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Title: Belowground Response to Drought in a Tropical Forest Soil. I. Changes in Microbial Functional Potential and Metabolism

We report that global climate models predict a future of increased severity of drought in many tropical forests. Soil microbes are central to the balance of these systems as sources or sinks of atmospheric carbon (C), yet how they respond metabolically to drought is not well-understood. We simulated drought in the typically aseasonal Luquillo Experimental Forest, Puerto Rico, by intercepting precipitation falling through the forest canopy. This approach reduced soil moisture by 13% and water potential by 0.14 MPa (from -0.2 to -0.34). Previous results from this experiment have demonstrated that the diversity and composition of these soil microbial communities are sensitive to even small changes in soil water. Here, we show prolonged drought significantly alters the functional potential of the community and provokes a clear osmotic stress response, including the production of compatible solutes that increase intracellular C demand. Subsequently, a microbial population emerges with a greater capacity for extracellular enzyme production targeting macromolecular carbon. Significantly, some of these drought-induced functional shifts in the soil microbiota are attenuated by prior exposure to a short-term drought suggesting that acclimation may occur despite a lack of longer-term drought history.
Authors:
 [1] ;  [2] ;  [3] ;  [1] ;  [3] ;  [1] ;  [4] ;  [5] ;  [1] ;  [3] ;  [6] ;  [7]
  1. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Earth Sciences Division
  2. USDA Forest Service, Rio Piedras, PR (United States). Institute of Tropical Forestry; Puerto Rican Conservation Foundation, San Juan, PR (United States)
  3. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Life Sciences Division
  4. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Earth Sciences Division; Univ. of Oklahoma, Norman, OK (United States); Tsinghua Univ., Beijing (China)
  5. Univ. of Oklahoma, Norman, OK (United States)
  6. Univ. of California, Berkeley, CA (United States)
  7. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Earth Sciences Division; Univ. of California, Berkeley, CA (United States)
Publication Date:
OSTI Identifier:
1256971
Grant/Contract Number:
AC02-05CH11231; EAR-08199072
Type:
Accepted Manuscript
Journal Name:
Frontiers in Microbiology
Additional Journal Information:
Journal Volume: 7; Journal ID: ISSN 1664-302X
Publisher:
Frontiers Research Foundation
Research Org:
Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)
Sponsoring Org:
USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC-23)
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES