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Non-native tree (NNT) species have been transported worldwide to create or enhance services that are fundamental for human well-being, such as timber provision, erosion control or ornamental value; yet NNTs can also produce undesired effects, such as fire proneness or pollen allergenicity. Despite the variety of effects that NNTs have on multiple ecosystem services, a global quantitative assessment of their costs and benefits is still lacking. Such information is critical for decision-making, management and sustainable exploitation of NNTs. We present here a global assessment of NNT effects on the three main categories of ecosystem services, including regulating (RES), provisioning (PES) and cultural services (CES), and on an ecosystem disservice (EDS), i.e. pollen allergenicity. By searching the scientific literature, country forestry reports, and social media, we compiled a global data set of 1683 case studies from over 125 NNT species, covering 44 countries, all continents but Antarctica, and seven biomes. Using different meta-analysis techniques, we found that, while NNTs increase most RES (e.g. climate regulation, soil erosion control, fertility and formation), they decrease PES (e.g. NNTs contribute less than native trees to global timber provision). Also, they have different effects on CES (e.g. increase aesthetic values but decrease scientific interest), and no effect on the EDS considered. NNT effects on each ecosystem (dis)service showed a strong context dependency, varying across NNT types, biomes and socio-economic conditions. For instance, some RES are increased more by NNTs able to fix atmospheric nitrogen, and when the ecosystem is located in low-latitude biomes; some CES are increased more by NNTs in less-wealthy countries or in countries with higher gross domestic products. The effects of NNTs on several ecosystem (dis)services exhibited some synergies (e.g. among soil fertility, soil formation and climate regulation or between aesthetic values and pollen allergenicity), but also trade-offs (e.g. between fire regulation and soil erosion control). Our analyses provide a quantitative understanding of the complex synergies, trade-offs and context dependencies involved for the effects of NNTs that is essential for attaining a sustained provision of ecosystem services.

Successful invasive species commonly depend on the establishment of mutualistic interactions with native and nonnative biota. In turn, invasive species can affect native mutualisms and community stability. Here, we examine different forms of mutualist acquisition by invasive species and the causes and consequences of mutualism abandonment for invasion processes. Additionally, we delve into the quantitative and qualitative effects of invaders on native biota via mutualism disruption that can occur through direct and diverse indirect pathways. These effects of invasive species on native biota via mutualistic interactions can often be a consequence of the invaders' abundance, which should be considered a prime predictor when evaluating the impact of invasive species on native mutualisms and community stability. We propose that the ecological as well as the evolutionary consequences of mutualism disruption and switches caused by invasive species can play crucial roles in determining future biodiversity. [ABSTRACT FROM AUTHOR]

An ongoing restoration challenge is to recover native communities after the removal of invasive species. Because priority effects (i.e. the order and timing of species arrival) can strongly determine the trajectory of community assembly, their intentional manipulation is gaining attention to manage invasive plants and achieve restoration goals. Yet, ecologists and conservationists rarely consider how the order and timing of species removal—inverse priority effect—may impact future plant communities.Here, we evaluated the dependence of community reassembly on inverse priority effects by experimentally removing the target invasives Sweetbriar rose (Rosa rubiginosa) and Scotch broom (Cytisus scoparius) in field and mesocosm communities. We manipulated removal order (rose before broom vs. broom before rose) and timing (simultaneously early vs. simultaneously late in the season). We performed a hierarchical modeling of species sommunity to assess differences in community structure in response to order and timing of removal, and to evaluate whether species origin and leaf and seed traits were associated with species responses.We found that the order of removal was as important as timing driving community reassembly. Simultaneous removal favoured nonnatives, more so when performed early. Sequential removals led to contrasting communities. Rose before broom removal also favoured nonnative grasses at expense of native species, whereas the inverse order produced small changes in communities. In general, species with high specific leaf area were boosted, regardless of their seed size.Synthesis and applications. Inverse priority effects are neglected mechanisms that can drive variability in the reassembly of plant communities and can potentially upgrade invasive species management. These historical contingencies suggest the existence of an optimal order of removal that facilitates the recovery of the native community. We found that simultaneous removal promoted secondary invasions to a greater extent than sequential removals. Furthermore, removal order affected post‐removal community structure. In our system, we suggest removing the rose before the broom to hinder nonnatives and pave the way for restoration of native communities. Our results show that manipulation of the order and timing of removal can help to achieve restoration goals. [ABSTRACT FROM AUTHOR]

As biological invasions increasingly threaten biodiversity, the removal of invasive nonnative species emerges as a possibility to recover the structure and function of native communities. Yet, we have limited knowledge of how communities assemble after nonnative removals. Since most ecosystems are invaded by multiple nonnative species, the impact of their removal likely depends on the interactions among nonnative species which, in turn, are contingent on the environmental context in which they occur.We evaluated the community assembly after the targeted removal of two highly invasive shrubs, Sweetbriar rose (Rosa rubiginosa) and Scotch broom (Cytisus scoparius). The removal was performed at two different times in the growing season (early or late removal) in field and mesocosm communities. In search of general patterns across species, we modelled species responses as a function of their origin (i.e. native/nonnative) and functional traits.We found evidence for negative and asymmetric interactions between dominant invasive species that translated into changes in the abundances of the rest of the species in the community. Depending on the identity of the removed species, the removal of invasive species affected community assembly by promoting other nonnative species or hindering the performance of native species. These effects were modulated by the timing of removal and did not depend on leaf or seed traits.Synthesis. Accounting for nonnative interactions and their temporal dependency should improve our inferences about assembly processes and the effectiveness of nonnative removal aimed at reducing the accumulation of nonnatives. [ABSTRACT FROM AUTHOR]