天然常绿阔叶和半落叶林林隙胖大海更新特征

以越南同奈天然文化自然保护区的不同胖大海优势度林分林隙内胖大海更新为研究对象,对不同优势度林分林隙下胖大海更新种群的生命表、空间分布格局以及更新密度分布特征进行研究。结果表明：在3个优势度等级林分中胖大海SL1的个体株数最大,其中SL1到SL5的个体数量单调递减, SL4至SL5呈较为稳定状态；在优势度3级林分胖大海SL1的死亡率为0.358,均小于优势度2级林分的0.480和1级林分的0.413,而胖大海SL2至SL4的死亡率均大于优势度2级和1级林分；在不同林隙大小等级中胖大海幼树幼苗的空间分布型均呈聚集型；在优势度1级林分中,胖大海随着林隙面积增加,更新平均密度单调增加,林隙面积<80 m2时,胖大海幼树幼苗的平均密度均较小,林隙面积401-500 m2时,胖大海幼树幼苗平均密度达到峰值,在优势度1级和3级林分中胖大海幼树幼苗生长发育最适林隙面积为401-500 m2,但优势度2级林分中林隙面积为201-300 m2最适于胖大海幼树幼苗生长。虽然,胖大海幼树幼苗耐荫,需要光照强度不高,但林隙面积过小,光照强度过弱也不利于胖大海幼树幼苗生长。

Characteristics of Sterculia lychnophora regeneration under gaps in natural evergreen broad-leaved and semi-deciduous forests

The object of this study is to understand Sterculia lychnophora Hance regeneration under gaps in different forest domi-nance levels of Dongnai natural and cultural reserve in Vietnam. The life table, spatial distribution pattern and regeneration density distribution of S. lychnophora population under gaps in different forest dominance levels were studied in this paper. The results showed as follows. In the three forest dominance levels, the individual number of S. lychnophora in the first phase was the highest, whereas individual number of S. lychnophora monotonically decreasing from the first to fifth phase. However a relatively steady status was noticed in the fourth to fifth phase. The mortality rate of the first phase S. lychnophora decreased in the order of second dominance level (0.480) > first dominance level (0.413) > third dominance level (0.358). The mortality rate of the second phase through the fourth phase of third dominance level were more than that of second dominance level and first dominance level. The spatial distribution pattern of saplings of S. lychnophora in different forest gaps size gradient appeared to be aggregated. In the first forest dominance level, along with the increase of forest gaps area, average regeneration density monotonically increased. If the forest gaps area were smaller than 80 m2 , where average density of S. lychnophora was all relatively small. The average density of sapling of S. lychnophora reached peak, where forest gaps area was from 401 to 500 m2 . In the first and third forest dominance levels and gap area of 401-500 m2 , the saplings growth and development of S. lychnophora were optimum, but in the second forest dominance level, the gap area for optimum growth and development of the sapling of S. lychnophora was 201-300 m2 . S. lychnophora saplings were shade-tolerant and required light intensity was not high, but S. lychnophora saplings growth was inhibited when the gap area was too small and the light intensity was too weak.