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

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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.