白榆不同造林密度与生长量关系的研究

Study on the Relation of Different Afforestation Densities to Increment of White Elm

营造株行距１×１ｍ、１×２ｍ、２．５×３ｍ不同造林密度的白榆试验林，１４年的试验结果表明，３种不同栽植密度对林分的高生长影响不大，但对胸径生长影响非常明显。２．５×３ｍ密度的试验林比１×１ｍ、１×２ｍ密度的胸径生长大３２．０３％和５２．４８％；１×２ｍ密度的比１×１ｍ密度的胸径大１５．４９％。根据树冠与胸径生长的关系推算合理的栽植密度，兼顾用材等经济效益营造白榆成片林，培育８ｃｍ以上的小径材，初植密度每公顷不能大于５０００株；培育１６ｃｍ以上的中径材，初植密度每公顷不能大于１５００株。

On the basis of creating experimental stands of white elm for 14 years, with different afforestation densities of 1×1m, 1×2m, 2.5×3m, the results indicate that different afforestation densities have no remarkable affect on increment of height, but very much on diameter increment, the diameter increment of 2.5×3m′s experimental stands is 32.03% and 52.48% more then that of 1×1m and 1×2m′s respectively, and that of 1×2m′s is 15.49% more than that of 1×1m′s. The optimal afforestation density could be worked out according to the relation of canopy to diameter increment, with regarding to economic effect of wood. The initial stand density should be less than 5000 per hm 2 for ≥ 8cm undersized trees, and 1500 per hm 2 for ≤16cm intermidate trees.