关帝山云杉次生林活立木和枯立木的数量特征与分布格局

Quantitative characteristics and distribution pattern of living and dead standing trees of secondary Picea forest in Guandi Mountain,northern China

本研究以山西关帝山庞泉沟自然保护区4 hm^(2)云杉次生林样地2010年和2015年两次调查数据为基础,从物种组成、径级结构、空间格局,以及不同径级活立木与枯立木的空间关联性、枯立木不同径级间的相互关联性4个方面,分析5年间活立木与枯立木的数量特征、分布格局及相互关联性。结果表明:样地内2010年胸径(DBH)≥1 cm的活立木共有25811株,隶属于11科22属30种,所有个体径级分布呈倒"L"型,个体数量随着径级增大呈断层式减少;2010—2015年5年间形成枯立木共2145株,涉及5科10属12种,以5~10 cm径级分布为主。在0~50 m尺度上,活立木与枯立木在空间分布上具有一定相似性,表明枯立木的空间格局在一定程度上受活立木空间格局限制。各径级活立木与枯立木空间关联分析表明,随着样地内树木个体径级的增大,对空间资源竞争的加剧可能是导致枯立木产生的主要原因。随着枯立木径级的增大,活立木与枯立木的空间关联性不同程度的减弱,表明环境可能成为大径级枯立木形成的关键因素。从枯立木内部看,5 cm≤DBH<20 cm枯立木与DBH<5 cm枯立木、10 cm≤DBH<20 cm枯立木与5 cm≤DBH<10 cm枯立木、DBH≥20 cm枯立木与5 cm≤DBH<20 cm枯立木整体上都表现为显著正相关,说明枯立木会对后续活立木枯死产生影响。

Based on the survey data from a 4 hm^(2)secondary Picea forest plot in the Pangquangou Nature Reserve,Guandi Mountain,Shanxi Province in 2010 and 2015,we analyzed the quantitative characteristics,distribution pattern,and correlation of living and dead standing trees during five years from four aspects,including species composition,diameter class structure,spatial pattern,spatial correlation between different diameter classes of living standing trees and dead standing trees,and intercorrelation between different diameter classes of dead standing trees.The results showed that there were 25811 living standing trees with DBH≥1 cm in the plot in 2010,belonging to 30 species,22 genera,and 11 families.The distribution of individual diameter class was an inverted"L"type,and the number of individuals decreased in a fracture pattern with the increases of diameter class.During the five years(2010-2015),a total of 2145 dead standing trees were formed,involving 12 species,10 genera,and 5 families.Most of the dead standing trees were distributed in diameter of 5-10 cm.At the scale of 0-50 m,the spatial distribution of living and dead standing trees was generally similar,indicating that the spatial pattern of dead standing trees was limited by that of living standing trees to some extent.The spatial correlation analysis of each diameter class of dead standing trees and living standing trees showed that with the increases of individual diameter class of trees,the intensified competition for space resources might be the main reason for the generation of dead standing trees.With the increases of diameter class of dead standing trees,the spatial correlation between living and dead standing trees was weakened to varying degrees,indicating that environment might be the key factor for the formation of large diameter class of dead standing trees.For the the dead standing trees,there was an obvious positive correlation between 5 cm≤DBH<20 cm dead standing trees and DBH<5 cm dead standing trees,between 10 cm≤DBH<20 cm dead standing trees and 5 cm≤DBH<10 cm dead standing trees,and between DBH≥20 cm dead standing trees and 5 cm≤DBH<20 cm dead standing trees.Our results indicated that dead standing trees would impact the subsequent dying of living standing trees.