| Soil and water loss is very serious in south red soil hilly region. It is very impendent mission for this region to construct soil and water conservation forest. The artificial soil and water conservation forest construction and its mechanism on soil and \vater conservation have been studied at lanxi experimental station of soil and water conservation in zhejiang province from Apr.2001 to Jun.2002. This study was consisted of artificial soil and water conservation forest construction and its hydrological effect, the law of forest crown intercepting rainfall , the annual change of litter and its hydrological effect , soil anti-scourability intensified effect by artificial forest root system .the dimensional variation characteristic of soil physical peculiarity and microclimate variation character of artificial forest. The results showed as fellows 1 The artificial soil and water conservation forest construction and its soil and water conservation effect(l)The trend of forest height increase, chest diameter widen, crown layer gloomy degree rise was in consistent. This is to say, they all increased with growing season. But ihere were difference among different forest types .For phyllostachys pubescens ,its height slow increase, chest diameter relative stabilization, fallen leaves peak in Apr. and may; For mixed forests, forest height increase and chest diameter widen is slow. The change of crown gloomy degree was in consistent to fallen leaves; For cunning lanceolate , the speed of forest height increase exceed to chest diameter widen. The crown gloomy degree keep in very low. For citrus reticulate, the trunk of tree was low and its growth mainly embodied forest crown widen and gloomy degree rise.(2)The soil and water loss took on firstly rapid decrease, then slow decrease, finally keeping steady state. This dynamic law was embodied with these indexes of soil and water loss as follows. First, for phyllostachys pubescens .mixed forests and cunning lanceolate , the earth surface runoff didn't obviously have appeared after three years since these forests were planted,but for normal citrus reticulate and dense citrus reticulate, the earth surface runoff didn't have appeared after six years since these forests were planted, because normal citrus reticulate and dense citrus reticulate impaired the earth surface runoff in the process of them construction comparatively slow. Second. As a whole soil suspended matter little by little reduced with time prolonging of forest development .In the same time there were difference in different forests. These differences were classified two kinds. One kind was phyllostachys pubescens .mixed forests and cunning lanceolate .The dynamic change of their suspended matter had a obvious dividing points that is second years after forests planted. Before dividing point, the quantity of suspended matter was 93.7% of nine years total quantity. After dividingpoint, suspended matter quantity rapidly reduced .At fifth year there wasn't suspended matter .The other kind was normal citrus reticulate and dense citrus reticulate. Their dividing points were at the third year.Before the dividing point, suspended matter quantity was 76.7% of nine years total quantity. After the dividing point, suspended matter slowly cut down. At ninth year there still was a little suspended matter. Third, the dynamic change of pushed matter differed in suspended matter, but all forest plots' were in consistent .After the second year, there weren't pushed matter in each forest plot. Fourth, the proportion of suspended matter and pushed matter in soil erosion total quantity decided their effect on the dynamic change law of soil erosion modulus. From the dynamic change of soil suspended matter and pushed matter in three years, the pushed matter was main in soil erosion at the first year. After the first year suspended matter took the place of pushed matter step by step. After the third suspended matter became main in soil erosion.2 the law of crown layer intercepting rainfall in different artificial...
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