The Tibetan Plateau, the low-latitude and high-altitude cold region, has a variety of soils rich in organic carbon (C). Climate change will have large impacts on soil carbon dioxide (CO2) efflux in the region. These impacts will subsequently affect global-scale climate and C cycle links. However, the magnitude of this feedback is still uncertain. Here we use a laboratory incubation experiment to investigate how soil temperature and moisture affected the rate and temperature sensitivity of heterotrophic respiration of three alpine ecosystems (alpine meadow [M], alpine shrubland [SB], alpine swamp [SP]) on the Tibetan Plateau. Soil samples were incubated under three temperature (0°C, 15°C, and 30°C) and two moisture (50% and 100% water-holding capacity) conditions. The response of soil respiration to temperature and moisture varied with ecosystems. Soil respiration in SP was the most temperature sensitive, and higher moisture increased its temperature sensitivity (Q10). The respiration and Q10 depended on total nitrogen in soils. Moreover, high moisture increased the dependence of Q10 on total nitrogen. Our results suggest that rising temperature in Tibetan Plateau may cause a positive feedback to the soil C cycle, particularly coupled with increasing precipitation and N addition.
1Key Laboratory of Adaptation and Evolution of Plateau Biota, Haibei Alpine Meadow Ecosystem Research Station, Northwest Institute of Plateau Biology, Chinese Academy of Sciences, Xining, China.
2Institute of Soil and Water Conservation, Northwest A & F University, Yangling, China.
3Graduate University, Chinese Academy of Sciences, Beijing, China.
4Laboratory of Alpine Ecology and Biodiversity of Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing, China.
5Naqu Ecological and Environmental Observation and Research Station, University of Tibet and Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Naqu, China.
6College of Life and Geography, Qinghai Normal University, Xining, China.
Address for correspondence: Xiaofeng Chang, PhD, Northwest Institute of Plateau Biology, 23 Xin’ning Road, Xining, Qinghai, 810008, China; E-mail: email@example.com
Financial Disclosures/Conflicts of Interest: This research was funded by the Chinese National Natural Science Foundation (41030105), the Special Program of Carbon Sequestration of the Chinese Academy of Sciences (XDA05070205), the National Basic Research Program (2010CB833502), and the Kunlun Scholarship of Qinghai Province.
X.C. and X.Z. made an equal contribution to this article.
Financial Disclosures/Conflicts of Interest: None reported.
Received February 8, 2012.
Accepted for publication July 25, 2012.