© 1991 Heron Publishing—Victoria, Canada
Relationship of forest productivity to nutrient and carbon supply—a modeling analysis
Ross E. McMurtrie
School of Biological Science, University of New South Wales, P.O. Box 1, Kensington N.S.W. 2033, Australia /
Summary
A simple model of photosynthetic and nutritional controls over foliar dynamics is analyzed to compare the magnitude of the
growth response of forest stands to increased rates of photosynthesis and nutrient supply. According to the model, productivity
achieved at canopy closure is sensitive to nutrient supply, except where nutrient availability exceeds the plants’ uptake
capacity. Plants growing under nutrient-limited conditions can only respond positively to enhanced photosynthetic rates if
they simultaneously increase their nutrient uptake, or reduce nutrient concentrations in stem, branch, root or senescing leaf
tissue, or shift their carbon allocation in favor of biomass components with low nutrient concentrations. In particular, a
response is more likely where considerable internal cycling of nitrogen occurs before leaf senescence, or where foliar allocation
decreases with decreasing leaf nutrient concentration.
