青藏高原高寒草甸土壤物理性质及碳组分 对增温和降水改变的响应

自2011年起,在青藏高原高寒草甸实施人工模拟增温和降水改变实验,2013年7月采集实验区土壤样品,监测土壤物理特性(土壤粒径和pH值)以及碳组分(全碳、有机碳、可提取有机碳、微生物生物量碳)的变化,得到如下结果。1)增温显著改变0~20 cm土壤温度和含水量,增水和减水显著提高和降低0~20 cm土壤含水量,但不影响土壤温度。2)在0~10 cm土层深度,增温显著降低土壤微生物生物量碳;增水降低土壤可提取有机碳含量,增加土壤微生物生物量碳;减水显著增加土壤黏粒比例和可提取有机碳含量,降低土壤砂粒比例和微生物生物量碳。在10~20 cm土层深度,增水显著降低土壤可提取有机碳含量。3)增温和降水改变对土壤测定指标的影响不存在交互作用。4)主成分分析结果表明,土壤总体格局发生趋同主要是因为降水改变,而不是增温。结果表明,在未来青藏高原高寒草甸降水持续增加的情景下,土壤黏粒比例和可提取有机碳含量的降低可能会进一步对高寒地区的植物生产力以及微生物群落产生重要影响。

Effects of Warming and Altered Precipitation on Soil Physical Properties and Carbon Pools in a Tibetan Alpine Grassland

The authors conducted experiments to simulate warming and alter precipitation since 2011, and investigated soil physical properties (soil particle size and pH) and carbon pools (soil total carbon (STC), soil organic carbon (SOC), soil extractable organic carbon (EOC) and microbial biomass carbon (MBC)) in July 2013. The results showed that warming significantly increased soil temperature and decreased soil moisture at the depths of 0-20 cm, and altered precipitation affected soil moisture at 0-20 cm depth, but had no influence on soil temperature. At the depth of 0-10 cm, warming significantly increased SMBC; increased precipitation significantly reduced EOC content and elevated MBC content; decreased precipitation significantly decreased soil sandy proportion, MBC content and increased soil clay proportion and EOC content. At the depth of 10-20 cm, increased precipitation led a reduction on EOC content. The interactions of warming and altered precipitation on soil indexes were not detected. The pattern of soil properties was changed mainly by altered precipitation, not warming, according to the results of PCA. The results suggest that given precipitation will be continuously increased in the future, increased precipitation may lead a reduction in soil clay proportion and EOC content in the topsoil, and subsequently affect plant primary production and micrbial communities in this region.