Emanuela W. A. Weidlich, Cara R Nelson, John L Maron, Ragan M. Callaway4, Benjamin M. Delory, Vicky M. Temperton1

Priority effects refer to the order or timing of species arrival, including how species that arrive early to a site either positively or negatively affect establishment, growth, or reproduction of species that arrive later. Despite clear implications of priority effects on ecological restoration, to date there are no reviews of how and where priority effects have been studied and the extent to findings can be applied to restoration practice. Here, we survey the literature on priority effects and a) summarize patterns that are relevant to restoration; b) synthesize information on the mechanisms through which priority effects operate, and on how these mechanisms can be manipulated to achieve particular restoration goals; and c) highlight potential future research needed to improve use of priority effects in restoration. We found that even small delays in arrival time, as opposed to simultaneous arrival of species, can promote differences in subsequent community composition. Even so, there have been very few studies on the long-term stability of these priority effects, and the majority were conducted in temperate grasslands. Given the lack of information for other biomes, the general importance of priority effects, as well as its application to restoration, is unknown. Our findings suggest that creating alternative vegetation states via priority treatments might be a promising avenue to further explore, but that for the concept to be operationalized for restoration practice there is a need for research in the diverse types of ecosystems that are priorities for restoration and that occurs over longer time periods.