油松人工林养分循环的研究——Ⅲ.养分元素生物循环和林分养分的平衡

在1983年4月至1984年10月两个生长季中,我们对河北隆化的一片油松人工林养分元素生物循环进行了研究,同时,实测了林分养分元素的输入、输出量。实验林分养分总积累量(五种元素总量为575.46公斤/公顷,林木年吸收量为122.72公斤/公顷,归还量为69.9公斤/公顷·年,养分归还主要是以枯落物形式到达林地,这部分占总归还量的86％。以归还/吸收作为循环速率参数,各元素平均为0,57。林分养分的输入、输出主要受降雨和林地状况影响,由于实验地区年均降雨量较小(<500毫米),近几年又连续受旱,大气输入养分量及林分输出养分量均较小。林分的养分平衡,氮、磷略有盈余,钾、钙、镁有少量亏损。

STUDIES ON THE NUTRIENT ELEMENTAL CYCLING IN THE PINUS TABULAEFORMIS PLANTAIONⅢ. Biological cycling and the balance of the nutrient elements

The biological cycling of the nutrient elements was studied and inputs-outputs of the nutrient elements was measured meanwhile over a 2-years period (1983.4.-1984.10.)in a Pinus tabulaeformis plantation located in Long Hua county, He Bei province. Total accumulation of the elements in the experimental stand was 575.46kg/ha. The uptake was 122.7kg/ha.yr and the return was 69.9kg/ha.yr. The return of nutrient elements was mainly by litterfall of the trees which was 86% of total return. If we take return/uptake as the rate of the nutrient cycling, it averaged 0.57. Inputs-outputs of the nutrient elements were mainly affected by the atmospheric precipitation and the case of forest-floor. As the precipitetion in the experimental area was low (<500mm) and it was drought continually in recent years, the quantity of atmospheric inputs and outpust of the nutrient elements was small. The nutrient elemental balance shown, N, P had a small surplus, K, Ca, and Mg had a small deficit.