Decomposition in Drylands: Soil Erosion and UV Interactions

This collaborative project seeks to understand the fundamental drivers of decomposition in arid grasslands. Recent independent studies have suggested that both UV and soil erosion/deposition play critical roles in this important ecosystem process, potentially in contrasting ways. This project tests the hypothesis that radiant energy (UV) and soil movement drivers interact, such that UV effects on litter decomposition predominate up to a certain level of soil deposition and are then negated. Therefore, shifts in grass-woody plant abundance in drylands affect decomposition rates by mediating soil transport processes that determine the extent of litter-soil contact; and that enhancement of microbial activity by soil accumulation more than offsets associated reductions in UV photodegradation. We provide part of the microbial component of this project. We have developed phospholipid fatty acid profiles of the litter as it degrades, which tells us something about the dominant microbial taxonomic groups present in the litter and their response to environmental drivers like UV, soil mixing, and water availability. We are currently expanding this work onto the European continent, looking at the role of UV in litter decomposition in cork oak woodlands in Portugal that are being invaded by a native shrub -Cistus ladanifer.

Collaborators: Steve Archer (University of Arizona),  Dave Breshears (University of Arizona), Heather Throop (New Mexico State University), Paul Barnes (Loyola University New Orleans)
Both the Arizona and Portugal field decomposition projects have ended.  Lab work, data analysis, and manuscript development continue.
 
Associated Manuscripts:
Barnes, P.W., H.L. Throop, S.R. Archer, D.D. Breshears, R.L. McCulley, and M.A. Tobler. 2015. Sunlight and soil-litter mixing: drivers of litter decomposition in drylands. Progress in Botany 76:273-302.  doi: 10.1007/978-3-319-08807-5_11
Lee, H., J. Fitzgerald, D.B. Hewins, R.L. McCulley, S.R. Archer, T. Rahn, and H.L. Throop. 2014. Soil moisture and soil-litter mixing effects on surface litter decomposition: A controlled environment assessment. Soil Biology & Biochemistry 72:123-132.
Hewins, D., S. Archer, G. Okin, R.L. McCulley, and H. Throop. 2013. Soil-litter mixing accelerates decomposition in a Chihuahuan Desert grassland. Ecosystems 16:183-195.
 
Please contact Rebecca for copies.