Functional group dominance and not productivity drives species richness

• Published in: Plant ecology & diversity 2016-03, Vol.9 (2), p.141-150
• Main Authors: Li, Wenjin, Knops, Johannes M. H., Brassil, Chad E., Lu, Junfeng, Qi, Wei, Li, Jinhua, Liu, Minxia, Chang, Shenghua, Li, Wenlong
• Format: Article
• Language: English
• Subjects: Abundance; Biomass; Dominance; dominance-richness; Dominant species; Flowers & plants; Forbs; Functional groups; graminoid abundance; graminoid dominance; Herbivores; Meadows; Measurement methods; Plant species; Productivity; productivity-richness relationship; species diversity; Species richness; Tibetan Plateau
• ISSN: 1755-0874; 1755-1668
• DOI: 10.1080/17550874.2016.1180563

Background: There is a lack of consensus about the productivity-richness relationship, with several recent studies suggesting that it is not productivity but other factors that are the important drivers that determine species richness. Aims: Here, we examine the relationship between productivity, functional group dominance and plant species richness at the plot scale in Tibetan Plateau meadows. These alpine meadows are ideal to examine the species productivity-richness relationship because they have a very high species richness, a large gradient in productivity, and can be dominated by either graminoids (grasses and sedges) or forbs. Methods: We measured plant species richness and above-ground biomass along a natural gradient of functional group abundance in 44 plots distributed across five natural, winter-grazed but otherwise undisturbed sites in the eastern part of the Qing-Hai Tibetan Plateau, in Gansu province, China in 2008. Results: Graminoid abundance (i.e. graminoid biomass as percent of the total above-ground biomass) explained 39% of plot differences in species richness while neither productivity nor the biomass of the three most abundant plant species, either individually or combined, were a significant predictor of species richness. Conclusions: Our results show that within these alpine meadows, a shift from graminoid to forb dominance, rather than the individual dominant species or productivity itself, is strongly correlated with species richness. Thus, differences in functional group abundance can be a strong driver of observed plant species richness patterns.