气候因素对大果榆分布的影响

气候是决定植被类型和分布的主要因素之一,气候变化会导致植物分布区和植物群落结构发生改变.大果榆(Ulmus macrocarpa Hance)属于榆科(Ulmaceae)榆属(Ulmus L.)植物,具有较高的经济价值与医用价值,是榆科植物中重要的种质资源.本文利用基于最大熵模型(Maximum Entropy)的MaxEnt软件和GIS分析技术,对大果榆在当代气候背景条件下的适生区与潜在分布区进行预测分析.结果表明:模型具有良好的模拟结果,当前大果榆潜在分布区主要集中在山西、陕西、河北、河南等地区.影响大果榆分布的主效生态因子有年平均温、月均气温变化范围、等温性、温度季节性变化方差、年平均降水量、最湿润月降水量和降水季节性变化方差,其累计贡献率达99.9%.根据大果榆预测分布概率将其划分为4个气候适宜性等级.基于气候适宜性等级分组的PCA结果表明:PC1(77.25%)与PC2(22.70%)总共可以解释99.95%的大果榆种群气候差异.非参检验和多因素方差检验结果表明不同分组间的气候条件存在显著差异(P<0.05).本文研究结果为大果榆生态适宜区的界定与保护提供了理论基础,对大果榆种质资源的开发与合理利用具有指导意义.

Effects of Climatic Factors on the Distribution of Ulmus macrocarpa Hance

Climate is one of the main driving forces to determine the type and distribution of vegetation.Climate change will lead to variations in plant distribution and community structure.In recent years,the climate’s influence has expanded so rapidly that it is more essential to explore the impact of climate factors on species distribution.Ulmus macrocarpa Hance,a deciduous tree or large shrub,mainly distributed in North China,is a precious germplasm resource due to its medicine and economic value.In our research,MaxEnt software based on Maximum Entropy was used to predict and analyze the suitable and potential distribution areas of the Ulmus macrocarpa Hance under the contemporary climate background.The results showed that the model had a good simulation situation with a pretty high AUC value(0.992).The main ecological factors contained bio1(Annual Mean Temperature),bio2(Mean Monthly Temperature Range),bio3(Isothermality),bio4(Temperature Seasonality),bio12(Annual Precipitation),bio13(Precipitation of Wettest Month)and bio15(Precipitation Seasonality).Their cumulative contribution rate was 99.9%.At present,the potential distribution areas of the Ulmus macrocarpa Hance are mainly in Shanxi,Shaanxi,Hebei and Henan.According to the predicted distribution probability of Ulmus macrocarpa Hance,it could be divided into four climatic suitability grades.The results of PCA analysis based on climate suitability classification showed that PC1(77.25%)and PC2(22.70%)could explain 99.95%of the climatic differences of Ulmus macrocarpa Hance populations.Non-parametric test and Multi-way ANOVA(MANOVA)indicated that there were significant differences in climatic conditions among different groups(P<0.05).In this paper,the potential distribution area of Ulmus macrocarpa Hance was predicted,and the impact of different ecological factors on the distribution of Ulmus macrocarpa Hance was analyzed,which provided a theoretical basis for the definition and protection of the ecological suitable areas of the Ulmus macrocarpa Hance.