Priority effects: Emerging principles for invasive plant species management

Abstract

Many anthropic activities generate soil disturbances, favoring competitive, fast growing invasive plant species at the expense of natives. Active restoration of invasionresistant plant communities is increasingly recognized as a relevant strategy to combat invasive plant colonization in disturbed areas, but results are often unsatisfying. Historical effects, referred as "priority effects" (i.e. the effects generated by the order in which species arrive at a local site), can have a major role in community assembly and invasion success because they involve early colonists altering the performance of later colonists. Taking these priority effects into account in restoration projects is emerging as a relevant way to improve native species restoration success and prevent invasion. The present review discusses two strategies considering priority effects that would help to achieve the classic restoration goal of "more natives, less invasives". The first strategy relies on tackling priority effects of invasive plants using different management options adapted to local environmental conditions, including removal, reduction of propagule sources, or mitigation of soil legacies. Indeed, invasive plants often generate strong priority effects providing themselves a substantial 2 competitive advantage through early emergence and quick growth, but also self-induced soil modifications that can persist after their removal or death, commonly termed "soil legacies".In fertile and stable conditions, the reduction of invasive species priority effects must be coupled with the restoration of an invasion-resistant native plant cover to avoid reinvasion and secondary invasions. The second strategy is to bring about situations in which the restored native species are more likely to exert strong priority effects, decreasing invasion success. For this purpose, we sketch possible options open to restorationists based on resource or nonresource mechanisms. First, we discuss ways to maximize resource preemption by extending the time advance given to restored native species and manipulating restored species characteristics. Second, we consider the potential effect of increasing niche overlap between native and invasive species. Third, we introduce the potential manipulations of non-resource mechanisms, such as allelopathy, herbivory, disease, or the presence of mycorrhizae, to increase priority effects. This review incorporates recent research on priority effects to draw the outlines of priority effects-based restoration strategies and define future research questions that need to be addressed to test and improve these strategies.

The exotic species Senecio inaequidens pays the price for arriving late in temperate European grasslands

“…Our results showed that S. inaequidens benefited more from arriving early in the community than the native species, and this effect was particularly strong when it was followed by a mixture of grasses and legumes. This result is in agreement with the hypothesis that, due to their earlier emergence, greater germination rates, and faster growth, exotics would benefit more than native species from arriving early in the community (Dickson et al 2012;Wainwright et al 2012;Wilsey et al 2015;Hess et al 2019). This result, however, contradicts other priority effect studies that showed that exotic species benefited equally (Stuble & Souza 2016) or less (Cleland, Esch & Mckinney 2015) than natives when they were the first to arrive in a community.…”

“…There is now an expanding body of literature claiming that the creation of priority effects would be a useful technique to restore degraded habitats, alter competitive relationships, and steer plant communities towards desirable states in terms of biodiversity and functioning (Wilsey et al 2015;Temperton et al 2016;Weidlich et al 2017Weidlich et al , 2018Young et al 2017). Manipulating plant community assembly to promote native species that will ultimately exert strong priority effects on exotics is also a very interesting approach to lower the risk of invasion (Hess et al 2019). Most of the research in this field has been performed in the USA (Young et al 2017;Goodale & Wilsey 2018).…”

“…Depending on the timing of arrival of an exotic species and the desired outcome (resistance of the community to invasion), priority effects can be considered as positive or negative. During ecological restoration of degraded landscapes, for example, there is much potential for creating positive priority effects by sowing natives before the arrival of exotics (Hess, Mesléard & Buisson 2019). If exotic species with strong competitive abilities are given a headstart (e.g., after a disturbance), however, they can quickly outcompete native species (Abraham, Corbin & D'Antonio 2009;Grman & Suding 2010;Stevens & Fehmi 2011;Dickson, Hopwood & Wilsey 2012;6 Wainwright et al 2012;Ulrich & Perkins 2014;Wilsey et al 2015;Stuble & Souza 2016), and such priority effects can persist for several years (Martin & Wilsey 2012;Vaughn & Young 2015).…”

Using limiting similarity to enhance invasion resistance: Theoretical and practical concerns

“…Therefore, in a case where invasive species are already present in the immediate vicinity and thus threatening the site, this strategy may be less effective. Combining this strategy with approaches giving a rapid and strong invasion resistance, for example through priority effects (Hess, Mesléard, & Buisson, 2019), would seem a more promising way of effectively hinder invasive species' early establishment.…”

Jute bioblanket as a soil rehabilitation strategy in Sorocaba, Brazil: Soil chemistry and SWOT approaches

“…Usually, we control invasive plants by applying herbicides or cutting them down (Knezevic, Osipitan, Scott, & Nedeljkovic, ). However, both of these methods are expensive, and the use of herbicides causes environmental contamination (Hess, Mesléard, & Buisson, ; Kumar, Jha, Jugulam, Yadav, & Stahlman, ; Pagès, Fischer, van der Wal, & Lambin, ).…”