不同密度桉树能源林数量成熟龄与经济效益的关系

Relations between quantitative maturity ages and economic benefits of Eucalyptus energy forest with different densities

通过分析1年生9种不同初植密度的尾巨桉优良无性系DH32-29的生长数据,计算了连年生长量、平均生长量、干重生物量以及净现值。结果表明:不同密度随着初植密度的增加,林分干重生物量逐渐增加,并且高密度与低密度在各个月存在不同程度显著差异;能源林林分生长前期,株距对林分生物量累积影响较大,当林分基本郁闭后,行距产生较大影响;密度M156、M204、M252、M244、M2524的数量成熟龄均为11个月,M152和M254需要12个月达到数量成熟,M154以及M202为13个月,各密度数量成熟龄均集中在11到13个月之间;初植密度较小的M254、M156由于其生物量较小而未盈利;初植密度最大的M152由于苗木及人工费用过高而未盈利。利润净现值大于零的各密度排名为:M202>M154>M204>M252,这时的净现值分别为2841.15、2552.8、961.28、361.21元/hm2。

Through analyzing the growth data of one-year-old DH32-29Eucalypt clone with nine kinds of initial density,the current annual increment,average increment,dry weight biomass and net present value（NPV） were calculated.The results show that the biomass of stands increased as the stand density increased and the biomass differences between the stands with high density and low density reached significant level in each month in the first year;The influence of row space on the stand biomass was larger than the line space in the early growth,while the situation was on the contrary after the stand was close canopy;The ages at quantitative maturity of row space M156,M204,M252,M244,M2524 were 11 months,the M152 and M254 were 12 months while M154 and M202 needed 13 months to be mature;The M254 and M156 with small initial density had no revenue because of low biomass and the M152 with big initial density was not profitable because of the high costs for seedlings and labors,the other initial density which’s profit net present values were bigger than zero ranked by magnitude： M202 M154 M204 M252 and theirs NPV were 2841.15,2552.8,961.28 and 361.21 Yuan/hm2 respectively.