毛竹入侵对落叶阔叶林土壤理化性质和胞外酶活性的影响

Effects of Phyllostachys edulis invasion on soil physical and chemical properties and extracellular enzyme activities in deciduous broad-leaved forest

【目的】研究毛竹(Phyllostachys edulis)入侵亚热带北缘落叶阔叶林对土壤理化性质和土壤胞外酶活性的影响,为探究毛竹入侵条件下森林生态系统养分循环过程与固碳潜力及森林的毛竹入侵治理提供科学依据。【方法】在毛竹入侵样带上,选择落叶阔叶林(麻栎林Quercus acutissima)、竹阔混交林(混交林)和毛竹林3种林分为研究对象,采集其林下地表0~10 cm土壤,进行土壤理化性质和土壤酶活性的测定,包括土壤pH、含水率和有机碳、全氮、NH_(4)^(+)-N、NO_(3)^(-)-N、全磷、有效磷含量,以及β-葡糖苷酶(BG)、β-N-乙酰氨基葡萄糖苷酶(NAG)、亮氨酸氨基肽酶(LAP)、酸性磷酸酶(AcP)、酚氧化物酶(POX)、过氧化物酶(PER)活性和酶计量(V_(C/N)、V_(N/P)、V_(C/P)),比较不同林分的土壤指标。【结果】①随着毛竹入侵,毛竹林土壤pH值和含水率显著增大,且与混交林、麻栎林差异显著(P<0.05);其土壤有机碳、NO_(3)^(-)-N和全氮含量显著下降(P<0.05),NH_(4)^(+)-N、有效磷和全磷含量与混交林、麻栎林差异不显著。②土壤碳、氮和磷循环相关的水解酶(BG、NAG+LAP、AcP)活性均随毛竹入侵呈下降趋势,氧化酶(POX、PER)活性变化趋势与之相反;酶计量分析表明,毛竹林土壤的V_(N/P)显著低于混交林和麻栎林(P<0.05),而V_(C/N)、V_(C/P)在不同林分间差异不显著。③酶活性的矢量分析表明,毛竹林土壤微生物的磷限制程度高于混交林和麻栎林。④土壤水解酶活性与土壤有机碳、NO_(3)^(-)-N、全氮、有效磷含量或pH有显著相关关系,氧化酶活性与土壤性质相关性总体不显著。【结论】毛竹林取代落叶阔叶林(麻栎林)后,土壤有机碳和养分含量及相关水解酶活性降低,不利于原有落叶阔叶林土壤碳库与养分库的保存。

【Objective】The effects of Phyllostachys edulis invasion into deciduous broad-leaved forest on soil physical and chemical properties and extracellular enzyme activities were studied to provide basis for investigating nutrient cycling and carbon sequestration potential of forest ecosystem as well as the management of P.edulis invasion in forests.【Method】The deciduous broad-leaved forest(Quercus acutissima),mixed P.edulis-broad-leaved forest(transitional zone)and pure P.edulis forest were selected on the P.edulis invasion transect.Surface soil at 0-10 cm depth in forests was collected to determine soil physical and chemical properties as well as enzyme activities,including soil pH,water content,organic carbon,total nitrogen,NH_(4)^(+)-N,NO_(3)^(-)-N,total phosphorus,available phosphorus,β-Glucosidase(BG),β-N-Acetylglu-cosaminidase(NAG),leucine aminopeptidase(LAP),acid phosphatase(AcP),phenoloxidase(POX)and peroxidase(PER)and V_(C/N),V_(N/P),V_(C/P).Then,soil indexes of different stands were compared.【Result】①With P.edulis invasion,soil pH and water content of P.edulis forest increased,showing significant differences with mixed forest and Q.acutissima forest(P<0.05),and soil organic carbon,NO_(3)^(-)-N and to-tal nitrogen contents significantly decreased(P<0.05),NH_(4)^(+)-N,available phosphorus and toal phosphorus had no significant difference with mixed forest and Q.acutissima forest.②The activities of soil hydrolases(BG,NAG+LAP and AcP)related to carbon,nitrogen and phosphorus cycles decreased by P.edulis in-vasion,while oxidase(POX and PER)activities showed opposite trends.Soil V_(N/P)in P.edulis forest was significantly lower than that in mixed and Q.acutissima forests(P<0.05),but there was no significant difference in V_(C/N)and V_(C/P)among different stands.③The vector analysis of enzyme activities showed that the phosphorus limitation of soil microorganism in P.edulis forest was higher than that in mixed and Q.acutissima forests.④Soil hydrolase activity was significantly correlated with soil organic carbon,NO_(3)^(-)-N,total nitrogen,available phosphorus and pH,while oxidase activity was not significantly correlated with soil properties.【Conclusion】Contents of organic carbon and nutrients as well as activities of related hydrolase decreased after replacing deciduous broad-leaved forest(Q.acutissima forest)with P.edulis forest,which was unfavorable for the preservation of soil carbon and nutrient pools in original deciduous broad-leaved forests.