Soil animal responses to moisture availability are largely scale, not ecosystem dependent: Insight from a cross-site study

Authors: SILVAIN, ZACHARY - Colorado State University; WALL, DIANA - Colorado State University; CHERWIN, KARIE - Colorado State University; Peters, Debra; REICHMANN, LARA - Non ARS Employee; SALA, OSVALDO - Arizona State University

Submitted to: Global Change Biology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/6/2013
Publication Date: 2/15/2014
Publication URL: http://handle.nal.usda.gov/10113/61730
Citation: Silvain, Z., Wall, D., Cherwin, K.L., Peters, D.C., Reichmann, L.G., Sala, O.E. 2014. Soil animal responses to moisture availability are largely scale, not ecosystem dependent: Insight from a cross-site study. Global Change Biology. 20:2631-2643.

Interpretive Summary: We examined how communities of mites and nematodes respond to changes in moisture availability and whether common patterns occur along fine-scale gradients of soil moisture within four individual ecosystem types (mesic, xeric and arid grasslands and a polar desert), as well as across a cross-ecosystem moisture gradient (CEMG) of all four ecosystems considered together. We found that while both mites and nematodes increased with available soil moisture across the CEMG, within individual ecosystems increases in soil moisture resulted in decreases to nematode communities at all but the arid grassland ecosystem; mites showed no responses at any ecosystem. Changes in proportional abundances of mite and nematode trophic groups as soil moisture increased within individual ecosystems may lead to shifts within soil food webs with important consequences for ecosystem functioning. We suggest that communities of soil animals at local scales may respond predictably to changes in moisture availability regardless of ecosystem type but that additional factors, such as climate variability, vegetation composition and soil properties may influence this relationship over larger scales.

Technical Abstract: Climate change will result in reduced soil water availability in much of the world either due to changes in precipitation or increased temperature and evapotranspiration. Responses of communities of mites and nematodes to changes in moisture availability are not well known, yet these organisms play important roles in decomposition and nutrient cycling processes. We determined how communities of these organisms respond to changes in moisture availability and whether common patterns occur along fine-scale gradients of soil moisture within four individual ecosystem types (mesic, xeric and arid grasslands and a polar desert) located in the western United States and Antarctica, as well as across a cross-ecosystem moisture gradient (CEMG) of all four ecosystems considered together. An elevation transect of three sampling plots was monitored within each ecosystem and soil samples were collected from these plots and from existing experimental precipitation manipulations within each ecosystem once in fall of 2009 and three times each in 2010 and 2011. We found that while both mites and nematodes increased with available soil moisture across the CEMG, within individual ecosystems increases in soil moisture resulted in decreases to nematode communities at all but the arid grassland ecosystem; mites showed no responses at any ecosystem. Changes in proportional abundances of mite and nematode trophic groups as soil moisture increased within individual ecosystems may result in shifts within soil food webs with important consequences for ecosystem functioning. We suggest that communities of soil animals at local scales may respond predictably to changes in moisture availability regardless of ecosystem type but that additional factors, such as climate variability, vegetation composition and soil properties may influence this relationship over larger scales.