Landscape-level determinants of the spread and impact of invasive grasses in protected areas

Abstract

Anthropogenic disturbances play an important role in invasibility, and the traits of exotic species act as mediators of invasion success. The impact of exotic species can be evaluated through an association with invasion potential. The magnitude and potential severity of exotic species impacts can aid in decision making regarding the best conservation, restoration, management and control actions. In this sense, our objectives were to (1) evaluate the potential invasion risk of naturalized graminoid species in the Cerrado biome using risk analysis; (2) understand the magnitude of the impact of these species on protected areas by analysing the relationships between invasiveness, invasion potential and proximity to strictly protected areas, as well as to the biome as a whole; and (3) identify the drivers of spread contributing to species richness and abundance in the Cerrado. Our results showed that naturalized graminoid species in the Cerrado biome present invasion risks and potential impacts varying from medium to high. Additionally, these landscapes were vulnerable due to their proximity to protected areas, which act as filters against these species and against anthropogenic agents (human population and road density) that may increase the richness and population sizes of these plants. Based on our results, we recommend developing and prioritizing management and control strategies in strictly protected areas and in their surrounding areas to avoid the dispersal and establishment of aggressive species (African grasses) in their interiors, homogenization risks and the consequent loss of native biodiversity.