亚热带不同人工林对土壤酶活性及其动力学特征的影响

在江西省大岗山区选取杉木林、马褂木林、马尾松林、马褂木 桤木混交林4种人工林及对照次生林，通过对林下土壤脲酶、过氧化物酶、多酚氧化酶的活性及其动力学特征进行比较分析，探讨天然次生林采伐更新为不同人工林类型后，对土壤酶活性及其动力学特征的影响. 结果表明:①4种人工林的土壤脲酶、过氧化物酶和多酚氧化酶的活性，Vmax和Vmax/Km随土壤深度的增加而降低.②与对照次生林相比，杉木林0～0.2 m土层的脲酶、过氧化物酶、多酚氧化酶活性分别降低了35%、4%、58%；脲酶的Vmax和Vmax/Km降低了46%和47%，其他土壤酶的动力学参数也有降低的趋势.③马褂木林的土壤酶活性及各项动力学参数均出现下降现象.④马尾松林0～0.2　m和0.2～0.4　m土层的脲酶活性分别降低了54%和62%，过氧化物酶活性均增加了23%，多酚氧化酶活性分别增加了28%和42%；过氧化物酶Km值分别降低了44%和48%，Vmax/Km增加了58%和92%，脲酶各项动力学参数明显降低，而多酚氧化酶各项动力学参数均增加.⑤混交林0～0.2 m土层的脲酶和多酚氧化酶活性分别降低了38%和9%，但过氧化物酶活性变化不明显；多酚氧化酶、过氧化物酶、脲酶的Vmax/Km分别下降了7%、38%、54%. 

Effects of different plantations on the activity of soil enzymes and their kinetic characteristics in subtropical zone

The activity of three soil enzymes(ureases,peroxidases and polyphenol oxidases) and the corresponding kinetic characteristics(V_(max),V_(max)/K_m and K_m) were studied by comparing four regenerated plantations (Cunninghamia lanceolata plantation,Liriodendron chinense plantation,Pinus massoniana plantation,Alnus_Liriodendron mixed plantation) with the local natural secondary forests in subtropical zone of Dagang Mountains of Jiangxi Province.The results showed that: 1) the enzyme activity,V_(max) and V_(max)/K_m of soil ureases,peroxidases and polyphenol oxidases of the four different plantations decreased with the increase of soil depth;2) comparing with the natural secondary forests,the activity of ureases,peroxidases and polyphenol oxidases of C.lanceolata plantation decreased by 35%,4% and 58% respectively in the depth of 0--0.2 m,while V_(max) and V_(max)/K_m of soil ureases decreased by 46% and 47%;3) the activity of other soil enzymes had the same tendency in this plantation;4) and the soil enzyme activity and kinetic characteristics in the L.chinense plantation decreased too.In the soil depth of 0(--)0.2 m and 0.2(--)0.4 m in P.massoniana plantation,the activity 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;5) the activity of soil ureases and polyphenol oxidases in the depth of 0(--)0.2 m of the Alnus_Liriodendron mixed forests decreased by 38% and 9%,and V_(max)/K_m of ureases,peroxidases and polyphenol oxidases decreased by 7%,38% and 54% respectively,but the activity of peroxidases showed no evident changes.