Sierra Nevada meadows: species alpha diversity

Abstract

Plant species diversity refers to variety and abundance; it does not necessarily relate to meadow health but may provide information important in an ecosystem context. Monitoring to detect change in diversity usually begins with estimating alpha (within) diversity of plant communities. Because few such estimates exist for meadow site classes or specific sites of the Sierra Nevada, California, we computed Margalef's diversity index (D_m), which stresses species richness, and Simpson's index (D_s), which stresses species dominance, for two sets of frequency data. Frequency was estimated by the nearest shoot-to-point method and the rooted quadrat method. In addition, a relative index (D_r) was calculated on the basis of the number of species on individual sites divided by the average number of species recorded for 107 meadow sites. Regardless of the data set or index, species diversity was lower for sites at or near the environmental extremes of moisture. The methods used to estimate frequency, estimating species numbers, and the value of diversity estimates are discussed.

Citation

Ratliff, Raymond D. 1993. Sierra Nevada meadows: species alpha diversity. Res. Note PSW-RN-415. Albany, CA: U.S. Department of Agriculture, Forest Service, Pacific Southwest Research Station. 5 p