离子交换树脂袋法研究森林土壤硝态氮及其对氮沉降增加的响应

用离子交换树脂袋法，研究了鼎湖山三种森林（马尾松林、马尾松针叶阔叶混交林和季风常绿阔叶林）土壤硝态氮对外加氮的响应特征。结果表明，土壤硝态氮显著地受森林类型、季节和氮处理的影响。整体而言，阔叶林土壤硝态氮极显著高于马尾松林和混交林，而马尾松林和混交林之间的差异则不显著。三种森林土壤硝态氮的季节变化均表现为春季和夏季极显著高于冬季和秋季，而冬季又显著高于秋季。外加氮处理提高土壤硝态氮水平，其中在马尾松林和阔叶林氮处理效应显著。所得结果与直接采集土壤或土壤水测定的硝态氮含量的结果一致，表明离子交换树脂袋法是评价土壤硝态氮水平行之有效的手段之一。

Response of soil NO3--N dynamics to N additions in Dinghushan forests,assessed by ion-exchange resin bag method

Dynamics of soil NO3--N and its response to N additions in the major forests (pine, mixed and monsoon evergreen broadleaf forests) of Dinghushan Biosphere Reserve were studied by using ion-exchange resin bags method. Soil NO3--N concentrations varied depending on forest type, season and N treated level. Overall, soil NO3--N concentrations were significantly higher in monsoon evergreen broadleaf forest than in mixed or pine forests, but the difference was not significant between mixed and pine forests. Soil NO3--N concentrations in all studied forests showed higher in spring and summer than in winter and fall, and higher in winter than in fall. Soil NO3--N concentrations responded N addition in all studied forests and were significantly increased in pine and monsoon evergreen forests. These results were consistent with results assessed by using common methods in the same forests, indicating that ion-exchange resin bags method is one of the effective methods to estimate soil NO3--N dynamics.