TitleRichness, not evenness, varies across water availability gradients in grassy biomes on five continents.
Publication TypeJournal Article
Year of Publication2022
AuthorsSmith MD, Koerner SE, Avolio ML, Komatsu KJ, Eby S, Forrestel EJ, Collins SL, Wilcox KR, Ahumada R, Morgan JW, Oliva G, Oñatibia GR, Overbeck GE, Peter G, Quiroga E, Sankaran M, Wu J, Yahdjian L, Yu Q
Date Published2022 Jul
KeywordsBiodiversity, China, Ecosystem, Poaceae, Water

We sought to understand the role that water availability (expressed as an aridity index) plays in determining regional and global patterns of richness and evenness, and in turn how these water availability-diversity relationships may result in different richness-evenness relationships at regional and global scales. We examined relationships between water availability, richness and evenness for eight grassy biomes spanning broad water availability gradients on five continents. Our study found that relationships between richness and water availability switched from positive for drier (South Africa, Tibet and USA) vs. negative for wetter (India) biomes, though were not significant for the remaining biomes. In contrast, only the India biome showed a significant relationship between water availability and evenness, which was negative. Globally, the richness-water availability relationship was hump-shaped, however, not significant for evenness. At the regional scale, a positive richness-evenness relationship was found for grassy biomes in India and Inner Mongolia, China. In contrast, this relationship was weakly concave-up globally. These results suggest that different, independent factors are determining patterns of species richness and evenness in grassy biomes, resulting in differing richness-evenness relationships at regional and global scales. As a consequence, richness and evenness may respond very differently across spatial gradients to anthropogenic changes, such as climate change.

Alternate JournalOecologia
PubMed ID35833986
Grant ListDEB-1354732 / / Directorate for Biological Sciences /
2018-67013-27400 / / National Institute of Food and Agriculture /