Premium
Ecological effects of extreme drought on Californian herbaceous plant communities
Author(s) -
Copeland Stella M.,
Harrison Susan P.,
Latimer Andrew M.,
Damschen Ellen I.,
Eskelinen Anu M.,
FernandezGoing Barbara,
Spasojevic Marko J.,
Anacker Brian L.,
Thorne James H.
Publication year - 2016
Publication title -
ecological monographs
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 4.254
H-Index - 156
eISSN - 1557-7015
pISSN - 0012-9615
DOI - 10.1002/ecm.1218
Subject(s) - ecology , species richness , forb , biodiversity , plant community , phylogenetic diversity , climate change , biology , herbaceous plant , precipitation , alpha diversity , beta diversity , geography , grassland , phylogenetic tree , biochemistry , meteorology , gene
Abstract Understanding the consequences of extreme climatic events is a growing challenge in ecology. Climatic extremes may differentially affect varying elements of biodiversity, and may not always produce ecological effects exceeding those of “normal” climatic variation in space and time. We asked how the extreme drought years of 2013–2014 affected the cover, species richness, functional trait means, functional diversity, and phylogenetic diversity of herbaceous plant communities across the California Floristic Province. We compared the directions and magnitudes of these drought effects with expectations from four “pre‐drought” studies of variation in water availability: (1) a watering experiment, (2) a long‐term (15‐yr) monitoring of interannual variability, (3) a resampling of historic (57‐yr‐old) plots within a warming and drying region, and (4) natural variation in communities over a broad geographic gradient in precipitation. We found that the drought was associated with consistent reductions in species richness and cover, especially for annual forbs and exotic annual grasses, but not with changes in functional or phylogenetic diversity. Except for total cover and cover of exotic annual grasses, most drought effects did not exceed quantitative expectations based on the four pre‐drought studies. Qualitatively, plant community responses to the drought were most concordant with responses to pre‐drought interannual rainfall variability in the 15‐yr monitoring study, and least concordant with responses to the geographic gradient in precipitation. Our results suggest that, at least in the short term, extreme drought may cause only a subset of community metrics to respond in ways that exceed normal background variability.