Postfire Herbicide Application Reduces Macartney Rose in Attwater's Prairie-Chicken Habitat

Abstract

Prescribed fire in coastal prairies maintains habitat diversity, improves nutrient cycling, and reduces impacts of invasive species. However, some invasive species thrive after disturbance, necessitating more nuanced management strategies. Managers in the Attwater Prairie Chicken National Wildlife Refuge use combinations of prescribed fire and herbicide to control the spread of Macartney rose (Rosa bracteata). However, literature suggests that the efficacy of such a strategy has been inconsistent, perhaps owing to differences in the seasonal timing and frequency of herbicide and burning treatments. We compared the timing of herbicide applications in relation to prescribed fire and their effects on Macartney rose by monitoring 160  ×  100 m² belt transects distributed among four categories of treatment strategy: prefire herbicide, postfire herbicide, both, or no herbicide (fire only). Prefire herbicide applications were conducted followed by prescribed fires in December 2021–January 2022, and postfire herbicide was applied in April–May 2022. We conducted plant surveys and measured Macartney rose density and cover in between and after each treatment. After all treatments, we collected arthropods by sweep netting and identified them to the order level. We also baited and collected ants and later identified and counted red imported fire ants under a microscope. We found that Macartney rose density declined by ∼40% and cover exhibited a five-fold decrease in transects that received herbicide both before and after fire, whereas plant and arthropod diversity were unchanged regardless of herbicide treatment. Prescribed fire and herbicide application are essential tools for modern coastal prairie management, but nuances regarding the different ways these tools might be combined should be considered to optimize invasive species control while limiting undesirable effects. In the case presented in this study, Macartney rose was most significantly reduced, and plant and arthropod diversity were maintained using strategies that combined fire and herbicide differently than most common practice.