| Soil moisture is the result of many environmental factors,which directly affect soil characteristics and plant growth.In this study,based on investigation in the forest and measurement of the soil moisture in the laboratory,the changing characteristics of soil moisture in different soil layers(0-10 cm,10-20 cm,20-40 cm and 40-80 cm)of aerially seeded Pinus massoniana plantations and environmental factors(vegetation,terrain,soil characteristics)were analyzed,and then the quantitative relationship between soil moisture and environmental factors was discussed by redundancy analysis.The results can provide reference for the development of management measures in improving water conservation ability and scientific management of aerially seeded Pinus massoniana plantations.The main research results and conclusions are as follows:(1)Vertical variation of soil moisture.The soil water content(SWC)and field water capacity(FWC)increased as the depth increased.SWC in the 40-80 cm was significantly greater than that in 0-10 cm and 10-20 cm(P<0.05).SWC in the 20-40 cm was significantly greater than that in 0-10 cm(P<0.05).FWC in the 40-80 cm was significantly greater than that in 0-10 cm(P<0.05).However,the capillary water capacity(CWC)and saturated water capacity(SWC)did not change significantly in different soil layers.The peak values of CWC and SWC were found in the 10-20 cm,but there was no significant difference between the different soil layers(P>0.05).The variation coefficients of SWC,FWC,CWC and SWC all decreased as the depth increased.(2)Vertical variation of soil factors.The bulk density(BD)increased,but non-capillary porosity(NCP)and soil organic matter(SOM)decreased as the depth increased.NCP in 0-10 cm and 10-20 cm was significantly greater than that in 40-80 cm(P<0.05)and SOM in 0-10 cm was significantly greater than that in other soil layers(P<0.05).However,capillary porosity(CP)and total porosity(TP)did not change significantly in different soil layers.The peak values of CP and TP were found in the10-20 cm,but there was no significant difference between the different soil layers(P>0.05).The variation coefficients of BD,NCP,CP,TP and SOM all decreased as the depth increased.(3)Among vegetation factors,average DBH and stand canopy density(C AN)were significantly positively correlated with shrub coverage(CS)and ground coverage(CG)(P<0.05).There was significant positive correlation between litter thickness(LT)and CAN,CS and herb coverage(CH)(P<0.05).Among the soil factors,SOM was significantly positively correlated with CP in 0-10 cm and 10-20 cm(P<0.05),and was negatively correlated with BD in 0-10 cm(P<0.05).There was a significant negative correlation between soil thickness and NCP in 0-10 cm,10-20 cm and 20-40 cm(P<0.05).There was no significant correlation among topographic factors(P>0.05).There was a significant positive correlation between CH and CP in 0-10 cm,10-20 cm and 20-40 cm(P<0.05),and there was a significant positive correlation between LT and CP in 0-10 cm and 10-20 cm(P<0.05).(4)Soil moisture of aerially seeded Pinus massoniana plantations was affected by the combined effects of soil,vegetation and topographic factors,and there was an interaction between environmental factors.It was mainly affected by soil factors such as BD and CP,followed by vegetation factors such as CH,LT and CG etc.The topographic factors had the least influence.The effect of BD on soil moisture gradually increased as the depth increased,while the effect of CH and CG on surface soil moisture was stronger than on deep soil moisture.In each soil layer,the soil factor was the independently dominant factor,and the secondary factor was the independent vegetation factor and its interaction with other factors.Vegetation and topographic factors changed soil moisture mainly through influencing soil factors. |
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