Invasive grass litter controls rangeland plant community dynamics

Area of Science:

• Ecology
• Invasive Species Management
• Plant Community Dynamics

Background:

• Invasive species, like Kentucky bluegrass (Poa pratensis), significantly impact global ecosystems.
• Altered fire and grazing regimes in North America facilitate invasive herbaceous plant expansion.
• Kentucky bluegrass thrives in the Great Plains, potentially due to thatch and litter accumulation.

Purpose of the Study:

• To investigate the mechanisms driving Kentucky bluegrass invasion.
• To assess the impact of litter and thatch removal on plant community dynamics.
• To identify effective management strategies for invasive grasses.

Main Methods:

• A 50-month field study in North Dakota.
• Targeted removal of litter and thatch layers.
• Monitoring of plant community metrics including species richness, evenness, and occurrence.

Main Results:

• Kentucky bluegrass invasion negatively affected plant species richness, evenness, and occurrence.
• Removal of litter and thatch led to increased plant community dynamics metrics.
• Invasive litter cover and depth were primary drivers of these impacts, with species evenness also influenced by live bluegrass and thatch.

Conclusions:

• Litter accumulation, rather than thatch, is the primary mechanism driving Kentucky bluegrass invasion.
• Management strategies targeting litter formation, such as combined fire and grazing, are recommended.
• These strategies can facilitate native plant establishment and expression, controlling invasive grasses.