Do invasive plants structure microbial communities to accelerate decomposition in intermountain grasslands?

Area of Science:

• Ecology
• Plant-Soil Interactions
• Invasive Species Biology

Background:

• Invasive plants can alter ecosystem processes, including decomposition and soil nutrient cycling.
• The impact of invasive plants with diverse traits on decomposer communities and decomposition rates is not well understood.

Purpose of the Study:

• To compare decomposition rates and microbial communities (fungal and bacterial) of invasive and native plant litter.
• To determine if decomposer communities are species-specific and if a home-field advantage exists.

Main Methods:

• Litter from three invasive plants (cheatgrass, spotted knapweed, leafy spurge) and one native (bluebunch wheatgrass) was incubated in different grassland communities.
• Decomposition rates and microbial community composition (using T-RFLP) were analyzed over six months.

Main Results:

• Litter from invasive forbs (spotted knapweed, leafy spurge) decomposed faster than native grasses and invasive cheatgrass, irrespective of the incubation community.
• No home-field advantage was observed; decomposition rates were not highest in the species' own community.
• Fungal and bacterial communities in litter were species-specific and differed between roots and shoots.
• Fungal communities also varied across different plant community types.

Conclusions:

• Invasive plant litter decomposition rates vary, with forbs decomposing faster than grasses.
• Decomposer communities are species-specific and persist despite changes in plant communities due to invasions.
• These findings highlight the distinct roles of invasive species in altering grassland ecosystem functions.