鼎湖山马尾松林降水再分配对养分动态影响

在鼎湖山马尾松林中 ,降水到达森林重新分配后 ,pH值的大小变化顺序为 :茎流 >径流 >穿透雨 >降水 ,且它们均呈酸性。与 pH值变化基本上相类似 ,养分元素浓度在各过程中均以茎流最高 ,降水最低。不同元素比较 ,其大小次序为 :Ca>N >Mg>P。Ca、P和Mg三种元素浓度在各过程中的月变化较明显 ,但pH值和N元素浓度的月际变化不强。该生态系统养分元素呈积累状态 ,大气降水的养分输入为 (kg·hm 2 ·a 1) :2 0 .62 9(N)、1 .0 1 5 (P)、46.3 3 2 (Ca)、3 .5 0 8(Mg) ;输出为 (kg·hm 2 ·a 1) :7.1 2 0 (N)、0 .63 2 (P)、2 3 .640 (Ca)、2 .1 3 3 (Mg)。此外 ,还对该生态系统生物地球化学循环特征进行了讨论。

Effects of rainfall reallocation on nutrient dynamic of a pine forest in Dinghushan

Effects of rainfall reallocation on nutrient dynamic of a pine forest in Dinghushan were studied using small catchment method during the period of 1997～1999. Results indicated that pH values were all acid and varied in the following order: stemflow>throughfall>runoff>rainfall. Similarly, nutrient concentrations in different processes showed the highest in stemflow and the lowest in rainfall. Comparing with different elements, their concentration order was: Ca>N>Mg>P. Monthly rhythm of nutrient concentrations was significant for Ca, P and Mg in all processes, but not for pH values and N. Nutrients in this ecosystem were accumulating, with nutrient input by rainfall(kg·hm -2·a -1): 20.629(N), 1.015(P), 46.332(Ca), 3.508(Mg), and output via runoff(kg·hm -2·a -1): 7.120(N), 0.632(P), 23.640(Ca), 2.133(Mg), respectively. The amount of nutrient leaching via stemflow and throughfall was(kg·hm -2·a -1): 1.414(N), 0.531(P), 46.897(Ca), 1.057(Mg). The characteristic of biogeochemical cycling of this ecosystem was discussed in this paper