全文总字数：2475字

1. 毕业设计（论文）的内容、要求、设计方案、规划等

前言树木的分枝是与主干生长有着密切关系的营养器官。

量度其分枝长(bli)、分枝距(hb)、分枝数(bn)、枝干高(hon)、枝下高(ho)和主梢长(hn)等因子可以反映树木分枝性状的特点。

由于分枝数、分枝长及其在主干上分布状况的不同，构成了树木冠型的差异，一般认为用材树木优良的冠型是窄冠浓密型。

2. 参考文献（不低于12篇）

[1] codesido v, fernndez-lpez j. juvenile genetic parameter estimates for vigor, stem form, branching habit and survival in three radiata pine (pinus radiata d. don) progeny tests in galicia, nw spain [j]. european journal of forest research, 2008, 127(4): 315-325.

[2] de wit i, keulemans j, cook n c. architectural analysis of 1-year-old apple seedlings according to main shoot growth and sylleptic branching characteristics [j]. trees, 2002, 16(7): 473-478.

[3] lauridsen e b, kjaer e d. provenance research in gmelina arborea linn., roxb. a summary of results from three decades of research and a discussion of how to use them [j]. the international forestry review, 2002: 20-29.