College of Resources and Environment, Shanxi University of Finance & Economics, Taiyuan 030006, China.
Institute of Grassland Sciences, Northeast Normal University, Key Laboratory for Vegetation Ecology, Ministry of Education, Changchun 130024, China.
Int J Environ Res Public Health. 2019 Jul 29;16(15):2705. doi: 10.3390/ijerph16152705.
Soil and soil microbial biomass (SMB) carbon: nitrogen: phosphorus (C:N:P) stoichiometry are important parameters to determine soil balance of nutrients and circulation of materials, but how soil and SMB C:N:P stoichiometry is affected by climate change remains unclear. Field experiments with warming and N addition had been implemented since April 2007. Infrared radiators were used to manipulate temperature, and aqueous ammonium nitrate (10 g m yr) was added to simulate nitrogen deposition. We found that molar nutrient ratios in the soil averaged 60:11:1, warming and warming plus N addition reduced soil C:N by 14.1% and 20% ( < 0.01), and reduced soil C:P ratios by 14.5% and 14.8% ( < 0.01). N addition reduced soil C:N significantly by 17.6% ( < 0.001) (Figs. 2B, 2D). N addition and warming plus N addition increased soil N:P significantly by 24.6% and 7.7% ( < 0.01). The SMB C:N, C:P and N:P ratios increased significantly with warming, N addition and warming plus N addition. Warming and N addition increased the correlations between SOC and soil microbial biomass C (SMBC), soil total P and soil microbial biomass P (SMBP), warming increased the correlation between the soil total N and soil microbial biomass N (SMBN). After four years' treatment, our results demonstrated that the combined effects of warming and N fertilization could change the C, N, P cycling by affecting soil and SMB C:N:P ratios significantly and differently. At the same time, our results suggested SMB might have weak homeostasis in Sonnen Grassland and warming and N addition would ease N-limitation but aggravate P-limitation in northeastern China. Furthermore, these results further the current demonstration of the relationships between the soil and SMB C:N:P stoichiometry in response to global change in temperate grassland ecosystems.
土壤和土壤微生物生物量（SMB）碳：氮：磷（C：N：P）化学计量是确定土壤养分平衡和物质循环的重要参数，但气候变化如何影响土壤和 SMB C：N：P 化学计量仍不清楚。自 2007 年 4 月以来，已经进行了升温与氮添加的田间实验。使用红外线辐射器来操纵温度，并添加水溶性硝酸铵（10 g m yr）模拟氮沉降。我们发现，土壤中养分的摩尔比平均为 60：11：1，升温与升温加氮分别降低了土壤 C：N 比 14.1%和 20%（<0.01），并降低了土壤 C：P 比 14.5%和 14.8%（<0.01）。氮添加显著降低了土壤 C：N 比 17.6%（<0.001）（图 2B、2D）。氮添加和升温加氮分别显著增加了土壤 N：P 比 24.6%和 7.7%（<0.01）。SMB 的 C：N、C：P 和 N：P 比随着升温、氮添加和升温加氮而显著增加。升温和氮添加增加了 SOC 与土壤微生物生物量 C（SMBC）、土壤总 P 与土壤微生物生物量 P（SMBP）之间的相关性，升温增加了土壤总 N 与土壤微生物生物量 N（SMBN）之间的相关性。经过四年的处理，我们的结果表明，升温和氮施肥的综合作用可以通过显著改变土壤和 SMB C：N：P 比并以不同的方式影响碳、氮、磷循环。同时，我们的结果表明 SMB 在 Sonnen 草原可能具有较弱的内稳态，升温和氮添加会缓解东北地区的氮限制，但会加剧磷限制。此外，这些结果进一步证明了在温带草原生态系统中，土壤和 SMB C：N：P 化学计量对全球变化的关系。
