Gains and losses of plant species and phylogenetic diversity for a northern high-latitude region

Vulnerability and driving mechanism of four typical grasslands in China under the coupled impacts of climate change and human activities

Understanding of how different grasslands types respond to climate change and human activities across different spatial and temporal dimensions is crucial for devising effective strategies to prevent grasslands degradation. In this study, we developed a novel vulnerability assessment model for grasslands that intricately evaluates the combined impact of climate change and human activities. We then applied this model to analyze the vulnerability and driving mechanism of four representative Chinese grasslands to climate change and human activities. Our findings indicate that the vulnerability of the four grasslands would show a pattern of higher in the west and lower in the east under the influence of climate change alone. However, when human activities are factored in, the vulnerability across the four grasslands tends to homogenize, with human activities notably reducing the vulnerability of alpine grasslands in the west and, conversely, increasing the vulnerability of grasslands in the east. Furthermore, our study reveals distinct major environmental drivers of grasslands vulnerability across different regions. The two western alpine grasslands exhibit higher vulnerability to annual mean temperature and isothermality compared to the eastern temperate grasslands, while their vulnerability to precipitation of the coldest quarter is lower than that of the eastern temperate grasslands. These findings are helpful for understanding the multifaceted causes and mechanisms of grasslands degradation, providing a scientific foundation for the sustainable management and conservation of grassland resources.

Climatic variables are more effective on the spatial distribution of oak forests than land use change across their historical range

The current research is conducted to model the effect of climate change and land use change (LUC) on the geographical distribution of Quercus brantii Lindl. (QB) forests across their historical range. Forecasting was done based on six general circulation models under RCP 2.6 and RCP 8.5 future climate change scenarios for the future years 2050 and 2070. In order to model the species distribution, different modeling methods were used. The results indicated that, in general, climatic variables had a higher influence on the distribution of QB than land use-related attributes. The mean diurnal range (bio2), the precipitation seasonality (bio15), and the mean temperature of the driest quarter (bio9) were the main predictors in the distribution of QB forests, while land use variables were less important in oak species distribution. The GBM, MaxEnt, and RF had higher accuracy and performance in modeling species distribution. The outputs also showed that in the current climate circumstances, 97,608.81 km2 of the studied area has high desirability for the presence of QB, and by 2070, under the pessimistic scenario, 96.29% of these habitats will be lost under the concomitant effect of LUC and climate change. By using the results of this research, it is possible to predict and identify the effective factors in changing the habitat of this oak species with more certainty. Based on the insights obtained from the results of such studies, the protection and restoration planning of the habitat of this key species, which supports diverse species, will be provided more efficiently.

Identifying priority areas for bat conservation in the Western Ghats mountain range, peninsular India

Understanding patterns of species distribution and diversity plays a vital role in biodiversity conservation. Such documentation is frequently lacking for bats, which are relatively little studied and often threatened. The Western Ghats biodiversity hotspot in peninsular India is a bat hotspot with 63 species. We conducted a comprehensive bat survey across the southern Western Ghats and used maximum entropy modeling (MaxEnt) to model the potential distribution of 37 bat species for which sufficient data were available. We generated binary maps of each species using species-specific thresholds to estimate suitable habitat areas and overlaid binary maps of species to produce bat hotspots (we use the term “bat hotspot” for regions that were suitable for more than 25 bat species). We also estimated species richness across protected area networks in the southern Western Ghats to assess the level of protection. The highest levels of species richness were found mainly along the southmost Periyar–Agastyamalai landscape. The study also identified a 1,683 km2 area of potential bat hotspot and 726 km2 (43%) of the total bat hotspots are currently within the protected area network. However, more than 50% of suitable habitats for each of the 37 species remain unprotected. Therefore, conservation decisions are needed to take into account both bat hotspots and species with restricted distributions.

Forecasting the combined effects of future climate and land use change on the suitable habitat of Davidia involucrata Baill

Accurately predicting the future distribution of species is crucial for understanding how species will response to global environmental change and for evaluating the effectiveness of current protected areas (PAs). Here, we assessed the effect of climate and land use change on the projected suitable habitats of Davidia involucrata Baill under different future scenarios using the following two types of models: (a) only climate covariates (climate SDMs) and (b) climate and land use covariates (full SDMs). We found that full SDMs perform significantly better than climate SDMs in terms of both AUC (p < .001) and TSS (p < .001) and also projected more suitable habitat than climate SDMs both in the whole study area and in its current suitable range, although D. involucrate is predicted to loss at least 26.96% of its suitable area under all future scenarios. Similarly, we found that these range contractions projected by climate SDMs would negate the effectiveness of current PAs to a greater extent relative to full SDMs. These results suggest that although D. involucrate is extremely vulnerability to future climate change, conservation intervention to manage habitat may be an effective option to offset some of the negative effects of a changing climate on D. involucrate and can improve the effectiveness of current PAs. Overall, this study highlights the necessity of integrating climate and land use change to project the future distribution of species.

Phylogenetic diversity and conservation of crop wild relatives in Colombia

Crop wild relatives (CWR) are an important agricultural resource as they contain genetic traits not found in cultivated species due to localized adaptation to unique environmental and climatic conditions. Phylogenetic diversity (PD) measures the evolutionary relationship of species using the tree of life. Our knowledge of CWR PD in neotropical regions is in its infancy. We analysed the distribution of CWR PD across Colombia and assessed its conservation status. The areas with the largest concentration of PD were identified as being in the northern part of the central and western Andean mountain ranges and the Pacific region. These centres of high PD were comprised of predominantly short and closely related branches, mostly of species of wild tomatoes and black peppers. In contrast, the CWR PD in the lowland ecosystems of the Amazon and Orinoquia regions had deeply diverging clades predominantly represented by long and distantly related branches (i.e. tuberous roots, grains and cacao). We categorized 50 (52.6%) of the CWR species as 'high priority', 36 as 'medium priority' and nine as 'low priority' for further ex-situ and in situ conservation actions. New areas of high PD and richness with large ex-situ gap collections were identified mainly in the northern part of the Andes of Colombia. We found that 56% of the grid cells with the highest PD values were unprotected. These baseline data could be used to create a comprehensive national strategy of CWR conservation in Colombia.

Reduction in the potential distribution of bumble bees (Apidae: Bombus) in Mesoamerica under different climate change scenarios: Conservation implications

Bumble bees are an ecologically and economically important group of pollinating insects worldwide. Global climate change is predicted to affect bumble bee ecology including habitat suitability and geographic distribution. Our study aims to estimate the impact of projected climate change on 18 Mesoamerican bumble bee species. We used ecological niche modeling (ENM) using current and future climate emissions scenarios (representative concentration pathway 4.5, 6.0, and 8.5) and models (CCSM4, HadGEM2-AO, and MIROC-ESM-CHEM). Regardless of the scenario and model applied, our results suggest that all bumble bee species are predicted to undergo a reduction in their potential distribution and habitat suitability due to projected climate change. ENMs based on low emission scenarios predict a distribution loss ranging from 7% to 67% depending on the species for the year 2050. Furthermore, we discovered that the reduction of bumble bee geographic range shape will be more evident at the margins of their distribution. The reduction of suitable habitat is predicted to be accompanied by a 100-500 m upslope change in altitude and 1-581 km shift away from the current geographic centroid of a species' distribution. On average, protected natural areas in Mesoamerica cover ~14% of each species' current potential distribution, and this proportion is predicted to increase to ~23% in the high emission climate change scenarios. Our models predict that climate change will reduce Mesoamerican bumble bee habitat suitability, especially for rare species, by reducing their potential distribution ranges and suitability. The small proportion of current and future potential distribution falling in protected natural areas suggests that such areas will likely have marginal contribution to bumble bee habitat conservation. Our results have the capacity to inform stakeholders in designing effective landscape management for bumble bees, which may include developing restoration plans for montane pine oak forests habitats and native flowering plants.

Niche divergence of evolutionarily significant units with implications for repopulation programs of the world's largest amphibians

The niche divergence and potential climate change-induced loss of evolutionarily significant units (ESUs) of flagship amphibian species in China, the Chinese giant salamander clade, were investigated. We tested niche-related ecological hypotheses and identified suitable habitats that are essential for the conservation of ESUs in response to future climate change according to ecological niche models (ENMs). We predicted the localized habitat loss crisis of ESUs induced by global climate heating using the predicted climate derived from two representative concentration pathway (RCP) scenarios 2.6 and 8.5, respectively. In our study, a niche conservatism pattern was found between the two distinctive northern and southern ESUs with sufficient distributional records, but their niches were not equivalent. Furthermore, there was neither abrupt environmental change in nor remarkable biogeographic barriers between the suitable habitats of the species, as indicated by random linear, blob and ribbon range-breaking tests. Under the low-emission scenario RCP2.6, the northern ESU had a moderate loss of suitable range, while the southern ESU had range expansion in the 2070s. The climatic velocities were low in the ranges of both ESUs. However, under the high-emission scenario RCP8.5, the climatic velocities were found to become larger in the suitable ranges of both ESUs. Moreover, the northern ESU had severe habitat loss, bringing it to the edge of extinction, while the southern ESU also had intensified range loss. Considering this, climatic velocity can be an effective indicator of range loss. We argued conclusively that conservation prioritization of ESUs should effectively take into account the underlying geographic and ecological mechanisms driving the speciation process. The conservation of ESUs should consider the conservation of both evolutionary potential and ecological adaptation capacity of each lineage. The present study provided practical guidelines for repopulation programs for endangered species and the conservation of evolutionary diversity.

Machine learning predicts large scale declines in native plant phylogenetic diversity

Though substantial effort has gone into predicting how global climate change will impact biodiversity patterns, the scarcity of taxon-specific information has hampered the efficacy of these endeavors. Further, most studies analyzing spatiotemporal patterns of biodiversity focus narrowly on species richness. We apply machine learning approaches to a comprehensive vascular plant database for the United States and generate predictive models of regional plant taxonomic and phylogenetic diversity in response to a wide range of environmental variables. We demonstrate differences in predicted patterns and potential drivers of native vs nonnative biodiversity. In particular, native phylogenetic diversity is likely to decrease over the next half century despite increases in species richness. We also identify that patterns of taxonomic diversity can be incongruent with those of phylogenetic diversity. The combination of macro-environmental factors that determine diversity likely varies at continental scales; thus, as climate change alters the combinations of these factors across the landscape, the collective effect on regional diversity will also vary. Our study represents one of the most comprehensive examinations of plant diversity patterns to date and demonstrates that our ability to predict future diversity may benefit tremendously from the application of machine learning.

The potential impact of future climate on the distribution of European yew (Taxus baccata L.) in the Hyrcanian Forest region (Iran)

The Hyrcanian Forest region is rich in relict species, and endemic and endangered species. Although there are concerns about climate change, its influence on tree species in the Hyrcanian forests in the north of Iran is still unidentified. Taxus baccata is among the few conifer species found in the region, and the present study aims to evaluate the potential impact of climate change on the distribution of T. baccata. For this purpose, we used ensemble species distribution modeling with ten algorithms and based on two geographic extents (global and regional) and climate data for different climate change scenarios. For the regional extent, we calibrated the models in Hyrcanian forests including the three provinces in the north of Iran. For the global extent, we calibrated the models on the whole range distribution of T. baccata. In both cases, we applied the models to predict the distribution of T. baccata in northern Iran under current, 2050, and 2070 climates. In regional extent modeling, precipitation of coldest quarter and in global extent modeling temperature seasonality emerged as the most important variables. Present environmental suitability estimates indicated that the suitable area for T. baccata in Hyrcanian forests is 5.89 × 10³ km² (regional modeling) to 9.74 × 10³ km² (global modeling). The modeling suggests that climate change under representative concentration pathways (RCP) 8.5 is likely to lead to strong suitability reductions in the region, with just between 0.63 × 10³ km² (regional modeling) and 0.57 × 10³ km² (global modeling) suitable area in 2070. Hence, T. baccata risks losing most currently suitable areas in the Hyrcanian forests under climate change. The results of the present study suggest there should be focus on conservation of areas predicted to remain suitable through near-future climate change and provide an estimate of the availability of suitable areas for the regeneration of T. baccata and its use in reforestation.

Gene flow and climate-associated genetic variation in a vagile habitat specialist

Previous work in landscape genetics suggests that geographic isolation is of greater importance to genetic divergence than variation in environmental conditions. This is intuitive when configurations of suitable habitat are a dominant factor limiting dispersal and gene flow, but has not been thoroughly examined for habitat specialists with strong dispersal capability. Here, we evaluate the effects of geographic and environmental isolation on genetic divergence for a vagile invertebrate with high habitat specificity and a discrete dispersal life stage: Dod's Old World swallowtail butterfly, Papilio machaon dodi. In Canada, P. m. dodi are generally restricted to eroding habitat along major river valleys where their larval host plant occurs. A series of causal and linear mixed effects models indicate that divergence of genome-wide single nucleotide polymorphisms is best explained by a combination of environmental isolation (variation in summer temperatures) and geographic isolation (Euclidean distance). Interestingly, least-cost path and circuit distances through a resistance surface parameterized as the inverse of habitat suitability were not supported. This suggests that, although habitat associations of many butterflies are specific due to reproductive requirements, habitat suitability and landscape permeability are not equivalent concepts due to considerable adult vagility. We infer that divergent selection related to variation in summer temperatures has produced two genetic clusters within P. m. dodi, differing in voltinism and diapause propensity. Within the next century, temperatures are predicted to rise by amounts greater than the present-day difference between regions of the genetic clusters, potentially affecting the persistence of the northern cluster under continued climate change.

Northern protected areas will become important refuges for biodiversity tracking suitable climates

The Northern Biodiversity Paradox predicts that, despite its globally negative effects on biodiversity, climate change will increase biodiversity in northern regions where many species are limited by low temperatures. We assessed the potential impacts of climate change on the biodiversity of a northern network of 1,749 protected areas spread over >600,000 km² in Quebec, Canada. Using ecological niche modeling, we calculated potential changes in the probability of occurrence of 529 species to evaluate the potential impacts of climate change on (1) species gain, loss, turnover, and richness in protected areas, (2) representativity of protected areas, and (3) extent of species ranges located in protected areas. We predict a major species turnover over time, with 49% of total protected land area potentially experiencing a species turnover >80%. We also predict increases in regional species richness, representativity of protected areas, and species protection provided by protected areas. Although we did not model the likelihood of species colonising habitats that become suitable as a result of climate change, northern protected areas should ultimately become important refuges for species tracking climate northward. This is the first study to examine in such details the potential effects of climate change on a northern protected area network.

Range shifting species reduce phylogenetic diversity in high latitude communities via competition

Under anthropogenic climate change, many species are expanding their ranges to higher latitudes and altitudes, resulting in novel species interactions. The consequences of these range shifts for native species, patterns of local biodiversity and community structure in high latitude ecosystems are largely unknown but critical to understand in light of widespread poleward expansions by many warm-adapted generalists. Using niche modelling, phylogenetic methods, and field and laboratory studies, we investigated how colonization of Scotland by a range expanding damselfly, Ischnura elegans, influences patterns of competition and niche shifts in native damselfly species, and changes in phylogenetic community structure. Colonization by I. elegans was associated with reduced population density and niche shifts in the resident species least related to I. elegans (Lestes sponsa), reflecting enhanced competition. Furthermore, communities colonized by I. elegans exhibited phylogenetic underdispersion, reflecting patterns of relatedness and competition. Our results provide a novel example of a potentially general mechanism whereby climate change-mediated range shifts can reduce phylogenetic diversity within high latitude communities, if colonizing species are typically competitively superior to members of native communities that are least-closely related to the colonizer.