Thursday, August 6, 2009

PS 73-170: Evaluating reintroduction of American chestnut Castanea dentata ((Marshall) Borkh.) on reclaimed mine sites in Ohio

Keith E. Gilland and Brian C McCarthy. Ohio University

Background/Question/Methods
American chestnut once accounted for a large portion of the Eastern Deciduous Forest canopy prior to the accidental introduction of the Chestnut blight (Cryphonectria parasitica). As a result, chestnut was effectively removed from canopy dominance throughout most of the Appalachians by the 1940’s. Through a traditional backcross breeding program using Chinese chestnut, The American Chestnut Foundation has generated a potentially blight-resistant hybrid tree for reintroduction. Characteristics of the American chestnut may make it an ideal candidate for use on former coal-mine lands being reclaimed with the newly developed Forestry Reclamation Approach (FRA) methods. This study had three objectives: (1) determine if direct-seeding is a viable option for reintroduction of American chestnut (2) elucidate procedures necessary for successful seed introduction and (3) evaluate the performance of different hybrid genetic lines on reclaimed mine sites.  The study was conducted at Jockey Hollow Wildlife Management Area (JHWMA) in Belmont County, Ohio. The site was reclaimed using FRA methods. The upper strata was loosely dumped into mounds roughly 10 m in diameter and 5 m high to provide a loose rooting medium. Two groups of seeds were planted at JHWMA in March 2008. One group determined a protocol for seed planting and a second evaluated the performance of different hybrid lines. To study planting techniques, 190 pairs of seeds were planted on individual mounds with one seed receiving a 30 cm plastic tube shelter and one as a control. The second group of seeds evaluated differences in hybrid genetic lines. The seeds included pure American, pure Chinese, and three intermediate hybrid lines. The seeds were planted in complete experimental blocks of five seeds, each block contained one individual of each genetic type for 690 seeds and 132 experimental blocks. Blocks were established in a 2 x 2 factorial design where the fixed effects were mound aspect and planting position.

Results/Conclusions                                                                                                                                                                       The planting protocol study yielded germination rates of 87% for protected seeds and 45% for controls. Survival through November was 82.5% and 38.6% respectively. In the hybrid tree study total germination was 89% and survival was 82%. Mean height growth was 18.2 cm (± 0.306 SE). No significant difference was seen between hybrid lines or planting positions. These relatively high germination and survival rates indicate that chestnut will be a viable candidate for mine reclamation projects as blight-resistant hybrids become more readily available and seed protection at the time of planting is required for success.