ROW: Nutrient Uptake and Growth in Eastern Deciduous Tree Seedlings

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This study will examine the relationship between ion absorption rate, relative growth rate, and the soil nutrient dependence of a suite of forest tree species that vary widely in both relative growth rate and canopy gap colonization ability. It is hypothesized that: 1) Gap colonizing species with high relative growth rates will have higher maximum ion absorption capacities than slowly growing species; 2) Shade tolerant species with low relative growth rates will have higher root absorption capacities at low nutrient concentrations than fast growing, gap colonizing species; 3) These differences will be greatest for soil mobile ions such as NO3 and K and less for soil immobile ions such as PO4 and NH4; 4) Nutrient uptake rates will be greater for seedlings acclimated to low nutrient conditions than to high nutrient conditions, and that this plasticity will be greater for species with high relative growth rates; 5) In the field, gap colonizing seedlings will be more responsive than slowly growing, shade tolerant species not only to increased light availability in gap sites but also to increased nutrient availability in fertilized sites. Six tree species of the eastern deciduous forest will be grown from seed. Three of these species represent gap colonizing species with high relative growth rates (Prunus serotina, Quercus coccinea, and Betula populifolia), and three represent shade tolerant species with low relative growth rates (Fraxinus americana, Carya ovata, and Quercus borealis). Three separate experiments will be performed to test the hypotheses.