阿尔泰山小东沟林区植被随地形分布规律

Distribution of vegetation types with topography in the Xiaodonggou forest region of Altai Mountains, northwest China

在高度异质性的山区景观中,地形通过不同生态因子时空分布的影响而成为植被分布的决定性因素.在野外调查的基础上,将植被遥感影像分类图基本像元分别与由DEM推算出来的坡度、坡向、海拔和剖面曲率图相叠加,定量分析新疆阿尔泰山小东沟林区不同植被类型分布与地形因子之间的关系.通过遥感影像并结合地面调查数据,可将阿尔泰山小东沟林区的植被划分为针叶林、阔叶林、针阔混交林、灌木林和草地5种类型.该区域的地形特征如下:坡度以斜陡坡为主,占总面积的64.32%;坡向以西南坡最多,其次是东北坡,分别占总面积的15.02%和14.78%,东南坡和南坡所占面积较少,分别占总面积的9.30%和10.20%;海拔以1 200-2 000 m居多,占总面积的87.19%,是整个研究区的主要海拔分布范围;剖面曲率以5-10°面积最多,占总面积33.31%,其次是剖面曲率3-5°和0-3°,分别占总面积的22.84%和22.44%.剖面曲率>10°的区域占总面积比例较小.各植被类型分布频率最高的地形生境因子组合分别为:针叶林是坡度15-35°的斜陡坡,西北坡,海拔1 800-2 000 m,剖面曲率0-3°;阔叶林是坡度15-35°的斜陡坡,西北坡,海拔1 400-1 600 m,剖面曲率5°-10°;针阔混交林是坡度15-35°的斜陡坡,北坡,海拔1 600-1 800 m,剖面曲率5-10°;灌木林是坡度15-35°的斜陡坡,西坡,海拔1 400-1 600 m,剖面曲率5-10°;草地是坡度15-35°的斜陡坡,南坡,海拔1 200-1 400 m,剖面曲率5-10°.研究不同植被类型随地形生境的变化规律可为生物多样性保育宏观规划和森林可持续经营提供重要科学依据.

The distribution of vegetation often changes along habitat gradient. To a large extent, the patch mosaic pattern of vegetations in a landscape can reflect the spatial heterogeneity of habitats. In the heterogeneous landscapes of mountainous areas, topography is regarded as the most important factor of restricting vegetation distributions. In this paper, our aim was to explore the general distribution of major vegetation types with the variation of topography, and to select the optimum combination of topographic factors for each vegetation type, so that rational conservation management plan can be made based on the optimum mosaics of vegetation types in the landscape. Filed sample plot investigation was carried out to get vegetation data. Topographic factors were calculated by digital elevation model （DEM）. Vegetation types were classified by ground investigation and remote sensing imagery interpretation. The relationship between vegetation distribution and topographic factors was analyzed by overlaying the remote sensing classification pixel map and maps of slope, aspect, altitude, and profile curvature. The vegetation in Xiaodonggou of Altai Mountains could be classified into five types including coniferous forest, broadleaved forest, conifer-broadleaf mixed forest, shrubs, and grassland. The topographic features in the study region are as follows： the slope mainly ranges from 15° to 35°, accounting for 64.32% of the study area. West-south aspect is the main aspect, followed by east-north aspect, accounting for 15.02% and 14.78% respectively of the study area. There are lesser areas in east-south and south aspect, accounting for 9.30% and 10.20% of the study area respectively. In the Xiaodonggou of Altai Mountains, the main altitude gradient ranges from 1 200 m to 2 000 m, accounting for 87.19% of the study area. The value of profile curvature ranges from 5° to 10°, accounting for 33.31% of the study area, while the ranges from 3°to 5° and from 0° to 3°, accounting for 22.84% and 22.44% of the study area respectively. The optimal （high frequency of distribution） combination of topographic factors for different vegetation types are as follows： coniferous forest mainly distributed in slopes from 15°to 35° on west-north aspects with altitude of 1 800 m to 2 000 m, and profile curvature from 0° to 3°. Broadleaved forest is mainly distributed in slopes from 15° to 35° on west-north aspects, with altitude of 1 400 m to 1 600 m, and profile curvature of 5° to 10°. Conifer-broadleaf mixed forest is mainly distributed in slopes from 15° to 35° on north aspects, with altitude of 1 600 m to 1 800 m, and profile curvature from 5° to 10°. The optimal combination of topographic habitat for shrubs is in slopes from 15° to 35° on west aspects, with altitude of 1 400 m to 1 600 m, and profile curvature from 5° to 10°. The optimal combination of topographic habitat for grassland distribution is in slopes from 15° to 35° on south aspects, with altitude from 1 200 m to 1 400 m, and profile curvature from 5° to 10°. The results of this paper can be an important reference for biodiversity conservation, resources utilization and sustainable management planning at landscape scale.