title: Soil Respiration and Bacterial Structure and Function after 17 Years of a Reciprocal Soil Transplant Experiment.
abstract: The effects of climate change on soil organic matter-its structure, microbial community, carbon storage, and respiration response-remain uncertain and widely debated. In addition, the effects of climate changes on ecosystem structure and function are often modulated or delayed, meaning that short-term experiments are not sufficient to characterize ecosystem responses. This study capitalized on a long-term reciprocal soil transplant experiment to examine the response of dryland soils to climate change. The two transplant sites were separated by 500 m of elevation on the same mountain slope in eastern Washington state, USA, and had similar plant species and soil types. We resampled the original 1994 soil transplants and controls, measuring CO2 production, temperature response, enzyme activity, and bacterial community structure after 17 years. Over a laboratory incubation of 100 days, reciprocally transplanted soils respired roughly equal cumulative amounts of carbon as non-transplanted controls from the same site. Soils transplanted from the hot, dry, lower site to the cooler and wetter (difference of -5°C monthly maximum air temperature, +50 mm yr-1 precipitation) upper site exhibited almost no respiratory response to temperature (Q10 of 1.1), but soils originally from the upper, cooler site had generally higher respiration rates. The bacterial community structure of transplants did not differ significantly from that of untransplanted controls, however. Slight differences in local climate between the upper and lower Rattlesnake locations, simulated with environmental control chambers during the incubation, thus prompted significant differences in microbial activity, with no observed change to bacterial structure. These results support the idea that environmental shifts can influence soil C through metabolic changes, and suggest that microbial populations responsible for soil heterotrophic respiration may be constrained in surprising ways, even as shorter- and longer-term soil microbial dynamics may be significantly different under changing climate.
authors.affiliation: Pacific Northwest National Laboratory, Joint Global Change Research Institute at the University of Maryland-College Park, 5825 University Research Court #3500, College Park, MD, 20740, United States of America.
authors.forename: Ben
authors.initials: B
authors.lastname: Bond-Lamberty
authors.affiliation: Pacific Northwest National Laboratory, 902 Battelle Boulevard, Richland, WA, 99352, United States of America.
authors.forename: Harvey
authors.initials: H
authors.lastname: Bolton
authors.affiliation: Pacific Northwest National Laboratory, 902 Battelle Boulevard, Richland, WA, 99352, United States of America.
authors.forename: Sarah
authors.initials: S
authors.lastname: Fansler
authors.affiliation: Pacific Northwest National Laboratory, 902 Battelle Boulevard, Richland, WA, 99352, United States of America.
authors.forename: Alejandro
authors.initials: A
authors.lastname: Heredia-Langner
authors.affiliation: Pacific Northwest National Laboratory, 902 Battelle Boulevard, Richland, WA, 99352, United States of America.
authors.forename: Chongxuan
authors.initials: C
authors.lastname: Liu
authors.affiliation: Pacific Northwest National Laboratory, 902 Battelle Boulevard, Richland, WA, 99352, United States of America.
authors.forename: Lee Ann
authors.initials: LA
authors.lastname: McCue
authors.affiliation: USDA-ARS, 215 Johnson Hall, Washington State University, Pullman, WA, 99164, United States of America.
authors.forename: Jeffrey
authors.initials: J
authors.lastname: Smith
authors.affiliation: Pacific Northwest National Laboratory, 902 Battelle Boulevard, Richland, WA, 99352, United States of America.
authors.forename: Vanessa
authors.initials: V
authors.lastname: Bailey
mesh_terms: D000531:Altitude; D001419:Bacteria / Q000145:classification / Q000254:growth & development / Q000378:metabolism*; D002245:Carbon Dioxide / Q000737:chemistry* / Q000378:metabolism; D002980:Climate; D017753:Ecosystem; D052836:Heterotrophic Processes; D059013:Microbial Consortia / Q000502:physiology*; D015233:Models, Statistical; D010944:Plants / Q000378:metabolism; D012987:Soil / Q000737:chemistry; D012988:Soil Microbiology; D013696:Temperature; D014861:Washington; D014867:Water / Q000737:chemistry
chemical_list: D012987:Soil; D014867:Water; D002245:Carbon Dioxide