Invasive species influence ecosystem resilience by altering the biological diversity, interaction networks, and physical processes that allow ecosystems to absorb disturbance and return to prior states. Research by David Tilman at the University of Minnesota demonstrates that higher species richness and functional diversity generally increase resistance to perturbations and stabilize ecosystem processes. When invasive organisms reduce native diversity or replace key functional groups, that insurance effect can be weakened and ecosystems become more prone to change.
Mechanisms of impact
Invasive species affect resilience through several linked mechanisms. They can outcompete natives for resources, simplifying community composition and reducing the pool of species that can compensate after disturbance. David Simberloff at the University of Tennessee has documented cases where invaders drive local extinctions and reorganize communities, producing novel assemblages that respond differently to stress. Invasive predators or herbivores can rewire food webs and generate trophic cascades that amplify indirect effects, while invasive plants can alter nutrient cycling and soil properties, changing the conditions for native regeneration. These shifts in interactions and processes change both the magnitude and direction of ecosystem responses to events like drought, fire, and pollution.
Consequences for social and environmental systems
Changes in resilience have tangible consequences for people and places. Stephen R. Carpenter at the University of Wisconsin-Madison has shown how biological invasions can precipitate regime shifts in lakes and wetlands, moving systems from clear to turbid states with major losses in fisheries and recreational value. In terrestrial systems, invasive grasses that promote more frequent fire regimes can transform culturally important landscapes and undermine traditional land uses for Indigenous and rural communities. Context-dependent outcomes also occur: Mark A. Davis at Macalester College has argued that some invasions temporarily increase local species richness, but this apparent gain often masks long-term losses in unique native taxa and altered ecosystem functions.
Management responses shape whether an invasion becomes a long-term impairment of resilience or a contained disruption. Restoration that rebuilds native functional diversity and connectivity can restore resilience, but such efforts are often costly and limited by ongoing pressures like climate change, land-use change, and continued propagule pressure from global trade. Preventing establishment through biosecurity is widely seen as more effective than post-establishment control.
Recognizing the multifaceted effects of invaders requires integrating ecological science with local knowledge about cultural values and land use. Because impacts vary by region, species, and social context, policy and management benefit from interdisciplinary assessment that combines the ecological insights of scientists such as David Tilman, David Simberloff, Stephen R. Carpenter, and Mark A. Davis with the lived experience of affected communities. That combined approach increases the likelihood of maintaining or restoring resilience in the face of ongoing biological invasions.