Journal Article

Plant invasions and extinction debts

Gilbert, Benjamin, Levine, Jonathan M.

2013

Overview

Whether introduced species invasions pose a major threat to biodiversity is hotly debated. Much of this debate is fueled by recent findings that competition from introduced organisms has driven remarkably few plant species to extinction. Instead, native plant species in invaded ecosystems are often found in refugia: patchy, marginal habitats unsuitable to their nonnative competitors. However, whether the colonization and extinction dynamics of these refugia allow long-term native persistence is uncertain. Of particular concern is the possibility that invasive plants may induce an extinction debt in the native flora, where persistence over the short term masks deterministic extinction trajectories. We examined how invader impacts on landscape structure influence native plant persistence by combining recently developed quantitative techniques for evaluating metapopulation persistence with field measurements of an invaded plant community. We found that European grass invasion of an edaphically heterogeneous California landscape has greatly decreased the likelihood of the persistence of native metapopulations. It does so via two main pathways: (i) decreasing the size of native refugia, which reduces seed production and increases local extinction, and (ii) eroding the dispersal permeability of the matrix between refugia, which reduces their connectivity. Even when native plant extinction is the deterministic outcome of invasion, the time to extinction can be on the order of hundreds of years. We conclude that the relatively short time since invasion in many parts of the world is insufficient to observe the full impact of plant invasions on native biodiversity.

• Publisher: National Academy of Sciences,National Acad Sciences
• Subject: Algorithms / Animal, plant and microbial ecology / Annuals / Applied ecology / Biodiversity / Biological and medical sciences / Biological Sciences / California / Conservation of Natural Resources / Conservation, protection and management of environment and wildlife / Dispersal / Ecological invasion / Ecosystem / ecosystems / Environment / Environmental Monitoring / Extinct species / Extinction / Extinction, Biological / Flora / Fundamental and applied biological sciences. Psychology / Geography / grasses / Habitats / Indigenous plants / Indigenous species / Introduced Species / Invasions / Invasive plants / Invasive species / landscapes / Metapopulation ecology / Metapopulations / Models, Biological / Nonnative species / Organisms / Parks, reserves, wildlife conservation. Endangered species: population survey and restocking / permeability / Plant communities / Plant Physiological Phenomena / Plant species / Plants / Poaceae - growth & development / Population Dynamics / quantitative analysis / Refuge habitats / Refugia / Seed production / Species extinction