title: Soil microbial and nutrient responses to 7 years of seasonally altered precipitation in a Chihuahuan Desert grassland.
abstract: Soil microbial communities in Chihuahuan Desert grasslands generally experience highly variable spatiotemporal rainfall patterns. Changes in precipitation regimes can affect belowground ecosystem processes such as decomposition and nutrient cycling by altering soil microbial community structure and function. The objective of this study was to determine if increased seasonal precipitation frequency and magnitude over a 7-year period would generate a persistent shift in microbial community characteristics and soil nutrient availability. We supplemented natural rainfall with large events (one/winter and three/summer) to simulate increased precipitation based on climate model predictions for this region. We observed a 2-year delay in microbial responses to supplemental precipitation treatments. In years 3-5, higher microbial biomass, arbuscular mycorrhizae abundance, and soil enzyme C and P acquisition activities were observed in the supplemental water plots even during extended drought periods. In years 5-7, available soil P was consistently lower in the watered plots compared to control plots. Shifts in soil P corresponded to higher fungal abundances, microbial C utilization activity, and soil pH. This study demonstrated that 25% shifts in seasonal rainfall can significantly influence soil microbial and nutrient properties, which in turn may have long-term effects on nutrient cycling and plant P uptake in this desert grassland.
authors.affiliation: Natural Resource Ecology Laboratory, Colorado State University, Fort Collins, CO, 80524 - 1499, USA; Department of Biological Sciences, Texas Tech University, Lubbock, TX, 79409 - 3131, USA.
authors.forename: Colin W
authors.initials: CW
authors.lastname: Bell
authors.forename: David T
authors.initials: DT
authors.lastname: Tissue
authors.forename: Michael E
authors.initials: ME
authors.lastname: Loik
authors.forename: Matthew D
authors.initials: MD
authors.lastname: Wallenstein
authors.forename: Veronica
authors.initials: V
authors.lastname: Acosta-Martinez
authors.forename: Richard A
authors.initials: RA
authors.lastname: Erickson
authors.forename: John C
authors.initials: JC
authors.lastname: Zak
mesh_terms: D001419:Bacteria / Q000378:metabolism; D057231:Climate Change; D003889:Desert Climate; D005658:Fungi / Q000378:metabolism; D065948:Grassland; D064307:Microbiota; D011891:Rain; D012621:Seasons; D012987:Soil / Q000737:chemistry*; D012988:Soil Microbiology; D013781:Texas
chemical_list: D012987:Soil
keywords: Big Bend National Park; desert ecosystems; extreme climate events; precipitation manipulation; soil microbial communities