title: Carbon and nitrogen additions induce distinct priming effects along an organic-matter decay continuum.
abstract: Decomposition of organic matter (OM) in soil, affecting carbon (C) cycling and climate feedbacks, depends on microbial activities driven by C and nitrogen (N) availability. However, it remains unknown how decomposition of various OMs vary across global supplies and ratios of C and N inputs. We examined OM decomposition by incubating four types of OM (leaf litter, wood, organic matter from organic and mineral horizons) from a decay continuum in a subtropical forest at Ailao Mountain, China with labile C and N additions. Decomposition of wood with high C:N decreased for 3.9 to 29% with these additions, while leaf decomposition was accelerated only within a narrow C:N range of added C and N. Decomposition of OM from organic horizon was accelerated by high C:N and suppressed by low C:N, but mineral soil was almost entirely controlled by high C:N. These divergent responses to C and N inputs show that mechanisms for priming (i.e. acceleration or retardation of OM decomposition by labile inputs) vary along this decay continuum. We conclude that besides C:N ratios of OM, those of labile inputs control the OM decay in the litter horizons, while energy (labile C) regulates decomposition in mineral soil. This suggests that OM decomposition can be predicted from its intrinsic C:N ratios and those of labile inputs.
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.affiliation: Key Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, 11A Datun Road, Chaoyang District, Beijing 100101, China.
authors.forename: Xingliang
authors.initials: X
authors.lastname: Xu
authors.affiliation: Key Laboratory of Tropical Forest Ecology, Chinese Academy of Sciences, Xishuangbanna Tropical Botanical Garden, Menglun, Mengla, Yunnan 666303, China.
authors.forename: Yuehua
authors.initials: Y
authors.lastname: Hu
authors.affiliation: Department of Soil Science of Temperate Ecosystems, and Department of Agricultural Soil Science, University of Göttingen, Göttingen, Germany.|Institute of Physicochemical and Biological Problems in Soil Science, Russian Academy of Sciences, Institutskaya, 26 Pushchino, Moscow Region, Russia, 142290.
authors.forename: Evgenia
authors.initials: E
authors.lastname: Blagodatskaya
authors.affiliation: Key Laboratory for Earth Surface Processes, Ministry of Education, Peking University, Beijing 100871, China.
authors.forename: Yongwen
authors.initials: Y
authors.lastname: Liu
authors.affiliation: Key Laboratory of Tropical Forest Ecology, Chinese Academy of Sciences, Xishuangbanna Tropical Botanical Garden, Menglun, Mengla, Yunnan 666303, China.
authors.forename: Douglas
authors.initials: D
authors.lastname: Schaefer
authors.affiliation: Department of Soil Science of Temperate Ecosystems, and Department of Agricultural Soil Science, University of Göttingen, Göttingen, Germany.
authors.forename: Yakov
authors.initials: Y
authors.lastname: Kuzyakov