中幼龄湿地松人工林生长过程的密度效应

Evaluation of the Economic Benefit and the Density Effects on the Growth of Young and Half-mature Slash Pine Plantations

用16a连续测定资料，对不同密度中幼龄湿地松人工林生长情况进行了分析研究．结果表明：密度对林分平均树高生长量有一定影响，但没有明显的规律性，差异不显著；林分的平均胸径和单株材积随密度的增加而减小，其中胸径在1～4a差异不显著，5～7a差异处于显著水平，8～13a差异达到极显著水平，此后随着林冠生长的稳定，不同密度的胸径差异稳定在一定的显著水平；林分蓄积量则随密度的增加而增大，各密度间存在显著差异，8～10a差异极显著．

Based on the data collected during 16 years, the economic benefit and density on the growth of 4 young and half-mature slash pine plantations with different densitieshave been studied. The results show that although there exists a certain effect of densityon density on average height growth,the law of effect is not conspicuous and the differenceis not significant. The average diameter at breast-height and mean sample-tree volume decrease with density increase. Along with the growth of plantations,the difference of diameter at breast-height among treatments is not significant at the age of 1 to 4,but becomessignificant at the age of 5 to 7 and turns to be extremely significant at the age of & to 13,and then remains a certain level due to the stability. of canopy growth. However,the standstock volume increases with density increase,and the difference is not only significant butbecomes extremely significant at the age of 8 to 10.