Extreme precipitation promotes invasion in managed grasslands

Area of Science:

• Ecology
• Climate Change Biology
• Invasive Species Management

Background:

• Climate change intensifies extreme weather events, exacerbating threats like invasive species.
• Soil moisture critically influences prairie ecosystems, with drought typically hindering and wet conditions favoring invasion.

Purpose of the Study:

• To investigate the impact of extreme wet and dry precipitation regimes on invasive plant species abundance in northern tallgrass prairies.
• To determine how altered precipitation patterns affect overall invasive abundance and specific invasive grasses (Poa pratensis, Bromus inermis).

Main Methods:

• Long-term monitoring (2010-2019) of 25 managed prairies in western Minnesota, USA.
• Utilized 267 transects and 6675 plots to assess invasive species abundance.
• Quantified the relationship between the frequency of extremely wet/dry months and invasive species abundance.

Main Results:

• Increased occurrence of abnormally wet months correlated with higher invasive species abundance.
• Evidence for abnormally dry conditions hindering invasion was mixed.
• Both moderately wet and dry months led to reduced native grass abundance.

Conclusions:

• Extremely wet months may intensify invasive species dominance in tallgrass prairies.
• Dry months did not appear to counteract the effects of wet months on invasion.
• This study quantifies precipitation extremes' complex influence on invasion dynamics in managed ecosystems.