喀斯特地区不同植被类型土壤微生物量磷、碱性磷酸酶及植酸酶的变化特征

Change characteristics of soil microbial phosphorus,alkaline phosphatase and phytase under different vegetation types in karst area

【目的】研究喀斯特地区不同植被类型下土壤微生物量磷(MBP)、碱性磷酸酶(ALP)和植酸酶(PHY)的变化特征,以及土壤磷有效性变化,为改善喀斯特地区磷胁迫现状提供参考依据。【方法】以喀斯特地区的耕地、草地、园地、灌木和林地5种植被类型为研究对象,比较不同植被类型及不同土层(0~5 cm、5~10 cm、10~20 cm、20~30 cm和30~40 cm)的MBP含量及ALP和PHY活性,通过建立回归方程及冗余分析揭示三者与速效磷及土壤环境因子的相关性。【结果】不同植被类型土壤MBP含量、ALP和PHY活性均随土壤深度的增加而逐渐降低。灌木土壤0~5 cm土层MBP含量为25.08 mg/kg,显著高于除林地0~5 cm土层MBP含量(23.63 mg/kg)外的其他植被类型(P<0.05,下同);5种植被类型中林地土壤0~5 cm土层ALP活性最高,为101.96 mg/(g·d),各植被类型在20~40 cm土层间土壤ALP活性无显著差异(P>0.05);灌木、草地和园地土壤在0~5 cm和20~40 cm土层PHY活性有显著差异。不同植被类型影响下,土壤MBP、ALP和PHY均与土壤速效磷呈正相关。土壤MBP、ALP和PHY均与土壤全氮、有机质、碱解氮、全磷和砂粒呈极显著正相关(P<0.01,下同),其中有机质贡献率最高;与容重和黏粒呈显著或极显著负相关。【结论】喀斯特地区土壤MBP含量、ALP和PHY活性及分布受植被类型及土壤生态环境的影响,灌木和林地土壤磷素利用率高且磷素来源丰富,耕地磷素利用率较低且来源单一。MBP、ALP和PHY是表征土壤磷素有效性变化的敏感因子,喀斯特地区有机质是影响土壤MBP、ALP和PHY的关键环境因子。

【Objective】To study the changes of phosphorus(MBP),alkaline phosphatase(ALP)and phytase(PHY)in soil microorganisms under different vegetation types in karst areas,and the change of soil phosphorus availability,in order to provide a reference for improving the current situation of phosphorus stress in karst area.【Method】The five planting cover types of cultivated land,grassland,garden,shrub,forest and different soil layers(0-5 cm,5-10 cm,10-20 cm,20-30 cm and 30-40 cm)in karst area were taken as the research object.The content of MBP and activities of ALP and PHY in microbial biomass of different vegetation types were compared,the correlation between the three factors and available phosphorus and soil environmental factors was revealed by establishing regression equation and redundancy analysis.【Result】The MBP content,ALP and PHY activities of different vegetation types decreased gradually with the increase of soil depth.The results showed that,the MBP content in 0-5 cm soil layer of shrub soil(25.08 mg/kg)was significantly higher than that of other vegetation types except 0-5 cm layer of forest soil(23.63 mg/kg)(P<0.05,the same below).Among the 5 vegetation types,the highest ALP activity was 101.96 mg/(g·d)in the 0-5 cm soil layer of forest soil,and there were no significant differences among vegetation types in the 20-40 cm soil layer(P>0.05).There were significant differences in PHY activity of shrub,grassland and garden soils in 0-5 cm and 20-40 cm soil layers.Under the influence of different vegetation types,soil MBP,ALP and PHY were positively correlated with soil available phosphorus.Soil MBP,ALP and PHY were extremely significantly positively correlated with total nitrogen,organic matter,alkali-hydrolyzed nitrogen,total phosphorus and sand(P<0.01,the same below),and the contribution rate of organic matter was the highest.There was significant or extremely significant negative correlation with bulk density and clay particles.【Conclusion】The content of MBP,activities of ALP and PHY and their distribution in soil are affected by vegetation restoration type and ecological environment in karst area.Shrub and forest soils have high phosphorus utilization rate and rich phosphorus sources,while cultivated land has low phosphorus utilization rate and the source was single,which are positively correlated with soil available phosphorus.Organic matter are the key environmental factors affecting soil MBP,ALP and PHY in karst area.