Commercial thinning of lodgepole pine in Alberta - 15-year growth response

米勒西部森林产品有限公司经营着两家锯木厂，一家纸浆厂和相关的林地业务，靠近阿尔伯塔山麓的怀特科特社区。由于火灾和山松甲虫爆发的影响，预计该地区短期到中期的木材供应将减少。商业间伐是增加这些黑松林中期锯木供应的一个潜在选择，因为它减少了每棵树达到可销售尺寸所需的时间。商业间伐也将立即产生可销售的木材，并有可能在轮作过程中通过收获未来的死亡（即捕获自然排水）捕获更大的体积。然而，在商业间伐在整个景观中实施之前，仍有许多与不同站点类型的树木生长响应和死亡率相关的问题需要解决。Millar Western在1996年至2003年期间对32块土地进行了减薄处理，并每五年对未减薄的对照地块进行重新测量。本研究的目的是量化和解释不同年龄和不同立地类型的成熟黑松林分对商业间伐的树木生长反应（包括单株和林分水平）。森林部门在加拿大直接雇用了20多万人，为国民经济贡献了230亿美元。这一重要行业依赖于不断增长的木纤维的可持续供应，而木纤维正面临减少的风险。加强森林管理措施，如商业间伐，是解决这一问题的一个潜在办法。

Millar Western Forest Products Ltd. operates two sawmills, a pulp mill, and associated woodlands operations near the community of Whitecourt in the Alberta foothills. There is an expected decrease in the short to mid-term timber supply in this region due to the impacts of fires and the mountain pine beetle outbreak. Commercial thinning is a potential option for increasing mid-term sawlog timber supply in these lodgepole pine forests by decreasing the time needed for individual trees to reach merchantable size. Commercial thinning will also produce merchantable timber immediately and potentially capture greater volume over the course of a rotation by harvesting the future mortality (i.e. capturing natural drain). However, there are many questions related to tree growth responses and mortality across different site types that must still be addressed before commercial thinning can be implemented operationally across the landscape. Millar Western operationally thinned 32 plots between 1996 and 2003 and has been remeasuring them along with unthinned control plots every five years. The purpose of this work is to quantify and explain the tree growth response (both individual tree and stand level) to commercial thinning in mature lodgepole pine stands of different ages and on different site types. The forest sector directly employs over 200,000 people in Canada and contributes $23 billion to the national economy. This important industry relies on a sustainable supply of growing wood fibre which is at risk of decreasing. Enhanced forest management practices, such as commercial thinning, offer a potential solution to this issue.