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No significant changes in topsoil carbon in the grasslands of northern China between the 1980s and 2000s
作   者:Liu, Shangshi; Yang, Yuanhe; Shen, Haihua; et.al
期刊名称:SCIENCE OF THE TOTAL ENVIRONMENT
影响因子:5.102
出版年份:2018
卷 期 号:624
页     码:: 1478-148
论文摘要:
The grasslands of northern China store a large amount of soil organic carbon (SOC), and the small changes in SOC stock could significantly affect the regional C cycle. However, recent estimates of SOC changes in this region are
highly controversial. In this study, we examined the changes in the SOC density (SOCD) in the upper 30 cmof the grasslands of northern China between the 1980s and 2000s, using an improved approach that integrates fieldbased
measurements into machine learning algorithms (artificial neural network (ANN) and random forest (RF)). The RF-generated SOCD averaged 5.55 kg C m−2 in the 1980s and 5.53 kg C m−2 in the 2000s, and the change ranged from −0.17 to 0.22 kg C m−2 at the 95% confidence level, suggesting that the overall SOCD did
not vary significantly during the study period. However, the change in SOCD exhibited large regional variability; the topsoil of the InnerMongolian grasslands experienced significant C loss (4.86 vs. 4.33 kg Cm−2),while that of
the Xinjiang grasslands exhibited an accumulation of C (5.55 vs. 6.46 kg Cm−2). Furthermore, the topsoil C in the Tibetan alpine grasslands remained relatively stable (6.12 vs. 6.06 kg Cm−2). A comparison of the different grassland types indicated that SOCD significantly decreased in typical steppe,whereas it increased inmountainmeadow, and remained stable in the other grasslands (alpine meadow, alpine steppe, mountain steppe and desert
steppe). Climate change could partly explain the changes in the SOCD of the different grassland types. Increases in precipitation could lead to SOC accumulation in temperate grasslands and SOC loss in alpine grasslands,while
climate warming is likely to cause SOC loss in temperate grasslands. Overall, our study suggests that the grasslands of northern China remained a neutral SOC sink between the 1980s and 2000s.
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