Christmas trees are another important agricultural product, and Michigan forests produce large quantities of pulpwood pr圣诞树是另一个重要的农产品，而密西根境内的森林则生长数量庞大的纸浆用树木。
The results showed that stem volume (V) and wood basic density (BD) were the most important traits in selection breeding结果表明，马尾松制浆造纸材的良种选育应以材积和木材基本密度作为主要指标，首先进行种源的选择，在此基础上进行林分和个体的选择。