Soil Physical And Chemical Properties And Soil Quality Evaluation On The North And South Slopes Of Huoditang Forest Region

Huoditang forest area is located in the central area of Qinling Mountains.The flora and fauna of Huoditang forest area have obvious transitional zone characteristics,the ecosystem is easily affected by environmental changes.In order to ensure the ecological environment safety of Huoditang forest region and realize the sustainable development,the soil quality evaluation was carried out.Based on the fire to pond forest region,north and south slope as the research object,through field investigation and indoor analysis,the method of combining analysis fire pond forest region,north and south slope hydrology,soil physical and chemical properties change along altitude gradient distribution characteristics,and screening for fire pond forest soil quality evaluation system,fire pond forest soil quality comprehensive evaluation.The results can provide basic data for the study of soil properties in Huoditang forest area,and also provide data support for the study of soil quality and the protection of land resources in this area.The main research conclusions are as follows:(1)The soil mechanical composition of the north and south slopes of Huoditang forest region was mainly silt and sand,but few clay.In both the northern and southern slopes,large aggregates with the size of >0.25 mm are the main aggregates of mechanical stability and water stability.With the increase of altitude gradient,large aggregates tend to transform into small aggregates,the content of large aggregates gradually increases with the depth of soil layer.The fragmentation rate of aggregates in the Northern Slope first decreased and then increased with the increase of altitude gradient,increased with the increase of soil depth.The fragmentation rate of aggregates in the southern slope first increased and then decreased with the increase of altitude gradient,but showed no obvious change rule with the increase of soil depth.The destruction rate of soil aggregates in the Northern Slope was higher than that in the southern slope.In Huoditang forest area,soil bulk density decreased gradually with the increase of altitude gradient,and soil porosity increased gradually.With the increase of soil depth,soil bulk density increased gradually,and soil porosity decreased gradually.(2)In the 0-10 cm and 20-40 cm soil layers,the field capacity showed a fluctuating increasing trend with the elevation gradient.In the 10-20 cm soil layer,the field capacity presented a parabolic distribution,and increased first and then decreased with the elevation gradient.In the 700-1300 m gradient,the field capacity on the Northern Slope was higher than that on the southern slope.In the 0-10 cm soil layer,the saturated water content was significantly higher than that of other soil layers.In the 10-40 cm soil layer,the saturated water content of the Northern Slope was higher than that of the southern slope.In the 10-40 cm soil layer,the saturated water content of the Northern Slope was higher than that of the southern slope.The saturated water conductivity showed a fluctuating trend with the elevation gradient increasing,and fluctuated sharply.There was no obvious rule with the increase of soil depth on the Northern Slope,but it showed a decreasing trend with the increase of soil depth on the southern slope.The saturated water conductivity of soil on the southern slope was significantly higher than that on the Northern Slope.(3)The distribution range of soil p H in the Northern Slope of Huoditang is 4.26-6.04,and the range of soil p H in the southern slope is 3.73-6.24.Soil organic matter and total nitrogen fluctuate and increase with the elevation gradient,and gradually decrease with the increase of soil depth.Soil total phosphorus increased first and then decreased with the elevation gradient,and there was no significant change with the increase of soil depth.The soil total potassium content was stable,and the soil total potassium content in the southern slope was higher than that in the Northern Slope,and had no significant change with the elevation gradient and soil depth increasing.Soil alkali-hydrolyzable nitrogen showed a fluctuated increasing trend with the increase of altitude gradient,and a decreasing trend with the increase of soil depth.Soil available phosphorus content showed a fluctuating decreasing trend with the increase of altitude gradient,and the variation range of soil available phosphorus content with the increase of altitude gradient was much greater in the south slope than in the north slope.The content of soil available K was the highest,and the fluctuation range was the largest with the increase of altitude gradient.The content of soil available P decreased with the increase of soil depth.The soil cation exchange capacity fluctuated with the elevation gradient,and the fluctuation range of the southern slope was larger than that of the Northern Slope.(4)Based on principal component analysis,combined with correlation analysis and Norm value,the minimum data sets of Huoditang forest slope were selected as alkali-hydrolyzable nitrogen,silt content,cation exchange capacity,total potassium,saturated water conductivity,and total phosphorus,with weight values of 0.17,0.19,0.11,0.18,0.18,and 0.17,respectively.The soil quality in Huoditang forest region fluctuated and decreased with the increase of altitude gradient.The soil quality in the north and south slope was mainly at the higher level in the low altitude range,the soil quality in the north slope was higher than that in the south slope,and the soil quality in the high altitude gradient was mainly at the middle level.On the Northern Slope,the soil quality gradually decreased with the increase of soil depth,while on the southern slope,the soil quality fluctuated sharply with the change of soil depth without an obvious trend.