Fourteen plots were chosen along with the altitude of 1600-2600 m in Guandi Mountain, Shanxi Province, China to investigate all the trees in the plots, and the species diversity indexes were calculated for analyzing t...
详细信息
Fourteen plots were chosen along with the altitude of 1600-2600 m in Guandi Mountain, Shanxi Province, China to investigate all the trees in the plots, and the species diversity indexes were calculated for analyzing the effects of altitudinal gradient on plant species diversity. The results showed that the order of dominant species from low altitude to high altitude is as Quercus liaotungensis Koidz, Pinus tabulaeformis, Betula platyphylla, B. albo-sinensis, Picea wilsonii, P. Meyeri and Larix principis-rupprechtii. With altitude increasing, the average height and DBH of the arbor firstly increase and then decrease, the maximal height and DBH of the arbor present the unimodal variable trend, the maximal height of coniferous and broad-leaved trees firstly increases and then decreases, the maximal DBH of broad-leaf trees has no clear fluctuation, and the maximal DBH of the needle-leaf trees decreases gradually. Moreover, in middle altitudinal communities （the altitude of 1900-2200 m）, the maximal height and DBH of the needle-leaf trees are larger than these of broad-leaf trees. Both Shannon-wiener index and Margalef index of the communities present the unimodal variable trend, with a peak in the mid-altitude. Plant species diversity in the mid-altitude （1900-2200 m） is higher than that of the low altitude （1600-1900 m） and the high altitude （2200-2600 m）. In addition, the unimodal variable trend of α species diversity is clearly correlated with the altitudinal gradient. The change of plant species diversity is significantly correlated with the altitudinal gradient, and also related to the community structure, the community composition, the feature of species and the human disturbance.
The secondary forests on northern slope of Mt. Changbai were sampled to investigate the effect of human disturbance on their tree species diversity and community structure. Compared with broad-leaved Korean Pine (Pinu...
详细信息
The secondary forests on northern slope of Mt. Changbai were sampled to investigate the effect of human disturbance on their tree species diversity and community structure. Compared with broad-leaved Korean Pine (Pinus koraiensis) forests, secondary forests were much lower in tree species diversity, community structure indices and stand volume. Secondary forests were dominated by pioneer species, and nearly no natural regeneration of Korean Pine was observed in most of our plots. Stepwise regression revealed that, stand volume was the most powerful predictor for tree species diversity. Tree species diversity decreased with the decrease of volume in secondary forests, while increased in broad_leaved Korean Pine forests. Community structure indexes also dropped significantly with decreasing stand volume in secondary forests under different human disturbances. However, broad_leaved Korean Pine forests did not show significant change in community structure under natural disturbance. These results indicated that, broad_leaved Korean Pine forests were strongly resistant to natural disturbance, while secondary forests were sensitive to human disturbance. The analysis of variance showed that the tree species diversity declined significantly under intensive disturbance (volume was below 100 m3·hm -2),the community structure was influenced significantly under moderate disturbance (volume was below 150 m3·hm -2). Our results suggested that the secondary forests were poor in stand quality, and the tree species diversity and community structure index were sensitive to human disturbance. More effort should be make to protect secondary forests, together with human regeneration of Korean Pine under canopy, in order to promote the recovery of the secondary forests to the broad_leaved Korean Pine forests.
暂无评论