Effects of Biennial Fire and Clipping on Woody and Herbaceous Ground Layer Vegetation: Implications for Restoration and Management of Oak Barren Ecosystems

Abstract

Savannas and oak barrens are threatened in North America, due, in part, to removal of natural disturbance regimes. However, the periodic prescribed fires used in savanna and oak barren management sometimes accelerate the formation of a shrub layer, which can displace herbaceous species. This may be because periodic low severity fires act much like clipping, topkilling shrubs, yet allowing them to accumulate reserves in intervals without fire for more vigorous sprouting. To test this, we compared biennial dormant season burn prescriptions to a fire surrogate (clipping) using three oak barrens sites in the Bluegrass Region of southern Ohio. Fire and clipping treatments did little to suppress the resprouting ability of shrubs (woody stems <2 cm dbh), which regrew rapidly and in equivalent densities following treatment. However, both treatments reduced shrub cover, resulting in a 35% decrease in shrub cover over the course of the study. In contrast, non-manipulated plots experienced a 44% increase in shrub cover over the same time period. Despite this reduction in shrub cover, treatments had no effect on herbaceous plant cover, richness, diversity, or evenness. These results suggest that the use of biennial prescribed dormant season fire, as employed in this study, is equivalent to clipping, and although effective at temporarily reducing shrub cover, is not effective in reducing shrub densities or resprouting potential. Thus, burning during marginal conditions should be avoided for achieving a short-term restoration goal of shrub removal, but can be effective for maintaining the current shrub layer.

Resprouting of woody species encroaching temperate European grasslands after cutting and burning

“…In several other studies, burning and cutting did not result in a different resprouting of individuals either (Pyke et al. ; Petersen & Drewa ), but our study is the first to demonstrate this for temperate European woody species.…”

“…cutting or burning), causing the complete loss of the above‐ground biomass of woody species, induced similar resprouting rates, both in the field and the experimental study. This similarity indicates that none of the applied treatments damaged the collar meristems, which are vital for resprouting, although the treatments were severe enough to induce the resprouting process (see also Petersen & Drewa ). Despite the nutrient input to the soil from the burned above‐ground biomass (Blodgett et al.…”

“…; Petersen & Drewa ). The major effect of shrub encroachment in grasslands is the displacement of herbaceous species through competition for light, moisture and nutrients (Petersen & Drewa ). Thus, there is a serious threat that many grassland species adapted to open areas and continuous human management will disappear (Pykälä ).…”

“…; Lett & Knapp ; Valkó et al. ; Petersen & Drewa ). The major effect of shrub encroachment in grasslands is the displacement of herbaceous species through competition for light, moisture and nutrients (Petersen & Drewa ).…”

Effects of frequent fire and mowing on resprouting shrubs of Florida scrub, USA

“…Disturbance type (mowing versus burning) had a limited effect on resprouting dynamics of scrubby flatwoods shrub species. Similarly, many studies have found little difference in resprouting or woody cover after burning versus mowing or cutting or clipping (e.g., Hmielowski et al 2014;Peterson and Drewa 2014;Michielsen et al 2017). In contrast, some studies have found that burning results in higher mortality and lower post-disturbance growth than cutting (Peguero and Espelta 2011;Noble and Diggle 2014).…”