Effects of land-use change and related pressures on alien and native subsets of island communities

Abstract

Island species and habitats are particularly vulnerable to human disturbances, and anthropogenic changes are increasingly overwriting natural island biogeographic patterns.However, quantitative comparisons of how native and alien assemblages respond to human disturbances are scarce. Using data from 6,252 species (vertebrates, invertebrates and plants), 7,731 sites and 80 islands, we model how land-use change, human population density and distance to the nearest road affect local assemblages of alien and native species on islands. We found that these pressures reduce both richness and abundance of natives, whereas the number and abundance of alien species are high in plantation forests and agricultural or urban sites. In contrast to the long-established pattern for native species, more isolated islands have a higher number of alien species across most land uses than do less isolated islands. Finally, our models of compositional similarity comparing sites in minimallydisturbed primary vegetation with other land uses, and sites within the same land use show that alien species play a major role in the turnover and homogenization of island assemblages.The declines of native species on islands in the face of human pressures, and the proneness to invasions of even the more remote islands, highlight the need to reduce the intensity of human pressures on islands and so far as possible to prevent the establishment of alien species.

Biogeographic origins and drivers of alien plant invasions in the Canary Islands

“…Both climate similarity and geographic distance are clearly important in explaining floristic relationships of the invasive flora within the Canarian archipelago. Nevertheless, our results also illustrate how archipelago‐dependent processes can cause idiosyncratic, yet prevalent patterns of invasion success, ultimately reinforcing the view of biotic homogenization as a main driver of insular floras (Castro et al, 2010; Kueffer et al, 2010; Sánchez‐Ortiz et al, 2020).…”

Intensive human land uses negatively affect vertebrate functional diversity

“…This may be because non‐native species are more likely to become established in disturbed assemblages. Previous work has shown that land‐use disturbance facilitates biological invasions in island ecosystems (Jesse et al, 2018; Sanchez‐Ortiz et al, 2019), but to our knowledge, this has not been tested specifically across continental areas for invasive vertebrates (but see Pyšek et al (2010)). It is also possible that disturbed areas harbour synanthropic species that do not occur in primary vegetation, leading to substantial functional gain.…”

What Will the Future Bring for Biological Invasions on Islands? An Expert-Based Assessment

“…The drivers associated with the environment (e.g., climate change and biodiversity loss and degradation) and human activity (e.g., land use/cover change, socio-economy or demography and migration) become prevalent at the establishment stage. Anthropogenic habitat destruction has indeed been shown to strongly increase alien species richness and abundance across habitats, at the expense of native species richness (Sanchez-Ortiz et al, 2019). Other anthropogenic disturbances like infrastructure development additionally increase alien species establishment (Alexander et al, 2016;Haider et al, 2018), and urban and artificial environments already hold a high diversity of alien species, often buffering them from adverse environmental conditions (Strubbe and Matthysen, 2009).…”