Surface mining for coal in the Appalachian region of the U.S. has resulted in large scale alteration of the landscape, with many areas differing greatly from the eastern deciduous forest vegetation that was present prior to mining. Restoration efforts utilizing the Forestry Reclamation Approach have primarily used nursery seedlings during the tree planting phase, which limits tree planting to the winter dormant season. Tree shelters are often recommended for use when planting seedlings to protect them from herbivory, but may not be necessary when planting from seed. Research on the use of direct planting by seed in this region is limited, but if successful, could open up an additional planting season, as well as potentially reduce planting costs. In Fall 2011, a collaborative small-scale research project was designed to explore whether direct seeding could be successful on a surface mine that had previously been reclaimed. A 2x2 factorial design was used to explore two main treatment effects- planting type (by seed or 1-year nursery stock) and use of tree shelter (present or absent). Three replicate plots of each of the four treatment combinations were planted with black walnut (50 per plot). Differences in tree height, diameter, volume index, and survival in 2012, 2013, and 2016 were detected by ANOVA, using PROC MIXED (SAS 9.4), with treatments (shelter, planting method) and their interaction modeled as fixed effects and individual tree within block modeled as random effects.
Results/Conclusions
Planting type had a significant effect on all response variables (being greater for the nursery seedlings compared to those from seed) in all years, although the differences were less pronounced by 2016. Tree shelter presence had a significant effect on height and volume for 2012 and 2013 data, but it was no longer significant by 2016. Interestingly, interaction of the two main treatment effects on survival rate was significant in all years, and showed there was a trend for shelters to not make a difference for nursery seedlings, but to hinder those from seed. Although survival rate was lower from seed (61 vs. 84% in 2016) given the decreased cost of planting from seed it may still offer a viable approach to plantings. Further research is needed, but this preliminary data shows promise for the use of a fall planting season, both for 1-yr nursery stock and for direct seeding using black walnuts.