Impact of silvicultural treatment on chestnut seedling growth and survival

Putatively blight-resistant advanced backcross chestnut seedlings will soon be available for outplanting on a regional scale. Few studies have examined the importance of silvicultural treatment or seedling quality to chestnut reintroduction in the U.S. This paper examines results from a silvicultural study of high-quality chestnut seedlings on the Cumberland Plateau of southeastern Kentucky. Three hundred American (Castanea dentata), three hundred advanced backcross (BC2F3) and one hundred fifty Chinese chestnut (Castanea mollissima) seedlings were planted in three silvicultural treatments, ranging from low-light to high-light, on the Daniel Boone National Forest in Mar 2009. Seedlings were planted in a completely randomized design with a split-plot treatment arrangement, with silvicultural treatments as whole plots, and species in a randomized block design in the sub-plot. After three years, chestnut seedlings in the high-light treatment sites grew significantly more in height and root collar diameter, on average, compared to seedlings in the moderate- and low-light treatments. Survival did not differ among silvicultural treatments and averaged 64% over all sites. Low survival was due in part to the non-native root-rot disease organism, Phytophthora cinnamomi, which was confirmed at the site. This study suggests that while chestnut grows best in highlight environments, the species can become established under varying light-levels, which will give forest managers flexibility when choosing management strategies for chestnut reintroduction.