Variability in community productivity-mediating effects of vegetation attributes

Authors: POLLEY, HERBERT; WILSEY, BRIAN - IOWA STATE UNIVERSITY

Submitted to: Functional Ecology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/18/2018
Publication Date: 4/23/2018
Citation: Polley, H.W., Wilsey, B.J. 2018. Variability in community productivity-mediating effects of vegetation attributes. Functional Ecology. 32:1410-1419. https://doi.org/10.1111/1365-2435.13080.
DOI: https://doi.org/10.1111/1365-2435.13080

Interpretive Summary: Agricultural managers usually seek to increase temporal stability (reduce inter-annual variability) of plant productivity. Improving our capacity to do so in extensively managed grasslands and other mixed-species forage systems with perennial plant species may require that we identify properties of production systems that are predictive of stability at different spatial scales. We evaluated two vegetation properties, species diversity and leaf area per unit of leaf mass (specific leaf area; SLA), as predictors of stability of aboveground productivity of mixed species grasslands in central Texas, USA. Increasing SLA stabilized grassland yield at the largest spatial scale considered by increasing annual productivity. Conversely, increased variability in SLA stabilized productivity of grassland patches (local scale) by reducing the influence of precipitation variability on yield. Stability was reduced slightly by increasing species diversity over the narrow range measured. Our results indicate that forage production on grasslands may be stabilized by both high values of and large inter-annual variability in SLA and, more generally, identify SLA variation as a management tool to facilitate timely intervention to maintain or increase grassland yield stability.

Technical Abstract: Improving our capacity to manage spatially-variable ecosystems is a priority in a rapidly changing world. One technique to do so is to use readily-measurable vegetation properties as surrogates or predictors of management targets. We evaluated two vegetation properties, species diversity and community-weighted values of specific leaf area (SLA), as predictors of inter-annual stability (inverse of variability) of aboveground net primary productivity (ANPP) at local and meta community scales. Meta communities were created by aggregating patches (local scale) of spatially-distinct assemblages of perennial plant species from grassland biodiversity experiments in Texas, USA. Increasing SLA stabilized productivity of meta communities by increasing ANPP. Increasing the variance in weighted SLA stabilized local ANPP because patch-scale differences in both the SLA effect on ANPP and SLA response to precipitation reduced the influence of precipitation variability on productivity. Conversely, increasing species diversity over the narrow range measured destabilized productivity by reducing mean ANPP because stability was high among exotic C4 grasses that dominated productive, low-diversity plots. Our results indicate that community ANPP may be stabilized by both high values of and large inter-annual variability in weighted SLA and, more generally, identify SLA variation as a tool to estimate community stability and contributing mechanisms.