Risk of biodiversity collapse under climate change in the Afro-Arabian region

Risk from future climate change to Pakistan's protected area network: A composite analysis for hotspot identification

As climate change becomes a primary driver of global ecosystem deterioration and biodiversity loss, protected areas (PAs) are posed to play a crucial conservation role. At a global scale, 17 % of land is currently covered by PAs; a figure expected to reach 30 % by 2030 under the UN post-2020 global biodiversity framework. However, focusing only on the percent coverage of PAs without assessing their efficacy may not accomplish the intended conservation goals. Here, we present the first assessment of the risk from climate change to existing PAs and non-protected lands across Pakistan by combining data on the local exposure and vulnerability of 409 species of birds, mammals, reptiles and amphibians to multidimensional changes in climate by mid (2040-2060) and late (2061-2080) century under two climate emission scenarios (RCP4.5 and RCP8.5). We find that between 7 % (2050 RCP4.5) and 19 % (2080 RCP8.5) of the current network of PAs, mostly located in the eastern and southeastern parts of the country, are projected to be under future extreme risk (i.e., highly exposed areas containing highly vulnerable communities). Importantly, hotspots of risk within these PAs are projected to significantly expand over time and with increasing severity of the scenario. In contrast, PAs in the northern part of the country are projected to remain under moderate to low risk. Results are subject to variability across the country reflecting interesting differences in climate change exposure and species vulnerability between protected and non-protected lands. Importantly, significantly lower level of risks from future climate change are projected for PAs than non-protected lands across emission scenarios and periods suggesting potential candidate areas for the future expansion of the country's PA network. Our analysis provides novel insights that can help inform conservation decisions and management at a time when the country is investing in ambitious efforts to expand its network of protected areas.

Population Genetics, Genetic Structure, and Inbreeding of Commiphora gileadensis (L.) C. Chr Inferred from SSR Markers in Some Mountainous Sites of Makkah Province

Commiphora gileadensis (L.) C. Chr is a perennial plant existing mainly in the southern and western mountains of the Arabian Peninsula. In the Makkah province, the remaining populations are threatened by many factors such as overcutting, overgrazing, and urban developments. These dangers are expected to be aggravated by the progression of aridification factors arising from climate change. To overcome the decline in remaining populations of this valuable species, a timely evaluation of the population's genetic variables and genetic structure is vital for the conservation of existing C. gileadensis populations. In this study, we used 61 SSR primers to achieve this objective. Only 50 loci showed polymorphisms, which led to further analysis of the population genetics for 600 genotypes that were collected from 50 populations of C. gileadensis found in 10 different sites in the Makkah region: Gebel Al Muliesaa, Wadi Albathna, Wadi Houra, Wadi Albaidaa, Wadi Elebiedia, Gebel Kniethl, Wadi Sayaa, Wadi Elbarasa, Wadi Alfawara, and Wadi Alkharar. The results showed an obvious decrease in genetic diversity variables in all studied populations. The range of PPL was between 8 and 40; additionally, the low H_T value of 0.804 and the high value of inbreeding, F_is = 0.238, reflected a severe lack of heterozygotes. High levels of F_ST and G_ST and low gene flow indicate considerable segregation among the C. gileadensis populations, which creates a barrier to gene migration. Our data suggest the need for conservation planning for C. gileadensis in order to avoid the species' forthcoming extinction. Efforts should be largely oriented around managing water consumption, prohibiting overcutting and overgrazing, and establishing appropriate seed banks.

Tracing production carbon emission transfer through global value chains: Towards a top gainer principle

This study proposes the top gainer principle (TGP) and builds a calculation model based on the TGP to measure production carbon emissions transfer (PCET) in the context of global value chains. Compared with embodied carbon research, the innovative TGP model establishes a traceability mechanism based on the difference between responsibility and actual emissions from the perspective of the value chain, avoiding the endless debate between producer and consumer responsibility, which makes the TGP model more reasonable and fairer. In addition, using long-term input-output data, this study measures spatiotemporal patterns and the network evolution of global PCET. The results show that the total amount of global PCET has increased, and the regions with high outflows of PCET mainly include East Asia, North America, Central and Western Europe, and Russia. Among these regions, the United States and China accounted for the largest proportion of PCET outflow. By contrast, South America and Africa are typical low-outflow regions. From North America via central Europe, Turkey, Iran, South Asia to China, is a "W"-shaped high net outflow belt. The overall concentration of the global PCET network first decreased and then increased, and the network structure evolved into a bipolar network group with China and the United States as the core. Under the shock of the COVID-19 pandemic, the network structure showed a trend towards decentralization. This study suggests that efforts should be made to strengthen the responsibility of major countries, enhance the supervision of lead firms, establish a carbon emission transfer compensation system within value chains, and promote the development and spread of carbon emission reduction technologies to facilitate the reduction of global carbon emissions.

Rising temperature drives tipping points in mutualistic networks

The effect of climate warming on species' physiological parameters, including growth rate, mortality rate and handling time, is well established from empirical data. However, with an alarming rise in global temperature more than ever, predicting the interactive influence of these changes on mutualistic communities remains uncertain. Using 139 real plant-pollinator networks sampled across the globe and a modelling approach, we study the impact of species' individual thermal responses on mutualistic communities. We show that at low mutualistic strength plant-pollinator networks are at potential risk of rapid transitions at higher temperatures. Evidently, generalist species play a critical role in guiding tipping points in mutualistic networks. Further, we derive stability criteria for the networks in a range of temperatures using a two-dimensional reduced model. We identify network structures that can ascertain the delay of a community collapse. Until the end of this century, on account of increasing climate warming many real mutualistic networks are likely to be under the threat of sudden collapse, and we frame strategies to mitigate this. Together, our results indicate that knowing individual species' thermal responses and network structure can improve predictions for communities facing rapid transitions.

Molecular Assessment of Genetic Diversity and Genetic Structure of Rhanterium epapposum Oliv. in Scarce Populations in Some Regions of Western Saudi Arabia

Rhanterium epapposum Oliv. is a perennial medicinal shrub growing mainly in desert habitats in the Arabian Peninsula. In western Saudi Arabia, the remaining few populations of this species are exposed to many threats, including overcutting, overgrazing, and recently, increasing human activities. These threats are predicted to be exacerbated by the advancement of aridification caused by climate change. The conservation and recovering of the diminished populations of R. epapposum necessitate measurement of their genetic diversity and genetic differentiation. To accomplish this objective, we tested 150 simple sequence repeat (SSR) primer pairs, with which 40 polymorphic loci were identified. These polymorphic loci were used to determine the population genetics of 540 plant accessions sampled from a total of 45 populations of R. epapposum located in 8 sites in western Saudi Arabia: Wadi Khurieba, Wadi Al Khamas, Gebel Al Twaal, Al Asaafer, Wadi ALHamda, Wadi Al Nassayeif, Wadi Qaraba, Wadi Kuliayah, and Wadi Dahban. Low levels of genetic diversity were found in all populations (the values of the PPL ranged between 52.5 and 15) along with a declined value of H_T (0.123) and a considerable inbreeding value (F = 0.942), which confirmed a noticeable shortage of heterozygotes. High genetic differentiation among the populations and a low value of gene flow are indicative of high isolation among the R. epapposum populations, which has caused a severe deficiency in gene migration. The data obtained herein inspire several recommendations for conservation and retrieval of the existing populations, including seed banks, restoration of diminished populations, and monitoring and prevention of cutting and grazing activities at threatened sites. All of these measures are urgently required to avoid imminent extinction.

A Review on Climate Change Impacts on Forest Ecosystem Services in the Mediterranean Basin

The Mediterranean Basin covers more than 2 million square kilometres and is surrounded by three continents: Africa, Asia and Europe. The Basin that is rich in biodiversity has tilted towards warmer and drier conditions over the last decades. The emerging climatic conditions particularly the increase in the number of climate extremes are bringing new threats and risks that will exacerbate existing pressures. The present study thoroughly reviewed the recent scientific literature and synthesized existing body of knowledge on the impacts (direct and indirect) of climate change on forest ecosystem services in the Mediterranean Basin. Despite many uncertainties about climate change in the Basin, there appears to be a consensus among a number of studies that climate change is having and will continue to have mostly negative impacts on the Mediterranean forest ecosystem services (wood and non-wood forest products, water resources, carbon storage and recreation and tourism) with possible substantial impacts in the future. Further, evidence is mounting that climate-induced natural disturbances (fires, insect pests, and pathogenic diseases) are becoming frequent and severe. The Mediterranean plants are known for their resilience to natural disturbances. However, the novel climatic conditions may exceed their resilience and alter the ecosystem services. Therefore, there is the need to mitigate the challenges posed by climate change and adapt forest management practices to impending changes to sustain the forest ecosystem services.

The future distribution of wetland birds breeding in Europe validated against observed changes in distribution

Wetland bird species have been declining in population size worldwide as climate warming and land-use change affect their suitable habitats. We used species distribution models (SDMs) to predict changes in range dynamics for 64 non-passerine wetland birds breeding in Europe, including range size, position of centroid, and margins. We fitted the SDMs with data collected for the first European Breeding Bird Atlas and climate and land-use data to predict distributional changes over a century (the 1970s–2070s). The predicted annual changes were then compared to observed annual changes in range size and range centroid over a time period of 30 years using data from the second European Breeding Bird Atlas. Our models successfully predicted ca. 75% of the 64 bird species to contract their breeding range in the future, while the remaining species (mostly southerly breeding species) were predicted to expand their breeding ranges northward. The northern margins of southerly species and southern margins of northerly species, both, predicted to shift northward. Predicted changes in range size and shifts in range centroids were broadly positively associated with the observed changes, although some species deviated markedly from the predictions. The predicted average shift in core distributions was ca. 5 km yr−1 towards the north (5% northeast, 45% north, and 40% northwest), compared to a slower observed average shift of ca. 3.9 km yr−1. Predicted changes in range centroids were generally larger than observed changes, which suggests that bird distribution changes may lag behind environmental changes leading to ‘climate debt’. We suggest that predictions of SDMs should be viewed as qualitative rather than quantitative outcomes, indicating that care should be taken concerning single species. Still, our results highlight the urgent need for management actions such as wetland creation and restoration to improve wetland birds’ resilience to the expected environmental changes in the future.

Palearctic passerine migrant declines in African wintering grounds in the Anthropocene (1970-1990 and near future): A conservation assessment using publicly available GIS predictors and machine learning

The Anthropocene causes many massive and novel impacts, e.g., on migratory birds and their habitats. Many species of migratory birds have been declining on the Palearctic-African flyway in recent decades. To investigate possible impacts on a continental scale, we used 18 predictors extracted from 16 publicly available GIS layers in combination with machine learning methods on the sub-Saharan distributions of 64 passerine migrant species. These bird species were categorized as having experienced a 'Large Decline' (n = 12), a 'Moderate Decline' (n = 6) or 'No Decline' (n = 46) based on European census data from 1970 to 1990. Therefore, we present the first study for these species which uses publically available Open Access GIS-data and a multivariate (n = 18) and multi-species (n = 64) machine learning approach to deduce possible past impacts. We furthermore modelled likely future human population change and climate change impacts. We identified three predictor themes related to the distributions and declines of these migratory birds: (I) locations, represented by African ecosystems, countries, and soil types; (II) human population pressures and land-use intensities, the latter represented by land-use categories, habitat area, and cropland proportion; and (III) climatic predictors. This is the first study to relate migratory bird declines to human population pressures and land-use intensities using this type of analysis. We also identified areas of conservation concern, such as the Sahel region. Our models also predict that the declining trends of migratory birds will continue into the foreseeable future across much of Africa. We then briefly discuss some wider conservation implications in the light of the increasing drivers of biodiversity change associated with the Anthropocene as well as some possible solutions. We argue that only comprehensive systemic change can mitigate the impacts on the migratory birds and their habitats.

Horn growth patterns of Nubian ibex from the Sinai, Egypt

Documenting patterns of horn growth and horn-age relationships of Nubian ibex (Capra nubiana) can contribute to a more comprehensive understanding of their natural history, horn development in ibex in general, and future conservation of the species. Our specific objectives included (1) documenting age-horn growth patterns; (2) contrasting horn growth patterns of Nubian ibex with other ibex species; and (3) determining whether horn development accurately reflects age of Nubian ibex in Sinai, Egypt. As expected, all male and female horn measurements had significant relationships with age. Horn growth in males started plateauing at ca. age 7–8, whereas female horn growth started plateauing at ca. age 4–6. The extremely arid environment of Nubian ibex in the Sinai may account for the slowing of horn growth at a younger age than seen in populations of some other ibex species. We found a significant relationship between the number of horn ridges and age, indicating that counting horn ridges provides a viable method of aging males to within ±1 y. Thus counting horn ridges may be a useful and non-invasive method to determine age or age class, which can further our understanding of age structure, the natural history, and management of Nubian ibex populations.

Uncovering the dynamics in global carbon dioxide utilization research: a bibliometric analysis (1995-2019)

The anthropogenic emission of carbon dioxide (CO₂) into the atmosphere is recognized as the main contributor to global climate change. To date, scientists have developed various strategies, including CO₂ utilization technologies, to reduce global carbon emissions. This paper presents the global scientific landscape of the CO₂ utilization research from 1995 to 2019 based on a bibliometric analysis of 1875 publications extracted from Web of Science. The findings indicate a major increase in the number of publications and citations received from 2015 to 2019, denoting a fast-emerging research trend. The dynamics of global CO₂ utilization research is partly driven by China's policies and research funding to promote low-carbon economic development. Applied Energy is recognized as a core journal in this research topic. The utilization of CO₂ is a multidisciplinary topic that has progressed by multidimensional collaborations at the country and organizations levels, while the formation of co-authorship networks at the individual level is mostly influenced by the authors' affiliations. Keyword co-occurrence analysis reveals a rapid evolution in the CO₂ utilization strategies from chemical fixation in carbonates and epoxides to pilot-scale testing of power-to-gas technologies in Europe and the USA. The development of efficient power-to-fuel technologies and biological utilization routes (using microalgae and bacteria) will probably be the next research priorities in CO₂ utilization research.

Classifying biogeographic realms of the endemic fauna in the Afro-Arabian region

AIM

Understanding diversity patterns and identifying the environmental factors that shape these patterns are essential for ecology and conservation. The Afro-Arabian region comprises one of the most important biogeographic areas connecting continents. Yet, little emphasis has been put on understanding its endemic fauna in relation to its biogeographic realms. Our objective is to fill the gaps in knowledge on diversity patterns and biogeography that are essential for prioritizing the overdue conservation efforts.

LOCATION

The study area covers mostly the hot desert climate region in North Africa and Arabia, and includes the Mediterranean, Sahel, and Ethiopian highlands (hereafter "Afro-Arabian region").

METHODS

We used distribution maps developed by IUCN and BirdLife for species endemic to the Afro-Arabian region belonging to the four tetrapod classes, amphibians, reptiles, birds, and mammals, to identify the endemic richness hotspots. We then used multivariate analyses to delineate biogeographic regions and evaluate their relationship with the environmental factors.

RESULTS

Our study reveals a complex map of the richness hotspots for the endemic tetrapod classes. The main hotspots of endemism were concentrated at the margins of the study area, along the Mediterranean coast, Ethiopian highlands, and along the Red Sea Mountains. We propose classifying the Afro-Arabian region into three discrete biogeographic realms for endemic amphibians, four for reptiles and birds, and five discrete biogeographic realms for endemic mammals. The identified realms are defined by their environmental conditions and the historical geological processes.

MAIN CONCLUSIONS

Richness hotspots of endemic tetrapod classes were heterogeneously distributed in the Afro-Arabian region. Our results support the hypothesis that species diversity patterns and endemism have been shaped by the environmental conditions and the paleogeographic processes. Each of the identified bioregions is associated with a characteristic set of tetrapod species. Our results are a benchmark for assessing the effectiveness of the protected areas and for implementing conservation plans for biodiversity.

Predictive genetic plan for a captive population of the Chinese goral (Naemorhedus griseus) and prescriptive action for ex situ and in situ conservation management in Thailand

Captive breeding programs for endangered species can increase population numbers for eventual reintroduction to the wild. Captive populations are typically small and isolated, which results in inbreeding and reduction of genetic variability, and may lead to an increased risk of extinction. The Omkoi Wildlife Breeding Center maintains the only Thai captive Chinese goral (Naemorhedus griseus) population, and has plans to reintroduce individuals into natural isolated populations. Genetic variability was assessed within the captive population using microsatellite data. Although no bottleneck was observed, genetic variability was low (allelic richness = 7.091 ± 0.756, H_e = 0.455 ± 0.219; H_e < H_o) and 11 microsatellite loci were informative that likely reflect inbreeding. Estimates of small effective population size and limited numbers of founders, combined with wild-born individuals within subpopulations, tend to cause reduction of genetic variability over time in captive programs. This leads to low reproductive fitness and limited ability to adapt to environmental change, thereby increasing the risk of extinction. Management of captive populations as evolutionarily significant units with diverse genetic backgrounds offers an effective strategy for population recovery. Relocation of individuals among subpopulations, or introduction of newly captured wild individuals into the captive program will help to ensure the future security of Chinese goral. Implications for future conservation actions for the species are discussed herein.

Potential Consequences of Regional Species Loss for Global Species Richness: A Quantitative Approach for Estimating Global Extinction Probabilities

Because the biosphere is highly heterogeneous, species diversity impacts are typically assessed at local or regional scales. Because regional species richness impact metrics refer to different species compositions, they cannot be easily compared or aggregated to global impacts. Translating regional species richness impacts into global impacts allows for comparisons between impacts and facilitates the estimation of global species extinctions. This requires a conversion (or weighting) factor that takes into account the characteristics of regionally specific species compositions. We developed a methodology for deriving such conversion factors based on species' habitat ranges, International Union for Conservation of Nature threat levels, and species richness. We call these conversion factors global extinction probabilities (GEPs) of the reference location or region. The proposed methodology allows for the calculation of GEPs for any spatial unit and species group for which data on spatial distribution are available and can be implemented in methodologies like life cycle impact assessment. Furthermore, the GEPs can be used for the identification of conservation hot spots. The results of the proposed GEPs (for various taxonomic groups) show that the risk that regional species loss may result in global species extinctions significantly differs per region and informs where irreversible biodiversity impacts are more likely to occur.