温度和湿度对暖温带落叶阔叶林土壤氮矿化的影响

TEMPRATURE AND MOISTURE EFFECTS ON SOIL NITROGEN MINERALIZATION IN DECIDUOUS BROAD-LEAVED FOREST

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。在实验室条件下 ,控制土壤的温度与含水量。将不同含水量 (0 .12、0 .2 0、0 .2 8、0 .35、0 .40 kg· kg- 1 )的土柱置于 5℃、15℃、 2 5℃和 35℃条件下培养 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 :在 5～ 2 5℃的温度范围内 ,氮的矿化速率和硝化速率与温度和湿度呈正相关。当温度超过 2 5℃ ,含水量超过 0 .2 0 kg· kg- 1 时 ,净矿化速率和净硝化速率随着温度和含水量的升高反而降低。温度和湿度对土壤的矿化和硝化过程存在比较明显的交互作用。我们建立了二维的方程 (T,θ)来描述温度和湿度对土壤氮矿化速率的影响。暖温带土壤氮矿化的最佳条件是温度 2 2 .4℃、含水量 0 .40 kg· kg- 1 。另外试验过程中 。

A better understanding of the effect of temperature and moisture on soil nitrogen mineralization is important to aid our ability to predict soil N cycling. The objective of this study was to evaluate the effects of temperature ( T ) and soil water content ( θ ) on nitrogen mineralization in a deciduous broad-leaved forest. Extracted soil cores were kept in a PVC tube adjusted to different soil water contents (0 12 kg·kg -1 , 0 2 kg·kg -1 , 0 28 kg·kg -1 , 0 35 kg·kg -1 and 0 4 kg·kg -1 ) and incubated at 5 ℃, 15 ℃, 25 ℃ and 35℃ for 30 days. The inorganic N in the soil extracts before and after incubation was analyzed. The results showed that soil nitrogen net mineralization and net nitrification rates were positively related to T and θ effects ( p <0 001) from 5℃ to 25℃. And that there was a decrease in net mineralization rate and nitrification rate when the temperature was raised above 25℃ and water content was more than 0 20 kg·kg -1 These results suggest an interactive effect of temperature and moisture on mineralization rate and nitrification rate. Two dimensional ( T,θ) equations were developed to describe these effects.