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为研究重庆酸雨区森林生态系统中氮湿沉降在不同林分中的分布特征,以重庆缙云山为站点,于2012年5月到10月间,测定了针阔混交林、常绿阔叶林和毛竹林三种典型林分内大气降水、穿透雨和树干茎流的铵态氮(NH4+-N)、硝态氮(NO3--N)和可溶性有机氮(DON,Dissolved Organic Nitrogen)浓度,并进行系统分析。结果表明:(1)各林分降雨组分中氮浓度均值关系为:NH4+-N>NO3--N>DON,NH4+-N和NO3--N的最小值分别为1.84 mg L-1和1.11 mg L-1,而DON浓度不超过0.47 mg L-1;(2)相比于大气降水,各林分的穿透雨和树干流的氮浓度都有增加,林分上分布表现为:针阔混交林>常绿阔林>毛竹林;(3)在时间尺度上,各林分穿透雨NH4+-N和NO3--N浓度的最高值、次高值和最低值分别出现在10月份、8月份和6月份,林分间差异不显著。树干茎流无明显时间分布规律,林分间无显著差异。研究指出,降雨量不是决定氮浓度的关键因子,而林分对氮浓度的影响作用显著。
In order to study the distribution of nitrogen deposition in different forest stands in Chongqing acid rain forest ecosystem, taking Jinyun Mountain of Chongqing as a site, from May to October in 2012, the coniferous and broad-leaved mixed forest, evergreen broad-leaved forest and The results showed that there were significant differences among the three typical stands in the precipitation, the concentrations of ammonium nitrogen (NH4 + -N), nitrate nitrogen (NO3 - N) and dissolved organic nitrogen (DON) And conduct systematic analysis. The results showed as follows: (1) The mean value of nitrogen concentration in rainfall was as follows: the minimum values of NH4 + -N> NO3 - N> DON, NH4 + -N and NO3 - N were 1.84 mg L-1 and 1.11 mg L-1, while the DON concentration did not exceed 0.47 mg L-1. (2) Compared with the precipitation in the atmosphere, the nitrogen penetration rates in all the rainstorm and trunk flows increased, Broadleaved mixed forest> evergreen broadleaved forest> moso bamboo forest. (3) On the time scale, the highest concentrations of NH4 + -N and NO3 - N penetrated rainstones in each forest, the second highest value and the lowest value appeared in October In August and June, there was no significant difference between the stands. No significant temporal distribution of stem flow, no significant difference between the stands. The study pointed out that rainfall is not the key factor that determines the nitrogen concentration, but the effect of stand on nitrogen concentration is significant.