Dynamics Of Nutrient Content In Different Ages Of Cunninghamia Lanceolata Plantation In Huitong,Hunan Province

Cunninghamia lanceolata plantation is the main fast-growing and High-yielding afforestation species in southern China.The area and volume of Cunninghamia lanceolata Plantation in China rank first in the whole ecosystem.It can alleviate the shortage of wood supply and demand in China.Five plots of young,middle and mature Cunninghamia lanceolata Plantation in Huitong Ecological Station of Hunan Province were set up and their soil nutrients,soil enzymes and organs of Cunninghamia lanceolata were also studied.Nutrients were measured.Variance analysis and correlation analysis were used to study the soil nutrient changes of Cunninghamia lanceolata plantations at different ages.The purpose of this study is to further explore the trend and regularity of soil nutrient change among different ages of Cunninghamia lanceolata plantation based on the previous studies on the location of Cunninghamia lanceolata plantation by using the principle of interaction and interaction between soil and vegetation.The main conclusions are as follows:(1)The soil bulk density,soil water content and soil aeration of Cunninghamia lanceolata plantations with different forest ages increased with the change of forest age,while the total soil porosity decreased with the increase of forest age.(2)The soil of Cunninghamia lanceolata plantation showed strong acidity in general,and the soil pH value of young and middle forest age showed a downward trend,but the soil pH value of mature forest increased.(3)The contents of soil organic matter and major elements in Cunninghamia lanceolata vary greatly in different age stands.Among them,the change characteristics of soil organic matter content in different age stands are as follows:mature forest middle forest young forest middle forest total nitrogen content in different age stands:mature forest young forest middle forest middle forest soil total potassium,total phosphorus,total calcium,total magnesium and total magnesium.The variation characteristics of available phosphorus content in different forest ages are as follows:young forest age middle forest age mature forest;soil available potassium content in different forest ages:young forest mature forest middle forest age.There was a significant correlation between the contents of some major elements in soils of Cunninghamia lanceolata,but no significant correlation between the contents of some major elements.(4)The content of trace elements in the soil of Cunninghamia lanceolata has a decreasing trend with the increase of stand age.There are obvious vertical gradient characteristics in the same age standi.The change law varies with the difference of soil trace elements,and the order of the same soil trace elements content varies with stand age.The contents of Hg,Pb and Cd in soil decreased with the increase of stand age,which indicated that forest could purify soil heavy metal pollutants.The correlation between soil trace elements and the content of major elements is complex.Total potassium is positively correlated with the content of Cu,Zn,Cd and Pb,while total phosphorus is positively correlated with the content of Cd and Pb.The correlation between other major elements and other trace elements is not significant.(5)The contents of C,N and P in different organs of Cunninghamia lanceolata plantation differ significantly in different age groups.The order of C,N and P contents in different organs is the same from high to low,which is annual leaf>biennial leaf>root.In the same organs,the contents of C,N and P varied with age.The change trend showed that the carbon,nitrogen and phosphorus accumulated by leaves increased with the growth of forest age,and the contents of potassium and magnesium were more in middle forest age than in mature stage.Therefore,it was necessary to apply potassium fertilizer reasonably to promote the growth of Cunninghamia lanceolata at forest age.Nutrients in organs of Cunninghamia lanceolata are related to soil nutrients.Among them,organic matter,total nitrogen and total phosphorus in soil are strongly related to the nutrients of current-year-old leaves of Cunninghamia lanceolata,while total calcium,total nitrogen and total phosphorus in soil are positively related to the nutrients of biennial leaves.Therefore,soil nutrient content directly affects the growth and development of Cunninghamia lanceolata.(6)The soil enzyme content of Cunninghamia lanceolata varies with the stand age,among which sucrase,acid phosphatase and urease decrease with the increase of stand age,while catalase increases with the increase of stand age.The change trend of soil enzyme content with stand age is obvious because of the difference of stand age stage and soil depth.Among them,the differences of soil catalase,alkaline phosphatase,urease and sucrase in soil layer were not significant,but the differences of sucrase and acid phosphatase in forest age were significant.Soil enzymes were correlated with soil nutrients in Cunninghamia lanceolata,among which soil sucrase was positively correlated with U,total nitrogen,total phosphorus and Pb,soil urease was positively correlated with total nitrogen,available phosphorus and total potassium,soil acid phosphatase and total phosphorus were positively correlated with total nitrogen,soil catalase and available potassium were positively correlated with total nitrogen,soil acid phosphatase and total phosphorus were positively correlated with total nitrogen,soil catalase and available potassium were positively correlated with total nitrogen There was a significant positive correlation.