Minimizing hybrid poplar tree mortality and plantation yield losses due to competition

杂交白杨人工林正在成为加拿大西部纸浆和造纸工业增加纤维供应的重要战略。艾伯塔-太平洋林业公司自2000年以来，阿尔伯塔东北部的Al-Pac公司一直在为此目的与私人土地所有者签订长期租赁协议。 到目前为止，这些种植园都是采用传统的造林做法（如系统的人工造林）建立的，土壤间隙休耕，间歇性施用除草剂，以控制竞争植被。在这些种植园18年的预计寿命中，这些做法导致了巨大的投入成本，从而降低了他们的盈利能力。在前3年降低种植园建立和维护成本，或减少杂草对树木死亡率和生长的影响的运营策略，将提高纤维供应和盈利能力。此外，减少休耕或除草剂使用的战略可能具有相关的环境效益，包括减少土壤侵蚀、碳损失以及农药使用和积累。在本研究中，我们探讨了一系列问题的替代管理策略，建立和维持杂交白杨人工林通过3个实验。这些试验1）量化了杂草组成和丰度对杂种白杨生长和存活的影响（1-3年）的时间，包括发生在地上和地下的时间，2）确定空间目标杂草控制在树干附近和远离树干的相对重要性，以及3）评估替代性种植园建立策略（即初始休闲间隔长度和直接草皮种植）以改善树木性能和环境健康。这些信息将提供一个更详细的了解的基本因素，减少树木的生存和生长在杂交白杨人工林，并最终导致改善管理策略，增加木材纤维供应的数量和可靠性。

Hybrid poplar plantations are becoming an important strategy for the pulp and paper industry to increase fiber supply in western Canada. Alberta-Pacific Forest Industries Inc. (Al-Pac) in NE Alberta has been establishing extended lease agreements with private landowners for this purpose since 2000. To date, these plantations have been established using conventional silvicultural practices (e.g. systematic ally planting) with fallowing of soil interspaces and intermittent herbicide applications used to control competing vegetation. Over the 18 year projected life of these plantations, these practices result in significant input costs, in turn reducing their profitability. Operational strategies that reduce the cost of plantation establishment and maintenance during the first 3 years, or that reduce the impact of weeds on tree mortality and growth, will enhance fiber supply and profitability. Moreover, strategies that reduce fallowing or herbicide application may have associated environmental benefits, including reductions in soil erosion, carbon loss, and pesticide use and accumulation. In this research we explore a series of questions related to alternative management strategies to establish and maintain hybrid poplar plantations using 3 experiments. These experiments 1) quantify the impact of weed composition and abundance on hybrid poplar growth and survival during the establishment (1-3 year) period, including that occurring above and below-ground, 2) identify the relative importance of spatially targeted weed control both near and far from the tree bole, and 3) evaluate alternative plantation establishment strategies (i.e. initial fallow interval length and direct sod planting) for improving tree performance and environmental health. This information will provide a more detailed understanding of the fundamental factors reducing tree survival and growth in hybrid poplar plantations, and ultimately lead to improved management strategies that increase the amount and reliability of wood fiber supply.