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.