Shift in relative importance of complementarity and selection drives different effects of community evenness on richness-invasibility relationships

How biodiversity affects ecosystem functioning is context-dependent. Competition for different resources (e.g., light vs. soil water) may lead to differential effects of species richness and their relative abundance (evenness) on ecosystem functioning. We constructed experimental communities with different richness and evenness levels and let them be invaded by an exotic annual Conyza canadensis or not at both xeric and mesic sites. Community invasibility negatively correlated with species richness at both high and low evenness in the xeric site, but only at high evenness in the mesic site. In the xeric site, soil water competition determined community invasibility, and complementarity effects and changes in niche overlap between invader and native species were the main mechanism for diversity effect on invasibility. In contrast, in the mesic site, light competition determined community invasibility, and selection effects due to presence of competitively superior native species played k..., Study sites
We conducted two experiments in two sites with contrasting environmental conditions. One site was located in Linhai (28°09′N, 121°53′E), Zhejiang Province, in southeastern China, and the other site was located in Shenmu (38°83′N, 110°51′E), Shanxi Province, in northwestern China. Linhai has a subtropical monsoon climate with a mean annual temperature of 19.5°C and an annual mean rainfall of 1800 mm, and Shenmu has a semi-arid continental climate with a mean annual temperature of 8.9°C and an annual mean rainfall of 423 mm. 
We carried out a survey of the natural grassland communities in both Linhai and Shenmu. We selected 10 plots of 1 m × 1 m in each site. In Linhai, a total of 34 plant species were recorded, and species richness in 1 m × 1 m plots was 10 ± 2 (mean ± SE). Of the 34 species, 16 were common and used for the Linhai ex..., , # Data from: Shift in relative importance of complementarity and selection drives different effects of community evenness on richness-invasibility relationships

[https://doi.org/10.5061/dryad.3ffbg79t7](https://doi.org/10.5061/dryad.3ffbg79t7)

## Description of the data and file structure

## Linhai experiment

In the mesic Linhai site, we used 16 common native species (electronic supplementary material, table S1) to construct experimental communities with five levels of species richness (1, 2, 4, 8 and 12 species) and two levels of evenness (low and high). In October 2010, we built 352 plots (1 m × 1 m × 1 m) aboveground with bricks in an abandoned farmland in Linhai, and each plot was filled with a loamy soil collected in the Yunfeng mountain area near Linhai (organic matter: 1.44 ± 0.19 g kg-1; total P: 0.13 ± 0.03 g kg-1; total N: 0.62 ± 0.17 g kg-1). We planted two plots with monocultures of each of the 16 species (totaling 32 plots) and four plots with each of the 20 mixtures co...,