桂西南2种不同更新方式桉树人工林生长及其经济效益的研究-森林培育学专业论文.docxVIP

差异，植苗林地上部分营养元素积累量分别为967．60 差异，植苗林地上部分营养元素积累量分别为967．60 kg／hm2．,565．80 kg／hm2， 萌芽林分别为954．85 kg／hm2、527．73 kg／hm2。植苗林除K元素积累量低于 萌芽林外，其他元素积累量均高于萌芽林，但萌芽林生产1t干物质所需营 养元素少于植苗林。各林分土壤容重随土层加深而增加，其他土层物理性 质指标、有机质及各样分含量随土层深度增加而减少，林地土壤中N元素 含量最高，其次是P元素。 (4)两种不同造林密度的桉树植苗林林分总利润为33984．1 1元／hm2、 17776．07元／hm2。从2种更新方式的桉树造林项目经济效益评价指标来看， 4年生2种造林密度的桉树植苗林林分净利润、年投资利润率、内部收益率 均小于萌芽林，且萌芽林投资回收期比植苗林短，说明萌芽林投资造林后 能更快获得盈利，经济效益更好。 关键词：更新方式桉树人工林生长量经济效益桂西南 万方数据 STUDY STUDY IN SoUTHWEST OF TWo DIFFERENT REGENERATIoN PATTERNS oF E彤C么上I?丁之愿 PLANTATIoNS oF ECoNoMIC GRoWTH ABSTRACT In recent years，the supply of timber market is not adequate to the demand． This phenomenon makes the development of plantation has been accelerated． Eucalyptus has the feature of fast growing，straight trunk，good material and SO on．Eucalyptus，one species of myrtaceae，is one of three major world recognized species of fast—growing．Guangxi has the largest area of Eucalyptus plantations． Based on the 4 years and planting density of 2500／hm2 and 1 250／hm2 and two different regeneration pattens of Eucalyptus plantation in Guangxi southwest，compares and analyses indicators of growth conditions，productivity, volume，stock volume，nutrient content，soil physical and chemical properties and economy effectiveness，that hoping to provide reference for Eucalyptus plantation management．The main findings are as follows： (1)Because of planting density and update mode，the indicators of growth conditions，biomass and productivity of Eucalyptus sprout forests are better than planting seedlings forest．Planting seedlings forest varies in the number of trees diameter class，appearing most in the 1 2 cm． (2)There are some difference between two different regeneration pattens． the planting density of 2500／hm2 and 1 250／hm2 of Eucalyptus plantation The 万方数据 volume volume of average tree of seedlings is 0．0779 m3 and 0．0865 m3，sprout forest are 0．0983 m3 and O．1 1 20 m3 respectively；the volume of Eucalyptus plantation ofseedlings are 162．1503 m3 and 95．5310 m