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...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.展开更多
Understanding stand structure and height-diameter relationship of trees provides very useful information to establish appropriate countermeasures for sustainable management of endangered forests. Populus euphratica, a...Understanding stand structure and height-diameter relationship of trees provides very useful information to establish appropriate countermeasures for sustainable management of endangered forests. Populus euphratica, a dominant tree species along the Tarim River watershed, plays an irreplaceable role in the sustainable development of regional ecology, economy and society. However, as the result of climate changes and human activities, the natural riparian ecosystems within the whole river basin were degraded enormously, particularly in the lower reaches of the river where about 320 km of the riparian forests were either highly degraded or dead. In this study, we presented one of the main criteria for the assessment of vitality of P. euphrafica forests by estimating the defoliation level, and analyzed forest structure and determined the height-diameter （height means the height of a tree and diameter means the diameter at breast height （DBH） of a tree） relationship of trees in different vitality classes （i.e. healthy, good, medium, senesced, dying, dead and fallen）. Trees classified as healthy and good ac- counted for approximately 40% of all sample trees, while slightly and highly degraded trees took up nearly 60% of total sample trees. The values of TH （tree height） and DBH ranged from 0-19 m and 0-125 cm, respectively. Trees more than 15 m in TH and 60 cm in DBH appeared sporadically. Trees in different vitality classes had different distribution patterns. Healthy trees were mainly composed more of relatively younger trees than of degraded tress. The height-diameter relationships differed greatly among tress in different vitality classes, with the coefficients ranging from 0.1653 to 0.6942. Correlation coefficients of TH and DBH in healthy and good trees were higher than those in trees of other vitality classes. The correlation between TH and DBH decreased with the decline of tree vitality. Our results suggested that it might be able to differentiate degraded P. euphratica trees from healthy trees展开更多
文摘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.
基金supported by International Science & Technology Cooperation Program of China (2010DFA92720-12)the National Natural Science Foundation of China (31360200)+1 种基金the German Volkswagen Foundation Eco CAR Project (Az88497)the German Federal Ministry of Education and Research (BMBF) within the framework of the Su Ma Ri O Project (01LL0918D)
文摘Understanding stand structure and height-diameter relationship of trees provides very useful information to establish appropriate countermeasures for sustainable management of endangered forests. Populus euphratica, a dominant tree species along the Tarim River watershed, plays an irreplaceable role in the sustainable development of regional ecology, economy and society. However, as the result of climate changes and human activities, the natural riparian ecosystems within the whole river basin were degraded enormously, particularly in the lower reaches of the river where about 320 km of the riparian forests were either highly degraded or dead. In this study, we presented one of the main criteria for the assessment of vitality of P. euphrafica forests by estimating the defoliation level, and analyzed forest structure and determined the height-diameter （height means the height of a tree and diameter means the diameter at breast height （DBH） of a tree） relationship of trees in different vitality classes （i.e. healthy, good, medium, senesced, dying, dead and fallen）. Trees classified as healthy and good ac- counted for approximately 40% of all sample trees, while slightly and highly degraded trees took up nearly 60% of total sample trees. The values of TH （tree height） and DBH ranged from 0-19 m and 0-125 cm, respectively. Trees more than 15 m in TH and 60 cm in DBH appeared sporadically. Trees in different vitality classes had different distribution patterns. Healthy trees were mainly composed more of relatively younger trees than of degraded tress. The height-diameter relationships differed greatly among tress in different vitality classes, with the coefficients ranging from 0.1653 to 0.6942. Correlation coefficients of TH and DBH in healthy and good trees were higher than those in trees of other vitality classes. The correlation between TH and DBH decreased with the decline of tree vitality. Our results suggested that it might be able to differentiate degraded P. euphratica trees from healthy trees
