Evidence for the Reserve Shelterwood System for Managing Quaking Aspen

The extent to which inter- and intra-specific competition may limit the nutrition of crop trees over the length of a rotation is quantified for a quaking aspen ecosystem. The accepted clearcutting management regime for aspen often regenerates dramatically overstocked stands. Consequently, half way into a 40-year rotation only 36% of the aspen aboveground woody biomass production was being added to what would eventually be harvestable stems. The allocation of large amounts of woody production onto non-crop trees is inefficient for fiber production and displaces nutrient capital from crop trees. The amounts of P, K, and Mg residing in understory plant tissues represented 14, 24, and 13% of the total plant available ecosystem pools, respectively. The data indicate that individual aspen trees would have higher concentrations of all macronutrients in woody tissues, provided the competition among aspen stems and between aspen and understory were reduced. An alternative strategy for managing aspen, based on manipulation of ecosystem nutrient storage pools and the specific biology of the species, is proposed. This method relies on leaving some dominant trees uncut to suppress the initial restocking levels, thereby focusing more of the early rotation production onto potential crop trees. North. J. Appl. For. 7:58-62, June 1990.