Demographic mechanisms of disturbance and plant diversity promoting the establishment of invasive Lupinus polyphyllus

AimsCommunity characteristics, such as disturbances and interspecific competition that affect the availability of microsites and resources, contribute to the success or failure of the establishment of exotic plant species. In particular, these two community characteristics may have adverse effects on plant emergence and survival, which are particularly important for population establishment and therefore it may be necessary to consider both these vital rates simultaneously when assessing demographic mechanisms. Here, we investigated the impacts of disturbance and interspecific competition on the establishment of a perennial invasive herb, Lupinus polyphyllus Lindl.MethodsOver the course of 2 years, we conducted an experiment in 10 populations of this species in Finland in which we manipulated the levels of soil disturbance. We recorded community characteristics (i.e. the number of vascular plant species, vegetation height, and the proportions of bare ground, litter and moss), and observed the emergence and survival of L. polyphyllus individuals in study plots.Important FindingsA mild disturbance (breaking the soil surface mechanically) slightly increased seedling emergence but did not affect plant survival. Instead, an intense disturbance (vegetation and litter removal) had no effect on seedling emergence, although it significantly increased the proportion of bare ground and, consequently, seedling survival. Survival was not affected by the height of the surrounding vegetation, but both seedling emergence and plant survival increased with an increasing number of plant species in the study plots. These findings demonstrate that single disturbance events may considerably promote the establishment of invasive herbs, although the overall effect and demographic mechanisms behind the increased establishment are likely to vary depending on disturbance type. Moreover, our results suggest that species diversity per se may not be a crucial mechanism for locally preventing the establishment of exotic plants

Impacts of past abrupt land change on local biodiversity globally

Abrupt land change, such as deforestation or agricultural intensification, is a key driver of biodiversity change. Following abrupt land change, local biodiversity often continues to be influenced through biotic lag effects. However, current understanding of how terrestrial biodiversity is impacted by past abrupt land changes is incomplete. Here we show that abrupt land change in the past continues to influence present species assemblages globally. We combine geographically and taxonomically broad data on local biodiversity with quantitative estimates of abrupt land change detected within time series of satellite imagery from 1982 to 2015. Species richness and abundance were 4.2% and 2% lower, respectively, and assemblage composition was altered at sites with an abrupt land change compared to unchanged sites, although impacts differed among taxonomic groups. Biodiversity recovered to levels comparable to unchanged sites after >10 years. Ignoring delayed impacts of abrupt land changes likely results in incomplete assessments of biodiversity change

The Role of Tourism and Recreation in the Spread of Non-Native Species: A Systematic Review and Meta-Analysis

Managing the pathways by which non-native species are introduced and spread is considered the most effective way of preventing species invasions. Tourism and outdoor recreation involve the frequent congregation of people, vehicles and vessels from geographically diverse areas. They are therefore perceived to be major pathways for the movement of non-native species, and ones that will become increasingly important with the continued growth of these sectors. However, a global assessment of the relationship between tourism activities and the introduction of non-native species–particularly in freshwater and marine environments–is lacking. We conducted a systematic review and meta-analysis to determine the impact of tourism and outdoor recreation on non-native species in terrestrial, marine and freshwater environments. Our results provide quantitative evidence that the abundance and richness of non-native species are significantly higher in sites where tourist activities take place than in control sites. The pattern was consistent across terrestrial, freshwater and marine environments; across a variety of vectors (e.g. horses, hikers, yachts); and across a range of taxonomic groups. These results highlight the need for widespread biosecurity interventions to prevent the inadvertent introduction of invasive non-native species (INNS) as the tourism and outdoor recreation sectors grow

Linking species traits of alien plants with environmental characteristics of agricultural habitats

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Spatial heterogeneity and disturbance create positive native-alien relationship in agricultural habitats

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