间伐对尾叶桉人工林土壤理化性质、土壤微生物和土壤酶活性的影响

Effects of Thinning on Physical and Chemical Characteristics,Soil Microorganism and Soil Enzyme Activities of Eucalyptus urophylla Plantation

【目的】本研究探讨了抚育间伐对人工林土壤因子的重要影响。【方法】以东莞大岭山林场4种种间伐强度(CK:0%,M1:30%,M2:70%,M3:100%)的12年生尾叶桉人工林为研究对象,探讨了间伐7年后林分土壤的理化性质、微生物和酶活性在冬季和夏季的变化。【结果】(1)间伐对土壤理化性质的季节变化存在不同程度影响。冬季,间伐提高了土壤电导率、铵态氮、速效K、交换性Mg和交换性Na含量,M1显著减低土壤硝态氮,M1和M3林分显著减低土壤交换性Ca;夏季,间伐提高土壤全N、铵态氮、硝态氮和全P,降低土壤交换性Ca。(2)间伐对土壤微生物的影响存在着显著的季节差异性,间伐后夏季的土壤微生物碳和微生物氮显著高于冬季;随着间伐强度增大,土壤微生物碳和微生物氮在冬季和夏季均呈先上升后下降趋势。(3)间伐对土壤过氧化氢酶活性变化不显著,但能促进土壤磷酸酶和脲酶活性增大;磷酸酶活性表现为夏季较高,冬季较低;脲酶活性则相反。(4)PCA表明,不同季节间伐林分与未间伐林分在冬季和夏季对土壤因子响应显著不同,冬季间伐林分样地分布较散,夏季M2和M3林分能较好聚为一类,与土壤pH、铵态氮、硝态氮和过氧化氢酶因子相关。【结论】尾叶桉人工林间伐后林地的土壤理化性质向好的方向发展,对维持土壤生态系统的平衡和可持续发展具有重要的意义。

【Objective】This study aimed to discuss the important effect of thinning on the artificial forest.【Method】Taken four transformed stands（ CK： 0 %,M1： 30 %,M2： 70 %,M3： 100 %） of 12-year-old Eucalyptus urophylla plantations in the Dongguan Forest Research Park,Guangdong as study objects,the effects of thinning on the physical and chemical characteristics,microorganism and enzyme activities of soils in winter and summer 7 years after thinning were studied in this paper. 【Result】（ i） Thinning had some effects on soil physical and chemical properties between seasonal variations. In winter,the thinning treatment could increase soil conductivity,NH4-N,available K,exchangeable Mg and Na content,total N significantly reduced in M1 stand,and exchangeable Ca significantly reduced in M1 and M3 stands;In summer,thinning increased soil total N,NH4-N,NO_3-N and total P but decreased exchangeable Ca.（ ii） There were significant differences in soil microorganism between seasonal variations,and thinning had significant effects on soil microbial biomass C and N,and the soil microorganism in summer was significantly higher than that in winter. The soil microbial biomass C and N showed a trend of increasing first and then decreasing in winter and summer with the increase of thinning intensity.（ iii） thinning had no significant effects on soil enzyme but could increase phosphatase and urease activities; The phosphatase activity was higher in summer and lower in winter; However,the urease activities were opposite.（ iv） PCA indicated that the soil factors responses the thinning and unthinned stands in winter and summer.Thinning stand was scattered in winter,while the M2 and M3 stand in summer were sorted together,which related to the soil pH,NH4-N,NO_3-N and catalase activity. 【Conclusion】The soil physical and chemical properties would closely related to the balance and sustainable development of soil ecosystem after thinning of Eucalyptus urophylla plantation.