Effects Of Stand Density On Hydrological Effects Of Three Forests Typical In Sai Han Ba Area

In order to explore the effect of stand density on the hydrological effect of typical forest in the Saihanba area,the main forest types（coniferous forest,broadleaf forest and coniferous and broad-leaved mixed forest）in the Saihanba were studied,and the hydrological functions of forest canopy,litter and soil layer of different forest types were studied by typical sampling methods.The forestry production and management in this area provides a theoretical basis.The results of the study are as follows:（1）The influence of different forest density on the canopy hydrological function.The variation of the total amount of soaking rain in coniferous forests is 133.67¹39.29mm,When throughfall is greater than 1.20³.65mm,throughfall may occur in the forest.The variation of canopy interception amount is 45.01⁴9.62mm,and the variation of stemflow is 2.70³.71mm.The range of throughfall in broad-leaved forest ranges from143.67¹51.09mm.When the outside of forest rainfall is greater than 1.28⁴.53mm,the throughfall may occur,and the total variation of canopy interception is between40.87⁴3.05mm.The variation range of stemflow is between 4.84⁶.58mm.The throughfall of the coniferous broad-leaved mixed forest ranges from 138.35¹42.29mm.When the outside of forest rainfall is greater than 1.24⁴.11mm,it is possible to pass through the rain.The total variation of canopy interception is between 31.07³6.75mm.The variation of stemflow is 3.84⁵.60mm.The sequence of canopy interception and stemflow are 1200plants/hm²>1000 plants/hm²>1400 plants/hm²>600 plants/hm²>800 plants/hm²,but the index of penetrating rain in forest is not consistent with the reflection of the two indices at different stand density.（2）The influence of different forest density on hydrologic function of litter layer.The total reserves of coniferous forest litter ranged from 11.55¹6.64 t·hm^-2,the maximum water holding capacity varies from 27.88⁴7.62 t·hm^-2,the maximum storage range is between 25.55⁴2.65 t·hm^-2,and the effective range of interception varies from21.37³5.51 t·hm^-2.The total reserves of litter in the broad-leaved forest range from11.11²8.89 t·hm^-2,the maximum water holding capacity varies from 32.37¹01.90 t·hm^-2,the maximum storage volume varies from 29.54⁹7.87 t·hm^-2,the effective range of interception varies from 24.68⁸2.59 t·hm^-2.The total reserves of litter in mixed forests of coniferous and broad-leaved forests varied from 10.61²3.39 t·hm^-2,the maximum water holding capacity varies between 26.37⁶2.75 t·hm^-2,and the maximum change range is between 25.02⁶2.71 t·hm^-2,and the change range of effective storage capacity is between21.06⁵3.30 t·hm^-2.The hydrologic effect of the litter layer with different stand density in the litter layer is from large to small:1200 plants/hm²>1000 plants/hm²>1400 plants/hm²>800 plants/hm²>600 plants/hm².（3）Effects of different forest density on soil hydrological function.The variation range of soil bulk density in coniferous forest is between 0.98¹.28g/cm³,the maximum water holding capacity of soil varies between 466.02⁵68.25t hm^-2,the range of effective water holding capacity is between 34.51⁹7.35t/hm²,the change range of initial infiltration rate is between 18.51³3.24mm.min^-1,and the range of the change of stability rate is1.68³.35mm.min^-1.The range of soil bulk density in broad-leaved forest is between1.01¹.21g/cm³,the range of the maximum water holding capacity of soil is between612.13⁷24.36t/hm^-2,the range of effective water holding capacity is between68.11¹21.69t/hm2,the range of initial infiltration rate is between 22.37⁴5.21mm.min^-1,and the range of the change of the rate of stability is 1.91⁴.32 between mm.min^-1,the variation range of soil bulk density in the mixed forest of coniferous and broad-leaved forest is between 1.05¹.25g/cm³,the range of the maximum water holding capacity of soil is between 548.21⁶24.32t/hm²,the range of effective water holding capacity is between48.17⁸3.18t/hm²,the variation range of initial infiltration rate is between 24.38⁵2.13mm.min^-1,andthevariationofthesteadyinfiltrationratebetween1.97⁴.61mm.min^-1.The hydrological effects of different stand densities in soil layers ranged from:1200 plants/hm²>1000 plants/hm²>1400 plants/hm²>800 plants/hm²>600 plants/hm²（4）The different forest density was evaluated comprehensively by entropy weight method.The comprehensive evaluation of 1200 plants/hm²broadleaf forest was the best,followed by 1000 plants/hm²broadleaf forest,and 600 plants/hm²mixed forest was the worst.The hydrological effect of stand density of 1200 strain/hm²¹000/hm²in three different forest types was significantly stronger than that in other three species.