As a basic measure for forest management,pruning has an important impact on the tree trunk shape,wood qulity,etc. At present,in the process of growing fast-growing and high-yielding plantation,afforestation was took i...As a basic measure for forest management,pruning has an important impact on the tree trunk shape,wood qulity,etc. At present,in the process of growing fast-growing and high-yielding plantation,afforestation was took into account,whereas management after planting was ignored,which had much detrimental effect on woodland’s quality and productivity. The paper studied the topic to find a scientific pruning model that could provide a guideline for the management in forest production. The plantation and the intercropping of poplar-crop were pruned in four different levels in Hebei and Shandong province. The levels were respectively light p1 (1/6 crown was pruned),medium p2 (2/6 crown was pruned),strong p3 (3/6 crown was pruned),heavy p4 (4/6 crown was pruned) and the control (unpruned). Heights and diameters at breast height(DBH) were measured. Diameter growth and cutting-area increment in one year from ten parsed trees were counted. The volume growth of trunk (below 9 m) was calculated. The results were:1) the difference of relative growth rate for different pruning treatment was not significant (P<0.05),which demonstrated the nutrition for height growth came from the branches and leaves of the top crown; 2) The difference of relative growth rate of DBH was significant(P<0.01). That is,the greater of pruning intensity,the smaller relative growth in the DBH. 3) The stem growth of parsed disk at different height was fluctuant among the different treatments. From stem base (0.0 m) to 9 m height of the trunk,the stem increase of the lower half reduced along with the increase of pruning intensity,while the growth of the upper half in pruning trees was bigger than that of non-pruning ones. 4) The difference of volume growth rate for different treatments was significant,all of the pruning treatments were bigger than the control. The medium p2 had the biggest growth,and the order was CK<p4<p1<p3<p2,which suggested that reasonable pruning can improve the growth of volume. However an excessive pruning reduced volume growth. 5) Pruning can decrease relative taper of trunk,make trunk straight and satiety,and increase the rate of volume increasing for one year. 6) In conclusion,in the process of production,the reasonable pruning should be moderate intensity as pruning p2,in which 1/3 crown length was removed.展开更多
文摘As a basic measure for forest management,pruning has an important impact on the tree trunk shape,wood qulity,etc. At present,in the process of growing fast-growing and high-yielding plantation,afforestation was took into account,whereas management after planting was ignored,which had much detrimental effect on woodland’s quality and productivity. The paper studied the topic to find a scientific pruning model that could provide a guideline for the management in forest production. The plantation and the intercropping of poplar-crop were pruned in four different levels in Hebei and Shandong province. The levels were respectively light p1 (1/6 crown was pruned),medium p2 (2/6 crown was pruned),strong p3 (3/6 crown was pruned),heavy p4 (4/6 crown was pruned) and the control (unpruned). Heights and diameters at breast height(DBH) were measured. Diameter growth and cutting-area increment in one year from ten parsed trees were counted. The volume growth of trunk (below 9 m) was calculated. The results were:1) the difference of relative growth rate for different pruning treatment was not significant (P<0.05),which demonstrated the nutrition for height growth came from the branches and leaves of the top crown; 2) The difference of relative growth rate of DBH was significant(P<0.01). That is,the greater of pruning intensity,the smaller relative growth in the DBH. 3) The stem growth of parsed disk at different height was fluctuant among the different treatments. From stem base (0.0 m) to 9 m height of the trunk,the stem increase of the lower half reduced along with the increase of pruning intensity,while the growth of the upper half in pruning trees was bigger than that of non-pruning ones. 4) The difference of volume growth rate for different treatments was significant,all of the pruning treatments were bigger than the control. The medium p2 had the biggest growth,and the order was CK<p4<p1<p3<p2,which suggested that reasonable pruning can improve the growth of volume. However an excessive pruning reduced volume growth. 5) Pruning can decrease relative taper of trunk,make trunk straight and satiety,and increase the rate of volume increasing for one year. 6) In conclusion,in the process of production,the reasonable pruning should be moderate intensity as pruning p2,in which 1/3 crown length was removed.
文摘【目的】削度方程可以很好地描述树干直径随树高变化的情况,基于地基激光雷达(terrestrial laser scanner,TLS)的高精度三维点云数据建立准确的削度方程并进行立木材积估算,对活立木尺度的材积估计具有重要意义。【方法】以江苏省黄海海滨国家森林公园杨树人工林为研究对象,获取4块样地的TLS点云数据,通过MATLAB 2020a软件计算点云平坦度和法向量以提取单木主干,采用圆拟合方法进行不同高度处的直径拟合,利用32株样木的数据,选取6种削度模型进行建模,得到杨树树干削度方程最优拟合模型,并进行材积估算。【结果】利用TLS数据提取的胸径能替代实测胸径,其平均误差小于0.90 cm。通过对6种模型的拟合优度检验,Schumacher and Hall模型为该地区杨树削度方程最优拟合模型,模型的决定系数R2=0.984,均方根误差为1.00 cm,相对百分误差为2.79%,平均预估误差为0.271%。利用Schumacher and Hall削度方程最优拟合模型进行活立木材积的估算,经与二元材积方程估计结果进行对比,其相对差异为3.34%,二者在统计上无显著差异。【结论】该方法可以减少地面调查对树木造成的永久性破坏,为人工林的蓄积量调查提供有效的技术支持。
