Studies On The Effects Of Vegetation On Soil Properties In Typical Subtropical Plantations

The effects of different regeneration patterns on soil fertility were studied by comparing the soil physical-chemical properties and soil enzyme (soil ureases, peroxidases polyphenol oxidases and catalases) properties of four regenerated plantations (Pinus massoniana, Liriodendron chinense plantation, Cunninghamia lanceolata plantation, Alnus -Liriodendron mixed plantation) with the local natural secondary forests in subtropical zone of Dagang Mountains of Jiangxi Province. The correlation between soil physical-chemical properties and soil enzyme was also studied.The results showed that: the soil total porosity (non-capillary porosity and capillary porosity)in the depth of 0-20cm all decreased except that of L. chinense plantation. The soil macro nutrient level under all plantations decreased significantly with L. chinense plantation the lowest; There was a sharp decrease both in soil available Fe and Zn, but the available Fe was still sufficient while the available Zn was more insufficient. C. lanceolata plantation improved the supply of soil available Cu in soil depth of both 0-20cm and 20-40cm, but the results of other plantations showed an increase in depth of 0-20cm and a decrease in depth of 20-40cm.The enzyme activities, V_max and V_max/K_m of soil enzymes of the four different plantations decreased with the increase of soil depth.Comparing with the natural secondary forests, the activities of ureases, peroxidases and polyphenol oxidases of C. lanceolata plantation decreased by 35%,4% and 58% respectively,in the depth of 0-20cm,while V_max and V_max/K_m of soil ureases decreased by 46% and 47%.The activities of other soil enzymes had the same tendency in this plantation. The soil enzyme activities and kinetic characteristics in the L. chinense plantation decreased too. In the soil depth of 0-20cm and 20-40cm in P. massoniana plantation, the activities of ureases decreased by 54% and 62% respectively,while the peroxidases both increased by 23%, and polyphenol oxidases decreased by 28% and 42% respectively. K_m of peroxidases decreased by 44% and 48%, while V_max/K_m increased by 58% and 92% respectively. All the kinetic parameters of soil ureases decreased evidently, while polyphenol oxidases increased. The activities of soil ureases and polyphenol oxidases in the depth of 0-20cm of Alnus-Liriodendron mixed forests decreased by 38% and 9% respectively, and V_max/K_m of ureases. peroxidases and polyphenol oxidases decreased by 7%,38% and 54% respectively, but the activities of peroxidases showed no evident changes. At the same time, there is correlation between soil enzyme and soil physical-chemical properties ,and soil enzyme can be seen as an important index for soil fertility.