Fertilizer stimulates growth and mortality in a young Populus–Betula stand: 10-year results

Following a uniform thinning, a young bigtooth aspen (Populusgrandidentata Michx.), quaking aspen (Populustremuloides Michx.), paper birch (Betulapapyrifera Marsh.), and red maple (Acerrubrum L.) stand was treated with nitrogen (N), phosphorus (P), and lime, singly and combined. Nitrogen increased the growth of all species. Lime and P also tended to increase the growth of bigtooth aspen and paper birch. Nitrogen increased mortality and lime reduced mortality. Quaking aspen suffered proportionally greater mortality than other species. The results suggest that both N and lime will be required for an optimum response of aspen and birch growing on acid spodosols in the Northeast, but the cause of and a means to avoid increased mortality caused by fertilizer needs to be determined before large-scale N fertilizer treatments are adopted.