国槐古树健康评价模型的构建及应用

Construction and Application of Health Assessment Model for Old Sophora japonica Trees

科学、准确地评价古树的健康状况,有利于及时、合理地制定保护措施,使古树得以健康长久存活。本研究以甘肃省崇信县80株国槐古树为对象,综合遴选反映国槐古树枝梢、叶部、树干和整体状况的4个方面共15个健康评价指标,运用结构方程模型确定指标权重,加权汇总得出国槐古树健康综合分值,并进行聚类分析,划分健康等级。结果表明:1)用于评价国槐古树健康的结构方程模型与观测数据拟合效果良好,其适配度指数NC值为1.164,介于1~3;RMSEA为0.046,小于0.05;NFI、TLI和CFI的值分别为0.910、0.982、0.986,均大于0.9,满足国槐古树健康评价的需要。2)评价模型中,树势和顶梢枯死权重最高,均为0.0780,而倾斜状况权重最低,为0.0398。3)研究区内国槐古树健康状况主要有27株属于健康(占比33.75%),26株属于亚健康(占比32.5%),14株属于衰退(占比17.5%),12株属于极度衰退(占比15%),1株属于濒临枯死(占比1.25%),其中一级和二级国槐古树中多株出现明显衰退。综合而言,利用结构方程模型评价国槐古树健康状况的方法是可行、科学、合理的,可为古树健康评价提供一个全新思路。本研究建立的健康评价模型可为其他古树的保护和管理提供依据与借鉴。

Old trees are precious historical relics and cultural heritage.Scientific and accurate health assessment of the old trees is conducive to timely and reasonable formulation of protection measures,to make them healthy and long-term survival.In this study,taking 80 old Sophora japonica trees growing in Chongxin County,Gansu Province as the research objects to carry out the health evaluation.Fifteen health indicators that reflected four aspects of the old trees were comprehensively selected,i.e.,the status of tree tops,leaves,trunks,and the whole trees.The index weights were determined using structural equation model,and the integrated health scores were obtained by weighted summation,and the classification of health levels was performed by cluster analysis.The results showed that 1)the fitness index NC was 1.164,between 1 and 3;RMSEA was 0.046,less than 0.05;NFI,TLI and CFI were 0.910,0.982 and 0.986,respectively,which were all greater than 0.9.The structural equation model used to assess the health of old S.japonica trees presented good fitting effect with the observed data,meeting the needs of health evaluation of old S.japonica trees.2)In the evaluation model,the weight of tree vigor and tree apex mortality was the highest(0.0780),and the weight of inclination degree was the lowest(0.0398).3)Among the 80 old trees studied,27(accounting for 33.75%)were in healthy level,26(32.5%)that were sub-healthy,14(17.5%)were in decline state,12(15%)were in extreme decline state,and one(1.25%)was on the verge of dying.Most of the old S.japonica trees with the first and second protection level declined significantly.In summary,the method of using structural equation model to evaluate the health status of the old S.japonica trees is feasible,scientific and reasonable,which can provide a new idea for the health evaluation of old trees.The health evaluation model established in this study can provide basis and reference for the protection and management of other old trees.