Shao-peng Li and Bingwei Lv, East China Normal University, discuss their article: Multidimensional diversity recovery following invasive species removal: Roles of colonization, extinction, and abundance shifts.
Background
Plant invasion is a global ecological challenge, and invasive species often outcompete native plants, leading to a loss of biodiversity and disruption of ecosystem functions. Removing these unwelcome invaders is a common strategy to help native communities recover. Ecologists hope that when invasive plants are kicked out, the native biodiversity will bounce back. But what actually happens after invasive species are removed? Recovery is shaped not only by how many species are gained or lost, but also by which species colonize, which disappear, and the relative abundances of the remaining species. Understanding these dynamics is crucial for predicting whether the removal efforts will succeed, and for designing strategies that foster long-term ecological restoration.
What we did
We set up a three-year field experiment in a subtropical old field that had been overrun by invasive plants (most notably Canadian goldenrod, Solidago canadensis). Rather than an all-or-nothing approach, we applied four different removal treatments: no removal, removal of non-dominant invaders, removal of the dominant invader, and removal of all invaders. Each summer we recorded plant cover to track which species appeared, which disappeared, and how the remaining species shifted in their relative cover. Crucially, we tracked multiple facets of biodiversity over time, including taxonomic diversity (how many species), phylogenetic diversity (how species are related in the tree of life), and functional diversity (how species differ in functional traits). This multidimensional approach gave us a rich picture of how the community assembled after removal.
What we found
The good news is that removing invasive plants did promote the recovery of community diversity, but the story goes far beyond simple species gains. While new colonization and reduced local extinctions both contributed to recovery, the strongest signals came from shifts in species abundance distributions. After invader removal, the abundance distribution among species became more balanced. Strikingly, the species that increased in dominance were not close relatives with similar traits, but instead distantly related and functionally distinct species. This reshuffling of winners led to substantial increases in phylogenetic and functional diversity. Therefore, changes in relative abundance, often overlooked, proved to be a key mechanism of diversity recovery. In fact, abundance shifts may serve as an early and sensitive indicator of restoration success, often more informative than simply counting species gained or lost.
What it means
Invasive species management is often a long battle, but our findings offer a hopeful message. Removing invaders not only allows native species to return; it also helps the remaining community reassemble itself, collectively promoting the recovery of phylogenetic and functional diversity. By integrating species gains, losses, and abundance shifts, our study provides a comprehensive framework for tracking biodiversity dynamics over time. It shows that restoration is not just about which species return or disappear but how the community reorganizes. By paying attention to early signs of recovery, such as which kinds of species increase or decrease in abundance, we can guide more effective interventions on the path to a thriving ecosystem.
