浙江省三门县古树资源特征和空间分布格局分析

Resource Characteristics and Spatial Distribution Pattern Analysis for Large Old Trees in Sanmen County,Zhejiang Province

为进一步掌握浙江省台州市三门县古树资源现状构成特征,探索其空间分布格局,基于2019年三门县古树普查基础数据,分析了全县古树的优势树种、物种多样性和结构特征,并结合ArcGIS的空间分析方法,系统研究了全县古树的空间分布格局。结果表明,(1)三门县共有古树681株,隶属24科30属35种,其中针叶树种7种,阔叶树种28种,常绿15种,落叶20种;优势种包括樟Camphora offici-narum、枫香树Liquidambar formosana、糙叶树Aphananthe aspera、朴树Celtis sinensis等9种,占总株数的85.46%,构成古树资源的主体;一级、二级和三级古树分别占比12%、21%和67%。(2)物种多样性和灰色关联度分析显示:海游街道的物种多样性综合排序最高(H′=2.265,D=0.854,J=0.507,关联度=0.978),而蛇蟠乡的排序最低。(3)结构特征方面,古树的树龄集中在100~150 a、胸径集中在110~160 cm、树高集中在15~20 m、冠幅集中在15~20 m;胸径和冠幅呈极显著的线性关系,拟合方程为y=0.61437x-0.375(R2=0.455,P<0.01)。(4)空间分布方面,各乡镇(街道)古树的核密度分布差异显著,高密集区主要位于西北部(海游街道、海润街道和健跳镇)和中部(横渡镇);最近邻分析显示,古树整体(NNI=2.968,Z=42.929,P<0.000)和二级古树(NNI=2.968,Z=42.916,P<0.000)呈显著的离散分布,而一级、三级古树及主要单一树种则呈显著的聚集分布。

To further grasp the current compositional characteristics of large old trees(LOTs)resources in Sanmen county,Taizhou city,Zhejiang province,and explore their spatial distribution patterns.This study an-alyzed the dominant tree species,species diversity,and structural characteristics of LOTs in Sanmen county,based on the basic data from the 2019 tree survey.Utilizing ArcGIS spatial analysis methods,the research sys-tematically investigated the spatial distribution pattern of LOTs in the county.The results showed that(1)San-men county has a total of 681 LOTs belonging to 24 families,30 genera,and 35 species,including 7 conifer-ous species,28 broad-leaved species,15 evergreen species,and 20 deciduous species.Dominant species like Camphora officinarum,Liquidambar formosana,Aphananthe aspera,Celtis sinensis,and 9 other species,ac-counting for 85.46%of the total tree count,forming the core resources of LOTs.The distribution of LOTs is as follows:first-level trees account for 12%,second-level for 21%,and third-level for 67%.(2)Analysis of species diversity and grey relational analysis(GRA)reveals that Haiyou Street exhibits the highest level of spe-cies diversity,with comprehensive indices of H′=2.265,D=0.854,J=0.507,and relational degree=0.978.In contrast,Shepan Township demonstrates the lowest ranking.(3)In terms of structural characteris-tics,the age of LOTs primarily falls within the range of 100-150 years,with the diameter at breast height(DBH)concentrated around 110-160 cm,the tree height is typically ranging from 15-20 m,and the crown width concentrated between 15-20 m.A notable linear relationship exists between the DBH and the crown width,represented by the equation y=0.61437x-0.375(R2=0.455,P<0.01).(4)Significant variations are observed in the kernel density distribution of LOTs across different townships and streets,with dense clusters predominantly situated in the northwest(including Haiyou street,Hairun street,and Jiantiao township)and the central region(Hengdu town)of the county.The nearest neighbor analysis(NNA)reveals that the overall LOTs(NNI=2.968,Z=42.929,P<0.000)and second-level LOTs(NNI=2.968,Z=42.916,P<0.000)exhibit a significant dispersed distribution,while first,third-level LOTs,along with major single species,are notably clustered.The above research findings hold significance for the preservation and management of LOTs′s resources and biodiversity in Sanmen county.