Temporal stability of grassland metacommunities is regulated more by community functional traits than species diversity

Authors: Polley, Herbert; Yang, Chenghai; WILSEY, BRIAN - Iowa State University; Fay, Philip

Submitted to: Ecosphere
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/13/2020
Publication Date: 7/8/2020
Citation: Polley, H.W., Yang, C., Wilsey, B.J., Fay, P.A. 2020. Temporal stability of grassland metacommunities is regulated more by community functional traits than species diversity. Ecosphere. 11(7):e03178. https://doi.org/10.1002/ecs2.3178.
DOI: https://doi.org/10.1002/ecs2.3178

Interpretive Summary: Improving our capacity to sustainably manage grasslands for livestock or bioenergy production requires that we better understand how plant communities affect the reliability (stability) in grassland biomass production through time. Stability in aboveground biomass production potentially is influenced by several attributes of plant communities. We assessed effects of two groups of attributes on temporal stability in biomass production of restored grassland growing on two soil types in central Texas, USA. Attributes included two components of plant species diversity (diversity of local communities and species dissimilarity among local communities) and spatial differences in two community ‘functional’ traits’ [mean aboveground biomass and community leaf dry matter content (LDMC), the ratio of leaf dry weight to leaf saturated weight]. Community LDMC was calculated by weighting LDMC per species by the abundance of each species in the plant community. Results demonstrated that grassland production at the spatial scale of paired local communities was stabilized over 4 years primarily by differences in community functional traits rather than by increased diversity. Spatial differences in community mean biomass and LDMC stabilized biomass production by increasing differences in the production responses of spatially distinct communities to inter-annual variation in precipitation. We conclude that reliability in grassland biomass production can be improved by increasing spatial variation in the abundances of species that differ in functional attributes that link plant growth responses to precipitation variation.

Technical Abstract: Temporal stability in aboveground net primary productivity (ANPP) is influenced by several attributes of plant communities. Identifying the primary regulators of stability and their roles across spatial scales is of both practical and theoretical importance. We assessed effects of species diversity (local or alpha diversity and species dissimilarity among local communities) together with spatial differences in two community functional attributes (mean aboveground biomass and community leaf dry matter content, LDMC) on temporal stability in spring ANPP of restored grassland. Biomass, community LDMC, and species dissimilarity were derived from remote measurements of canopy reflectance of grassland on two soil types. Results demonstrated that productivity at the larger spatial scale of the metacommunity (communities connected by dispersal) was stabilized primarily by spatial differences in community functional traits rather than by increased diversity. Spatial differences in community biomass and LDMC stabilized metacommunity productivity by increasing differences in the productivity responses of spatially distinct communities to interannual variation in precipitation (by increasing spatial asynchrony in ANPP response), but de-stabilized ANPP on one soil type by reducing the temporal stability of local communities. Our results demonstrate the utility of remote sensing for quantifying community attributes useful to assess or predict temporal stability of grassland ANPP. We conclude that stability in productivity depended largely on community differences in functional attributes that couple plant growth to changes in resource availability.