EFFECTS OF PRESCRIBED FIRE AND TREE GIRDLING ON OVER-DOMINANT TREE MORTALITY AND FOREST STRUCTURE IN THE NEOSHO RIVER BOTTOMS

Abstract

Bottomland hardwood (BLH) forests play an important role in maintaining biodiversity,nutrient cycling, and ecosystem stability in floodplain environments. However, some regenerated BLH forests can become dominated by fast-growing pioneer species, which may influence forest structure and limit the establishment of other native species. This study evaluated the short-term ecological responses of non-chemical management strategies to manage over-dominant early successional trees in a regenerated BLH forest in the Neosho River Bottoms, Oklahoma. Experimental treatments included prescribed burning, mechanical tree girdling, a combined burning and girdling treatment, and untreated control plots. Tree mortality of the dominant species, green ash (Fraxinus pennsylvanica) and box elder (Acer negundo), vegetation responses using NDVI derived from Sentinel-2 imagery, understory vegetation diversity, as well as soil nutrients and total organic carbon were compared among treatments and to the control. Results showed that tree mortality differed significantly among treatments. The combined treatment produced the highest mortality rates, followed by burning alone, while girdling alone showed no detectable mortality within the short-term monitoring period. The interaction between treatment and size class was not statistically significant. NDVI declined immediately after burning but recovered to near pre-treatment levels within five months, indicating rapid vegetation recovery. Understory vegetation diversity showed no significant short-term changes among treatments. Soil analyses indicated that some nutrients, particularly sulfate-sulfur and ammonium nitrogen, increased in burned areas, and total organic carbon also increased after burning, while the responses of several other nutrients were not detectable at the time of sampling. Overall, these findings suggest that prescribed fire played a key role in inducing short-term mortality of over-dominant pioneer species and influencing early ecosystem responses, while girdling effects may require longer monitoring periods to become detectable. This study provides useful insight into early restoration responses and may guide management of regenerated bottomland hardwood forests.