Forest dynamics on the hickory ridge of St. Catherine's Island

Abstract

The Hickory Ridge of the Georgia barrier island, St. Catherine’s Island, stands as one of the few remaining of its kind and recently received its own habitat designation by the Georgia Department of Natural Resources. While the site is in no immediate danger, past studies by Sewanee students have found that pignut hickory recruitment has steadily decreased in recent years. In the wake of the almost complete loss of red bay to ambrosia beetle and the subsequent wilt (98.4% loss in the study area), the hickory ridge canopy has opened up significantly, theoretically leaving room for pignut hickory recruitment across the site. However, an inventory of 9, 1/10th ha plots on the hickory ridge has revealed almost no pignut seedlings and in fact no pignut stems estimated to be younger than 35 years of age (no single tree measured less than 4cm DBH). This condition has come about in spite of the availability of seed trees and canopy space. Pignut hickories are dominant in the area, composing 66.8% of total live stems at an average of 168.9 live stems per hectare, vs. 87.9 stems per hectare for every other species combined. Evidence suggests browsing by local deer and feral hog populations as a possible culprit for the lack of recruitment. To simulate a growing environment free from animal browse, exclusions have been constructed on the periphery of the study plots within range of seed trees, and will be the subject of study in years to come.