Effects of functional diversity and functional dominance on complementary light use depend on evenness

Abstract

AbstractQuestionsDoes functional diversity play a more important role than species richness in complementary resource use? Is the effect of functional diversity on complementarity greater when species evenness is higher? Does functional dominance play an important role in resource use when species evenness is low?LocationAn arable field in Linhai City, Zhejiang Province, China.MethodsWe assembled experimental plant communities with different species richness (one, two, four, eight and 12 species) and evenness (low and high). In each community, we quantified light interception efficiency (LIE) and light complementarity index (LC) to reflect light use. We measured four functional traits related to light capture to quantify functional diversity and functional dominance. We then tested effects of observed species richness, functional diversity and functional dominance on LIE, LC and above‐ground biomass in the low and high evenness communities.ResultsFunctional diversity was positively related to LIE, LC and above‐ground biomass in the high evenness communities, but not in the low evenness communities. In contrast, functional dominance was positively related to LIE and negatively related to LC in the low evenness communities, but not in the high evenness communities. Moreover, functional dominance had a larger promotion to above‐ground biomass in the low evenness communities. Observed species richness and evenness had a significant interactive effect on LIE and LC. LIE of a species mixture of the low evenness communities was positively correlated with LIE of the monoculture consisting of the species with the highest initial abundance in the species mixture, while LC of a species mixture of the low evenness communities was negatively correlated with it.ConclusionsFunctional diversity and functional dominance play a crucial role in light complementary use of plant communities, and their effects on light complementarity are mediated by species evenness. Thus, interactions of functional traits and evenness may greatly affect ecosystem functioning.