辽西大黑山北坡植物群落组成及多样性研究

Composition and biodiversity of forest communities on the northern slope of Dahei Mountain in western Liaoning Province.

在辽西大黑山自然保护区北坡,沿海拔400～1 000 m,选择典型地段设置3条垂直样带,样带间隔100 m,每条样带垂直梯度上隔100 m设置一个样地,共21个样地森林群落,进行了群落组成、群落多样性等随海拔上升变化情况的研究.结果表明,森林群落的郁闭度、平均胸径和胸高断面积等随海拔上升有较明显的增加,海拔800 m以上主要是分布于核心区内的山地原生植被,700 m以下主要为山地疏林和部分人工林;群落的优势种组成随海拔升高表现出由复杂多样逐渐向简单单一过渡的变化趋势;乔木种和灌木种的Shannon多样性指数随着海拔的增加而呈现近似于线性的降低趋势,二者的优势度随着海拔的增加有较明显的上升;草本植物和乔灌层相比优势度较高,多样性指数较低,而且随着海拔的变化幅度也较小,表明群落中草本植物随海拔并没有明显的变化;群落的水平β多样性随海拔增加呈明显的下降趋势,说明在本研究的空间范围内,森林组成在较低海拔更加斑块化.

From altitude of 400 to 1000 m on the northern slope of Dahei Mountain, western Liaoning three sample belts were set with 100 m horizontal intervals and in every belt seven plots were investigated with an interval of 100 m to study the composition and biodiversity of forest communities and their variations along altitude. The results showed that the canopy density and average DBH obviously increased with the increasing elevation, as well as the basal area. The area over 800 m was covered by original mountainous vegetation as core area, while the area under 700 m was mainly covered by sparse woods and plantation. The composition of dominant tree species displayed a transitional tendency from complexity to simplicity with the increasing elevation. The Shannon diversity index of arbors and shrubs nearly linearly decreased with the increasing elevation, while their extents of dominance increased obviously with altitude. Compared with the layers of arbors and shrubs, the herbs have higher extent of dominance and lower diversity index variation with altitude. Horizontal β diversity decreased quickly with the increasing elevation, showing that low-elevation forests were not only locally more diverse, hut also spatially more patchy.