Anthropogenic Change Research Articles

Watershed-Mediated Ecomorphological Variation: A Case Study with the Twin-Striped Clubtail Dragonfly (Hylogomphus geminatus).

Anthropogenic land-cover change is modifying ecosystems at an accelerating rate. Changes to ecomorphologically variable taxa within those ecosystems serve as early-warning signs that resources on which humans and other animals depend are being altered. One known ecomorphologically variable taxon is Hylogomphus geminatus, a species of dragonfly in the southeastern United States that shows pronounced variation in total body length across its limited geographic range. We measured total length of live as well as preserved museum specimens of H. geminatus and the sympatric species Progomphus obscurus (as a means for comparison). Both species showed significant size differences linked to HUC-8 watersheds in which they occur. H. geminatus showed additional significant differences on either side of the Apalachicola River, Florida, for all comparisons by sex. In overlapping watersheds, the species tended to show the same trends in length relative to their respective averages. Smaller body length was associated with more urban and agricultural land cover. These findings indicate that ecomorphological variation is tied to the watershed scale and point to significant variations on either side of the Apalachicola River. More thorough future analyses would be needed to verify trends in body length and identify the drivers behind them.

Diet variability of snappers (Teleostei: Lutjanidae) in a bay-to-reef ecosystem of the Mexican Caribbean

Fishes use environmental resources differently. Snapper ontogenic movements among coastal habitats lead to diverse diets. We investigated the diets of seven snapper species (Lutjanus apodus, L. analis, L. griseus, L. jocu, L. mahogoni, L. synagris, and Ocyurus chrysurus) in three interconnected coastal environments in the western Caribbean: Río Huach channel, Chetumal/Corozal bay, and the adjacent Xcalak reef lagoon. These three encompass all habitats used by the seven species in the study area. Snapper diets were mostly composed of fish and crustaceans, but dominance of either group varied among the studied habitats; for example, fish were the main prey for L. apodus from the reef lagoon zone, but second in the bay. Snappers are piscivorous-invertivorous mesopredators; the species that relied the most on fishes were L. griseus and L. jocu, whereas O. chrysurus preferred crustaceans. Stomach content results revealed a high degree of dietary overlap among species. Our findings suggested a tradeoff in relative weight between fish and crustaceans as the main food source of snappers at these connected areas, supporting the hypothesis of niche segregation. Our results can be used as a baseline to further our understanding of the ecology and differences in resource use by snapper species in an area undergoing important anthropogenic changes.

Malacological indicators of anthropogenic and natural environmental changes of the Podhale Basin during the last 2000 years. Studies in the Rogoźnik Stream valley (the Carpathian Mountains, Southern Poland)

The lithological and malacological studies covered sediments forming the low terrace of the Rogoźnik Stream in the northwest part of the Podhale Basin. This terrace is characterised by a uniform structure within a significant part of the valley. Three layers of gravel and four layers of sandy and silty muds were found there. A rich and diversified malacofauna was discovered in fine-grained sediments. Its analysis allowed us to characterise environmental conditions during sediment deposition. The age of the individual components of the sedimentary sequence was determined by radiocarbon dating. A distinct change was found in the upper intervals of the sequence, corresponding to the warm phase of the Medieval Climate Optimum. This period is associated with the robust development of agriculture, and processes related to human activities became the main factor shaping the environment, influencing the course of geological processes, and changing the taxonomical and ecological structure of the fauna and flora assemblages found in this area.

The reinstatement of Rafflesia banaoana (Rafflesiaceae), and implications for assessing species diversity and conservation requirements of the world's largest flowers

The Southeast Asian genus Rafflesia (Rafflesiaceae) is famous for possessing the world's largest flowers. All species are rare or threatened, so understanding taxonomic diversity in the genus is crucial for informing effective conservation practice. Here we examine R. banaoana, a poorly known taxon from the remote montane rainforests of the Kalinga Province in the Philippines. This species has been treated as conspecific with R. leonardi, and overlooked in systematic studies. Using stable yet hitherto neglected features such as the stigmatic fascia surface, disk shape, process structure, annulus interior and exterior distinction, and ovary shape, we demonstrate that R. banaoana is morphologically as well as ecologically distinct from R. leonardi, and requires reinstatement at the specific rank. We present our findings in the broader context of complexity in the genus Rafflesia in the Philippines, now considered the center of diversity, with 15 species described to date. We highlight the taxonomically confused R. banaoana as a case for careful observation of previously unexamined morphological characters, as well as ecology, to avoid overlooking cryptic taxa or species complexes and to inform representative sampling in systematic treatments. Such an approach will be essential for enhancing our understanding of the diversity of this enigmatic yet poorly understood genus at a time of unprecedented anthropogenic change and species extinction. In light of our findings, we recommend a holistic approach to the conservation of Rafflesia in the Philippines.

Land Change in Tirthan Valley: The Case of Great Himalayan National Park Conservation Area

Humans are dominant agent of landscape change. Off lately, anthropogenic induced changes have visibly degraded environment around the world putting a serious question over the sustainability of both natural and man-made ecosystems. The sustainability of the ecosystems has found to be directly linked to changes in LULC. The present study aims to analyse long-term land use change in the Tirthan Valley of Himachal Pradesh; the region is a part of protected area collectively known as GHNPCA. With the help of multi-temporal satellite images of LANDSAT, this study reconstructs the trajectory of land changes over a period of five decades. The data shows an increase in forest cover (7.29%), rocky/barren land (45.35%), agriculture/horticulture land (28.94%) and settlement/ built-up (190.48%) while decrease in pasture/open land (29.97%), snow cover (56.14%) and river/water body (54.52%). The results have shown significant land changes in post protected area status.

The CESM2 Single-Forcing Large Ensemble and Comparison to CESM1: Implications for Experimental Design

Abstract Single-forcing large ensembles are a relatively new tool for quantifying the contributions of different anthropogenic and natural forcings to the historical and future projected evolution of the climate system. This study introduces a new single-forcing large ensemble with the Community Earth System Model, version 2 (CESM2), which can be used to separate the influences of greenhouse gases, anthropogenic aerosols, biomass burning aerosols, and all remaining forcings on the evolution of the Earth system from 1850 to 2050. Here, the forced responses of global near-surface temperature and associated drivers are examined in CESM2 and compared with those in a single-forcing large ensemble with CESM2’s predecessor, CESM1. The experimental design, the imposed forcing, and the model physics all differ between the CESM1 and CESM2 ensembles. In CESM1, an “all-but-one” approach was used whereby everything except the forcing of interest is time evolving, while in CESM2 an “only” approach is used, whereby only the forcing of interest is time evolving. This experimental design choice is shown to matter considerably for anthropogenic aerosol-forced change in CESM2, due to state dependence of cryospheric albedo feedbacks and nonlinearity in the Atlantic meridional overturning circulation (AMOC) response to forcing. This impact of experimental design is, however, strongly dependent on the model physics and/or the imposed forcing, as the same sensitivity to experimental design is not found in CESM1, which appears to be an inherently less nonlinear model in both its AMOC behavior and cryospheric feedbacks.

In situ stannous reagent generator (SRG): An alternative hexavalent chromium treatment technology in drinking water industry

Access to safe drinking water is a basic necessity for human health. Rock and soil are rich sources of chromium, a metal that is present naturally. Chromium commonly exists in two oxidation states: trivalent chromium (chromium-3, Cr (III), Cr3+) and hexavalent chromium (chromium-6, Cr (VI), Cr6+), in the natural environment, as well as in the water treatment and distribution systems. While Cr (III) is an essential nutrient for humans, Cr (VI) is a dangerous pollutant that can build up in both the environment and the tissues of living things. The Cr (VI) treatment traditionally uses techniques such as electrodialysis reversal, ion exchange, electrochemical, reduction, coagulation, oxidation and filtration systems. Chemical costs, secondary waste production, and unintentional regeneration of Cr (VI) after treatment are difficulties with standard Cr (VI) treatment. In order to remediate Cr (VI) in raw water, this study looks into the in-situ stannous reagent generator (SRG) package as a potential disruptive green technology. SRG was able to reduce roughly 40 parts per billion (ppb) of Cr (VI) to below 1.0 ppb after being installed on a raw water source site for a 10-day trial period. The In Situ SRG technology provides an efficient and safe method for treating Cr (VI) in drinking water, reduces the health risks associated with Cr (VI) exposure by converting it to a less toxic form and reduces chemical handling risks. Reductive Cr (VI) treatment technologies based on the use of stannous tin hold tremendous promise in the future to overcome green-house gas (GHG) emissions and other anthropogenic environmental change, in addition to effectively reducing Cr (VI) in drinking water to the permissible limits and high energy cost challenges. In Situ Stannous Reagent Generator (SRG) technology is designed to convert Cr (VI) to its less toxic trivalent form, Cr (III), which is less harmful and easier to remove from water.

Nesting innovations in neotropical parrots associated to anthropogenic environmental changes.

Parrots are among the most diverse and widely distributed groups of birds and one of the most threatened bird orders mainly due to habitat loss and illegal poaching. Most parrots are obligate cavity nesters, so the logging of mature trees and the transformation of natural cliffs represent important threats to their conservation. Here, we report novel observations of Neotropical parrots nesting in previously unrecorded substrates. We show the first documented case of the cliff-nesting burrowing parrots trying to breed at ground level in an abandoned burrowing owl cavity. Additionally, we provide the first documented observations of this species attempting to nest in building cavities in three urbanized areas of Argentina. Moreover, we report data from four countries of 148 pairs of eight species typically breeding in tree cavity using palm tree bracts as nest sites. Behavioral plasticity in nest sites may allow parrots to maximize their nesting success by exploiting alternative breeding substrates. Moreover, these novelties could contribute to cope with habitat loss and further transformation. However, further research is needed to assess the consequences of these nesting innovations in terms of individual fitness and population dynamics as well as potential factors promoting their appearance.

Identifying a scenario for preindustrial cropland cover using cultivation data: A case study of France, Germany and Italy

Cropland expansion is effected by physiogeographic and sociocultural factors, which vary across region and over time, but have not been adequately represented in large-scale anthropogenic land cover change scenarios. Taking preindustrial cropland expansion in France, Germany, and Italy as a case study, this study first adopted a productivity-based estimation of cropland per capita, which converted crop yield to cropland demand per capita through negative correlations under different crop rotations, to improve the accuracy of national cropland areas. Then, a new allocation algorithm was proposed to allocate national cropland areas into 5′× 5′ grids. The algorithm combines land suitability, which characterizes regional differentiation of potential productivity indicated by physiogeographic factors (climate, topography, soil, etc.) that dominate cultivation, and cultivation preference, which quantifies sociocultural impacts by kernel density estimation based on city information (i.e., location, size, accessibility). The cropland cover scenario here shows similar phases but different modes of cropland expansion in these countries: (1) National cropland areas increased 1.73–2.46 times during the 11th–13th centuries, manifested by the expanding cultivated ranges in France and Germany and the increasing cultivation intensity in Italy. (2) National cropland fractions decreased by 9.16–19.98 percentage points in the 14th century, accompanied by widespread reductions in cultivation intensity. (3) Cropland gradually recovered toward its peak in 1300 AD during the 15th–18th centuries, achieved by general and remarkable increases in cultivation intensity. Compared to representative global datasets, this study is more consistent with cultivation-related descriptions in the literature, especially with respect to the cropland expansion in newly cultivated regions and on marginal lands.

Impact of anthropogenic and land use pattern change on spatio-temporal variations of groundwater quality in Odisha, India.

The groundwater physicochemical parameters were studied to understand their spatiotemporal variations and groundwater quality, using the statistical and entropy weights methods. Out of ten parameters that were considered, F-, TDS, and Cl- appear to be the major contributors influencing the quality of groundwater. The Principal Component Analysis (PC1, PC2) indicates that the majority of ions are derived from both natural and anthropogenic sources. Studies of saturation indices of gypsum, Halite, dolomite, and calcite indicate that dissolution of these salts also affects groundwater salinization. In coastal areas, a few of the water samples also appear to be contaminated by the mixing of seawater. The entropy weights, which are free from subjective biases were used to estimate the water quality index. The entropy-based water quality index (EWQI) varies from excellent to good quality for the year 2012-13, and appears to degrade after 2015 onwards. For the year 2018-19 and 2021-22, 71.42% and 68.42% of the study areas show excellent water quality, followed by 25.33% and 24.33% (good), 2.54% and 3.54% (average), 0.7% and 3.7% study area shows as poor quality respectively. The groundwater quality, particularly in the western, central, northern, and eastern parts of the region, appears to be average, poor, and very poor in several small patches, respectively. Industrial developments, mining activities, irrigation, changing land use patterns, agricultural activities, and increased anthropogenic activities may be contributing to the degradation of the water quality.

High-resolution land use and land cover dataset for regional climate modelling: historical and future changes in Europe

Abstract. Anthropogenic land use and land cover change (LULCC) is a major driver of environmental changes. The biophysical impacts of these changes on the regional climate in Europe are currently being extensively investigated within the World Climate Research Program (WCRP) Coordinated Downscaling Experiment (CORDEX) Flagship Pilot Study (FPS) Land Use and Climate Across Scales (LUCAS) using an ensemble of different regional climate models (RCMs) coupled with diverse land surface models (LSMs). In order to investigate the impact of realistic LULCC on past and future climates, high-resolution datasets with observed LULCC and projected future LULCC scenarios are required as input for the RCM–LSM simulations. To account for these needs, we generated the LUCAS Land Use and land Cover change (LUC) dataset version 1.1 at 0.1∘ resolution for Europe with annual LULC maps from 1950 to 2100 (https://doi.org/10.26050/WDCC/LUC_hist_EU_v1.1, Hoffmann et al., 2022b, https://doi.org/10.26050/WDCC/LUC_future_EU_v1.1, Hoffmann et al., 2022a), which is tailored to use in state-of-the-art RCMs. The plant functional type (PFT) distribution for the year 2015 (i.e. the Modelling human LAND surface Modifications and its feedbacks on local and regional cliMATE – LANDMATE – PFT dataset) is derived from the European Space Agency Climate Change Initiative Land Cover (ESA-CCI LC) dataset. Details on the conversion method, cross-walking procedure, and evaluation of the LANDMATE PFT dataset are given in the companion paper by Reinhart et al. (2022b). Subsequently, we applied the land use change information from the Land-Use Harmonization 2 (LUH2) dataset, provided at 0.25∘ resolution as input for Coupled Modelling Intercomparison Project Phase 6 (CMIP6) experiments, to derive LULC distributions at high spatial resolution and at annual time steps from 1950 to 2100. In order to convert land use and land management change information from LUH2 into changes in the PFT distribution, we developed a land use translator (LUT) specific to the needs of RCMs. The annual PFT maps for Europe for the period 1950 to 2015 are derived from the historical LUH2 dataset by applying the LUT backward from 2015 to 1950. Historical changes in the forest type changes are considered using an additional European forest species dataset. The historical changes in the PFT distribution of LUCAS LUC follow closely the land use changes given by LUH2 but differ in some regions compared to other annual LULCC datasets. From 2016 onward, annual PFT maps for future land use change scenarios based on LUH2 are derived for different shared socioeconomic pathway (SSP) and representative concentration pathway (RCP) combinations used in the framework of CMIP6. The resulting LULCC maps can be applied as land use forcing to the new generation of RCM simulations for downscaling of CMIP6 results. The newly developed LUT is transferable to other CORDEX regions worldwide.

Projection of Long‐Term Climate Change in China Under COVID‐19 Recovery Emission Scenarios

AbstractThe unexpected emergence of the 2019 coronavirus disease (COVID‐19) pandemic resulted in anthropogenic emissions changes, which have significant consequences for the regional and global climate. However, the long‐term impacts of emission reductions and recovery scenarios on regional climate change in China remain unknown. We use the COVID Model Intercomparison Project (CovidMIP) simulations to project climate change in China in the mid‐21st century under four recovery emission pathways in the post‐COVID era. We found that the temporary emission cut during the COVID‐19 lockdown under the 2‐year‐blip scenario has limited long‐term impact on regional climate change. Anthropogenic emissions are reduced under moderate and stringent greening recovery pathways, leading to reductions of 0.17 ± 0.09°C and 0.35 ± 0.10°C in surface air temperature (SAT) relative to the SSP2‐4.5 baseline in China, respectively. Although the reduction of greenhouse gas emissions decreases SAT, the simultaneous enhanced surface solar radiation due to reduced aerosol concentrations partly offsets the GHG‐induced cooling. Additionally, the weakened aerosol‐cloud interactions associated with reduced aerosols increase the national precipitation by 1.30 ± 0.88 mm month−1 (1.63 ± 1.11%) and 1.91 ± 0.60 mm month−1 (2.39 ± 0.77%) in two green scenarios. As a comparison, regional precipitation decreases by 0.40 ± 0.53 mm month−1 (0.50 ± 0.66%) in the fossil‐based recovery scenario. Therefore, long‐term climate change is more dominated by the emission recovery pathways rather than short‐term emission reduction during the pandemic for China.

Host–enemy interactions provide limited biotic resistance for a range‐expanding species via reduced apparent competition

AbstractAimAs species' ranges shift poleward in response to anthropogenic change, they may lose antagonistic interactions if they move into less diverse communities, fail to interact with novel populations or species effectively, or if ancestral interacting populations or species fail to shift synchronously. We leveraged a poleward range expansion in a tractable insect host–enemy community to uncover mechanisms by which altered antagonistic interactions between native and recipient communities contributed to ‘high niche opportunities’ (limited biotic resistance) for a range‐expanding insect.LocationNorth America, Pacific Northwest.MethodsWe created quantitative insect host–enemy interaction networks by sampling oak gall wasps on 400 trees of a dominant oak species in the native and expanded range of a range‐expanding gall wasp species. We compared host–enemy network structure between regions. We measured traits (phenology, morphology) of galls and interacting parasitoids, predicting greater trait divergence in the expanded range. We measured function relating to host control and explored if altered interactions and traits contributed to reduced function, or biotic resistance.ResultsInteraction networks had fewer species in the expanded range and lower complementarity of parasitoid assemblages among host species. While networks were more generalized, interactions with the range‐expanding species were more specialized in the expanded range. Specialist enemies effectively tracked the range‐expanding host, and there was reduced apparent competition with co‐occurring hosts by shared generalist enemies. Phenological divergence of enemy assemblages interacting with the range‐expanding and co‐occurring hosts was greater in the expanded range, potentially contributing to weak apparent competition. Biotic resistance was lower in the expanded range, where fewer parasitoids emerged from galls of the range‐expanding host.Main ConclusionsChanges in interactions with generalist enemies created high niche opportunities, and limited biotic resistance, suggesting weak apparent competition may be a mechanism of enemy release for range‐expanding insects embedded within generalist enemy networks.

Consistent foraging on marine resources by coyotes (Canis latrans) on the Southern California coast

The marine-terrestrial interface provides consumers with access to nutrient rich ocean-based resource subsidies. Coyotes, omnivorous generalists with large ranges that can span many landscape types including the coastal ecotone, might be a critical component of the intertidal food web, contributing to resource subsidy movement into the less productive adjacent coastal scrub habitat. This study utilized an array of camera traps along identified coastal game trails in two protected coastal properties in California to assess the consumption of marine fauna by coyotes in intertidal habitats. We captured coyotes consuming a variety of marine resources, including marine mammals, fish, and intertidal invertebrates. We therefore suggest that coyotes are a more consistent consumer in intertidal habitats than previously thought. We highlight the need for further research into the role of coyotes as a marine to terrestrial subsidy vector, especially under the pressure of anthropogenic change in coastal systems.

Introducing ICEDAP: An ‘Iterative Coastal Embayment Delineation and Analysis Process’ with Applications for the Management of Coastal Change

Coastal embayments provide vital benefits to both nature and humans alike in the form of ecosystem services, access to waterways, and general aesthetic appeal. These coastal interfaces are therefore often subject to human development and modifications, with estuarine embayments especially likely to have been anthropogenically altered. Frequent alterations include damming to eliminate tidal influx, backfilling to create new land, and development for the sake of economic gain, which may cause profound damage to local habitats. By providing a record of transitions in surface waters over time, satellite imagery is essential to monitoring these coastal changes, especially on regional to global scales. However, prior work has not provided a straightforward way to use these satellite-derived datasets to specifically delineate embayed waters, limiting researchers’ ability to focus their analyses on this ecologically and economically important subset of coastal waters. Here, we created ICEDAP, a geometry-based ArcGIS toolbox to automatically delineate coastal embayments and quantify coastal surface water change. We then applied ICEDAP to the coast of South Korea, and found that coastal habitat change was particularly profound within embayed regions identified using an 8 km epsilon convexity setting (denoting a moderate distance from the coast and degree of enclosure by surrounding land areas). In the mapped coastal embayments, more than 1400 km2 of coastal habitats were lost during the past 38 years, primarily due to human modification such as large-scale land reclamation projects and the construction of impoundments. Our results suggest that anthropogenic alterations have resulted in the widespread loss of more than USD 70 million of valuable coastal ecosystem services. Together, ICEDAP provides a new innovative tool for both coastal scientists and managers to automatically identify hotspots of coastal change over large spatial and temporal scales in an epoch where anthropogenic and climate-driven changes commonly threaten the stability of coastal habitats.

Assessing micro-macroparasite selective pressures and anthropogenic disturbance as drivers of immune gene diversity in a Neotropical wild cat

Anthropogenic environmental change is reducing available habitat for wild species, providing novel selection pressures such as infectious diseases and causing species to interact in new ways. The potential for emerging infectious diseases and zoonoses at the interface between humans, domestic animals, and wild species is a key global concern. In vertebrates, diversity at the major histocompatibility complex MHC is critical to disease resilience, and its study in wild populations provides insights into eco-evolutionary dynamics that human activities alter. In natural populations, variation at MHC loci is partly maintained by balancing selection, driven by pathogenic selective pressures. We hypothesize that MHC genetic diversity differs between guigna populations inhabiting human-dominated landscapes (higher pathogen pressures) versus more natural habitats (lower pathogen pressures). We predict that MHC diversity in guignas would be highest in human-dominated landscapes compared with continuous forest habitats. We also expected to find higher MHC diversity in guignas infected with micro and macro parasites (higher parasite load) versus non infected guignas. We characterized for the first time the genetic diversity at three MHC class I and II exons in 128 wild guignas (Leopardus guigna) across their distribution range in Chile (32–46° S) and Argentina, representing landscapes with varying levels of human disturbance. We integrated MHC sequence diversity with multiple measures of anthropogenic disturbance and both micro and macro parasite infection data. We also assessed signatures of positive selection acting on MHC genes. We found significantly higher MHC class I diversity in guignas inhabiting landscapes where houses were present, and with lower percentage of vegetation cover, and also in animals with more severe cardiorespiratory helminth infection (richness and intensity) and micro-macroparasite co-infection. This comprehensive, landscape-level assessment further enhances our knowledge on the evolutionary dynamics and adaptive potential of vertebrates in the face of emerging infectious disease threats and increasing anthropogenic impacts.

Carbon stock dynamics in a disturbed tropical forest ecosystem of Central India: Strategies for achieving carbon neutrality

Anthropogenic land use changes in the vicinity of forest catchments are explicitly responsible for the deforestation and degradation of tropical forest thereby altering the carbon (C) balance under rising atmospheric carbon dioxide (CO2). Thus, strategic mitigation measures are required to achieve climate neutrality by 2030. It becomes imperative to understand the impact of land cover conversion on the functioning of tropical forests and to determine the carbon dynamics. The present study examined the land cover changes (LUC) in dry tropical ecosystem of Central India during the last two decades and assessed its influence on the forest biomass, litter crop, and C stocks. Geospatial techniques coupled with ground measurements were employed in the study. The total biomass, vegetative C stocks and soil C were estimated as 64 to 338.3 Mg ha−1, 26.4 to 131.1 Mg C/ha and 24.6 to 50.2 Mg C/ha respectively. In the past decades (2000–2020), about 1851.8 ha of forest constituting 15.1% of the total area under study was lost (mainly to Agriculture) under open mixed forest, moderately mixed forest and mixed teak forest. The study demonstrated that forests of the studied region behave as a potential C source, which accounted for a net loss of 59 gigagram carbon (Gg C) equivalent to 216 Gg CO2eq. Besides, discussed three viable scenarios of restoration to offset C emissions and to achieve C neutral landscape by 2030. The conservation and restoration of 26–85% degraded forests (open mixed forest and moderately mixed dense forests), use of agroforestry on 1/5th of existing agricultural lands, or implementation of regenerative agricultural practices in 30% of the area will compensate for net losses, while attaining C neutrality. Further, the finding of this study helps to understand the climatic extremes as per the commitments of Paris Agreement, 2015 and Glasgow Pact, 2021.

Exposure to ultraviolet-B radiation increases the susceptibility of mosquitoes to infection with dengue virus.

By 2100, greenhouse gases are predicted to reduce ozone and cloud cover over the tropics causing increased exposure of organisms to harmful ultraviolet-B radiation (UVBR). UVBR damages DNA and is an important modulator of immune function and disease susceptibility in humans and other vertebrates. The effect of UVBR on invertebrate immune function is largely unknown, but UVBR together with ultraviolet-A radiation impairs an insect immune response that utilizes melanin, a pigment that also protects against UVBR-induced DNA damage. If UVBR weakens insect immunity, then it may make insect disease vectors more susceptible to infection with pathogens of socioeconomic and public health importance. In the tropics, where UVBR is predicted to increase, the mosquito-borne dengue virus (DENV), is prevalent and a growing threat to humans. We therefore examined the effect of UVBR on the mosquito Aedes aegypti, the primary vector for DENV, to better understand the potential implications of increased tropical UVBR for mosquito-borne disease risk. We found that exposure to a UVBR dose that caused significant larval mortality approximately doubled the probability that surviving females would become infected with DENV, despite this UVBR dose having no effect on the expression of an effector gene involved in antiviral immunity. We also found that females exposed to a lower UVBR dose were more likely to have low fecundity even though this UVBR dose had no effect on larval size or activity, pupal cuticular melanin content, or adult mass, metabolic rate, or flight capacity. We conclude that future increases in tropical UVBR associated with anthropogenic global change may have the benefit of reducing mosquito-borne disease risk for humans by reducing mosquito fitness, but this benefit may be eroded if it also makes mosquitoes more likely to be infected with deadly pathogens.

How Does Intensive Land Use Affect Low-Carbon Transition in China? New Evidence from the Spatial Econometric Analysis

Anthropogenic land cover change is one of the primary sources of increasing carbon emissions and affects the potential of terrestrial ecosystems to store carbon and act as carbon sinks. As a necessary means to reduce land expansion, land-use intensification significantly impacts greenhouse gas emission reduction and the low-carbon transition of the economy. This paper constructs a framework for the relationship between intensive land use (ILU) and low carbon transition (LCT), considering direct and spatially driven effects. First, this paper constructs a multidimensional indicator to measure intensive land use and documents the spatial pattern of intensive land use levels in China. Second, this paper assesses the spatial driving effect of intensive land use on China’s economic low-carbon transition. Based on data from 283 Chinese cities from 2006–2019 and using a spatial Durbin model, the study provides empirical evidence that intensive land use can significantly promote low-carbon transition in neighboring and economically linked cities (especially in eastern cities, large and medium-sized cities, and veteran economic circles). Tests introducing exogenous policy shocks further confirm the robustness of the findings. In addition, industrial structure transformation and technology spillovers are identified as the dual mechanism channels of intensive land use for low-carbon transition in China, and the spatial driving effect on neighboring cities attenuating with geographic distance is also confirmed.

Forests and fields in the pre-pyreneean neolithic and early Bronze Age based on fumier archaeobotanical records

The aim of this article is to present the current state of multidisciplinary archaeobotanical approaches that are being undertaken at Cova Gran de Santa Linya. Information from studies of seeds, charcoal, pollen, and NPP recovered from the Holocene levels of the site contribute to research questions regarding the anthropogenic transformation of the landscape. The signal of human activity in the environment can be detected through the bioarchaeological signatures of deforestation, forest management or agriculture practices. In this sense, the Cova Gran de Santa Linya is a cave deposit located in the northeast of Iberia used as an occupation site, recording mainly domestic activities during the Neolithic period. The settlement was also used as a pen during the Late Neolithic to the Early Bronze Age, preserving burnt and unburned dung layers that formed pen deposits, known as fumiers. The resolution provided by the multidisciplinary nature of this work shows how forests and fields created a mosaic landscape that provided crops, pastures, wood, and fuel and clearly reflects anthropogenic changes over time. The different methodological and analytical scales of this multidisciplinary approach, including taphonomic pollen alteration, provide a better understanding of the dynamics of the cave occupation and, from a broader perspective, the regional diversity related to the availability of plant resources.