小秦岭自然保护区秦岭冷杉死亡原因

Preliminary analysis of the cause of Abies chensiensis mortality in Xiaoqinling national nature reserve

小秦岭国家级自然保护区濒危植物秦岭冷杉(Abies chensiensis)近几年出现了不明原因的衰败死亡现象,并有不断扩展的趋势,分析研究就地保护这一珍稀植物资源迫在眉睫。在对小秦岭全部秦岭冷杉定位监测的基础上,通过对活树、死树分布和结构的对比分析,并采用相关分析、偏相关分析和结构等式模型(Structural Equation Models,SEM)结合环境因子,探讨了秦岭冷杉的生存状况和死亡原因。结果如下:(1)枯死树与活树分布基本相一致,活树个体中小树和大树相对较少,死亡个体主要为小树和中龄树;(2)秦岭冷杉的生长与海拔、坡度、土壤含水量和土壤温度呈显著的相关性;(3)SEM分析结果显示,秦岭冷杉活树与土壤含水量和温度呈明显的正相关系,而死树却表现出负相关关系,枯死树与空间位置和地形表现出的负相关关系要明显大于活树。上述结果说明,秦岭冷杉幼苗和小树较少,更新能力差,秦岭冷杉的死亡不是个别现象和局部环境变化所造成的;秦岭冷杉的生长与海拔、坡度、土壤含水量和土壤温度关系密切;土壤含水量和温度对秦岭冷杉生长具有促进作用,是影响秦岭冷杉死亡和衰败的重要环境因素。在今后秦岭冷杉经营保护过程中要注意微环境的变化,减少人为因素对环境的干扰。

Species conservation,especially of endangered species,has become a major focus of the international ecology community. Global biodiversity is in decline,which is affecting ecosystem functioning,and efforts to protect and mitigate this decline are necessary. Within the last few years,the endangered plant species Abies chensiensis has experienced unexplained mortality in the Xiaoqinling national nature reserve. The analysis of potential causes of this mortality is necessary to avoid further loss of A. chensiensis. This study examines the condition of living trees to identify the cause of this widespread mortality and suggests a management plan for the protection and population recovery of A. chensiensis. Ecological communities are complex systems characterized by multiple interacting processes,and the growth and death of species is a complex process. Univariate statistical methods do not provide sufficient information to identify the requirements of ecologicaldevelopment. The structural equation model（ SEM） is a multivariate statistical method that can solve complex problems and that is increasingly applied by ecologists to solve complex problems. SEMs provide a unique perspective in addressing scientific questions. A census of all living and dead A. chensiensis trees in Xiaoqinling was used for a comparative analysis.The distribution pattern and structure of living and dead trees,combined with correlation analysis,partial correlation analysis,and SEM was used to explore the conditions of live individuals and the cause of mortality. Dead trees had similar distribution patterns as living trees. The ratio of large and small trees was small for living A. chensiensis; dead trees were mostly young and middle-aged individuals. The distribution of A. chensiensis was significantly correlated with elevation,slope,soil moisture,and soil temperature. SEM analysis showed that the living individuals were significantly positively correlated with soil heterogeneity,while dead trees showed a negative correlation. There was a stronger negative correlation between dead trees and position and topography compared to living trees. These results suggest that the numbers of A.chensiensis seedlings and young trees are low and that the ability of the species to regenerate is poor. Abies chensiensis mortality is likely caused by local environmental changes,rather than by a single phenomenon,and the growth and regeneration of A. chensiensis is closely related to elevation,slope,and soil water content. To protect A. chensiensis,changes in the microenvironment must be minimized and human interference with the environment must be reduced. Heterogeneity of soil moisture and temperature promotes growth and is an important environmental factor that influences mortality. The observed mortality of A. chensiensis may be a result of human activity and gradual climate change that has affected precipitation,temperature,and other environmental factors.