马尾松中龄施肥木材密度和干缩率的研究

选用广西马尾松龄施肥材料（连续观测13年），根据国际《木材物理力学试验方法》，研究了施肥对木材密度和干缩率的影响，结果表明：N、P、K三要素中，以N、P肥对木材密度和干缩率的影响较大。⑴总的来说P增加木材密度和干缩率，N肥降低木材密度木材干缩率。N、P肥降低木材差异干缩。施K肥对木材密度和干缩率的影响规律性不明显。⑵N、P、K施肥对木材密度和干缩率的影响及其变化程度，与肥种、施肥量、树干部位、木纹方向、气干或全干状态有关。施P肥木材密度具有增加的趋势，而且树干下部基本密度方差分析各处理间差异显著。N、K肥对木材密度的影响，规律性不明显。P肥使木材干缩率增加，P肥主要增加的是全干干缩率和径向气干干缩率，特别是树干下部径向气干干缩率各处理间差异显著。K肥对干缩率的影响规律性不明显，有待进一步研究。⑶为了保证木材质量，对于纤维用材林，主要施P肥；对于结构用材林，可施P肥，适当考虑N肥、K肥施用应慎重。

Study on Effect of Fertilization in Middle-aged Pinus massoniana Stand on Wood Basic Density and Shrinkage

Observations during 13 years on effect of different fertilizers applied in middle-aged Pinus massoniana stand in Guangxi province on basic density and shrinkage of its wood showed that N and P fertilizer had greater impact on wood density and shrinkage. Generally speaking, wood density and shrinkage may be increased by P fertilizer while decreased by N fertilizer. Both N and P fertilizer may decrease T/R ratio of wood shrinkage. K fertilizer had no evident effect on wood density and shrinkage. Effect of application of N, P, K fertilizer on wood density and shrinkage and its change had close relation with kind of fertilizer, amount applied, position of the tree, directions of wood grain and air-dry or absolute-dry status. Application of P fertilizer could increase wood density, and the variance analysis of basic density in the lower part demonstrated evident difference among different treatments. N and K fertilizer had no evident effect on wood density. P fertilizer could increase shrinkage, mainly absolute-dry shrinkage and radial air-dry shrinkage, especially significant at the lower part of tree among different treatments. Effect of K fertilizer on wood shrinkage need to be studied. It is suggested P fertilizer using in fiber-wood stand, P fertilizer with some N fertilizer in structure wood stand and K fertilizer using carefully.