Disentangling native and alien plant diversity in coastal sand dune ecosystems worldwide

Abstract

Aims: (a) To disentangle the global patterns of native and alien plant diversity on coastal sand dune ecosystems across habitats and floristic kingdoms; (b) to determine the main drivers of variation in species richness in native and alien species in these endangered ecosystems; and (c) to test for an interaction between spatial scale and native-alien richness patterns, as predicted by the invasion paradox. Location: Global. Methods: We collated a dataset of 14,841 vegetation plots in coastal sand dune ecosystems from around the world. Generalized Linear Models (GLMs) and Generalized Linear Mixed Models (GLMMs) were used to assess the patterns and main ecological determinants underlying native and alien species richness. Variation partitioning revealed the relative importance of environmental and anthropogenic variables. Results: GLMs revealed strong differences among both habitats and floristic kingdoms in the number of native and alien species. Specifically, native species richness increased along the sea-inland gradient and was higher in the Cape and Paleotropical kingdoms. In contrast, alien species richness was relatively similar across habitats and kingdoms, though some differences were detected. There were strong differences between the drivers of native and alien richness; anthropogenic factors such as gross domestic product were positively associated with alien richness whereas native richness was more strongly related to environmental factors. Furthermore, we found a weak support for an invasion paradox effect. Conclusions: Our results revealed the complexity of causal processes underpinning coastal sand dune plant biodiversity and highlight the importance of considering native and alien species separately. Recognizing these differences while researching variation in biodiversity patterns and processes at multiple spatial scales will lead to a better mechanistic understanding of the causes of invasion worldwide, and in

Measuring Alpha and Beta Diversity by Field and Remote-Sensing Data: A Challenge for Coastal Dunes Biodiversity Monitoring

“…Therefore, updated monitoring protocols able to summarize its biodiversity trends are urgently needed [35]. Among multiple threats, coastal landscapes are seriously impinged by alien plant invasions [36][37][38], whose negative effects on natural ecosystems have been explored using field data or RS independently [39,40]. Field-research gave evidence of alterations of species diversity [41] and cover [42] in invaded areas, while RS research underlined significant functional traits modifications [43] and niche shifts [44].…”

Invasion success on European coastal dunes

“…The repeated introduction of alien species is a major component of ongoing global changes and a major threat to global biodiversity (Walther et al 2009). After their direct or indirect introduction by humans (Rodríguez-Labajos et al 2009;Pyšek et al 2010;Tordoni et al 2020), many plant species become naturalised, overcoming local abiotic and reproductive barriers to establish self-sustained populations. A subset of these spread across considerable distances and become invasive (Richardson et al 2000), with impacts on wildlife, plant biodiversity, and ecosystem functioning (Vilà et al 2011;Del Vecchio et al 2015;Blackburn et al 2019).…”

Macroecology of vegetation — Lessons learnt from the Virtual Special Issue

“…Two studies compared the ecology of native and alien species. Tordoni et al (2021) used vegetation plots of coastal dune habitats worldwide to derive models explaining the species richness of native and alien species. For native species, abiotic variables were more important, while for alien species, anthropogenic variables prevailed, as they were largely correlated to the gross domestic product (GDP) of the respective country.…”

“…Most of these studies rely on two large vegetation‐plot databases established and maintained by two working groups of the International Association for Vegetation Science (IAVS), the European Vegetation Archive (EVA; Chytrý et al, 2016) by the European Vegetation Survey (Axmanová et al, 2021; Boonman et al, 2021; Cao Pinna et al, 2021; Padullés Cubino et al, 2021; Sporbert et al, 2021; Večera et al, 2021; Wagner et al, 2021) and the GrassPlot database (Dengler et al, 2018) by the Eurasian Dry Grassland Group (Biurrun et al, 2021; Dembicz et al, 2021; Zhang et al, 2021). Testolin et al (2021) used data from the global vegetation‐plot database sPlot (Bruelheide et al, 2019), and four relied on regional data compilations (Bourgeois et al, 2021; Craven et al, 2021; Kusumoto et al, 2021; Tordoni et al, 2021). This pattern highlights that community efforts of collating extensive collaborative vegetation‐plot databases, such as EVA, sPlot and GrassPlot, have the potential to facilitate new research avenues (Bruelheide et al, 2019; Dengler et al, 2011; Wiser, 2016), often beyond the initial scopes imagined by the founders of these databases, not mentioning the aims of most original field workers.…”