The relationship between growth and mortality for seven co-occurring tree species in the southern Appalachian Mountains

1. Slow growth is associated with high mortality risk for trees, but few data exist to assess interspecific differences in the relationship between growth and mortality. Here we compare low growth tolerance for seven co-occurring species in the southern Appalachian Mountains: Acer rubrum, Betula lenta, Cornus florida, Liriodendron tulipifera, Quercus prinus, Quercus rubra and Robinia pseudo-acacia. 2. For all species, mortality was greater for understorey individuals than for canopy trees. Species varied widely in the length of growth decline prior to death, ranging from 6 years for L. tulipifera to more than 12 years for Q. rubra. 3. Growth-mortality functions differ among species, but we found little evidence of a trade-off between tolerance of slow growth and an ability to show rapid growth in high light conditions. 4. A. rubrum stands out in its ability both to grow rapidly and to tolerate slow growth, suggesting that its density may increase at our study site as in other parts of the eastern United States. In contrast, C. florida shows high mortality (15% per annum) as a result of infection with dogwood anthracnose. 5. We modified a forest simulation model, LINKAGES (which assumes that all species have the same ability to tolerate slow growth), to include our functions relating growth and mortality. The modified model gives radically altered predictions, reinforcing the need to rethink and re-parameterize existing computer models with field data.

Duke Scholars

Author James S. Clark Environmental Sciences and Policy