COMPARATIVE ECOPHYSIOLOGY OF AMERICAN CHESTNUT UNDER DIFFERENT PLANTING TREATMENTS ON RECLAIMED MINE SITES

American chestnut was once an abundant species that dominated the Eastern U.S. deciduous forests. Although this species is currently functionally extinct due to the chestnut blight, researchers are working on blight-resistant hybrids in hopes of restoring the species. As one potential vector for chestnut reintroduction and dispersal, the reclamation of mine sites are being considered. Recent research has found that reforestation efforts on these reclaimed mine sites provide productive tree growth while also complying with mine-reclamation laws. Understanding how American chestnut performs physiologically on mine sites will aid in the restoration of this species and reclamation of mine sites.

The objective of this study was to determine the effect planting treatments have on survival, physiology, and performance of American chestnut. The response of American chestnuts under planting treatments varying in planting method, slow-release fertilizer, a hydrophilic root polymer (Terra-Sorb), and the addition of native forest soil were examined at three sites: a mine site, a quarry, and a greenhouse. Results from this study suggest that fertilizer, hydrophilic root polymers and soil microorganisms produce varying effects on dissimilar sites. Greatest overall survival was found in greenhouse-grown bare-root seedlings. The introduction of fertilizer to the soil substrate lowered emergence and survival of directly-seeded trees at the mine site and quarry, but increased tree growth at all sites and photosynthetic rate at the quarry. However, use of fertilizer resulted in a more negative water potential at the mine site and higher transpiration rate, potentially increasing moisture stress and demand. Increased seed survival, growth, and water status can be accomplished through the use of Terra-Sorb, but only in direct seeded trees on sites with potentially deficient plant-available water. Native forest soil can increase survival in both direct seeded and bare-root planted trees. However, more research is needed on the benefits of native forest soil, as growth and physiological results conflict. It is recommended that site characterization be performed prior to selection of planting treatments. Results of this study can prove beneficial to reclamation specialists with an interest in using mine site reclamation in conjunction with American chestnut restoration.