Vegetation GAP Analysis In The Upper Reaches Of Minjiang River

Through collecting the vegetation and landform data of the upper reach of Minjiang River, this paper mainly applies ArcGIS (8.3) & RS technology to extracting elevation & aspect information from relief maps, RS images and so on. Based on the analysis of vegetation's present situation, with synthesizing the authoritative & actual data, it classifies the vegetation of the upper reach of Minjiang River into 7 types. Under the support of an essential hypothesis & advanced spatial analysis technology, the therotical vegetation distribution is obtained. Then make a contrast between the present situation and therotical distribution of vegetation, namely, GAP analysis, and find the "gaps", which should be restored & reconstructed. Finally, try to analyze the reasons and bring forward some countermeasures for these "gaps". According to results of vegetation mapping and GAP analysis, people who make decisions for vegetation protection or management will have a clear knowledge of the vegetation's present situation, which will be helpful and necessary for laying the foundation of biodiversity assement to construct a safe, sustainable & healthy eco-system in the upper reach of Minjiang River.Finally, under the consideration of vegetation, landform data, the influence of human activities and consultion of vast number of literature synthetically, this paper classifies the upper reach of Minjiang River into 8 zones, and will take different vegetation restoration & reconstruction countermeasures for different ones to protect their vegetation and eco-environment.(1) Vegetation-destroyed zone: It is limited to Minjiang mainstream and its banks' watersheds, which is shaped into a narrow belt along the Minjiang mainstream. Environment here is bad with cliffy slopes, little vegetation and severe soil & water loss. The human activities are quite violent, too. As this zone is not only nearly interrelated with its social and economy development, but also extremely important to the ecological restoration of the whole Minjiang valley, it must pay great attention to its vegetation restoration & reconstruction.(2) Vegetation-partly-destroyed zone: It lies to the west of the mainstream watershed, and lower reach of Minjiang anabranch, where vegetation has been partly destroyed and the human activities is not so violent as that of zone (1). Its vegetation restoration & reconstruction is pivotal, too. Or else, if it turns into zone (1), it will not only increase the cost, but also add the difficulty to its vegetation restoration & reconstruction.(3) Near-headstream eco-balance zone: It locates the upper reaches of Minjiang mainstream or anabranch, where the landform is comparatively flat, vegetation is in good status and the influence of human activities is weak. Here the vegetation restoration & reconstruction should be focused on protecting the present vegetation and trying to reduce the jamming.(4) Headstream eco-zone: It locates the west and north headstream of Minjiang River, includingnatural rock bare belts, alp snowmelt lakes, alp meadows and so on. On the whole, condition here is good with an elevation from 2500-3500m. and thick humus Great importance should be attached to this zone's vegetation protection.(5) Fostered forest eco-zone / man-planted zone: Area here is large, but with little biodiversity and hardly humus. Its vegetation restoration & reconstruction strategy should be "reconstruction firstly, restoration secondly". And during the course of reconstruction, relevant countermeasures should be taken to strengthen the vegetation protection & management and avoid destroy the afforestation.(6) Degraded or restorable forest zone: Area here is large, which are mainly trace spots after felling. Some of these trace spots are restoring naturally, while some others are quite difficult, even impossible to restore or reconstruct if there's no jamming like planting trees. Its vegetation strategy should be "seize the restoration & reconstruction all together" and try to increase the vegetation bestrow ratio to improve the exasperate environment and restore its eco-balance.(7) Agriculture eco-zone: There are 2 cases: human-planted fruit & economical forest zone and human habitation zone where the soil and water loss is violent. As to this area, based on complying to the national returning farmland to forest or meadow policy, its vegetation strategy must follow a principle, which is "adjust measures to local conditions".s(8) Hungriness / bare rock / arid vallly zone: The former mainly distributes high elevation regions, while the latter mainly distributes cliffy slopes which are constituted of Qianmei rock with very lilttle vegetation. As to this area, it is proposed that "maintain the present condition here", because the natural law can never be changed and human is not omnipotent. Keep it what it be may be the best strategy for this zone.