The effect of climatic and edaphic factors on soil organic carbon turnover in hummocks based on δ13C on the Qinghai-Tibet Plateau

Hanzhi Li; Feng Yan; Dengfeng Tuo; Bin Yao; Junhan Chen

doi:10.1016/j.scitotenv.2020.140141

The effect of climatic and edaphic factors on soil organic carbon turnover in hummocks based on δ¹³C on the Qinghai-Tibet Plateau

Sci Total Environ. 2020 Nov 1:741:140141. doi: 10.1016/j.scitotenv.2020.140141. Epub 2020 Jun 17.

Authors

Hanzhi Li¹, Feng Yan², Dengfeng Tuo¹, Bin Yao¹, Junhan Chen¹

Affiliations

¹ Institute of Desertification Studies, Chinese Academy of Forestry, 100091 Beijing, China.
² Institute of Desertification Studies, Chinese Academy of Forestry, 100091 Beijing, China. Electronic address: fyan@caf.ac.cn.

PMID: 32615420
DOI: 10.1016/j.scitotenv.2020.140141

Abstract

Hummocks (thúfur, pounus) are peculiar landforms usually formed by repeated freeze-thaw processes and differential frost heave, and are common in frost soil regions, especially in the Qinghai-Tibet Plateau. However, little is known about the response of δ¹³C in soil organic carbon (δ¹³C_SOC) to soil and climate properties in hummocks. The β value indicates the decomposition rate of soil organic carbon (SOC) in soil, and was obtained from the slope of the regression between the log10-transformed SOC concentration and δ¹³C_SOC in soil depth profiles. In this study, we investigated δ¹³C_SOC and SOC contents along a soil profile (0-60 cm), together with edaphic and climatic properties, both in hummocks and control plots (alpine grasslands) on the northeastern Qinghai-Tibet Plateau. Then, the variations in δ¹³C_SOC and β values, and the main factors affecting them, were analyzed. The results show that δ¹³C_SOC increases with soil depth, while SOC decreases both in the hummocks and control plots. However, β values in the hummocks were significantly (P < 0.05) higher than in the control plots while δ¹³C_SOC showed no difference between hummock and control. Redundancy analysis showed that altitude is the main control factor for δ¹³C_SOC and β in the hummocks. Climate type was the main factor affecting δ¹³C_SOC in the control plots, while mean annual precipitation and soil fractal dimension were the main factors controlling β. Overall, climate, rather than soil, is the key factor that affects the carbon turnover rate in the hummock in the northeastern QTP. The findings of this study will expand our understanding of the soil carbon cycle and δ¹³C_SOC changes, especially in the case of hummocks.

Keywords: Carbon isotope; Climate change; Hummock; Soil organic carbon turnover.