Open AccessElevated CO2 decreases soil carbon stability in Tibetan Plateau
Author(s) -
Guang Zhao,
Chao Liang,
Xiaojuan Feng,
Lingli Liu,
Juntao Zhu,
Ning Chen,
Yao Chen,
Li Wang,
Yangjian Zhang
Publication year - 2020
Publication title -
environmental research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.37
H-Index - 124
ISSN - 1748-9326
DOI - 10.1088/1748-9326/abbb50
Subject(s) - mineralization (soil science) , soil carbon , soil organic matter , cycling , human fertilization , ecosystem , environmental chemistry , carbon cycle , nitrogen cycle , organic matter , chemistry , plateau (mathematics) , nitrogen , environmental science , agronomy , soil water , ecology , soil science , biology , forestry , mathematical analysis , mathematics , organic chemistry , geography
The lack of ecosystem-scale CO 2 enrichment experiments in alpine regions considerably restricts our ability to predict the feedback of the global carbon (C) cycle to climate change. Here we investigate soil C response in an experiment with 5-year CO 2 enrichment and nitrogen (N) fertilization in a Tibetan meadow (4585 m above the sea level). We found that despite non-significant increase in bulk soil C pool, elevated CO 2 dramatically altered the allocation of C in different soil fractions and soil mineralization potentials. By changing soil microbial composition and enhancing enzyme activities, elevated CO 2 significantly accelerated soil organic matter (SOM) mineralization rates and stimulated the microbial utilization of ‘old C’ relative to that of ‘new C’. Furthermore, N fertilization under elevated CO 2 altered the decomposition process, increased the fungi to bacteria ratio, and decreased the coarse particulate organic matter pool and enzyme activities, indicating that N fertilization counters the CO 2 fertilization effect. Overall, our findings suggest a growing threat of elevated CO 2 in reducing SOM stability, and highlight the key role of N availability in driving soil C turnover under elevated CO 2 .