[Morphological characteristics and spatial heterogeneity of Nitraria sphaerocarp nebkhas in desert-oasis ecotone]

Taking the desert-oasis ecotone in Jinta and Linze of Gansu Province as study area, this paper studied the morphological characteristics of Nitraria sphaerocarp Nebkhas in the habitats of Gobi and desert, with the relationships among the morphological parameters, spatial pattern, and spatial heterogeneity analyzed quantitatively. The results showed that the N. sphaerocarp nebkhas was of convex and independent type, and obviously wind-eroded in Jinta. The average values of N. sphaerocarp nebkhas's height, volume, and plant canopy diameter were 1.43 m, 65.19 m3 and 94.06 m2, respectively, being larger in desert than in Gobi, and the maximum values were in Jinta's desert. The average values of the plant height and coverage in Linze desert were larger than those in Gobi, while those in Jinta were in adverse, with their maximum values being 0.48 m and 0.55, respectively. There were significant linear relationships between the long axis and short axis, and between the volume and plant canopy diameter of the nebkhas. The relationships between the height and area, and between the volume and plant canopy diameter were both linear. N. sphaerocarp nebkhas showed zonary distribution and patchy patterns along interdune. The spatial correlation of nebkhas in the Gobi of Jinta and Linze was comparatively strong, while that in Jinta's desert was moderate. There was the possibility that the spatial heterogeneity was chiefly resulted by the stochastic reason in Linze's desert. The spatial heterogeneity of N. sphaerocarp nebkhas was mostly derived from the variation formed by the structural reason. The spatial heterogeneity was the highest in Linze's Gobi and the lowest in Linze's desert, while that in Jinta's Gobi and desert was between the formers.