临安区不同森林类型竞争指数比较研究

Study on competition index of different typical forest types on Lin′an region

竞争对树木生长有重要影响,通常用竞争指数定量描述树木之间的竞争关系。以浙江省杭州市临安区的乔木林为对象,利用2004年临安区森林资源监测数据,基于Voronoi图的Hegyi竞争指数,在区域尺度上对临安区多种森林类型的竞争关系进行分析。结果表明:在单木水平上,不同森林类型单木的总竞争指数、种内竞争指数、种间竞争指数在胸径5—10 cm最大;单木平均竞争指数随着胸径的增大而降低,胸径>30 cm的竞争压力得以缓解;临安区林木的竞争主要来源于种内竞争,天然林的种内竞争占总竞争指数的比例>50%,人工林的种内竞争占总竞争指数的比例>60%。径级平均总竞争指数、种内竞争指数、种间竞争指数与胸径的关系均服从对数函数关系。在林分水平上,不同森林类型的林分总竞争指数、种内竞争指数、种间竞争指数存在显著差异。平均总竞争顺序为:天然阔叶林>天然针阔混交林>人工针叶林>天然针叶林>人工针阔混交林>人工阔叶林。种内平均竞争顺序为:人工针叶林>天然阔叶林>天然针叶林>天然针阔混交林>人工针阔混交林>人工阔叶林。种间平均竞争顺序为:天然针阔混交林>人工针阔混交林>天然阔叶林>天然针叶林>人工针叶林>人工阔叶林。人工阔叶林的平均总竞争指数、种内竞争指数和种间竞争指数均为最小,该森林类型以山核桃经济树种为优势树种,说明为提高山核桃产量,人为控制低种植密度的经营措施有效降低了林分竞争强度。

Competition has an important impact on tree growth.Competition index is widely used to quantitatively describe the competition relationship among trees.In this study,the arbor forests were taken as the research objects in Lin'an of Hangzhou city,Zhejiang Province.Based on the Hegyi Competition Index of Voronoi diagram,the competition relationship of various forest types was analyzed at regional scale in Lin'an in 2004.The results showed that at the level of single tree,the total competition index,intraspecific competition index,and interspecific competition index of individual trees of different forest types were the largest at diameter at breast height 5—10 cm.The average competition index of single tree decreased with the increase of diameter at breast height,and the competition pressure of diameter at breast height >30 cm was alleviated.The competition of forests in Lin'an region mainly comes from intraspecific competition.The intraspecific competition of natural forests accounts for more than 50% of the total competition index,and the intraspecific competition of plantations accounts for more than 60% of the total competition index.The relationship between average DBH class total competition index,intraspecific competition index,interspecific competition index and diameter at breast height obeys the logarithmic function.At stand level,there are significant differences in total competition index,intraspecific competition index,and interspecific competition index among different forest types.The average total competition order was natural broad-leaved forest>natural coniferous and broad-leaved mixed forest>artificial coniferous forest>natural coniferous forest>artificial coniferous and broad-leaved mixed forest>artificial broad-leaved forest.The average intraspecific competition order was:artificial coniferous forest>natural broad-leaved forest>natural coniferous forest>natural mixed coniferous and broad-leaved forest>artificial mixed coniferous and broad-leaved forest>artificial broad-leaved forest.The average competition order among different forest types was natural coniferous and broad-leaved mixed forest>artificial coniferous and broad-leaved mixed forest>natural broad-leaved forest>natural coniferous forest>artificial coniferous forest>artificial broad-leaved forest.The average total competition index,intraspecific competition index,and interspecific competition index of artificial broad-leaved forest are the smallest.The economic tree species Carya cathayensis is the dominant tree species in this forest type,which indicates that the management measures of artificial control of low planting density effectively reduce the competition intensity of the stand in order to increase the yield of Carya cathayensis.