Background and aims

Soil organic carbon (SOC) content dominates the organic carbon pools in grasslands. Thus, factors that influence and regulate SOC content must be clarified when addressing global climate change.

Methods

We investigated SOC in the top 10 cm of the soil layer from 109 plots of the Mongolian Plateau, including both desert-steppe and steppe landscapes. We then examined the association between SOC with grazing intensity, climatic factors, soil properties, and vegetation diversity indices.

Results

Desert-steppe samples had lower mean SOC than steppe samples (0.3% versus 1.5%). Desert-steppe SOC did not vary with grazing intensity, but steppe SOC did. Instead, desert-steppe SOC decreased and increased, respectively, with higher growing season temperature and soil electrical conductivity; these two variables were the major factors influencing SOC in this grassland type. Besides grazing, outside growing season precipitation and soil pH were the major environmental factors that correlated positively with steppe SOC.

Conclusion

The SOC of steppe grasslands was more sensitive to grazing than SOC of desert-steppe grasslands. Additionally, while climate, grazing, soil, and vegetation all regulated SOC, the most influential variables differed between the two grassland types. These findings enhance our understanding of SOC regulatory mechanisms in different grasslands on the Mongolian Plateau. Such knowledge is crucial for predicting the consequences of environmental change on carbon sequestration.

中文翻译：

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蒙古高原草原及荒漠草原土壤有机碳含量敏感性及调控因素

 背景和目标

土壤有机碳（SOC）含量在草地有机碳库中占主导地位。因此，在应对全球气候变化时，必须明确影响和调节SOC含量的因素。

 方法

我们调查了蒙古高原 109 个样地（包括荒漠草原和草原景观）土壤层表层 10 厘米的 SOC。然后我们研究了 SOC 与放牧强度、气候因素、土壤特性和植被多样性指数之间的关联。

 结果

沙漠草原样本的平均 SOC 低于草原样本（0.3% 与 1.5%）。荒漠草原 SOC 不随放牧强度变化，但草原 SOC 随放牧强度变化。相反，随着生长季温度和土壤电导率的升高，荒漠草原的 SOC 分别减少和增加；这两个变量是影响该草地类型SOC的主要因素。除放牧外，生长季外降水和土壤pH值是与草原SOC呈正相关的主要环境因素。

 结论

草原草地的SOC比荒漠草原草地的SOC对放牧更敏感。此外，虽然气候、放牧、土壤和植被都会调节 SOC，但两种草地类型之间影响最大​​的变量有所不同。这些发现增强了我们对蒙古高原不同草原SOC调控机制的理解。这些知识对于预测环境变化对碳封存的影响至关重要。