Foliar nutrient dynamics, growth, and nutrient use efficiency of Hamamelis virginiana in three forest microsites

To determine the relative importance of soil moisture and soil nutrient availability in determining levels of nutrient use efficiency, seasonal nutrient dynamics and growth rates were determined for individuals of Hamamelis virginiana L., an understory tree, in three forest microsites. The mixed oak site had the lowest levels of soil nutrients and moisture, the mixed mesophytic site the highest nutrient availability, and the valley bottom the highest moisture levels. Foliar nitrogen and phosphorus levels declined over the season in all trees, while calcium levels increased with time. Relative growth rates did not differ significantly among sites, though growth varied inversely with tree mass. Proportional nitrogen resorption was highest in trees at the fertile mesophytic site. Phosphorus and calcium use efficiency were higher at the infertile mixed oak site than the others, and phosphorus resorption was highest in trees from the mixed oak site. Projected nitrogen uptake needs for the next growing season w...