Gan Dezhao, Yu Dongsheng, Zuo Hongchao, Li Zheng, Zhang Zelong, Li Huinan, Lin Zhenrong, Wang Hui, Zhou Qingping, Wang Jinsong, Niu Shuli, Long Ruijun, Ma Lei
College of Atmospheric Sciences, Lanzhou University, Lanzhou, People's Republic of China.
College of Pratacultural Science, Gansu Agricultural University/Key Laboratory of Grassland Ecosystem, Ministry of Education, Lanzhou, People's Republic of China.
Glob Chang Biol. 2025 Jul;31(7):e70342. doi: 10.1111/gcb.70342.
Tibetan alpine grasslands (AG) serve as critical methane (CH) sinks, yet face degradation from anthropogenic and climatic disturbances that promote subterranean rodents (e.g., Plateau zokor [Myospalax baileyi] and pika [Ochotona curzoniae]) activities. Although rodent bioturbation (e.g., burrowing, foraging and excreting) alters soil structure, soil physico-chemical properties and productivity from AG, its impacts on CH uptake remain poorly understood. Among the first, we combined paired year-round CH flux measurements from Plateau zokor mounds (ZM) and surrounding healthy meadow (HM) patches in Tibetan alpine meadow with collated CH fluxes from meta- and synthetic analyses across Tibetan AG, temperate grasslands (TG) and tropical grasslands (TrG) globally. We observed that rodent bioturbation significantly (p < 0.001) doubled annual CH uptake (HM: -0.91 ± 0.08 kg C ha vs. ZM: -1.80 ± 0.19 kg C ha, mean ± standard error, negative values indicate uptake). Notably, 67% of this net increase (-0.89 ± 0.10 kg C ha year) due to rodent bioturbation occurred during the growing season. Meta-analysis results revealed this phenomenon associated with significantly (p < 0.001) decreased topsoil moisture and increased functional gene abundances of pmoA for methanotrophs. Non-growing season (NGS) CH uptake contributed 45% and 39% to annual CH uptake for HM and ZM, respectively, falling into the ranges of 12%-64% NGS CH uptake contributions from TG to AG of China. The TrG showed significant (p < 0.001) lower annual CH uptake than TG and AG globally, due to the fact that significant (p < 0.05) greater precipitation and soil moisture from the former than the latter. Our findings elucidate mechanisms underlying rodent-mediated CH flux changes and highlight soil moisture as a key driver for global CH sink variations. These results emphasise the need for long-term monitoring to better assess the ecological consequences of bioturbation in climate-sensitive alpine ecosystems.
青藏高原高寒草原是重要的甲烷汇，但正面临来自人为和气候干扰导致的退化，这些干扰促进了地下啮齿动物（如高原鼢鼠和高原鼠兔）的活动。尽管啮齿动物的生物扰动（如挖掘、觅食和排泄）改变了高寒草原的土壤结构、物理化学性质和生产力，但其对甲烷吸收的影响仍知之甚少。首先，我们结合了青藏高原高寒草甸中高原鼢鼠土丘和周围健康草甸斑块全年的配对甲烷通量测量数据，以及全球范围内青藏高原高寒草原、温带草原和热带草原的元分析和综合分析整理的甲烷通量数据。我们观察到，啮齿动物的生物扰动使年甲烷吸收量显著增加（p < 0.001），翻倍增长（健康草甸：-0.91±0.08千克碳/公顷，而鼢鼠土丘：-1.80±0.19千克碳/公顷，均值±标准误差，负值表示吸收）。值得注意的是，由于啮齿动物生物扰动导致的这一净增加量（-0.89±0.10千克碳/公顷·年）的67%发生在生长季节。元分析结果表明，这种现象与表土水分显著降低（p < 0.001）以及甲烷氧化菌的pmoA功能基因丰度增加有关。非生长季节的甲烷吸收分别占健康草甸和鼢鼠土丘年甲烷吸收量的45%和39%，在中国温带草原到高寒草原的非生长季节甲烷吸收贡献范围为12% - 64%。全球范围内，热带草原的年甲烷吸收量显著低于温带草原和高寒草原（p < 0.001），原因是前者的降水量和土壤湿度显著高于后者（p < 0.05）。我们的研究结果阐明了啮齿动物介导的甲烷通量变化的潜在机制，并强调土壤湿度是全球甲烷汇变化的关键驱动因素。这些结果强调了进行长期监测以更好地评估对气候敏感的高寒生态系统中生物扰动的生态后果的必要性。
