Risk analysis of soil polarization due to nutrient cycling and litter decay in pure coniferous forests in the Loess Hilly Area
[Objective] This study aimed to analyze the risk of soil polarization in 3 kinds of artificial pure coniferous forests.[Method] 3 kinds of artificial pure coniferous forests (Platycladus orientalis,Larix principis-rupprechtii and Pinus tabulaeformis) in the Loess Hilly Area were investigated,and the biomass,productivity,and nutrient cycling were measured.In addition,decay incubation experiments of different trees litters (leaf litters and roots) mixed with collected soils were carried out to investigate the effects of litter decomposition on soil biological properties.[Result] There were differences in the accumulation of N,P and K in different organs among the 3 tree species.N,P and K mainly accumulated in stem of P.orientalis,in root and stem of L.principis-rupprechtii,and in root of P.tabulaeformis.Because of the properties of nutrient cycling,there existed high risk of K negative polarization in soils of P.orientalis and P.tabulaeformis forests,and high risk of N negative polarization in soil of L.principis-rupprechtii forest in short growth-stage.While in long term,there existed high risk of P negative polarization in soils of all 3 forests in growth seasons.The mixed decomposition experiments showed that:decomposition of litters of P.orientalis and principis-rupprechtii would cause obvious negative polarization of polyphenoloxidase activity in soil;decomposition of root of P.orientalis would cause obvious negative polarization of microbes quantity,and sucrase and catalase activity in soil; decomposition of litter of P.tabulaeformis would cause obvious negative polarization of polyphenoloxidase and catalase activity in soil,and its root decay would cause obvious negative polarization of dehydrogenase activity in soil.[Conclusion] Risks of negative-biological soil polarization due to litters in P.orientalis and P.tabulaeformis forests were higher than in L.principis-rupprechtii forest.In growth stage,K should be added to soils of P.orientalis and P.tabulaeformis forests,and N should be added to soil of L.principis-rupprechtii forest.P should be added to soils of all the 3 forests in long term.
NETL
NSTL
万方数据
维普
