title: Interactions between soil and tree roots accelerate long-term soil carbon decomposition.
abstract: Decomposition of soil organic carbon (SOC) is the main process governing the release of CO(2) into the atmosphere from terrestrial systems. Although the importance of soil-root interactions for SOC decomposition has increasingly been recognized, their long-term effect on SOC decomposition remains poorly understood. Here we provide experimental evidence for a rhizosphere priming effect, in which interactions between soil and tree roots substantially accelerate SOC decomposition. In a 395-day greenhouse study with Ponderosa pine and Fremont cottonwood trees grown in three different soils, SOC decomposition in the planted treatments was significantly greater (up to 225%) than in soil incubations alone. This rhizosphere priming effect persisted throughout the experiment, until well after initial soil disturbance, and increased with a greater amount of root-derived SOC formed during the experiment. Loss of old SOC was greater than the formation of new C, suggesting that increased C inputs from roots could result in net soil C loss.
authors.affiliation: Department of Environmental Studies, University of California, Santa Cruz, CA 95064, USA. feike.dijkstra@ars.usda.gov
authors.forename: Feike A
authors.initials: FA
authors.lastname: Dijkstra
authors.forename: Weixin
authors.initials: W
authors.lastname: Cheng
mesh_terms: D000704:Analysis of Variance; D018533:Biomass; D002244:Carbon / Q000378:metabolism*; D002245:Carbon Dioxide / Q000378:metabolism; D041604:Pinus ponderosa / Q000378:metabolism* / Q000382:microbiology; D018517:Plant Roots / Q000378:metabolism* / Q000382:microbiology; D011157:Population Dynamics; D032107:Populus / Q000378:metabolism* / Q000382:microbiology; D027343:Rhizome / Q000378:metabolism; D012987:Soil; D012988:Soil Microbiology; D013045:Species Specificity; D013997:Time Factors
chemical_list: D012987:Soil; D002245:Carbon Dioxide; D002244:Carbon