Projected conservation status of forest species in Central America and southern Mexico under four different climate change scenarios by the year 2070.

We classified species in our dataset (n = 1924) into IUCN Red List categories following the A3 criterion [58]. Different colors represent the percentage of species in each category, which are further separated into two alternative RCPs (top semicircles, RCP4.5; bottom, RCP8.5) and two dispersal assumptions: outer circle (A), limited dispersal; inner circle (B), unlimited dispersal. The complete species dataset is presented in S4 Table).</p

Results of 1,000 generalized linear mixed model iterations to assess the effect of climatic variables on the proportion of species projected to become threatened under future climate change.

In each run, models with all variable combinations were compared and the best model was selected according to AIC. Variable importance was ranked by: (1) average of model weights (wg) over all models that included each variable; and (2) the number of models containing each variable (N).</p

Pearson correlation analysis of 18 variables obtained from Worldclim 1.4 [48] for 10,000 randomly chosen points across the study area.

Cells above the diagonal show the r value; cells below the diagonal show the density distribution. (PDF)</p

Name, number of occurrences, and parameters used to evaluate the species distribution model of 1924 plant species evaluated in this study.

Name, number of occurrences, and parameters used to evaluate the species distribution model of 1924 plant species evaluated in this study.</p

Model averaged coefficients of the effect of change in climate variables on the proportion of threatened species under the RCP8.5 and limited dispersal scenario.

Coefficients were estimated using only those models where the variable was included.</p

Dataset of occurrences used in this study.

Global biodiversity is negatively affected by anthropogenic climate change. As species distributions shift due to increasing temperatures and precipitation fluctuations, many species face the risk of extinction. In this study, we explore the expected trend for plant species distributions in Central America and southern Mexico under two alternative Representative Concentration Pathways (RCPs) portraying moderate (RCP4.5) and severe (RCP8.5) increases in greenhouse gas emissions, combined with two species dispersal assumptions (limited and unlimited), for the 2061–2080 climate forecast. Using an ensemble approach employing three techniques to generate species distribution models, we classified 1924 plant species from the region’s (sub)tropical forests according to IUCN Red List categories. To infer the spatial and taxonomic distribution of species’ vulnerability under each scenario, we calculated the proportion of species in a threat category (Vulnerable, Endangered, Critically Endangered) at a pixel resolution of 30 arc seconds and by family. Our results show a high proportion (58–67%) of threatened species among the four experimental scenarios, with the highest proportion under RCP8.5 and limited dispersal. Threatened species were concentrated in montane areas and avoided lowland areas where conditions are likely to be increasingly inhospitable. Annual precipitation and diurnal temperature range were the main drivers of species’ relative vulnerability. Our approach identifies strategic montane areas and taxa of conservation concern that merit urgent inclusion in management plans to improve climatic resilience in the Mesoamerican biodiversity hotspot. Such information is necessary to develop policies that prioritize vulnerable elements and mitigate threats to biodiversity under climate change.</div

Summary of the steps followed to obtain the final dataset used to model plant species distributions.

BIOTREE-NET includes occurrences from southern Mexico and Central America, while BIEN also includes data from Colombia and central and northern Mexico (Fig 1).</p

Fig 1 -

(A) Distribution of tropical and subtropical dry and moist broadleaf forests in Mexico, Central America, and the northwestern Andes, based on RESOLVE Ecoregions and Biomes database [61]. (B) Locations of 333,411 plant species occurrences obtained from the BIOTREE-NET [38] and BIEN databases [79] and used to generate species distribution models. Software: QGIS 3.28. Base map source: Natural Earth, available from http://www.naturalearthdata.com/. Ecoregion boundaries obtained from RESOLVE Ecoregions and Biomes database [61], available in https://ecoregions.appspot.com/ under a CC-BY 4.0 license.</p

Projected distribution of threatened species classified as vulnerable, endangered or critically endangered according to the A3 criterion [58].

(A) Projected areas where threatened species exceed 80% of the total number of species per pixel (30 arc seconds) for RCP4.5 and RCP8.5 under the assumption of limited dispersal. (B) The top 10 most threatened ecoregions according to our models, where ecoregions are defined by the RESOLVE Ecoregions and Biomes database [61] (see Table 2 for more details). Software: QGIS 3.28. Base map source: Natural Earth, available from http://www.naturalearthdata.com/. Ecoregion boundaries obtained from RESOLVE Ecoregions and Biomes database [61], available in https://ecoregions.appspot.com/ under a CC-BY 4.0 license.</p

Percentage of threatened species by family for RCP4.5 (dark bars) and RCP8.5 (dark + light bars) under the assumption of limited dispersal.

Different colors indicate different plant orders. Only families with > 30 species in the dataset are shown; S1 Fig depicts all families, including those with less than 30 species in the dataset.</p