鼎湖山生物圈保护区马尾松林凋落物的分解及其营养动态研究

LITTER DECOMPOSITION AND ITS NUTRIENT DYNAMICS OF A PINE FOREST IN DINGHUSHAN BIOSPHERE RESERVE

本文报道了鼎湖山生物圈保护区马尾松林凋落物分解及其营养动态的情况。松针和混合凋落物的失重率在试验过程中均呈直线下降。松针和混合凋落物的分解系数（Ｋ）分别为０．４４ａ－１和０．３７ａ－１。在凋落物分解过程中氮是５个元素中唯一的１个元素，它表现出浓度和绝对量均首先呈上升然后下降的变化。磷和钙的浓度和绝对量在凋落物分解过程中，表现相类似的变化模型。它们的释放速率较其它元素更类似于调落物的失重率。钾是５个元素中最活跃的元素。其浓度和绝对量的变化在凋落物分解过程中相类似：在分解初期（３到５０天）迅速下降后是缓慢的变化。镁的浓度和绝对量在分解初期以相对快的速率下降后，呈现两种绝然不同的变化：绝对量渐渐下降而浓度则慢慢上升。５个元素的流动性比较，在两种凋落物的分解过程中，均是Ｋ＞Ｍｇ＞Ｐ＞Ｃａ＞Ｎ的顺序变化。

Litter decomposition and its nutrient dynamics of a pine forest in Dinghushan Biosphere Reserve were studied in a period of 572 days. Mass loss in both decomposing pine needles and mixed litter (about half pine needles and half understorey litter) showed linear decrease with time during the experiment. The decomposition coefficients (k) were 0. 44 a-1 and 0. 37 a-1 for pine needles and mixed litter, respectively. Nitrogen was the only element that showed increase, in the first period,in concentrations (in the first 329 days for needles, 117 days for mixed litter) andin contents (at about 200～250 days), and thereafter showed decrease over the rest of the experiment. P and Ca exhibited similar pattern in terms of concentrations and contents, close to the linear rate of mass loss. K is the most mobile element.its patterns of concentrations and contents in decomposing litter were similar: the greatest loss during the first period (30 to 50 days), after then slightly fluctuate.Mg showed a relatively rapid initial loss in terms of concentrations and contents,thereafter followed a steady decline in contents but slowly increased in concentrations. The nutrient mobilities of the five elements in both processes of decomposing litter followed the following order: K>Mg>P>Ca>N.