Invader soil conditioning impacts invader and native plant performance.

Area of Science:

• Ecology
• Invasive Species Biology
• Plant-Soil Interactions

Background:

• Invasive plants can alter soil microbial communities, a process known as soil-conditioning, which influences invasion success.
• These soil-conditioning effects can change over time and may be modulated by the invader's functional traits.
• Native plant responses to these dynamic soil changes may depend on the invasion's extent and plant-specific traits.

Purpose of the Study:

• To investigate the temporal dynamics of soil-conditioning by the invasive plant *Oncosiphon pilulifer*.
• To determine how plant functional traits mediate native plant responses to invader soil-conditioning.
• To understand the feedback mechanisms between invasive plants, soil biota, and native plant communities.

Main Methods:

• A greenhouse experiment utilized a space-for-time substitution approach, using soil from varying *Oncosiphon pilulifer* invasion levels (uninvaded to monoculture).
• Native plants and *Oncosiphon pilulifer* were grown in live or sterilized soil inocula from these invasion gradients.
• Measurements included plant biomass, mycorrhizal root colonization, and leaf and root traits.

Main Results:

• Native plant growth was negatively impacted by soil from patchily invaded areas.
• Mycorrhizal root colonization in native plants decreased in soil from *Oncosiphon pilulifer* monocultures.
• *Oncosiphon pilulifer* exhibited reduced growth and consistently low root colonization as invasion progressed.

Conclusions:

• Invasive plant soil-conditioning effects on native plants vary with invasion intensity.
• Plant functional traits, specifically root and leaf characteristics, play a role in mediating plant vulnerability to soil-biota alterations.
• Understanding these trait-mediated interactions is crucial for predicting and managing invasive species impacts.