Variation characteristics of soil enzyme activity of Rhododendron pudingense habitat in different karst microhabitats

【Objective】 To investigate soil enzyme activity and its variation characteristics in different microhabitats of typical karst areas， and to provide scientific basis for vegetation restoration in karst regions.【Method】 Platycarya longipes+ Rhododendron pudingense communities in karst regions of Guizhou（Zhenning County，Qinglong County and Wangmo County）were taken as research object. Activities of soil intracellular enzymes（urease，sucrase，cellulase and protease） and extracellular enzymes［acid phosphatase（AP），peroxidase（POD），catalase（CAT）and superoxide dismutase（SOD）］ in 3 microhabitats［soil surface （SS）， rock gully （RG）， rock surface （RS）］were determined to analyze variation characteristics of enzymes activity in different microhabitats and their relationships with environmental factors.【Result】 In 3 microhabitats，activity of intracellular and extracellular enzymes was as SS>RS>RG，and activities of all intracellular enzymes were lower than activities of extracellular enzymes which accounted for 93% of total enzymes activity； significant difference in soil enzyme activity was found among different microhabitats（P<0.05）. Except for that the urease，POD，and SOD activities in Qinglong’s community showed a trend of SS>RS>RG，activity of the rest soil enzymes followed a trend of SS>RG>RS；soil enzyme activity was influenced by plant species diversity in the community，and as plants grew the most vigorously in the community of Qinglong，soil enzyme activity in Qinglong was higher than that in Zhenning and Wangmo.Differences among microhabitats （especially differences in moisture，temperature， humus content， and soil thickness）greatly affected soil enzyme activity，and differences among microhabitats led to uneven abundance of above-ground plant diversity，thereby influencing substrate supply，which imposed a certain impact；in karst region，SS boosted the best microhabitat condition，which was the most suitable for plant growth，followed by RG，and RS had the poorest condition. 【Conclusion】Soil enzyme activity in karst habitats is influenced by microhabitat type and soil enzyme activity in microhabitat of soil surface is usually higher than that of rock gully and rock surface. Variation of soil enzyme activity explains the growth of endemic R. pudingense in karst microhabitats to a certain degree.