16年生尾巨桉小初植密度生长规律研究

以小密度667株.hm-2在3个立地指数22、24和26条件下,16年生林分生长结论为：（1）立地指数22、24和26达到中大径材培育目标的时间和年均生长量指标分别为10 a、8 a和7 a,年均生长量分别为21.6、27.2和31.1m3.hm2。（2）胸径生长和分布：胸径生长量随着时间的推移逐年变小,前2 a胸径每年生长超过4 cm,第3年超过2cm,4~6年超过1cm,以后越来越小,但在16 a的观测过程中,每年都稳定超过0.4 cm;在生长前期,2年生时,只有2~3个径阶;到6年生时,径阶增加到7个;到16年生时,径阶增加到10~11个（。3）平均高生长量随着时间的推移逐年变小,前3 a树高生长均超过3 m;第4~5年超过2 m,5~10 a超过1 m,以后越来越小,但在16年的观测过程中,每年稳定超过0.6 m。（4）蓄积量生长的高峰值都出现在第4年,且峰值都很大,指数22、24和26的峰值分别为43.3、52.23和54.69 m3.hm-2,为平均生长量的2倍,峰值过后年生长量迅速下降,第1年下降超过10 m3.hm-2,第2年下降7 m3.hm-2,以后逐年下降,但降幅收窄;指数22、24和26的连年与平均蓄积生长曲线的交叉点均出现在第7年。

Growth Rhythm of 16- year- old Eucalyptus urophylla x E.grandis on Less Spacing

The research focus on the growth of spacing 666 trees · hm-2 on three site index of 22, 24 and 26, the results showed that： （I） the time for the target of middle ＆ large diameter timber of SI 22, 24, 26 were 10,8 and 7 years respectively, and their MAIS were 21.6, 27.2 and 31.1 m3 ＂ hm -2 respectively at that time. （2） DBH growth decreased with time going on, it was over 4 cm ~ a -~at first two years, 2 cm at 3＇d year, and over 1 cm at 4 ~ 6~ year; it were over 0.4 cm till the final measurement at 16~ year; the DBH distri- bution only covered 2 - 3 diameter grades in the first two years; 7 diameter grades at 6th year; 10- 11 diameter grades at 16th year. （3） Mean H growth decreased with time going on, it was over 3 m · a -1 at the first three years, over 2 m· a -1 at 4- 5th year, over 1 m · a -1 at 5- 10th year, it were over 0.6 m till the final measurement at 16th year; （4） CAI peak appeared at the 4th year, the values were 43.3, 52.23 and 54.69 m3· hm -2 for SI 22, 24, 26 respectively, two times for MAI, then sharply decreased 10 m3· hm -2 at 54 year and 7 m3 · hm -2 at 6th year; The cross points of CAI and MAI curves were appeared at the 7th year for all SI.