New insights into calcium depletion in northeastern forests

Acid rain and repeated harvests reduce the amount of calcium available for forest growth. Ecosystem budgets suggest that the exchangeable (a pool is insufficient for forest regeneration, yet young stands appear to mobilize more than enough (a from the soil to meet their needs. Extractions of soil parent materials indicate that apatite provides a previously unappreciated source of plant-available Ca for forests in New Hampshire, upstate New York, and Maine with granitold parent materials. The threat of Ca depletion may not be as grove as previously predicted on these soil types. In contrast, apatite is not important of sites in Pennsylvania With sedimentary parent materials.