西藏高寒草原沙化进程对土壤微生物代谢限制及其
对土壤碳固存的影响

doi:10.1016/j.jia.2024.07.038

摘要/Abstract

摘要：

作为重要的陆地碳（C）库，脆弱敏感的西藏高寒草原在全球变化和过度放牧的影响下沙化问题日益突出。草地沙化可能会加剧地上植物群落和地下微生物群落的养分限制状态，进而影响高寒草原土壤C储量。土壤氮（N）和磷（P）作为植物生长和微生物代谢的重要养分来源，然而，目前对沙化过程中植物和土壤微生物群落受N和P限制情况及其作用机理仍不清楚。本研究利用生态酶化学计量的方法评估了高寒草原五个不同沙化阶段（包含未退化、轻度、中度、重度和极度沙化）下植物和土壤微生物的养分限制状态。研究结果表明:（1）土壤微生物代谢主要受C和P限制，随沙化程度的加深，植物N限制和微生物C限制有所加剧，微生物P限制得到缓解；（2）植物-土壤-微生物相互作用对微生物C和P限制有显著的影响, 解释度分别为72%和61%。具体而言，沙化通过调节土壤pH、土壤养分和植物N限制来影响微生物代谢限制；（3）微生物C限制进一步降低了微生物的C利用效率（CUE），从而不利于沙化土壤中有机C的保留。本研究揭示了在植物-微生物相互作用下的微生物代谢限制是影响土壤微生物CUE的关键驱动因素，并为推进微生物调节养分循环和C固存提供了新的见解。

Abstract:

Tibetan alpine steppes are large and sensitive terrestrial carbon (C) reservoirs that are experiencing desertification due to global change and overgrazing, which can lead to stronger resource limitations for both above- and below-ground communities. Soil nutrients, especially nitrogen (N) and phosphorus (P), are the crucial resources for plant growth and microbial metabolism. However, whether both plant and soil microbial communities in the degraded alpine steppes are limited by these soil nutrients remains unclear, which limits our understanding of the mechanisms of desertification and subsequent ecosystem restoration. Here, we evaluated potential nutrient limitations of the plant and soil microbial communities in the alpine steppe across five stages of desertification using stoichiometry-based approaches. Our results showed that soil microbial metabolism was mainly limited by C and P, and the plant N limitation and microbial C limitation were intensified while the microbial P limitation was relieved during desertification. Plant-soil-microbe interactions had significant impacts on the microbial C and P limitations, explaining 72 and 61% of the variation, respectively. Specifically, desertification ultimately affected microbial metabolic limitations by regulating soil pH, soil nutrients, and the plant N limitation. Moreover, the microbial C limitation further reduced microbial C use efficiency (CUE) with desertification, which is detrimental for organic C retention in the degraded soil. Overall, this study revealed that microbial metabolic limitations through plant-microbe interactions were the key drivers affecting soil microbial CUE, and it provided insights that can advance our knowledge of the microbial regulation of nutrient cycles and C sequestration.

Key words: desertification gradient , ecoenzymatic stoichiometry , microbial metabolic limitation , carbon use efficiency , alpine steppe

Jialuo Yu, Peili Shi, Ning Zong, Yongxing Cui, Ge Hou, Xueying Chen, Tiancai Zhou, Xiaofang Huang. 西藏高寒草原沙化进程对土壤微生物代谢限制及其对土壤碳固存的影响[J]. Journal of Integrative Agriculture, 2025, 24(3): 845-858.

Jialuo Yu, Peili Shi, Ning Zong, Yongxing Cui, Ge Hou, Xueying Chen, Tiancai Zhou, Xiaofang Huang. The desertification process alters soil microbial metabolic limitations and their effects on soil carbon sequestration in a Tibetan alpine steppe[J]. Journal of Integrative Agriculture, 2025, 24(3): 845-858.

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