Forest Land Evapotranspiration And Water Balance Of Songhua River Water Conservation Forest

This paper studies on the quercus mongolica, mixed forest and manchurian linden,definite quantity analysis on the incoming and defraying of forestry water, we know betterabout hydrologic accounting of forestry ecological system in this area. Discussed the functionof water and soil conservation and water conservation in different forests.The results are:(1) the rainfall in the forest and Rainfall Interception are the main factors in acting on thehydrologic accounting in the forestry ecological system, the rainfall of quercusmongolica, mixed forest and manchurian linden are 30.65%, 43.24% and 47.48 indifferent growing seasons. In the whole growing season quercus mongolica's retentionrate is 69.35%, 15% more than manchurian linden's, there are many reasons on impactof canopy interception, besides the character of rainfall, the Stand Characters' is alsoobvious, canopy density and leaf area are main factors, because they decide thestructural feature of canopy, so they influence the distribution of rainfall. The moreproportion of rainfall in the forest is, the more rainfall supplies the forest, the moreeffectiveness of rainfall, but it is not mean that the largest effectiveness comes out whenthe rainfall in the forest is close to rainfall outside of forest, the worse cannopy densitywill debase the water conservation's function.(2) Evapotranspiration of quercus mongolica, manchurian linden and mixed forest are167.36mm, 184.7mm and 228.55mm, the same with transpiration. The allevapotranspiration of quercus mongolica, manchurian linden and mixed forest are29.87%, 30.95% and 38.31%.(3) accoding to balance between income and expenditure of water, it shows thatthetendency is the same in different forest: the water in june is most, and in july andaugust the water is self-sufficiency, and from September, as the rainfall reduces, thewater is scarce. In different forests, the water is least in the quercus mongolica, thenumber is -27.63mm; in the manchurian linden 6.96mm left after growing season;although there is -5.29mm's water lack, it will not affect and satisfy the growth of forest.