Native and alien species diversity at the local and regional scales in a grazed California grassland
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Authors: S. Harrison
Date: 1999
Journal: Oecologia
Volume: 121
Number: 1
Pages: 99-106
Summary of Methods: Plant species richness and the proportion of native species in a complex of adjacent serpentine and nonserpentine meadows was examined in northern Napa and southern Lake counties in California. Twenty sites were sampled at each of four treatments (serpentine/grazed, serpentine/ungrazed, nonserpentine/grazed, and nonserpentine/ungrazed). Species richness, percent cover, soil probes and site characteristics were recorded in 1998. In early June after the growing season had ended total biomass was clipped.
Article Summary / Main Points: Serpentine soils supported greater species richness at the 1-m2 scale and a higher proportion of native species than adjacent nonserpentine meadows. Species richness was not different between grazed and ungrazed sites. Serpentine meadows had lesser biomass, cover, soil depth, nitrogen, phosphorous and calcium, and greater magnesium than nonserpentine meadows. Again there was no difference among grazed and ungrazed sites. Beta diversity (ratio of the total number of species in each treatment to the average local richness at each site) was highest for native plants species in nonserpentine meadows regardless of the presence of absence of grazing. The status of low-productivity serpentine soils as a refuge for native grassland species appears to be the result of their abiotic resistance to alien species, but not of negative relationship between productivity and total species richness.
Vegetation Types: California Grasslands (including all annual grasslands) Oak Woodlands
MLRA Ecoregions: 15 Central California Coast Range
Agrovoc Control Words: Weeds Rangelands Grazing
Article Review Type: Refereed
Article Type: Experimental Research
Keywords: plants, diversity, invasion, serpentine, grasslands
Annotation: Grazing intensity is defined as "grazed" and "ungrazed". This study was conducted in California though it may have application across a broader spectrum of vegetations types. More research is needed to determine applicability of these findings.
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