CAS Key Laboratory of Aquatic Botany and Watershed Ecology, Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan 430074, P. R. China.
Hubei Key Laboratory of Wetland Evolution & Ecological Restoration, Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan 430074, P. R. China.
Environ Sci Technol. 2020 Mar 17;54(6):3267-3277. doi: 10.1021/acs.est.9b06716. Epub 2020 Mar 5.
Wetlands have numerous critical ecological functions, some of which are regulated by several nitrogen (N) and carbon (C) biogeochemical processes, such as denitrification, organic matter decomposition, and methane emission. Until now, the underlying pathways of the effects of environmental and biological factors on wetland N and C cycling rates are still not fully understood. Here, we investigated soil potential/net nitrification, potential/unamended denitrification, methane production/oxidation rates in 36 riverine, lacustrine, and palustrine wetland sites on the Tibet Plateau. The results showed that all the measured N and C cycling rates did not differ significantly among the wetland types. Stepwise multiple regression analyses revealed that soil physicochemical properties (e.g., moisture, C and N concentration) explained a large amount of the variance in most of the N and C cycling rates. Microbial abundance and diversity were also important in controlling potential and unamended denitrification rates, respectively. Path analysis further revealed that soil moisture and N and C availability could impact wetland C and N processes both directly and indirectly. For instance, the indirect effect of soil moisture on methane production rates was mainly through the regulating the soil C content and methanogenic community structure. Our findings highlight that many N and C cycling processes in high-altitude and remote Tibetan wetlands are jointly regulated by soil environments and functional microorganisms. Soil properties affecting the N and C cycling rates in wetlands through altering their microbial diversity and abundance represent an important but previously underestimated indirect pathway.
湿地具有众多关键的生态功能，其中一些功能受到几种氮（N）和碳（C）生物地球化学过程的调节，如反硝化作用、有机质分解和甲烷排放。到目前为止，环境和生物因素对湿地 N 和 C 循环速率的影响的潜在途径仍不完全清楚。在这里，我们研究了青藏高原 36 个河流、湖泊和沼泽湿地中土壤潜在/净硝化、潜在/未加修正的反硝化、甲烷产生/氧化速率。结果表明，所有测量的 N 和 C 循环速率在湿地类型之间没有显著差异。逐步多元回归分析表明，土壤物理化学性质（例如水分、C 和 N 浓度）解释了大部分 N 和 C 循环速率的大量方差。微生物丰度和多样性也分别在控制潜在和未加修正的反硝化速率方面起着重要作用。路径分析进一步表明，土壤水分和 N 和 C 的可利用性可以直接和间接影响湿地的 C 和 N 过程。例如，土壤水分对甲烷产生速率的间接影响主要是通过调节土壤 C 含量和产甲烷菌群落结构。我们的研究结果强调了许多高海拔和偏远的青藏高原湿地的 N 和 C 循环过程受到土壤环境和功能微生物的共同调节。通过改变其微生物多样性和丰度来影响湿地 N 和 C 循环速率的土壤特性代表了一个重要但以前被低估的间接途径。
