Results/Conclusions
After three growing seasons, seedling survival in the mechanically treated plots was 79-85% compared to 32% in the control plots (Cox Likelihood = 564, df = 3, P < 0.0001). Simply planting chestnut seedlings into existing grassland habitat is ineffective. Some type of surface treatment is necessary to reduce soil bulk density and competition. Results for relative growth rate (RGR) were similar. Seedlings in control plots exhibited the lowest RGR followed by the plow-disk, ripping, and plow-disk+ripping treatment, respectively (all pairwise comparisons P < 0.0001, ANOVA). Ripping of the soil increased RGR significantly (1 df, P < 0.05). This suggests that there may be an advantage to ripping associated with root development that will likely become more obvious with time. While first year results suggested that there might be a hybrid advantage to survival and/or growth, these patterns changed over time. After three years, there was no significant difference in seedling survival among the three chestnut types used; however, pure American chestnut seedlings and the most advanced hybrids performed better than the intermediate hybrid. In sum, surface treatment is necessary to facilitate tree seedling establishment in these habitats and American chestnut and advanced hybrids are good material for forest restoration.