鼎湖山南亚热带常绿阔叶林凋落物量20年动态研究

TWENTY YEARS OF LITTER FALL DYNAMICS IN SUBTROPICAL EVERGREEN BROAD-LEAVED FORESTS AT THE DINGHUSHAN FOREST ECOSYSTEM RESEARCH STATION

研究了鼎湖山森林生态系统定位研究站 2 0年来对常绿阔叶林凋落物量进行监测所积累的资料 ,探讨这一地带性植被演替过程中凋落物量动态变化格局及组成特征 ,并分析了主要优势种凋落叶的变化规律及其与凋落物总量的联系。鼎湖山南亚热带常绿阔叶林平均年凋落物量为 8.4 5t·hm-2 ,年际波动显著。总体来说年凋落物量呈下降趋势 ,这与植被所处演替阶段及本身林分特征有关。凋落物的凋落高峰发生在雨季初期 (4、5月 )和雨季末期 (8、9月 )。与多数森林不同 ,鼎湖山南亚热带常绿阔叶林各组分凋落物量的比例顺序为叶 >花果杂物 >枝。其中锥栗 (Castanopsischinensis)、荷木 (Schimasuperba)、厚壳桂 (Cryptocaryachinensis)、黄果厚壳桂 (C .concinna) 4种优势种 2 0年平均年凋落物量分别为 1.86、0 .5 0、0 .2 6、0 .4 0t·hm-2 ,合计占凋落叶量的 70 %左右 。

In this paper, we summarize 20 years of observations and measurements on the production, composition, and seasonal dynamics of litter and leaf litter production of dominant species in the southern subtropical evergreen broad-leaved forests at the Dinghushan Forest Ecosystem Research Station. Annual litter production ranged from 6.39 t·hm -2 to 11.04 t·hm -2 with an average of 8.45 t·hm -2. The variation in the annual litter fall was remarkable. Total litter production decreased over the past 20 years reflecting changes in the compositional characteristics and successional stages of the forest. There were two litter fall peaks each year: one at the beginning of the rainy season (April and May) and the other at the end of the rainy season (August and September). The different components of litter production showed a consistent annual temporal sequence in the following order: leaves; flowers and other mixed-materials; branches. The mean annual leaf litter production of Castanopsis chinensis, Schima superba, Cryptocarya chinensis and Cryptocarya concinna was 1.86, 0.50, 0.26 and 0.40 t·hm -2, respectively, which accounted for about 70% of the total leaf litter production. Leaf litter production of the dominant species greatly influenced the dynamics of total litter production, and, to some degree, the dynamics of litter production reflected changes in the forest biomass and community composition over the past 20 years.