DOI: 10.5061/dryad.r7sqv9sc2
title: Functional diversity response to geographic and experimental precipitation gradients varies with plant community type

description: Precipitation is a primary determinant of plant community structure in
 drylands. However, the empirical evidence and predictions are lacking for
 how plant functional diversity in desert and steppe communities respond to
 altered precipitation regimes. We examined how precipitation changes along
 the natural and experimental gradients affect different components of
 functional diversity in desert-shrub and steppe-grass communities. We
 compared the associations of precipitation changes with community-weighted
 means (CWM) of six traits, functional divergence (FDvar) of each
 single-trait, and multi-trait functional richness (FRic) and dispersion
 (FDis) for shrub and grass communities along the natural and experimental
 gradients. We also disentangle the roles of species turnover and
 intraspecific variations in affecting the responses of different
 functional diversity to precipitation changes. We found that in general,
 the similar responses of functional traits or diversity to both the
 natural and experimental precipitation gradient were dependent on plant
 community type. Across both two gradients, precipitation was positively
 associated with CWM of plant height and negatively associated with the CWM
 of specific leaf area and leaf thickness in grass community, while
 positively associated with FDvar of four traits and FDis in shrub
 communities. Both species turnover and intraspecific variations
 contributed to the responses of grass community traits to precipitation
 changes across both two gradients, and to functional divergence of traits
 and FDis in shrub community along the natural gradient. In contrast,
 species turnover variations contributed to functional divergence of traits
 and FDis in shrub community in experiment. These results suggest that
 there is better concordance between the effects of naturally and
 experimentally increased precipitation on functional diversity of plant
 communities, but different mechanisms behind the relationship of
 functional diversity-precipitation between shrub and grass communities.
 Grass communities can adapt to precipitation changes by average trait
 differences, while shrub communities persist through the functional
 divergence of single-trait and multi-trait dispersion, thus highlighting
 the important differences in adaptive strategies between shrub and grass
 communities. Our findings demonstrate that the short-term responses of
 plant communities to manipulative precipitation changes can reflect
 long-term shifts at spatial scales depending on the specific functional
 trait and diversity.
description: The dataset was collected
 form a comparative study of how precipitation changes along the natural
 and experimental gradients affect different components of functional
 diversity in desert-shrub and steppe-grass communities. The trait data on
 CWM were calculated by multiplying the trait value of each species by its
 relative biomass in the community. FDvar were calculated form the
 variation in single-trait value weighted by the abundance of each species
 in plant community. Functional richness (FRic) and dispersion (FDis) were
 calculated form log-transformed values of six single traits. Functional
 diversity indices of CWM, FDvar, FRic and FDis were calculated by the
 FDiversity and R package.