Wind, Waves, and Weeds: Hurricanes facilitate the spread of an invasive grass

Paper Citation

Bhattarai, G. P., & Cronin, J. T. (2014). Hurricane activity and the large-scale pattern of spread of an invasive plant species. PloS one, 9(5), e98478. https://doi.org/10.1371/journal.pone.0098478

Summary by Sofia M. A. Al-Shayeb, reviewed by Annette E. Evans

Summary 

Biological invaders can negatively alter ecosystem structure by displacing native species and altering habitat characteristics. Many invaders are spread following large-scale disturbance events, such as hurricanes, which are predicted to increase in both frequency and intensity under future climate conditions. However, the effects of hurricanes on the broad geographic patterns of spread remain unclear for many specific invasive species. Therefore, investigations into how storm disturbances influence the survival and spread of invasive Phragmites australis along the Atlantic and Gulf Coasts of the United States are necessary to understand how future storm events may drive invasion success and ecosystem changes in invaded wetland communities.

This study by Bhattarai and Cronin (2014) used historical aerial imagery across 13 marsh sites where invasive P. australis was established. The authors determined patch growth rates and estimated wind speeds of tropical storms and hurricanes over several decades. They found a strong positive correlation between hurricane frequency and P. australis growth rates across both non-native haplotypes studied, with hurricane-force wind frequency explaining over 80% of the variation in patch growth rates across the region. Hurricanes can facilitate invasion by destroying native vegetation and altering habitat characteristics such as hydrology and salinity, creating open space for invasives to establish. Phragmites australis is particularly well-suited to recover quickly after disturbance due to its extensive root system. These findings are especially concerning given that climate models predict increasing storm frequency and intensity, suggesting that the spread of invasive P. australis may accelerate in the coming decades. The authors emphasize that early detection and management are critical, as mechanical removal is costly and labor-intensive, and biological controls are not widely available, making prevention far more effective than remediation.

Take Home Points 

• Hurricane frequency is predicted to increase under future climate conditions, which may create more opportunities for invasive species, such as Phragmites australis, to establish and spread.

• Phragmites australis takes advantage of changes in biotic and abiotic conditions following large-scale storm events to spread in wetland areas where it is currently established. 

• Hurricane frequency and P. australis growth rates are strongly positively correlated, suggesting this invasive species will likely benefit from the increase in frequency of large-scale storm events in the future.

Management Implications

• Collecting baseline data on P. australis population densities and coverage is important for assessing the impacts of large-scale storm events on the survival and spread of this invasive grass in invaded wetland areas.

• In semiprotected areas where P. australis has already invaded, and chemical control may not be feasible, nonnative haplotypes are likely to grow rapidly. If populations are left unchecked, P. australis will likely become the dominant plant species in these ecosystems.

• Given that mechanical removal of P. australis is costly and labor-intensive and biological control is not currently feasible, prevention using early detection and rapid response strategies will be far more effective in controlling P. australis populations, particularly after large storm events.

Related Papers

This research summary is part of a series on the link between hurricanes and invasive species. For other research summaries on this topic see: Falk et al. 2024, Kraemer et al. 2017 and Colleran and Goodall, 2014. For the Research-to-Practice paper (R2P2) on this topic see: Rock you like a hurricane: The perfect storm for an invasion.

Keywords 

• Climate extremes

• Management efficacy

• Phragmites australis

• Wetlands

• Hurricanes 

• Spread

• Atlantic and Gulf Coasts