Changes in the temperature sensitivity of SOM decomposition with grassland succession: implications for soil C sequestration. Issue 15 (14th November 2013)

• Record Type: Journal Article
• Authors: Nianpeng, He; Ruomeng, Wang; Yang, Gao; Jingzhong, Dai; Xuefa, Wen; Guirui, Yu
• Is Part Of: Ecology and evolution. Volume 3:Issue 15(2013)
• Page Start: 5045
• Page End: 5054
• Publication Date: 2013-11-14
• Subjects: Heterotrophic respiration -- Q10 -- soil organic matter -- stoichiometry -- substrate -- succession -- warming; Ecology -- Periodicals; Evolution -- Periodicals; 577.05
• DOI: 10.1002/ece3.881
• Languages: English
• ISSNs: 2045-7758

Abstract

Abstract: Understanding the temperature sensitivity ( Q 10 ) of soil organic matter (SOM) decomposition is important for predicting soil carbon (C) sequestration in terrestrial ecosystems under warming scenarios. Whether Q 10 varies predictably with ecosystem succession and the ways in which the stoichiometry of input SOM influences Q 10 remain largely unknown. We investigate these issues using a grassland succession series from free‐grazing to 31‐year grazing‐exclusion grasslands in Inner Mongolia, and an incubation experiment performed at six temperatures (0, 5, 10, 15, 20, and 25°C) and with four substrates: control (CK), glucose (GLU), mixed grass leaf (GRA), and Medicago falcata leaf (MED). The results showed that basal soil respiration (20°C) and microbial biomass C (MBC) logarithmically decreased with grassland succession. Q 10 decreased logarithmically from 1.43 in free‐grazing grasslands to 1.22 in 31‐year grazing‐exclusion grasslands. Q 10 increased significantly with the addition of substrates, and the Q 10 levels increased with increase in N:C ratios of substrate. Moreover, accumulated C mineralization was controlled by the N:C ratio of newly input SOM and by incubation temperature. Changes in Q 10 with grassland ecosystem succession are controlled by the stoichiometry of newly input SOM, MBC, and SOM quality, and the combined effects of which could partially explain the mechanisms underlying soil C sequestration in the long‐term grazing‐exclusion grasslands in Inner Mongolia, China. The findings highlight the effect of substrate stoichiometry on Q 10 which requires further study. Abstract : Q10 decreased logarithmically with grassland succession, and varied from 1.43 in free‐grazing grasslands to 1.22 in 31‐year grazing‐exclusion grasslands. Q10 increased significantly with added substrates, and higher N:C resulted in higher Q10.