Effects Of Topographic Factors On Soil Nutrients In Pinus Koraiensis Plantation And Their Evaluation

Pinus toraiensis,as a precious tree species in the north,has many important values.In addition to its own genetic factors,site quality is also a key factor affecting the growth of Pinus koraiensis.This study in Tonghua ring three tents forest farm and Linjiang city branch 49-81 older artificial Pinus koraiensis forest farm as the research object,studied the terrain factors impact on soil nutrient,and the terrain factors and soil factors site factor and selection,the screening of the 15 site factors for site classification and site quality evaluation,they can be divided into terrain factors(soil A layer thickness,slope direction,slope position,slope and elevation)and soil factors(soil moisture content,bulk density,pH value,total carbon,total nitrogen,hydrolyze nitrogen,total phosphorus,effective phosphorus,total potassium and available potassium).The terrain factor using the entropy weight method,calculating weights and scores,soil factors by principal component analysis(PCA),cluster analysis,according to their score,in turn,site type classification and site quality evaluation,according to the analytical data fitting of Pinus koraienis wood high-age equation,and calculate the various status index,The regression equation of status index,topographic factor and soil factor was established to provide theoretical basis for the suitable location and tree management of Pinus koraiensis.The research results are as follows:(1)Effects of topographic factors on soil nutrients:soil nutrients show surface aggr egation,and the contents of total carbon,total nitrogen,total phosphorus and total pota ssium in soil are all shown as layer O>layer A>layer B,The content of hydrolyzed ni trogen and available phosphorus presented:layer A>layer AB>layer B.Shaded slope and gentle slope are beneficial to the accumulation of soil nutrients.(2)Topographic factors influence the quality of the opposite land:the thickness of soil layer A>slope position>elevation>slope direction>slope.(3)According to cluster analysis,the site types of Pinus koraiensis plantation are generally divided into 7 types,and the number of the first 3 types of sample lands accounts for 23%of the total sample lands;Category 5 has the largest number of sample plots,accounting for 50%of the total sample plots.The topography cannot be changed,and the soil can be improved through fertilization.(4)The artificial timber stands of Pinus koraiensis in Changbai mountains were planted under site conditions of shady slope,gentle slope(0°-15°),altitude of 500-900 m,and thickness of soil layer A was more than 20 cm.Among them,fruit trees are suitable for growing on the sunny slope.Fruit and wood forest selection of half cloudy slope or half sunny slope afforestation,other conditions and timber stand conditions consistent.(5)The regression equation of status index,topographic factor and soil factor was established by applying quantitative theory:SI=a0+a1x1+a2x2Where,SI stands for status index;a0,a1 and a2 are parameters,x1 is the standardized value of the total score of terrain factor;x2 is the standardized value of the total score of soil factors.After fitting,a0=14.8855,a1=1.0913,a2=1.0252,determination coefficient R2=0.7697,root mean square error RMSE=0.7559.Status index was positively correlated with topographic factor and soil factor.By comparing a1 and a2 values,it can be seen that topographic factor and soil factor have basically the same influence on status index.