Native hardwood tree seedling establishment following invasive autumn-olive (Elaeagnus umbellata) removal on a reclaimed coal mine.
The Appalachian region of the United States is home to the largest temperate deciduous forest in the world, though surface mining has caused significant forest loss. Many former coal mines are now dominated by invasive plants, which often inhibit establishment of desirable species, especially slower-growing native trees. Autumn-olive (Elaeagnus umbellata Thunb.) is a nonnative, nitrogen-fixing shrub that was historically planted on former coalfields, but now impedes reclamation. To better understand the influence of E. umbellata management practices on hardwood establishment, we evaluated two common management practices: cutting and cut stump herbicide treatment. Planted native tree species, including black cherry (Prunus serotina Ehrh.), pin oak (Quercus palustris Münchh.), and red maple (Acer rubrum L.), were monitored for survival and performance over two growing seasons following E. umbellata removal. In each plot, we also measured plant-available nitrate (NO3-) and ammonium (NH4+) in soils using ionic exchange membranes. At the end of the first growing season, native tree survival was high, and the presence or absence of E. umbellata had little effect on tree survival or growth, despite the higher plant-available nitrate where E. umbellata was present. By the end of the second growing season, native tree survival dropped to 20% to 60% and varied among E. umbellata treatments. Survival was highest when E. umbellata was cut and treated with herbicide, though tree growth was similar across all treatments without E. umbellata. When establishing native trees to replace E. umbellata, cutting and herbicide application treatment of the invader resulted in the highest overall efficacy (100% control), though the most cost-effective method may be to simply cut mature stands despite regrowth, as this resulted in equivalent native tree growth over 2 yr. While this allowed E. umbellata regeneration, it provided sufficient invader control to allow initial tree establishment. Cutting and herbicide application treatment resulted in less E. umbellata regeneration and appears to provide greater assurance that established trees will persist over the long term.