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用21年生造林密度试验林的观测资料,分析了造林密度对林分生长和经济效益的影响。结果表明：（1）4种不同造林密度（A 1 667、B 3 333、C 5 000、D 6 667株.hm-2）对林分生长、林分结构均有显著影响,其中,林分胸径、单株材积、冠幅随密度增大而减小,高径比随密度增大而增大,但16年生后,林分胸径、单株材积、冠幅、高径比随林龄增长均表现出差异逐步缩小的规律;（2）林分蓄积与出材量在幼林期与密度呈正相关,进入中龄期后差异变小。21年生林分A、B、C、D各密度的出材量分别为300.13、309.94、303.19、313.32 m3.hm-2,随着密度增大,小径阶株数率及小径材出材量所占的比例增大;（3）净现值随着林龄的增大与密度的相关性由正相关转化为负相关性。随着密度增大,林分经济收获期提前。根据马尾松林分生长规律,综合出材量与效益核算,培育马尾松纸浆材与小径材宜采用造林密度2 200 3 300株.hm-2,培育大、中径材宜采用造林密度1 667 2 200株.hm-2。

The effects of planting density on growth and economic benefit of Masson pine (Pinus massoniana) plantation were analyzed with the data of 21-year-old planting density experiment stand (the planting densities were 1 667, 3 333, 5 000, and 6 667 trees·hm-2 respectively), the results showed that the planting density had significant effect on stand growth and structure. With the increase of stand density, the diameter at breast height (DBH), the single tree volume and the crown diameter decreased, but the ratio of tree height/DBH increased. However, the difference of these factors decreased with stand age increasing at 16-year-old. The stand volume and the timber yield increased with stand density increasing at the juvenile stage, but the difference of these factors decreased when stand entered middle-aged stage. For 21-year-old stand, the timber yields of the four treatments of planting density were 300.13, 309.94, 303.19 and 313.32 m3·hm-2 respectively. The percentages of small-diameter trees and the yield of