This paper examines human impact on stands and individual trees of Pinus yunnanensis growing near the small mountain villages of Pianshui and Yangjuan in southwestern Sichuan Province,China.In an effort to assess whet...This paper examines human impact on stands and individual trees of Pinus yunnanensis growing near the small mountain villages of Pianshui and Yangjuan in southwestern Sichuan Province,China.In an effort to assess whether use of these forests was sustainable,we examined the effects of human use in two ways.First,we directly measured the effect of cutting branches,for fuel and fodder,on tree growth.We hypothesized that branch cutting would negatively impact tree growth.We established 12 plots on four hills and compared 14 pairs of trees,one tree in each pair with an apparently full crown and the other with a considerable portion of the crown removed.Second,we assessed stand and tree properties over a 500 m elevation gradient above the villages where we hypothesized that as elevation increases,stand and tree properties should show fewer human impacts.Although extensive branch cutting reduced the live crown,tree height and diameter,compensatory processes likely enabled trees to recover and to add basal area increments(BAIs) similar to those added by trees with full crowns.Trees and stands close to villages showed less growth and lower basal areas,respectively,than stands and trees at intermediate or distant elevations from villages.Areas relatively close to the villages showed considerable effects of human-related disturbances such as branch cutting,grazing,tree and shrub removal,losses of litter,and human and animal trails.Such areas had increased soil erosion and often loss of the ‘A' horizon.Stands close to villages had younger trees,lower stand basal areas,smaller basal area increments,and more stumps.Our results suggest an increasingly vulnerable interface between occupants of these two villages and their surrounding forests.展开更多
The growth process of Chinese fir trees under the pattern of reserving broad leaved tree species in Chinese fir plantation and in pure Chinese fir stand(control) were studied. The results showed that comparing with th...The growth process of Chinese fir trees under the pattern of reserving broad leaved tree species in Chinese fir plantation and in pure Chinese fir stand(control) were studied. The results showed that comparing with the control, the tree height, D.B.H and tree volume increment of Chinese fir under the pattern was a little slower in the early seven years and higher at 8～22 5 year old. After 22 5 year old the increment declined hardly (though total increment was higher than the control). All these reflected the effect of tree competition and soil fertility development on the tree growth of Chinese fir. In order to cultivate large timber under the pattern, the relationship of Chinese fir and broad leaved tree species must be adjusted in time and the broad leaved trees existed in the same forest canopy with Chinese fir must be cut over at about 20 year old.展开更多
基金Financial support was provided by an Asian Studies Grant to Harrell, NSF - IGERT 0333408the School of Environmental and Forest SciencesUniversity of Washington, Seattle, WA, USA
文摘This paper examines human impact on stands and individual trees of Pinus yunnanensis growing near the small mountain villages of Pianshui and Yangjuan in southwestern Sichuan Province,China.In an effort to assess whether use of these forests was sustainable,we examined the effects of human use in two ways.First,we directly measured the effect of cutting branches,for fuel and fodder,on tree growth.We hypothesized that branch cutting would negatively impact tree growth.We established 12 plots on four hills and compared 14 pairs of trees,one tree in each pair with an apparently full crown and the other with a considerable portion of the crown removed.Second,we assessed stand and tree properties over a 500 m elevation gradient above the villages where we hypothesized that as elevation increases,stand and tree properties should show fewer human impacts.Although extensive branch cutting reduced the live crown,tree height and diameter,compensatory processes likely enabled trees to recover and to add basal area increments(BAIs) similar to those added by trees with full crowns.Trees and stands close to villages showed less growth and lower basal areas,respectively,than stands and trees at intermediate or distant elevations from villages.Areas relatively close to the villages showed considerable effects of human-related disturbances such as branch cutting,grazing,tree and shrub removal,losses of litter,and human and animal trails.Such areas had increased soil erosion and often loss of the ‘A' horizon.Stands close to villages had younger trees,lower stand basal areas,smaller basal area increments,and more stumps.Our results suggest an increasingly vulnerable interface between occupants of these two villages and their surrounding forests.
文摘The growth process of Chinese fir trees under the pattern of reserving broad leaved tree species in Chinese fir plantation and in pure Chinese fir stand(control) were studied. The results showed that comparing with the control, the tree height, D.B.H and tree volume increment of Chinese fir under the pattern was a little slower in the early seven years and higher at 8～22 5 year old. After 22 5 year old the increment declined hardly (though total increment was higher than the control). All these reflected the effect of tree competition and soil fertility development on the tree growth of Chinese fir. In order to cultivate large timber under the pattern, the relationship of Chinese fir and broad leaved tree species must be adjusted in time and the broad leaved trees existed in the same forest canopy with Chinese fir must be cut over at about 20 year old.
