DOI: 10.5091/plecevo.185741

Authors: Kaio C.M. da Cunha, Flávia M. Durgante, Laura L. Rivera-Parada, Itamara G. da Gama, Glaucileide Ferreira, Semirian C. Amoêdo, Caroline C. Vasconcelos

Abstract: Background and aims – Understanding the distribution of Amazonian tree species is hindered by sparse occurrence data and strong environmental heterogeneity. Species with wide geographic ranges but restricted habitat occupancy challenge climate-only explanations of distribution patterns. Here, we investigate the environmental drivers shaping the distribution of Ragala ucuquirana-branca (Sapotaceae) and the environmental filters constraining its realized distribution. Material and methods – We compiled 72 occurrence records from herbarium specimens and forest monitoring plots across the Amazon Basin. Species distribution models were developed using an ensemble framework integrating climatic, edaphic, topographic, and land cover variables across multiple algorithms. Model performance was evaluated using threshold-independent and threshold-dependent metrics, and habitat suitability was projected across the Amazon Basin. Key results – Model performance was consistently high, indicating robust discrimination between suitable and unsuitable environments. Soil-related predictors collectively accounted for the largest share of model importance, exceeding climatic and other environmental variables. Soil pH in water emerged as the most influential predictor, followed by water vapor pressure, minimum temperature of the coldest month, and the cation exchange capacity. Although the species exhibits a broad Extent of Occurrence of ca 1.48 million km2, its Area of Occupancy is highly restricted, revealing a spatially aggregated distribution. This pattern, together with severe fragmentation among subpopulations and environmentally constrained suitable habitats, supports a preliminary conservation assessment of Endangered. Suitable habitats are concentrated in Central Amazonia and adjacent portions of Northwestern and Southwestern Amazonia, whereas marginal conditions predominated across Eastern and especially Southeastern Amazonia. Conclusion – The distribution of R. ucuquirana-branca is strongly constrained by edaphic conditions and atmospheric stability rather than by broad climatic gradients alone. This decoupling between geographic range size and effective habitat occupancy highlights ecological specialization and potential vulnerability. More broadly, the study underscores the importance of incorporating soil and atmospheric filters into assessments of species rarity, distribution, and conservation priorities in hyperdiverse tropical forests.

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DOI: 10.5091/plecevo.176900

Authors: Jovianne Birindwa, Antoine Karangwa, Emile Maheshe

Abstract: Background and aims – Cinchona species, the botanical source of quinine, remain essential for treating severe malaria and support rural livelihoods in eastern Democratic Republic of the Congo. Yet, increasing climate stress and land degradation threaten its future habitat suitability. This study assessed current and mid-century habitat suitability for Cinchona in North and South Kivu provinces and prioritised areas for conservation and replanting. Material and methods – Potential distributions were modelled with MaxEnt using 125 validated occurrences and ten environmental predictors (five bioclimatic, three topographic, two edaphic). To limit multicollinearity, we pre-selected variables with |r| < 0.7 and VIF < 10. Future projections used 2050s CMIP6 climates under SSP2-4.5 and SSP5-8.5. Key results – Model performance was high. Thermal variability together with elevation most strongly explained suitability, indicating a preference for moderate thermal regimes at 1,400–2,300 m. Under current climate, high suitability covers 4.13% of the study area, moderate 6.49%, low 27.67%, and 61.71% is unsuitable. By the 2050s, high suitability contracts to 1.27% (SSP2-4.5) and 1.07% (SSP5-8.5), while unsuitable area expands to 81.72% and 83.90%, respectively. High-suitability zones cluster along the eastern escarpment, notably Lubero, Oïcha, Kabare, Walungu, and Butembo, whereas lowland territories such as Shabunda and Fizi become largely unsuitable. Conclusion – Our results delineate micro-refugia for in situ protection, guide climate-resilient replanting toward highlands, and indicate where ex situ measures and assisted restoration will be needed under future climate conditions.

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DOI: 10.5091/plecevo.165628

Authors: David Gutiérrez-Duque, María Camila Ángel-Vallejo, Luis Fernando Coca, David Sanín, Diana Medellín-Zabala

Abstract: Background and aims – Gustavia santanderiensis is a tree species from the Magdalena Valley described around a century ago. Despite the species’ morphological plasticity, restricted range, and ecology, the species has been greatly understudied. This study aims to establish a clear taxonomic framework for the species based on its morphology and to determine its distribution and predicted range, ecological niche, and conservation status. Material and methods – A careful revision of herbarium specimens was performed along with field work in the type locality. We used the occurrence records to build an Ecological Niche Model (ENM) using the maximum entropy algorithm through the kuenm package. The accessibility area was constructed by overlapping the records with the ecoregions that encompass the Magdalena Valley. The model was generated using a unique set of bioclimatic variables, with their contributions and permutation importance estimated. Key results – The flower colour in Gustavia santanderiensis, previously described by Knuth and Mori as white petals, varies considerably. Surprisingly, none of the specimens cited by Mori and Prance (1979) in their monograph corresponds to G. santanderiensis. Its geographic range is more restricted than previously known, excluding its occurrence in Brazil, and it is now endemic to Colombia. According to the ENM, the species occurs between 100 and 680 m in areas where the annual mean temperature and annual precipitation range do not vary significantly. The annual mean temperature, isothermality, and temperature seasonality were the variables with the highest contributions and permutation importance in the model. Conclusion – Gustavia santanderiensis is an endangered, endemic species of the Magdalena Valley, characterised by remarkable flower colour variation that warrants further investigation. In addition to redescribing this species, we provide the first taxonomic key for Gustavia in the Magdalena Valley, which will serve as a diagnostic tool for the species in one of Colombia’s most diverse yet fragmented regions.

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DOI: 10.5091/plecevo.157560

Authors: Santiago A. García, María J. Nores, Fernando de Diego, Hernán G. Bach, Patricia A. Peralta, Federico O. Robbiati

Abstract: Background and aims – Climate change is driving biodiversity loss globally, including species with medicinal and aromatic properties. In this study, we assessed the potential distributions of three plants, Lippia alba, L. turbinata, and Salimenaea integrifolia, widely consumed in South America. In this study, we aimed i) to predict their current geographic distribution through SDM, ii) to estimate the importance of abiotic factors in their distribution, iii) to evaluate the potential change in future distribution under different scenarios of climate change. Material and methods – Using MaxEnt, we modelled the current and future potential distributions of these three species under three Representative Concentration Pathways (RCPs 2.6, 4.5, and 8.5) for the period 2070 (2061–2080). Key results – The distribution of L. alba is primarily influenced by precipitation seasonality and mean annual temperature, whereas L. turbinata and S. integrifolia are shaped by mean annual temperature and annual precipitation. The most favourable areas for L. alba are found in the Chacoan, Espinal, Pampean, Paranaense, Caatinga, Atlantic, and Amazonian biogeographic provinces (2,250,640 km2). Lippia turbinata thrives in the Chacoan, Espinal, Monte, Pampean, and Yungas provinces (671,851 km2), while S. integrifolia is best suited to the Monte, Chacoan, and Puna/Prepuna provinces (197,022 km2). Our results indicate heterogeneous responses to climate change in the future: L. turbinata and S. integrifolia may experience range expansion (15.12 to 19.86% and 1.48 to 3.46%, respectively), while L. alba is projected to face range contraction (-4.60 to -23.23%), particularly in the northern edge of its distribution. Conclusion – These findings emphasize the species-specific responses of medicinal and aromatic plants to climate change. Moreover, they highlight the need to develop tailored conservation strategies to safeguard vulnerable populations and preserve valuable medicinal resources.

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DOI: 10.5091/plecevo.122470

Authors: Gbèwonmèdéa Hospice Dassou, Gafarou Agoundé, Pathmos Akouété, Gnimansou Abraham Favi, Ghyslain Chabi Kpétikou, Kolawolé Valère Salako, Jéronime Marie-Ange Sènami Ouachinou, Judicael Makponsè, Amadou Malé Kouyaté, İdris Sari, Romain Lucas Glèlè Kakaï, Hounnankpon Yédomonhan, Aristide Cossi Adomou

Abstract: Background and aims – Climate change induces increasing temperatures and drought, with possible profound shifts in species’ presence and distribution. Ecological niche models are widely used to assess plant species responses to climate change. However, such data are scarce for West Africa, particularly for vulnerable multipurpose species. This study focuses on modelling the ecological niche and the conservation status of the multipurpose tree Detarium senegalense to improve insights into its habitat suitability in West Africa under past, present, and future climatic conditions. This will provide an essential basis for setting up global management plans through efficient conservation and ecological restoration policies. Material and methods – The potential distribution of D. senegalense under past, current, and future climate scenarios were assessed using four algorithms including generalized additive models (GAM), generalized linear models (GLM), random forest (RF), and Maximum Entropy (MaxEnt). We also assessed the shift direction of suitable habitats and the conservation status of the species based on IUCN criteria. Overall, 220 occurrences were combined with a set of five bioclimatic variables to run the models. Key results – Models performed well with good values of AUC (0.92) and TSS (0.73). Isothermality (41.10%) and Precipitation of Wettest Month (21.50%) contributed most to the distribution of the species. The distribution of D. senegalense was relatively constant from the past to the present but could decrease in the next decades. In the future, only 17.70% and 13.98% of the areas were predicted to be suitable under respectively ssp245 and ssp585. In protected areas, the suitable areas under ssp245 were estimated at 21.01% with a decrease of 2.50% and 14.60% with a decrease of 8.61% under ssp585 by 2050. The direction of the distribution shifted to the south-east under future climate scenarios. The conservation status assessment of the species is Least Concern (LC). Conclusion – This study improves our understanding of the past, present-day, and future distribution of the species and provides support to better manage the conservation of D. senegalense in West Africa.

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DOI: 10.5091/plecevo.90511

Authors: Taynara Rabelo-Costa, Paulo Weslem Portal Gomes, Brenda Oliveira Rocha, Iury Leite Cruz, Ravena Santiago Alves, Tiê Rocha de Sousa Oliveira, José Luís Passos Cordeiro, Moabe Ferreira Fernandes, Eimear Nic Lughadha, Marcelo Freire Moro

Abstract: Background and aims – Climatic fluctuations during the Pleistocene altered the distribution of many species and even entire biomes, allowing some species to increase their range while others underwent reductions. Recent and ongoing anthropogenic climate change is altering climatic patterns very rapidly and is likely to impact species’ distributions over shorter timescales than previous natural fluctuations. Therefore, we aimed to understand how Pleistocene and Holocene climatic fluctuations might have shaped the current distribution of Holoregmia and explore its expected distribution under future climate scenarios. Material and methods – We modelled the potential distribution of Holoregmia viscida (Martyniaceae), a monospecific plant genus endemic to the semi-arid Caatinga Domain in Brazil. We used an ensemble approach to model suitable areas for Holoregmia under present conditions, Paleoclimatic scenarios, and global warming scenarios in 2050 and 2090. Key results – Holocene climates in most Caatinga were too humid for Holoregmia, which restricted its suitable areas to the southern Caatinga, similar to its current distribution. However, under global warming scenarios, the Caatinga is expected to become too dry for this lineage, resulting in a steady decline in the area suitable for Holoregmia and even its possible extinction under the most pessimistic scenario modelled. Conclusion – The predicted extinction of the ancient and highly specialized Holoregmia viscida highlights the possible consequences of climate change for some species of endemic Caatinga flora. Invaluable phylogenetic diversity may be lost in the coming decades, representing millions of years of unique evolutionary history and consequent loss of evolutionary potential to adapt to future environmental changes in semi-arid environments.

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