedure able to handle highly heterogeneous data ranging from alpine talus to montane meadows. Species richness in vegetation assemblages were compared using a series of complementary methods including: Shannon's and Simpson's Indices, Coleman Rarefaction curves, and 'Chao 2' non-parametric species richness estimator curves. Classification and regression trees (CART) were used to describe the variables influencing species richness and composition in vegetation assemblages. A combination of ordination and classification was used to interpret vegetation pattern in wet meadows and fens. Cluster analysis identified 10 broad vegetation assemblages. Species richness indices and estimator curves revealed that Montane Wet Meadows, Subalpine Wet Meadows, and Lower Montane Woodlands and Chaparral were the most species rich assemblages. Combined Montane and Subalpine Wet Meadows had the highest species richness values of all groups, even though they occupied only 2% of the almost 350,000 hectare survey area. Wet Meadows were found to be important to species richness across the study area as well as being highly complementary to other vegetation assemblages in the park. Lower Montane Woodlands and Chaparral also make important contributions to species richness and occupy 6.5% of the survey area. CART models indicated that elevation, topographic wetness, and slope were important to species richness and vegetation assembly. This study suggests that a simple series of complementary methods can be used to analyze inventory data to assess patterns of species richness at landscape scales. These findings can inform future monitoring efforts and the protection of diverse habitats in montane regions.
Description
Rights Access
Subject
classification and regression trees
cluster analysis
plant diversity
richness estimation
Sierra Nevada
USA
wetland