晋西黄土区蔡家川流域景观地形分异格局研究

利用山西省吉县蔡家川流域1∶10 000地形图及2003年秋季时相的Quick Bird卫星遥感影像,结合野外调查资料进行景观制图,并与数字高程模型（DEM）数据进行图层叠加分析,研究典型嵌套流域内不同景观类型随地形变化呈现出的分异特征及变化成因.结果表明:① 在较大尺度上,地形因素是本区景观分异的首要因素；② 20世纪80年代以来的封山育林与生产性造林以及近年来实施的退耕还林,是局部地区景观组分在各种地形梯度上显著变化的根本原因,自然恢复过程对于这种格局变化也起到了积极的促进作用；③ 目前流域内人为的干扰活动主要是过度放牧,集中在自然景观与人为景观过渡的中游地带；④ 在本流域高程1 000～1 200 m、坡度25°～35°、坡向半阴坡的关键地区,应采用科学的人工促进自然生态恢复措施,逐渐增加近自然景观组分,尽量减少负面的人为干扰. 

Topographic variation pattern of landscape distribution in Caijiachuan watershed, the Loess Plateau of western Shanxi Province

Quick Bird satellite images taken in the fall of 2003, combined with field survey information and a topographic contour map (scale =1∶10 000) were used for landscape mapping of the Caijiachuan watershed of Shanxi Province. Using layer overlay analysis of the landscape pattern maps and a digital elevation model (DEM), the authors studied the distribution variation pattern of different landscape types along the topographic gradients and its causes in this typical, nested watershed. The results show: ① topographic characteristics are critical for the spatial variations of landscapes on a large scale map; ② the closure of land for reforestation and productive reforestation since the 1980s and the conversion of farmlands to forestland in recent years are the primary causes for the significant variation of the elements in landscape distribution patterns along topographic gradients in local regions; furthermore, natural recovery processes also give an impulse to the change in the pattern; ③ the major human disturbance activity in the Caijiachuan watershed_overgrazing is centralized in the area between natural and artificial landscapes; trampling of vegetation accelerates soil erosion and water loss, to which the local government should attach much importance; ④ the authors think that artificial measures should be adopted to stimulate natural regeneration, to increase the near_natural landscape elements and to reduce negative human activities in the key regions of this watershed, where the elevation is 1 000～1 200 m and the slopes are between 25° and 35° and half_shaded.