Study On Distribution Of Surface Soil Roots Of Rhododendron Delavayi And Hydrology Function Under Forest

Taking the Rhododendron delavayi forest in Baili Rhododendron scenic spot as the research object,the responses of the root biomass and fine roots ratio distribution of different roots diameters and rhizomes of Rhododendron delavayi under different health states to the forest health status were studied,then research the physical properties and hydrology functions of litter layer and soil layer under forest.The roots system was studied by roots drilling to collect the roots system of Rhododendron delavayi in different health states;the hydrology function of the litter layer with different decomposition levels under the forest of Rhododendron delavayi was studied by using indoor soaking method,and according to the theory of soil evaporation,the simulation experiment was carried out by using a self-made micro evaporation device,and the existing situation of litter under the Baili Rhododendron forest as a reference,to study the effect of litter with the same proportion of different mass and different proportion of the same mass on the inhibition of soil evaporation;Soil Moisture Determination of Physical Properties（LY-1215-1999）analysis.In order to provide scientific basis for the protection and restoration of Rhododendron delavayi forest and the management and maintenance of the local forest area under the litter layer and soil layer of Rhododendron delavayi forest,to avoid the unreasonable cleaning of the litter caused damage to the water conservation function of the forest.（1）The results show that in vertical distribution,the total biomass decreased with the deepening of soil depth,and the roots of different root diameters decreased with soil depth（P<0.05）,mainly concentrated in soil surface layer（0-10cm）（P<0.00）,and the proportion of total biomass of fine roots decreased with the decrease of health degree（P<0.05）.The proportion of fine roots in different soil layers varies with health There was significant difference between 0-10cm soil（P<0.01）,and the roots biomass decreased with increasing distance from tree trunk,but only healthy root biomass.At different tree crown projection positions,the proportion of fine root decreased with the decrease of health（P<0.03）,and the proportion of fine root biomass increased with the increase of altitude,while the proportion of unhealthy Rhododendron delavayi decreased with the decrease of altitude.Decreased number of litter on the fine roots of Rhododendron delavayi.The root biomass of Rhododendron delavayi had obvious vertical and horizontal changes,but its health status was mainly affected by the distribution of fine root ratio in soil-10cm soil layer and horizontal position,while fine roots ratio had a certain change rule at altitude,but there was no significant difference in its health status（P>0.05）.All factors had no significant effect on the biomass of middle and coarse roots（P>0.05）.（2）The results show that the litter storage and the maximum water holding capacity increase with the increase of the degree of decomposition（P<0.01）;with the increase of the degree of decomposition,the maximum storage capacity and the effective storage capacity show a decreasing trend（P<0.01）,the maximum storage rate,the effective With the decrease of the decomposition degree,the retention rate showed an overall increasing trend;the cumulative water holding capacity of litters with different decomposition degrees showed an inverted"J"shape,and the cumulative water holding capacity Q_tand the water immersion time t showed a very significant logarithmic function relationship（P<0.01）,the regression equation is:Q_t=a+bln t,which gradually increases at 0-4h and tends to a stable change trend at 4-48h;the water absorption rate V of litter at different decomposition levels has a significant power function relationship with the water immersion time（P<0.03）,the regression equation is:V=at^-b,the litter has the highest water absorption rate within 0-1h of immersion,and its ability to exert hydrology function is the strongest;When the proportion of litter cover was the same,but quality of litter cover was different,the evaporation of soil water decreased with the increase of litter quality;The soil moisture evaporation was decreased with soil moisture contents decreasing.When the moisture contents decreased by 0.5%,the soil moisture evaporation with litter cover of 60g,30g and 15g decreased by 0.11g,0.49g and 1.23g successively.When the cover quality of litter was the same,the inhibitory effect of litter with different decomposition degrees on soil water evaporation is different,which showed as follows:undecomposed>semi-decompose>decomposed.The more litter cover,the more significant the inhibition of soil evaporation;The lower the decomposition degree of litter,the better the inhibition of soil evaporation.（3）The results show that the soil bulk density increases with depth,and the soil bulk density increases（P<0.01）;the capillary porosity,non-capillary porosity,and total porosity all decrease with increasing soil depth（P<0.01）.The change trends of maximum water holding capacity,capillary holding capacity,field holding capacity,and mass water content of the soil layer of Rhododendron delavayi forest at different depths are consistent,and all show a decreasing trend with the increase of soil depth（P<0.01）.The indexes of soil bulk density and soil water holding capacity have a very significant negative correlation,and the capillary porosity,non-capillary porosity,total porosity and soil holding capacity indexes have a very significant positive correlation（P<0.01）;fine Root biomass was significantly positively correlated with soil water holding capacity（P<0.05）,and extremely negatively correlated with soil bulk density and soil water content（P<0.01）.The physical properties and water-holding properties of the 0-10cm soil layer of the Rhododendron delavayi forest are better than the 10-20cm soil layer.