鼎湖山季风常绿阔叶林大气降雨、穿透雨和树干流的养分特征研究

对鼎湖山季风常绿阔叶林大气降雨、穿透雨和树干茎流中的5种养分元素K、Ca、Mg、N、P进行了测定，结合水量分配规律，研究了森林降雨过程中养分在水相中的含量变化特征和输入规律。结果表明：(1)所有离子浓度均为大气降水<穿透雨<树干流，且增幅较大，而平均浓度以K+和总氮(TN)含量最高；总磷(TP)、磷酸盐(HPO42-)、总有机磷(TOP)含量均最低。(2) 大气降雨中的离子平均浓度中以总有机氮(TON)的变异系数最大，为1.282；最小的是NO3-(0.502)；穿透雨中变异系数最大的是TOP(2.357)；最小的是TN(0.621)。树干流中各养分元素浓度与树种的相关性不显著(P>0.05)。(3) 季风常绿阔叶林树干流和穿透雨各养分对森林土壤的年输入量为TN>K+>Ca2+>Mg2+>TP，树干流和穿透雨对森林土壤层Ca2+的输入大于凋落物分解输入。因此，大气降雨是养分从林冠层转移到土壤层的重要因素。

Nutrient Characteristics in Incident Rainfall, Throughfall, and Stemflow in the Monsoon Evergreen Broad-leaved Forest at Dinghushan

The characteristics of five nutrient elements (K, Ca, Mg, N and P) in precipitation, throughfall and stemflow were studied in an monsoon broad-leaved evergreen forest at Dinghushan, Guangdong Province. Based on the precipitation allocation principles, the variation and input characteristics of these nutrients were calculated. The results showed that the contents of nutrient elements were in order as rainfall < throughfall < stemfall, in which the contents of K+ and total nitrogen (TN) were the highest, and those of total phosphorus (TP), HPO42- and total organic phosphorus (TOP) were the lowest. The biggest variation coefficient (Cv) of ion contents in precipitation was 1.282 for total organic nitrogen (TON), and the smallest was 0.502 for NO3-, while those in throughfall were 2.357 for TOP and 0.621 for TN, respectively. There were no significant relation between tree species and the contents of element (P>0.05). The annual inputs of nutrient elements from throughfall and stemflow into the soil were in the order as: TN>K+> Ca2+>Mg2+>TP. The annual input of Ca2+ from throughfall and stemflow were higher than that from litterfall decomposition. It concluded that rainfall was an important factor in transferring nutrient elements from forest canopy to soils.