Common reed (Phragmites australis) harvest as a control method in a Neotropical wetland in Western México

Abstract

Common reed (Phragmites australis) has invaded wetlands worldwide and displaced native vegetation and wildlife. Control measures include herbicides, but their use can cause negative environmental impacts. An alternative is to harvest aerial biomass. We tested harvest as a control for common reed in Mintzita springs, Michoacán in Western Mexico. Results showed that harvest increased native plant species establishment, and that species richness varied with harvesting method. In plots where reed was completely removed every two months, 9 native species established, the same number as in plots where all reed biomass was removed if at least one stem was 2 m tall at the harvest date. When only reed stems 2m or taller where removed, 6 species established, whereas, in control plots only three species established. Species composition correlated with harvesting method (ANOSIM, R=0.4514, p < 0.01). Harvest reduced resprouting measured as standing biomass (F(3,20) = 27, p < 0.000001). After one year of treatment, full removal plots had the lowest aerial dry biomass (108 ± 15 g) followed by plots with full removal once a reed stem was at least 2m tall (197 ± 81 g), followed by plots where only 2 m or taller stems were removed (593 ± 466 g) and control (3296 ± 232 g). Several reed plants died after the first year of the experiment. Although more trials and long term follow up are needed, our results suggest that harvest can be an efficient control method for reed-infested wetlands in Western Mexico.