SURVIVORSHIP AND PREDATION ON THE SEEDS OF THE AMERICAN CHESTNUT, Castanea dentata, IN THE FREDERICK CITY WATERSHED, FREDERICK COUNTY, MARYLAND

Abstract

The American chestnut, Castanea dentata, was once an important part of the ecosystem, both ecologically and economically, in the northeastern United States. The introduction of the fungal pathogen, Cryphonectria parasitica, devastated the American chestnut population in the first half of the twentieth century. Much research and many efforts have been put forth to aid in the restoration of the American chestnut in native forests to its original status. An understanding of the threat of predation to the seeds of the American chestnut can only assist in conservation efforts. The purpose of this study was to assess the amount and type of predation, and survivorship probability of seeds produced by wild American chestnut trees in the Frederick City Watershed, Frederick County, Maryland. Twenty-five fruiting trees were monitored in this study. All trees were measured for height and diameter at breast height, and scored for blight severity. The number of seeds on each tree initially was recorded and the burrs were recounted three times each week from September through November 2000, In addition, sand tracking trays were set with American chestnut seeds to collect information on types and rates of predation. The data was analyzed using transition frequency data to determine the partial life history of the seeds of the American chestnut. Seed production increases with height and DBH but decreases with blight severity. The stages of development of the seeds of the American chestnut were found to be 1) seeds in green, closed burrs on the tree, 2) seeds in green, open burrs on the tree, and 3) seeds out of burr on the ground. The seeds are most at risk from predation in the final stage, out of burr on ground. The predators which pose the most risk to the seeds of the American chestnut seeds in order of decreasing importance, are the blue jay (Cyanocitta cristata), the Eastern chipmunk (Tamius striatus), the white-footed mouse (Peromyscus leucopus), the pine vole (Microtus pinetorum), the Eastern gray squirrel (Sciurus carolinensis), and a type of small bird. The probability of a seed of the American chestnut surviving through Stage 9 is 8.57%, and none survived beyond it.