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

杂交杨树种植园正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。自2000年以来，新艾伯塔省的阿尔伯塔-太平洋森林工业公司（Al-Pac）一直为此目的与私人土地所有者签订延长租赁协议。迄今为止，这些人工林是采用传统的造林方法（例如，系统的联合种植）建立的，并采用土壤间隙跟踪和间歇性使用除草剂来控制竞争植被。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，从而降低了它们的盈利能力。在头3年减少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经营战略，将增加纤维供应和盈利能力。此外，减少休耕或除草剂施用的策略可能具有相关的环境效益，包括减少土壤侵蚀、碳损失以及农药的使用和积累。本研究通过3个试验，探讨了建立和维持杂交杨树人工林的替代管理策略。这些试验1)量化杂草组成和丰度对杂交杨树生长和存活的影响，包括在建林（1-3年）期间，包括地上和地下发生的杂草；2)确定距离树洞近和远的空间定向杂草控制的相对重要性；3)评估不同的人工林建林策略（即初始休耕地间隔长度和直接铺草皮）对改善树木性能和环境健康的影响。这些信息将更详细地了解降低杂交杨树人工林树木存活和生长的基本因素，并最终导致改进管理策略，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.