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Net Soil Nitrogen Mineralization in Chinese Forest Ecosystems

中国森林生态系统的土壤净氮矿化研究


为了更好地了解温度和湿度对土壤氮矿化过程的影响,从而估计森林生态系统土壤有机氮的矿化速率,在中国7种典型森林生态系统中用PVC管采集森林土壤样品,通过在实验室控制土壤的温度与湿度,将不同湿度的土柱置于不同温度的生化培养箱中培养30 d,分析培养前后的NH+4-N和NO-3-N含量,确定土壤的净矿化速率和净硝化速率。结果表明,温度和湿度与土壤的矿化过程存在比较明显的相关关系(p<0.001)。同时建立了三元的方程来描述温度(t)和湿度(wfps)对土壤氮矿化速率(Rmin)的影响,Rmin=e-7.60+0.07×t+14.74×wfps-10.41×wfps2。利用这个实验模型估算了全国森林生态系统的年氮矿化量,估算结果与野外实测数据基本吻合。

A better understanding of the effect of temperature and moisture on soil microbial activity can improve our ability to predict soil N mineralization. The objective of this study was to evaluate the effects of temperature (t) and soil moisture (wfps: water filled pore space) on soil nitrogen mineralization in Chinese forest ecosystems. The soil cores were kept in PVC tubes, adjusted to different soil water content, and separately incubated at four temperatures for 30 days. The inorganic N in soil extracts before and after incubation was analyzed. The results showed that soil nitrogen mineralization rate (Rmin) and nitrification rate were linearly related to t and wfps (p<0.001). Three dimensional equations were developed to describe these effects: Rmin=e-7.60+0.07×t+14.74×wfps-10.41×wfps2. We scaled up the effect of temperature and moisture on soil nitrogen minerali zation to a national scale. Field measurements agree with the estimate of the re gression model.