喀斯特地区人工林土壤速效养分与酶活性的季节变化

The seasonal variation of available nutrients and enzyme activity in the plantation soils in karst areas

为合理管理退化的喀斯特地区新造人工林,对杜仲林、桤木林、冰脆李林的土壤速效养分和土壤酶活性的季节变化规律进行了研究。结果表明:3种林分土壤速效养分含量和土壤酶活性均表现出明显的季节动态。根据林地速效养分的减少主要由林木吸收所致,可知N肥施用,杜仲、桤木林以9月至次年1月为好,冰脆李林以11月至次年1月为好;P肥施用,杜仲、冰脆李林以7—11月或1—5月为好,桤木林以3—5月或7—9月为好;K肥施用,杜仲、桤木林以9—11月为好,冰脆李林以11月至次年3月为好。3种人工林的脲酶活性表现为春夏季高,冬季低,多酚氧化酶活性表现为春秋季高,冬季低,过氧化氢酶活性表现为秋冬季略高,春夏季略低,而碱性磷酸酶活性的季节变化3种人工林不尽相同。

For developing the reasonably managements in the new plantation in degraded karst areas,the seasonal variation of soil available nutrients and enzyme activity were studied in the Eucommia ulmoides,Alnus cremastogyne,and Prunus salicina plantations.The results indicated that there were the significantly seasonal dynamics of soil available nutrients and enzyme activity in three kinds of plantations.According to the decrease of soil available nutrients mainly resulted from tree absorption,it could be infered that nitrogen fertilizers should be applied from Spet to Jan in the E.ulmoides and A.cremastogyne plantations,and from Nov to Jan in the P.salicina plantations.Phosphorus fertilizers should be applied from Jul to Nov or from Jan to May in the E.ulmoides and P.Salicina plantations,and from Mar to May or from Jul to Sept in the A.cremastogyne plantations.As to potassium fertilizers,it should be applied from Sept to Nov in the E.ulmoides and A.cremastogyne plantations,and from Nov to Mar in the P.salicina plantations.The urease activities in three plantation soils studied were higher in spring and summer than that in winter,the polyphenol oxidase activities in three plantation soils were higher in spring and autumn than that in winter,and the catalase activities were higher in autumn and winter than that in spring and summer.The seasonal variations of alkaline phosphatase activities in three kinds of plantations were different.