title: Belowground Response to Drought in a Tropical Forest Soil. I. Changes in Microbial Functional Potential and Metabolism.
abstract: 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.affiliation: Earth Sciences Division, Ecology Department, Lawrence Berkeley National Laboratory Berkeley, CA, USA.
authors.forename: Nicholas J
authors.initials: NJ
authors.lastname: Bouskill
authors.affiliation: International Institute of Tropical Forestry, USDA Forest ServiceRio Piedras, PR, USA; Fundación Puertorriqueña de ConservaciónSan Juan, PR, USA.
authors.forename: Tana E
authors.initials: TE
authors.lastname: Wood
authors.affiliation: Life Sciences Division, Lawrence Berkeley National Laboratory Berkeley, CA, USA.
authors.forename: Richard
authors.initials: R
authors.lastname: Baran
authors.affiliation: Earth Sciences Division, Ecology Department, Lawrence Berkeley National Laboratory Berkeley, CA, USA.
authors.forename: Zaw
authors.initials: Z
authors.lastname: Ye
authors.affiliation: Life Sciences Division, Lawrence Berkeley National Laboratory Berkeley, CA, USA.
authors.forename: Benjamin P
authors.initials: BP
authors.lastname: Bowen
authors.affiliation: Earth Sciences Division, Ecology Department, Lawrence Berkeley National Laboratory Berkeley, CA, USA.
authors.forename: HsiaoChien
authors.initials: H
authors.lastname: Lim
authors.affiliation: Earth Sciences Division, Ecology Department, Lawrence Berkeley National LaboratoryBerkeley, CA, USA; Institute for Environmental Genomics and Department of Microbiology and Plant Biology, University of OklahomaNorman, OK, USA; State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua UniversityBeijing, China.
authors.forename: Jizhong
authors.initials: J
authors.lastname: Zhou
authors.affiliation: Institute for Environmental Genomics and Department of Microbiology and Plant Biology, University of Oklahoma Norman, OK, USA.
authors.forename: Joy D Van
authors.initials: JD
authors.lastname: Nostrand
authors.affiliation: Earth Sciences Division, Ecology Department, Lawrence Berkeley National Laboratory Berkeley, CA, USA.
authors.forename: Peter
authors.initials: P
authors.lastname: Nico
authors.affiliation: Life Sciences Division, Lawrence Berkeley National Laboratory Berkeley, CA, USA.
authors.forename: Trent R
authors.initials: TR
authors.lastname: Northen
authors.affiliation: Department of Environmental Science, Policy and Management, University of California-Berkeley Berkeley, CA, USA.
authors.forename: Whendee L
authors.initials: WL
authors.lastname: Silver
authors.affiliation: Earth Sciences Division, Ecology Department, Lawrence Berkeley National LaboratoryBerkeley, CA, USA; Department of Environmental Science, Policy and Management, University of California-BerkeleyBerkeley, CA, USA.
authors.forename: Eoin L
authors.initials: EL
authors.lastname: Brodie
keywords: drought; functional gene microarray; microbial ecology; osmolytes; tropical forests