Hydrology Mechanism Study On Forest Canopy And Litter Layers Of Water Conservation Forest In Qilian Mountains

Relationship of interaction between forest and water is the key topic of foresthydrology. As an effectual system for water conservation forest(WCF), It is not onlydifferent in composition and structure but also uniform in spatial configuration, whichdirectly lead to difference and coordination existed in hydrology-ecology function ofWCF. Through presenting the concept, research progress and practical exertion offorest hydrology, the paper analyzes the interactional characteristic between forest andwater. By the theory of moister relationship between forest canopy and litter layers,vegetation canopy controlling soil erosion and mechanism of litter layers, on the basisof long-term location research on water forest conservation of Qilian Mountains, thepaper analyzes the hydrological process of vegetation canopy and litter layers.1.The permeance rain amount inside forest increases with rainfall increasing,they present a good linearity relation. Within the certain range of rainfall, canopyinterception increases with rainfall increasing; Average canopy interception rate ofPicea crassifolia forest is 29.4%, it decreases with rainfall and intensity increasingand increases with canopy density. The interception rate is 43%—55% whenprecipitation is less 5mm, the interception rate is less 20% when precipitation morethan 15mm.2.The stem flow shows the increasing trend with rainfall increasing, and itsaccount for little proportion of outside forest rainfall. The stem flow amount has closecorrelativity with the water sop capability of cortex, ramification angle, tree trunkchest diameter, cortex roughness degree and stock density, has a little salience withcanopy density.3. The amount, natural water holding and saturation water holding capacity oflitter layers in order is moss- Picea crassifolia forest, alpine shrubs, shrubs- Piceacrassifolia forest, low quality forest, shrubs and Sabina prezewalskii forest. Theinterception rate of litter layers decreasing with precipitation increasing, the littershould be thick for absorbing the runoff, the thickness is less for controlling soilspatter and blocking runoff speed. The litter layers thickness should be media forimproving the surface soil resistant-clash capacity, the layers should be morethickness for controlling the soil evaporation.4. The natural water holding capacity of litter layers of different vegetation typesis not half of saturation water holding capacity in Qilian Mountains, effectivepotential water holding is great. The forest canopy and litter layers play a protect rolein preventing raindrop spatter. Although the stem flow amount is not large, it has animportant function in Picea crassifolia forest ecosystem, the main action isaccelerating nutrient cycle.