Effects of eucalypt plantation replacing Masson pine forest on soil physiochemical properties in Guangxi,southern China

By studying the soil physiochemical properties of eucalypt (Eucalyptus grandis×E. urophylla) plantation and Pinus massoniana forest in Qinnan Region,Qinzhou City of Guangxi,southern China,the objective of this study was to examine the effects of eucalypt plantations replacing P.massoniana forest on the soil physiochemical properties. The results showed that:1) making a comparison between both types of forests,the soil bulk density and capillary porosity decreased in 0-60 cm soil layer and the soil total porosity and non-capillary porosity increased in 0-20 cm soil layer of eucalypt plantation,but that of both forests was not significant different (P ranged from 0.42-0.91 ,df=4),after eucalypt plantation replacing P.massoniana forest; 2) the maximum water holding capacity,capillary water holding capacity and minimum water holding capacity in different soil layers also were not significant different (P ranged from 0.79-0.89 ) between both types of forests; 3) the content of total K,available P,exchangeable Ca,exchangeable Mg of eucalypt plantation was higher than that of P. massoniana forest,and soil organic matter,pH value,total P and hydrolyable N were less different between both forests,except total N (0-40 cm soil layer) and available K (0-20 cm soil layer) of eucalypt plantation were less than that of P. massoniana forest; test of the significance of difference indicated that soil organic matter,pH value,total P,hydrolyable N,available K and exchangeable Ca were not significant different (P ranged from 0.14-0.99) in 0-40 cm soil layer,and total K and available P in 0-20 cm soil layer and total N in 20-40 cm soil layer had a significant difference (P=0.05),exchangeable Mg,however,had significant or strong significant difference (P=0.05 in 0-20 cm and P=0.008 in 20-40 cm soil layer) between both forests. These implied that the soil physiochemical properties were stable,the consumption of soil nitrogen was accelerated and the content of soil available P and exchangeable Mg were improved,by ten years recovery after eucalypt plantations replacing P. massoniana forest.