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Hardwood reduction in pinelands

Sandhill pinelands in the southeastern United States are gradually being transformed into hardwood oak hammocks due to the suppression of natural fire regimes. These pyrogenic habitats require fast moving fires to maintain open pine dominated canopies with diverse herbaceous ground cover. Without fire, overtime hardwood species, specifically oaks (Quercus sp.), gradually begin to dominate the landscape, creating dense monocultures with little to no groundcover. Restoration of these historic pinelands centers around the reintroduction of fire, but requires oak thinning and groundcover restoration to be successful. This is usually accomplished using heavy machinery, herbicide application or a combination of these and other methods followed by prescribed fire once enough fuel has accumulated. 

Unfortunately, oaks are very resilient to current mechanical and chemical control methods and treatments usually only result in top kill of the plant, leading to vigorous re-sprouting from the surviving plant’s below ground biomass.  These survivors regrow into multi-trunked plants which create a less manageable, denser thicket of shrubs, making effective control of oaks in the first treatment critical. Therefore, the purpose of this project is to evaluate several herbicide treatments that have been observed to be successful in the field, determine which effectively kills problematic oak biomass both above and below ground, has the least negative impact on herbaceous species and has the most positive impact on species’ richness at each treatment site over time. Hopefully, we will be able to develop best management practices that land managers can use to restore oak-degraded pinelands, eliminating costly retreatments while also maintaining species diversity.

side by side images showing the before and after views of a restoration site

(Left) Before: An overgrown thatch of scrubby flatwoods before application of herbicide. (Right) After: Application of herbicide adds more fuel for a prescribed burn, which makes it easier for fire to reach the targeted area.