Inverse priority effects: Order of invasive species removal affects early plant community assemblage

TORRES, AGOSTINA; MARIANO A. RODRIGUEZ CABAL; NUÑEZ, MARTIN A.

Congreso; ESA - BRIDGING COMMUNITIES AND ECOSYSTEMS: INCLUSION AS AN ECOLOGICAL IMPERATIVE; 2019

Ecological Society of America

Background/Question/MethodsLocal species communities are a result of both stochastic and deterministic processes. History of assembly of plant communities (the order and timing of species arrival) has gained recent attention as a stochastic processes driving non-native (NN) species invasion. The order and timing of NN species arrival can drive different stable states and favor NN species invasion through priority effects. A similar rationale can be used to hypothesize that the history of disassembly of invaded communities would shape the identity and abundance of the remaining species. The removal of a NN species can change the strength of biotic interactions by releasing species from competition or disrupting positive interactions, and/or by shaping species performance through legacy effects. Here, we performed a field experiment on Isla Victoria (Patagonia, Argentina) to evaluate the effect of the history of disassembly on plant community structure. We selected 108 plots, 1 m of diameter, dominated by the highly invasive Rosa rubiginosa and Cytisus scoparius (target species). Then we randomly assigned nine treatments that combine the removal of only R. rubiginosa, only C. scoparius or both species at two different times. A no removal treatment was also added as a control.Results/ConclusionsWe found that the order of removal affected community structure of the non-target species. Plant communities where the target species were removed at the same time had 8% lower proportion of NN species and different composition than communities where invasive species were removed in sequence. However, there were no differences related to the identity of the early-removed species. Moreover, timing of removal had no effect on the early-assemblage of these communities, suggesting that order of removal and not stochastic contingencies of the moment of removal drive these changes. We found an increase in Shannon diversity index in non-target communities where both species were removed compared to communities where one or both target species remains. Taken together, our results suggest an early sign of inverse priority effects on the artificial disassembly of invaded plant communities that would possibly intensify as community develop. Understanding the history of community disassembly is not only an understudied topic in ecology, but can help address management of invasive species as well as species losses in the face of global change.