Study On Soil Characteristics And Water Conservation Capacity Of Cryptomeria Fortunei Plantation

Cryptomeria fortunei is a common coniferous forest in South China.It is one of the fast-growing and High-yielding timber in South China.It not only has high economic value,but also has high ecological benefits in forest soil improvement and water conservation.Because of the long-term pure forest management,lack of scientific theoretical knowledge and technical guidance of sustainable management,the problem of land capacity and water conservation capacity has aroused widespread concern.In the current ecological environment crisis,water conservation has become a major problem facing the forest ecological environment.It is of great significance to explore the soil characteristics and water conservation capacity of Cryptomeria fortunei plantation to accurately evaluate the ecological benefits of Cryptomeria fortunei plantation and formulate reasonable water and soil conservation measures.In this paper,the young,middle,near mature,mature and over mature stands of Cryptomeria fortunei Plantation in Dapo forest farm,Pingba District,Anshun City,Guizhou Province are taken as the research objects.By using the method of space instead of time,the current situation of soil nutrients of Cryptomeria fortunei plantation is revealed by studying the difference of soil physical and chemical properties with the age of forest and the depth of soil layer,and the water conservation capacity of different age groups of Cryptomeria fortunei plantation is also studied.The purpose of this study is to provide theoretical basis and practical reference value for the scientific management of soil nutrient resources and water conservation function of Cryptomeria fortunei plantation.The main conclusions of this paper are as follows:(1)With the growth of Cryptomeria fortunei,the soil bulk density and pH value decreased,the content of soil organic matter,total nitrogen,available nitrogen and total potassium increased,and the soil water content of 0?10 cm layer increased,while the soil water content of 10?30 cm layer from high to low was over mature forest > mature forest > medium forest age > near mature forest > young forest.The soil capillary porosity,non capillary porosity and total porosity increased first and then decreased,while the content of total and available phosphorus decreased first and then increased.With the deepening of soil layer,the soil bulk density of five age groups increased,and the content of water content,capillary porosity,non capillary porosity,total porosity,organic matter,total nitrogen,available nitrogen,total phosphorus,available phosphorus,total potassium and available potassium decreased.Variance analysis showed that soil bulk density was significantly affected by age group,soil moisture content,capillary porosity,non capillary porosity,total porosity,available nitrogen and available phosphorus content were significantly affected by age group and soil depth,and soil organic matter,total nitrogen,total phosphorus,total potassium and available potassium content were significantly affected by age group,soil depth and age group and soil layer interaction.The interaction of age group,age group and soil layer has significant effect on soil pH.(2)There is a close relationship between the fertility indexes of forest land,and each fertility index restricts each other.The evaluation index system of soil fertility was composed of 11 indexes of soil bulk density,water content,porosity,organic matter,total nitrogen,available nitrogen,total phosphorus,available phosphorus,total potassium and available potassium.The soil fertility scores of 5 age groups of Cryptomeria fortunei plantation were calculated by principal component analysis.The order of soil fertility from high to low was over mature forest > mature forest > near mature forest > middle age forest > young age forest.(3)The total litter thickness,total storage,maximum water holding capacity,effective retention rate and effective retention of 5 age groups of Cryptomeria fortunei plantation were all shown as mature forest > near mature forest > over mature forest >middle age forest > young age forest.The water holding capacity of litter in five age groups increased with the increase of soaking time,while the water absorption rate decreased with the increase of soaking time.Through regression analysis of water holding capacity,water absorption rate and soaking time of five age groups of litter,the relationship between water holding capacity and soaking time is logarithmic,and the relationship between water absorption rate and soaking time is power function.With the growth of Cryptomeria fortunei,the soil water holding capacity of five age groups of Cryptomeria fortunei plantation increased first and then decreased,the mature forest had the strongest water holding capacity.(4)Using entropy weight method,12 indexes of litter thickness,storage,maximum water holding capacity,maximum water holding capacity,effective storage capacity,effective storage capacity,soil bulk density,natural water content,capillary water holding capacity,non capillary water holding capacity,saturated water storage capacity and effective water storage capacity are comprehensively evaluated.According to the calculated weight,the water conservation capacity of the stand is comprehensively evaluated At the same time,the maximum water holding capacity,effective storage capacity,storage capacity,thickness,soil non capillary porosity and effective storage capacity of litter should be considered more.The water conservation capacity of 5 age groups of Cryptomeria fortunei plantation is from high to low in order of mature forest > near mature forest > over mature forest > middle age forest >young age forest,mature forest is in the best water conservation stage.(5)Through the analysis of the correlation between soil physical and chemical properties and water conservation function,we can see that: the natural water content of soil has a significant positive correlation with water conservation function(P <0.05),while the capillary porosity,non capillary porosity,total porosity and total nitrogen have a significant positive correlation with water conservation function(P <0.01);soil organic matter,total potassium and available nitrogen had a significant positive correlation with the water conservation function of litter(P < 0.05),and had a significant positive correlation with the water conservation function of litter(P <0.01);pH had a significant positive correlation with the water conservation function of litter(P < 0.01),and had a significant positive correlation with the water conservation function of soil(P < 0.05);among the water conservation indexes of forest land,except for the thickness of litter and the water conservation function oflitter There was a significant positive correlation(P < 0.05)between the effective retention rate of litter and other water conservation indexes(P < 0.01).