In a recent paper (In press at the Canadian Journal of Forest Research), Natalie Cleavitt and her colleagues charted the impact of calcium amendments on the survival and growth of sugar maple seedlings. Depletion of the soil calcium pool in the eastern deciduous forests due to acid precipitation has been linked to region-wide decline of sugar maple trees. Natalie tracked the fate of 5,400 sugar maple seeds for three years. These seeds were planted across the environmental gradients in the calcium treated and reference watershed. Calcium amendments clearly improved first-year survival of seedlings and this initial increase persisted for three years. However there was no calcium effect on seed germination or seedling growth. It seems that the population-level response to the watershed-scale fertilization is dissipating as calcium availability is decreasing with time since addition.
Battles Lab
Forest Ecology & Ecosystem Dynamics at the University of California, Berkeley