Afterlife effects of invasive wasp nests on ecosystem functioning

Area of Science:

• Ecology
• Invasive Species Biology
• Soil Science

Background:

• Legacy effects are persistent ecological impacts after species extirpation.
• While studied in plant invasions, invasive animal legacy effects are less understood.
• Subterranean nests of invasive Vespula wasps were investigated for their lasting ecological impacts.

Purpose of the Study:

• To assess the legacy effects of invasive Vespula wasp nests on soil properties and plant growth in Patagonia.
• To quantify changes in soil nutrients, microbial biomass, and enzyme activity post-wasp colony death.
• To determine the influence of wasp nest sites on subsequent plant development.

Main Methods:

• Soil samples were collected from former Vespula wasp nest sites and control areas approximately 16 months after colony demise.
• Laboratory analyses included measurements of soil total carbon (C), nitrogen (N), phosphorus (P), microbial biomass, and enzyme activity.
• A greenhouse experiment evaluated the impact of nest-affected soil on plant seedling biomass.

Main Results:

• Wasp nest sites exhibited significantly higher soil nutrient levels: 1.5-fold increase in total C, 2-fold increase in total N, and a 54-fold increase in P compared to controls.
• Microbial biomass increased by 1.5-fold, and enzyme activity by 1.75-fold in soils from nest sites.
• Plant seedlings grown in soil from former wasp nests showed a 13-fold increase in biomass, indicating enhanced plant performance.

Conclusions:

• Invasive Vespula wasps create substantial and lasting legacy effects on soil ecosystems, persisting over a year after colony extinction.
• These legacy effects significantly enhance soil fertility and microbial activity, promoting plant growth.
• The findings highlight the potential for invasive animals to alter ecosystem structure and increase spatial heterogeneity through their persistent afterlife impacts.