Zong Ning, Jiang Jing, Shi Peili, Song Minghua, Shen Zhenxi, Zhang Xianzhou
Lhasa National Ecological Research Station, Key Laboratory of Ecosystem Network Observation and Modelling, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, A11 Datun Road, Chaoyang District, Beijing 100101, China ; University of Chinese Academy of Sciences, No. 19A Yuquan Road, Shijingshan District, Beijing 100049, China.
Nanjing Agricultural Institute of Jiangsu Hilly Region, Nanjing, Jiangsu 210046, China.
ScientificWorldJournal. 2015;2015:617471. doi: 10.1155/2015/617471. Epub 2015 Aug 12.
Quantifying the effects of nutrient additions on soil microbial respiration (R m) and its contribution to soil respiration (R s) are of great importance for accurate assessment ecosystem carbon (C) flux. Nitrogen (N) addition either alone (coded as LN and HN) or in combination with phosphorus (P) (coded as LN + P and HN + P) were manipulated in a semiarid alpine meadow on the Tibetan Plateau since 2008. Either LN or HN did not affect R m, while LN + P enhanced R m during peak growing periods, but HN + P did not affect R m. Nutrient addition also significantly affected R m /R s, and the correlations of R m /R s with climatic factors varied with years. Soil water content (Sw) was the main factor controlling the variations of R m /R s. During the years with large rainfall variations, R m /R s was negatively correlated with Sw, while, in years with even rainfall, R m/R s was positively correlated with Sw. Meanwhile, in N + P treatments the controlling effects of climatic factors on R m /R s were more significant than those in CK. Our results indicate that the sensitivity of soil microbes to climatic factors is regulated by nutrient enrichment. The divergent effects of Sw on R m /R s suggest that precipitation distribution patterns are key factors controlling soil microbial activities and ecosystem C fluxes in semiarid alpine meadow ecosystems.
量化养分添加对土壤微生物呼吸（Rm）的影响及其对土壤呼吸（Rs）的贡献，对于准确评估生态系统碳（C）通量至关重要。自2008年以来，在青藏高原的半干旱高寒草甸中，对单独添加氮（N，编码为LN和HN）或氮与磷（P）结合添加（编码为LN + P和HN + P）进行了调控。单独的LN或HN对Rm没有影响，而LN + P在生长高峰期增强了Rm，但HN + P对Rm没有影响。养分添加也显著影响Rm/Rs，且Rm/Rs与气候因子的相关性随年份而变化。土壤含水量（Sw）是控制Rm/Rs变化的主要因素。在降雨量变化较大的年份，Rm/Rs与Sw呈负相关，而在降雨均匀的年份，Rm/Rs与Sw呈正相关。同时，在N + P处理中，气候因子对Rm/Rs的控制作用比对照更为显著。我们的结果表明，土壤微生物对气候因子的敏感性受养分富集的调节。Sw对Rm/Rs的不同影响表明，降水分布模式是控制半干旱高寒草甸生态系统中土壤微生物活动和生态系统碳通量的关键因素。
