Abstract:

The composition of landscape and function types of Xiannangou watershed in loess hilly-gully region was studied based on a field investigation on which the landscape patch type maps were drawn. After digitizing the maps with geographical information technology, the landscape classification system and patch type database of Xiannangou watershed were established. The relevant landscape indices were calculated in order to analyze the landscape composition of this watershed, which would provide evidence for optimizing landscape pattern and evaluating the watershed management effect. The result showed: 1) Robinia pseudoacacia (both mature and young) occupied the largest area of Xiannangou watershed, followed by Bothriochloa ischaemun-Artemisia giraldii+Artemisia sacrorum association, farmland, Sophora viciifolia and Artemisia sacrorum+Artemisia giraldii association. The 6 landscape types occupied 82.26% of landscape area and 60.23% of landscape patches, thus they constituted the main part of Xiannangou watershed. 2) The eco-protection type occupied more than 3/4 of total patch number and area in Xiannangou watershed. The area ratio of three landscape function types (eco-protection type, pro-economics type and living-service type) was around 3.63 ∶1 ∶0.08. 3) The area ratio of human directed landscape and natural landscape was almost 2 ∶1 and eco-protection type occupied about 2/3 area of human directed landscape. The landscape composition of Xiannangou watershed was characterized by diverse landscape types, abundant patches, tiny landscape granularity, landscape fragmentation and great human influence on landscape composition. In the future, the vegetation quality of eco-protection type should be improved and prevented from pollution caused by pro-economics type, meanwhile the living-service type should be planned reasonably, and all of these measures can favor establishing the small watershed model which is healthy in ecology and sustainable development in economy.

Key words: loess hilly-gully region, small watershed, landscape composition, landscape function type