Understanding the effects of exotic plant species on natural ecosystem processes remains elusive. Still, exotic species are a comprehensive ecological issue that we face today, as they species cost the global economy billions of dollars each year. While efforts to remove exotic species are often successful in suppressing the target species, in some cases they only facilitate further invasions. Therefore, it is imperative that when attempting to manage exotic species, a full evaluation of community-level response is considered.
This study focused on one example of a complex, invaded environment. The Albany Pine Bush Preserve (APB) in New York has been attempting to restore the native pine barren habitat in response to the introduction of the black locust tree (Robinia pseudoacacia). This study sought to answer the question of whether restoration led to new invasions.
We sampled percent cover of all vascular species in native, invaded, and invaded but restored sites at the APB. We compared the population and distribution of exotic species in each site type.
Percent exotic cover was significantly higher in Locust sites when compared to the two other site types. Frequency of exotics was similar across the three treatments. Therefore, we calculated the ratios of total species to number of invasives to find a significant result. An ANOVA test was also constructed to understand the implications of one of the most prominent exotic species, spotted knapweed. This ANOVA revealed no difference by site. Finally, ordination analysis revealed that communities in each site type were broadly similar.
It can be reassuring to see such overlap in invasive populations between Locust and Restored sites. Without a large gap in the composition of invasives, we can begin to rule out the suspicion that restoration efforts greatly alter the next stages of ecosystem regeneration.
There is an alternative view however, of the results of this study, and that is the Barrens represent a less “untouched” environment than we had originally expected.