南亚热带乡土阔叶树种和桉树人工林土壤酶活性分析

Analysis on Soil Enzyme Activities between Native Broadleaf and Eucalypt Plantations in South Subtropical China

为了解乡土阔叶树种和桉树(Eucalyptus spp.)人工林土壤酶活性差异,以南亚热带地区红锥(Castanopsis hystrix)、米老排(Mytilaria laosensis)、火力楠(Michelia macclurei)和山白兰(Paramichelia baillonii)4个乡土阔叶树种人工林及尾巨桉(Eucalyptus urophylla×E.grandis)人工林为研究对象,探讨土壤脲酶、蛋白酶、磷酸酶、蔗糖酶和纤维素酶5种酶活性在各林分不同土层(0~20、20~40和40~60 cm)的变化及其影响因素。结果表明,林分类型对土壤脲酶、磷酸酶活性影响显著,对蔗糖酶活性影响极显著,对蛋白酶及纤维素酶活性影响不显著;土层对5种土壤酶活性均有显著或极显著影响。4个乡土阔叶树种人工林间,土壤脲酶、磷酸酶和蔗糖酶活性均差异不显著;尾巨桉人工林40~60 cm土层脲酶活性显著高于米老排林,0~20 cm土层磷酸酶活性显著低于山白兰林,0~20 cm土层蔗糖酶活性显著低于4个乡土阔叶树种人工林,20~40 cm土层蔗糖酶活性显著低于米老排林。全部林分的5种土壤酶活性均随土层加深呈下降趋势。Pearson分析显示,土壤脲酶活性与土壤有机碳、速效磷、速效钾及微生物生物量碳和氮含量均呈显著或极显著正相关;蛋白酶活性与有机碳和速效磷含量均呈极显著正相关;磷酸酶活性与土壤有机碳、铵态氮、速效磷、速效钾及微生物生物量碳和氮含量均呈显著或极显著正相关,与pH呈极显著负相关;蔗糖酶活性与土壤有机碳、铵态氮、速效磷及微生物生物量碳和氮含量均呈极显著正相关,与pH呈极显著负相关;纤维素酶活性与土壤有机碳和速效磷含量均呈极显著正相关,与pH呈极显著负相关。总体而言,4个乡土树种人工林土壤有机碳矿化和有机磷向无机磷转化的能力强于尾巨桉人工林。造林时,可优先考虑乡土阔叶树种。

In order to understand differences of soil enzyme activities among native broadleaf plantations and eucalypt plantation,four native broadleaf plantations(Castanopsis hystrix,Mytilaria laosensis,Michelia macclurei and Paramichelia baillonii)and Eucalyptus urophylla×E.grandis plantation in south subtropical China were selected as research objects,and changes and influencing factors of five soil enzyme(urease,protease,phosphatase,sucrase and cellulase)activities in different soil layers(0-20,20-40 and 40-60 cm)were discussed.Results showed that stand type had significant influences on soil urease and phosphatase activities,had extremely significant influences on sucrose activity,and had no significant influences on protease and cellulase activities.Soil layer had significant or extremely significant influences on five soil enzyme activities.Activities of urease,phosphatase and sucrose had no significant differences among four native broadleaf plantations.Urease activity of E.urophylla×E.grandis plantation in 40-60 cm soil layer was significantly higher than that of M.laosensis plantation.Phosphatase activity of E.urophylla×E.grandis plantation in 0-20 cm soil layer was significantly lower than that of P.baillonii plantation.Sucrase activity of E.urophylla×E.grandis plantation in0-20 cm soil layer was significantly lower than that of four native broadleaf plantations,which in 20-40 cm soil layer was significantly lower than that of M.laosensis plantation.Five soil enzyme activities decreased with increase of soil depth in all plantations.Pearson analysis showed that soil urease activity had significantly or extremely significantly positive correlations with contents of soil organic carbon,available phosphorus,available potassium,microbial biomass carbon and nitrogen.Protease activity had extremely significantly positive correlations with contents of soil organic carbon and available phosphorus.Phosphatase activity had significantly or extremely significantly positive correlations with contents of soil organic carbon,ammonium nitrogen,available phosphorus,available potassium,microbial biomass carbon and nitrogen,and had extremely significantly negative correlation with pH.Sucrase activity had extremely significantly positive correlations with contents of soil organic carbon,ammonium nitrogen,available phosphorus,microbial biomass carbon and nitrogen,and had extremely significantly negative correlation with pH.Cellulase activity had extremely significantly positive correlations with contents of soil organic carbon and available phosphorus,and had extremely significantly negative correlation with pH.Generally,abilities of soil organic carbon mineralization and conversion of organic phosphorus to inorganic phosphorus in four native broadleaf plantations were better than those in E.urophylla×E.grandis plantation.It could be given priority to use native broadleaf species in afforestation.