Multivariate Statistical Analysis Application in Evaluation Soil Fertility of Coverting Land into Forests in Sichuan

Multivariate statistical principal component analysis was adopted to evaluate soil gertility rank,taking example for 17 soil fertility factors of four patterns of the coverting lands into forests and farmland in Hongya,Sichuan Province.The cumulative contribution of the first 5 principal components of soil fertility factors is 84.17%,and therefore they are sufficient to reflect the information of original factors.The 5 principal components include: ① soil available phosphate,soil NH_4~(+)-N,pH(H_2O),available N,total N,total P and soil NO~(-)_3-N;② soil total K,soil rapidly available K and soil slowly available K;③ total soil porosity,capillary porosity and max soil moisture capacity;④ soil bulk density,capillary capacity and pH(KCl);and ⑤ soil organic matter.The Integrated score was calculated in virtue of SPSS statistical software.As far as the improved effects on forest soil after converting lands into forests was concerned,pattern Ⅲ(Hemarthria) was the best one among all patterns about the top level soil;while pattern Ⅱ(Gramineae+Hemarthria) was the best one about the lower soil.