American chestnut (Castanea dentata) once accounted for a large portion of the Eastern Deciduous Forest canopy until the introduction of chestnut blight which effectively removed the species from canopy dominance by the 1930’s. A backcross breeding program conducted by The American Chestnut Foundation has yielded a putatively blight-resistant Chinese/American hybrid tree. Characteristics of the American chestnut may make it an ideal candidate for use on former coal-mine lands being reclaimed with the Forestry Reclamation Approach (FRA) which emphasizes compaction-reducing soil preparation. The purpose of this study was to determine which methods are most suitable for reintroduction of American chestnut on reclaimed mine lands. The study was conducted at the Jockey Hollow Wildlife Area (JHWA), a former surface-mine in Ohio. To compare reintroduction methods, 933 bare-root seedlings protected with 120 cm tree tubes, 275 seeds protected with 90 cm tubes, 190 seeds protected with 30 cm tubes, and 190 seeds without protection were planted. Seedlings were monitored for survival throughout the 2008 and 2009 growing season. Seeds were monitored for germination by the end of May 2008 and for survival at the same intervals as seedlings. Height was measured at the end of the growing season in both 2008 and 2009.
Results/Conclusions
Germination rates were greater for both classes of protected seeds (88.4% tall tube, 87.4% short tube) compared to unprotected seeds (45.3%). Bare-root seedling survival rates were significantly greater after two years compared to both classes of protected seedlings as well as unprotected seedlings originating from seed (Cox Proportional Hazard, likelihood = 388, df = 3, P <.0001, n = 1585). Relative growth rate (RGR, measured in cm mo-1) varied significantly between groups. Unprotected seedlings showed the lowest RGR while seedlings originating from seed with a tall (90 cm) tube showed the highest RGR. Based on these results, introduction by direct-seed is a viable although not preferable method for reintroduction of American chestnut compared with bare-root seedling introduction. Although seedlings from seed showed a significantly higher relative growth rate, the higher overall survival rates of bare-root seedlings would make this method of introduction preferable for coal-land reclamation projects using the Forestry Reclamation Approach and American chestnut.
