不同密度杉木林分下套种闽楠的生长分析

Analysis of forest growth of Cunninghamia lanceolate interplanted with Phoebe bournei in different densities

以福建省顺昌县杉木-闽楠复层林为研究对象,对不同保留密度杉木林下套种闽楠的林分生长进行调查分析。结果表明,随着杉木保留密度的增加,闽楠的平均胸径、树高、单株材积、冠幅、枝下高以及最大分枝粗均降低。西坑试验点内,1~6号样地(杉木保留密度为180株·hm^-2)的林下闽楠平均胸径和树高较7~8号样地(杉木保留密度为480株·hm^-2)的分别增加149.01%和88.95%;八一工区试验点内,1~2号样地(杉木保留密度为485株·hm^-2)的林下闽楠平均胸径和树高较3~4号(杉木保留密度为630株·hm^-2)、5~6号样地(杉木保留密度为825株·hm^-2)分别提高了19.75%、7.02%和40.04%、42.46%;西坑试验点内,1~6号样地,胸径超过30 cm的杉木株数占杉木总株数的88.30%,径阶分布更集中,7~8号样地,这一比例则仅为69.40%;八一工区试验地内,1~2号样地,胸径30~40 cm的杉木株数占杉木总株数的比例较3~4号、5~6号样地分别提高了70.89%和221.29%。结果表明,降低杉木保留密度(或增加间伐强度)有利于下层闽楠的生长和上层杉木大径材的培育。

Phoebe bournei were planted under existing Cunninghamia lanceolate plantations with different retention densities in Shunchang County,Fujian Province,and the growth status of Phoebe bournei and C.lanceolate was investigated.The results showed that the average diameter at breast height(DBH),tree height,single plant volume,average crown width,branch height,and maximum branch diameter of Phoebe bournei decreased with the increase in retention density of C.lanceolate,while the maximum branching angle exhibited the opposite trend.The average DBH and tree height of Phoebe bournei from sample plot No.1-No.6(C.lanceolate plantation with a density of 180 trees·hm-2) in the Xikeng test site increased by 149.01% and 88.95% compared to Phoebe bournei from sample plot No.7 and No.8(C.lanceolate plantation with a density of 480 trees·hm 2),respectively.The average DBH and tree height of Phoebe bournei from sample plots No.1 and No.2(C.lanceolate plantation with a density of485 trees·hm 2) in the test site of the Bayi industrial zone increased by 19.75%,7.02% and 40.04%,42.46% compared to Phoebe bournei from sample plots No.3 and No.4(C.lanceolate plantation with a density of 630 trees·hm 2) and sample plots No.5 and No.6(C.lanceolate plantation with a density of 825 trees·hm 2),respectively.The proportion of C.lanceolate trees with a DBH of more than 30 cm among the total number of C.lanceolate is 88.30% in sample plots No.1-No.6 from the Xikeng test site.In addition,the distribution of branch diameter in the C.lanceolate plantation was more concentrated than sample plots No.7 and No.8,and was estimated at 69.4%.The proportion of C.lanceolate plants with a DBH of 30-40 cm in the total population of C.lanceolate in the multi-layered forest in sample plots No.l and No.2 from the test site in the Bayi industrial zone increased by 70.89% and221.29%,compared to sample plots No.3,No.4,No.5,and No.6,respectively.These results indicate that reduction in the retention density of C.lanceolate(or increase in the thinning intensity) is conducive to the growth of Phoebe bournei in the lower forest,along with the cultivation of large diameter timber of C.lanceolate in the upper layer.