天山南麓中段戈壁区膜果麻黄种群空间分异特征

Spatial heterogeneity of Ephedra przewalskii populations in the stony desert in the middle of southern foot of Tianshan Mountains,China

在天山南麓中段戈壁区洪积扇顶部、中部和底部区域设置样地,以植株高度和冠幅为指标,采用地统计学方法,研究戈壁区膜果麻黄种群的空间分异特征,旨在掌握区域膜果麻黄种群空间分异规律,为戈壁区植被保护和生态修复提供科学依据。结果表明:在洪积扇顶部,膜果麻黄种群呈斑块状分布;在洪积扇中部和底部,种群呈带状分布,中部带状宽度大于底部。从洪积扇顶部到底部,膜果麻黄植株高度和冠幅均呈先减少后增加的趋势,洪积扇顶部、中部和底部植株高度分别为40.34、21.07、36.96 cm,植株冠幅分别为1.09、0.80、1.43 m2。在洪积扇顶部、中部和底部,膜果麻黄植株高度的最佳拟合模型分别为指数模型、指数模型和线性模型,而冠幅的最佳拟合模型分别为指数模型、球状模型和线性模型。从洪积扇顶部到底部,植株高度和冠幅分形维数在1.909~1.989,表明膜果麻黄种群空间格局简单,同质度高。从洪积扇顶部到底部,膜果麻黄植株高度和冠幅各向异性出现的空间距离逐渐变短,在顶部、中部和底部,植株高度和冠幅表现出各向异性的空间距离分别为>60、42~46和23~27 m。

Plots were set on the top,middle and bottom of the stony desert alluvial fan in the middle of southern foothills of the Tianshan Mountains.With plant height and crown size as indicators,the spatial heterogeneity of Ephedra przewalskii populations in the stony desert were studied using geostatistical methods.Understanding the spatial heterogeneity characteristics of E.przewalskii populations could provide scientific basis for vegetation protection and ecological restoration in stony deserts.The results showed that E.przewalskii had a patchy distribution at the top of the alluvial fan.At the middle and bottom of the alluvial fan,it showed a banded distribution.The band width in the middle was larger than that at the bottom.From the top to the bottom of the alluvial fan,the overall plant height and crown size of E.przewalskii populations decreased first and then increased.The average plant height on the top,middle and bottom of the alluvial fan was 40.34,21.07,36.96 cm,and the crown size were 1.09,0.80,1.43 m2,respectively.The best fitting models for plant height of E.przewalskii were the exponential model,the exponential model,and the linear model at the top,middle and the bottom of the alluvial fan,respectively,while the best fitting models for crown size were exponential model,spherical model,and linear model.From the top to the bottom of the alluvial fan,the fractal dimension value of plant height and crown size of E.przewalskii ranged from 1.909 to 1.889,indicating that the spatial pattern of E.przewalskii populations was simple and the spatial homogeneity was high.From the top to the bottom of the alluvial fan,the spatial distance of the anisotropy of plant height and crown size of E.przewalskii gradually shortened.At the top,middle and bottom of the alluvial fan,the spatial distances where the plant height and crown showed anisotropy were>60 m,42-46 m and 23-27 m,respectively.