title: Labile carbon retention compensates for CO2 released by priming in forest soils.
abstract: Increase of belowground C allocation by plants under global warming or elevated CO2 may promote decomposition of soil organic carbon (SOC) by priming and strongly affects SOC dynamics. The specific effects by priming of SOC depend on the amount and frequency of C inputs. Most previous priming studies have investigated single C additions, but they are not very representative for litterfall and root exudation in many terrestrial ecosystems. We evaluated effects of (13)C-labeled glucose added to soil in three temporal patterns: single, repeated, and continuous on dynamics of CO2 and priming of SOC decomposition over 6 months. Total and (13)C labeled CO2 were monitored to analyze priming dynamics and net C balance between SOC loss caused by priming and the retention of added glucose-C. Cumulative priming ranged from 1.3 to 5.5 mg C g(-1) SOC in the subtropical, and from -0.6 to 5.5 mg C g(-1) SOC in the tropical soils. Single addition induced more priming than repeated and continuous inputs. Therefore, single additions of high substrate amounts may overestimate priming effects over the short term. The amount of added glucose C remaining in soil after 6 months (subtropical: 8.1-11.2 mg C g(-1) SOC or 41-56% of added glucose; tropical: 8.7-15.0 mg C g(-1) SOC or 43-75% of glucose) was substantially higher than the net C loss due to SOC decomposition including priming effect. This overcompensation of C losses was highest with continuous inputs and lowest with single inputs. Therefore, raised labile organic C input to soils by higher plant productivity will increase SOC content even though priming accelerates decomposition of native SOC. Consequently, higher continuous input of C belowground by plants under warming or elevated CO2 can increase C stocks in soil despite accelerated C cycling by priming in soils.
authors.affiliation: Key Laboratory of Tropical Forest Ecology, Chinese Academy of Sciences, Xishuangbanna Tropical Botanical Garden, Menglun, Mengla, Yunnan, 666303, China; Graduate School of the Chinese Academy of Sciences, 19A Yuquan Road, Beijing, 100049, China.
authors.forename: Na
authors.initials: N
authors.lastname: Qiao
authors.forename: Douglas
authors.initials: D
authors.lastname: Schaefer
authors.forename: Evgenia
authors.initials: E
authors.lastname: Blagodatskaya
authors.forename: Xiaoming
authors.initials: X
authors.lastname: Zou
authors.forename: Xingliang
authors.initials: X
authors.lastname: Xu
authors.forename: Yakov
authors.initials: Y
authors.lastname: Kuzyakov
mesh_terms: D057486:Carbon Cycle; D002245:Carbon Dioxide / Q000378:metabolism*; D002681:China; D065928:Forests; D005947:Glucose / Q000378:metabolism; D012987:Soil / Q000737:chemistry*; D014329:Tropical Climate
chemical_list: D012987:Soil; D002245:Carbon Dioxide; D005947:Glucose
keywords: 13C; addition frequency; carbon balance; glucose; litter decomposition; priming effect; root exudates; soil organic matter stability; subtropical forest; tropical forest