Effects of light on the restoration of the American chestnut to the forests of Mammoth Cave National Park

The recent development of blight-resistant strains of American chestnut (Castanea dentata) made the re-establishment of chestnut stands feasible. Attempts at re-establishing chestnut stands under canopy in Mammoth Cave National Park have been hindered by 50% seedling mortality per year. The high level of mortality under the canopy has led to a decision to plant seedlings in large canopy gaps. Light availability may play an important role for seedlings; American chestnut saplings have been observed to grow extremely rapidly in nurseries, but saplings in the lower light conditions of forests grow slowly. To help judge if light is a factor in seedling survival, the rate of photosynthesis was measured for chestnuts and both white and red oaks under a wide range of light levels. This data was used to compare the light compensation, saturation points and light response curves of each species. We found the photosynthetic curve in response to light to be similar in all of the species measured.