林冠截留对杉木人工林生态系统物质循环的影响

Effects of Canopy Interception on Water and Nutrient Cycling in the Chinese Fir Plantation Ecosystem

根据1999—2002年连续4年的观测数据,对林冠截留在杉木林生态系统物质循环中的作用进行研究。结果表明:每年林冠截留降雨量267·0mm;林冠截留蒸发散量占杉木人工林总蒸发散量的27·2%,林冠截留水分的物理蒸发量占杉木林集水区水分输出的18·97%;林内净降水的营养物质为143·329kg·hm-2a-1,比冠上大气降水输入的63·924kg·hm-2a-1多74·905kg·hm-2a-1,增加了117·2%;林冠截留减少了到达林地表面和入渗土壤的水分,减少了集水区地表水和土壤漏水的输出,从而减少了营养物质的输出,可见,林冠截留是系统保存营养物质的重要机制之一。

The effects of canopy interception on nutrient cycling in the Chinese Fir plantation ecosystem was studied based on the 4 years located research data. The results indicated that the average amount of precipitation by canopy interception was 267.0 mm·a^-1, which did not arrive onto the stand, but took part in the water cycle and nutrient cycle in the ecosystem; and the canopy interception was an important part of evapotranspiration from the Chinese Fir plantation ecosystem, which was up to 27.2 percent of the whole evapotranspiration. The evaporation from the canopy interception was an important way of drainage from the ecosystem, which was 18.97 percent of the whole amount of drainage from the watershed; The flush-eluviate of branches and leaves caused by canopy interception brought nutrient input of 143.629 kg·hm^2a^-1 , which was 74.905 kg·hm^2a^-1 more than the input of 63.924 kg·hm^2a^-1 from the atmospheric precipitation and was 117.2% of the latter. The decreased amount of 80.1 mm precipitation input caused by canopy interception reduced the amount of rainfall onto the stand surface and infiltration into the soil, and reduced the output with of runoff and drainage, and decreased nutrient loss through with output water. Therefore, the additional preserve of nutrient by canopy interception was 8.664 kg·hm^2a^-1.