鼎湖山季风常绿阔叶林木本植物个体死亡动态

Dynamics and causes of woody plant death in the monsoon evergreen broad-leaved forest in Dinghushan Nature Reserve

采用永久样地生物多样性长期监测的方法,在对1hm2永久样地DBH≥1cm的植物进行4次测定的基础上,研究了鼎湖山季风常绿阔叶林植物个体死亡的动态及其成因,并对不同物种和不同径级植物死亡率的格局差异进行了分析。结果表明,从1992年到2004年,12a内该样地DBH≥1cm的植物共死亡2411株,为该样地现有活立木的69·34%。共有92种木本植物发生了个体死亡,占样地108种木本植物的85·19%,其中乔木70种,灌木22种;年平均死亡株数呈直线上升;死亡涉及木本植物种数也呈上升趋势;样地内种群数量最多的云南银柴(Aporosayunnanensis)和柏拉木(Blastuscochinchinensis)死亡株数也最多(分别为445株和440株),分别占所有死亡株数的18·46%、18·25%;优势树种黄果厚壳桂由于受虫害的影响,种群死亡率达90·83%;小径级树木死亡较多,其中DBH≤5cm死亡株数占样地死亡总株数的79·22%。自疏作用、灾害性天气、虫害和人为干扰直接影响到样地内植物个体的死亡动态。

The monsoon evergreen broad-leaved forest （MEBF） in Dinghushan Nature Reserve （DNR） has been considered as a zonal vegetation in lower subtropical China, with a history of more than 400 years. Its community structure, species diversity and community dynamics have been studied since 1956, so a lot of data have been well accumulated, which benefits the study on death dynamics of the plant individuals. The dynamics of plant death and its causes were studied based on the four times survey to the plant with DBH≥1cm in a 1hm^2 permanent plot of MEBF in DNR. The differences of death ratio among various species and diameter classes of these plants were explored. The results were showed as following： For the plants with DBH≥1cm from 1992 to 2004, there were 2411 plant individuals death occurred. These dead trees belonged to 92 species, amount for 85.19% of the total 108 species investigated in the plot. Within them,70 species were trees, and 22 were shrubs. The annual average number of plant death individuals increased linearly, also of the species involved death. Aporosa yunnanensis and Blastus cochinchinensis were abundant species, which the death individuals had the most, account of 18.48 % and 18.25 % on total death individuals. For the reason of insect irruption, the individuals＇ death ratio of the former dominant species Cryptocarya concinna, reached to 90.83 % . More death occurred on smaller diameter classes than on larger diameter classes, especially for DBH ≤ 5cm, 79.22% individuals were dead. Self-thinning rule, catastrophic weather, insect irruption and human disturbances directly influenced the death dynamics of the plant individuals in the permanent plot.