Han Chunxue, Sun Zhiqiang, Li Haigang
College of Resources and Environmental Sciences, Inner Mongolia Agricultural University, Hohhot, 010011, China.
Inner Mongolia Key Laboratory of Soil Quality and Nutrient Resource, Hohhot, 010018, China.
Sci Rep. 2025 May 25;15(1):18235. doi: 10.1038/s41598-025-01977-1.
Quantification of soil carbon emissions in desert steppes is a key issue in determining the carbon budget in arid regions. However, the changes in and driving mechanisms of soil respiration and its components in response to drought in ecosystems under long-term water stress remain unclear. In this study, rain reduction by 30% and 50% experiments were conducted to simulate drought during the growing season in 2023 in the Stipa breviflora desert steppe. Total soil respiration and soil heterotrophic respiration were measured, and simultaneously, the surface soil temperature and moisture were measured at 0-10 cm. Surface soil microorganisms, microbial biomass carbon, and enzymatic activity were also tested. The results showed that drought significantly decreased soil microbial biomass carbon and enzymatic activity, but had no significant effects on soil microbial richness and diversity, as well as the dominant flora. The inhibitory effect of drought on soil autotrophic respiration only appeared at the beginning of the growing season and then disappeared with plant growth because of the drought-resistant ability of perennial plants in the desert steppe. Heterotrophic respiration is the primary soil carbon release process occurring in the desert steppe, approximately four times that of autotrophic respiration. Soil temperature and moisture jointly regulated heterotrophic respiration under extreme drought conditions (rainfall reduction of 50%); however, their influence on autotrophic respiration became insignificant. This study indicates that drought slowed the decomposition of soil organic carbon and had a weak effect on plant root respiration in the S. breviflora desert steppe. The response process of Rs and its components to drought stress provided theoretical basis for soil carbon feedback in desert steppe under extreme drought conditions.
荒漠草原土壤碳排放的量化是确定干旱地区碳收支的关键问题。然而，长期水分胁迫下生态系统中土壤呼吸及其组分对干旱的响应变化和驱动机制仍不清楚。本研究于2023年生长季在短花针茅荒漠草原开展了30%和50%的降水减少试验以模拟干旱。测定了土壤总呼吸和土壤异养呼吸，同时测定了0-10厘米表层土壤温度和湿度。还测试了表层土壤微生物、微生物生物量碳和酶活性。结果表明，干旱显著降低了土壤微生物生物量碳和酶活性，但对土壤微生物丰富度、多样性以及优势菌群没有显著影响。干旱对土壤自养呼吸的抑制作用仅在生长季初期出现，随后由于荒漠草原多年生植物的抗旱能力随着植物生长而消失。异养呼吸是荒漠草原土壤碳释放的主要过程，约为自养呼吸的四倍。在极端干旱条件下（降水减少50%），土壤温度和湿度共同调节异养呼吸；然而，它们对自养呼吸的影响变得不显著。本研究表明，干旱减缓了短花针茅荒漠草原土壤有机碳的分解，对植物根系呼吸的影响较弱。土壤呼吸及其组分对干旱胁迫的响应过程为极端干旱条件下荒漠草原土壤碳反馈提供了理论依据。
