Extinction risk predictions for the world’s flowering plants to support their conservation

Abstract

More than 70% of all vascular plants lack conservation status assessments. We aimed to address this shortfall in knowledge of species extinction risk by using the World Checklist of Vascular Plants to generate the first comprehensive set of predictions for a large clade: angiosperms (flowering plants, ~330,000 species). We used Bayesian Additive Regression Trees (BART) to predict the extinction risk of all angiosperms using predictors relating to range size, human footprint, climate, and evolutionary history and applied a novel approach to estimate uncertainty of individual species level predictions. From our model predictions we estimate 45.1% of angiosperm species are potentially threatened with a lower bound of 44.5% and upper bound of 45.7%. Our species-level predictions, with associated uncertainty estimates, do not replace full Red List assessments, but can be used to prioritise predicted threatened species for full Red List assessment and fast-track predicted non-threatened species for Least Concern assessments. Our predictions and uncertainty estimates can also guide fieldwork, inform systematic conservation planning and support global plant conservation efforts and targets.

Re‐evaluating the importance of threatened species in maintaining global phytoregions

“…(2022), which may reveal the reason for differences in our results. A vascular plant‐wide phylogeny could also be used to refine predictions of extinction risk and reduce the variation in our modelled extinction scenarios, but recent work (Bachman, 2023) found that phylogenetic information is of limited use for predicting extinction risk for plants.…”

“…These biases favouring the documentation of introductions over extinctions may be amplified in studies at relative coarse spatial scales (Olden et al ., 2011). Further support for the idea that the impact of extinctions in redefining phytoregions may have been underestimated is provided by revised estimates of current extinction risk (Nic Lughadha et al ., 2020, Bachman, 2023). Recent research suggests that as many as two in five known vascular plant species are threatened with extinction (Nic Lughadha et al ., 2020) and emphasises that this estimate does not factor in plant species that are as yet unknown to science but are likely to prove threatened once assessed (Cheek et al ., 2020; Brown et al ., 2023a).…”

Why plant diversity and distribution matter

“…The scientific literature on global biodiversity extinction remains dominated by research on vertebrates. Several studies contribute to redressing this (Bachman et al, 2023;Gallagher et al, 2023;Soto Gomez et al, 2023;Brown et al, 2023a,b), by combining WCVP geographical data with extinction risk data from the International Union for Conservation of Nature (IUCN, 2022) Red List of Threatened Species (hereafter Red List). While WCVP is comprehensive at the species level, Red List coverage of vascular plants is incomplete; fewer than one-in-five plants have expert assessments despite concerted efforts to increase coverage (Bachman et al, 2023).…”

“…Pelletier et al, 2018;Zizka et al, 2021). Bachman et al (2023) address both biases simultaneously, by using predictors available for the majority of plant species, producing preliminary extinction risk estimates for all angiosperms, with an uncertainty estimate for each prediction. Geographic range size (estimated as the number of botanical countries in WCVP) was the most important predictor type, followed by human impacts and phylogenetic relationships and then year of description.…”

“…Plant extinctions at the scale suggested byBachman et al (2023) andBrown et al (2023a) are hard to imagine, butBrown et al (2023b) provide sobering scenarios that illustrate the potential scale of phytogeographic changes. The effects of loss of threatened species may outweigh the better-documented impacts of introduced species (e.g Winter et al, 2009;Daru et al, 2021).…”