杨树生长的密度效应与数量成熟研究

Effects of density on growth of poplar and its quantitative maturity research

在洞庭湖平原区采用南抗杨树无性系进行的8种不同密度造林试验,试验结果显示胸径生长于5年生、树高生长于8年生以后在不同造林密度间均具显著差异,其变化规律是胸径、树高生长均随造林密度的增加而降低,表明林木此时的生长已开始受制于单株营养面积之不足。根据材积的连年生长量曲线和平均生长量曲线交汇情况,8种造林密度杨树林分的经营目标可分为两大类型：一是单株营养面积为8～16 m^2造林密度的数量成熟为7～9年,所获材种为20 cm以下纸浆材、纤维板材等;二是单株营养面积为24～36 m^2造林密度的数量成熟在10年以上,可培育26 cm以上大径材。

The experiment on 8 different afforestation densities of southern type clones of aigeiros poplars with resistibility in Dongting Lake plain was conducted.The results showed that,the DBH growth of poplar older than 5 years old and the height growth of poplar older than 8 years old were significantly different from among different afforestation densities.The rule was that the growth of DBH and height decreased with increase of afforestation density,which indicated that the forest growth at this time was confined by the deficiency of individual nutrient area.According to the cross between annual growth curve of timber volume and average growth curve of timber volume,the management objectives of poplar stands with 8 different afforestation densities could be divided into two main types： one was to breed pulpwood,fiber board and so on with diameter less than 20 cm,while the afforestation density met the individual nutrient area of 8～16 m^2 and the quantitative maturity age was 7～9 years.And the other was to cultivate the huge wood with diameter more than 26 cm,while the afforestation density met the individual nutrient area of 24～36 m^2 and the quantitative maturity age was above 10 years.