Anthropogenic Change Research Articles

Climate change and human impacts on aquatic communities at Etoliko Lagoon in western Greece

The Etoliko Lagoon in western Greece has experienced extensive human modification since the 20th century, both on the surrounding land and in the aquatic environment. To examine human impacts and disentangle climatic from anthropogenic changes, we present a suite of biomarker records that span the past two centuries (∼1790–2011). Specifically, we use terrigenous (n-alkanes, polycyclic aromatic hydrocarbons (PAHs), and phytosterols) and aquatic (dinosterol, brassicasterol, cholesterol, and stigmasterol) biomarkers to document changes in nutrient inputs, combustion, and algal productivity. During most of the 19th and 20th centuries, aquatic communities respond to temperature, forced mainly by solar irradiance and volcanic activity, and precipitation, controlled largely by summer and winter North Atlantic Oscillation (NAO) patterns that determine freshwater runoff. PAHs illustrate the acceleration of coal combustion during the 1800s, and declining concentrations since the 1950s correspond to the implementation of emission controls and reductions in rainfall that likely inhibited PAH transport. As human pressures increased in the late 1900s and water column anoxia grew, the absence of a clear human waste and eutrophication signal suggests that other factors also contributed to limited oxygen availability. Overall, environmental degradation of the late 20th and early 21st centuries is clear and can be attributed to a combination of especially arid conditions and human interferences that altered lagoon hydrography, trophic state, and aquatic community composition.

The role of artificial ponds for anuran diversity in managed areas of the Atlantic Forest

ABSTRACT Artificial ponds can be important reproductive sites for anurans in human-disturbed habitats. However, this capacity depends on the configuration of the habitat where they are inserted. We evaluated how anuran beta diversity was influenced by the configuration of the surrounding habitat and water parameters in artificial ponds in southern Brazil. Physicochemical parameters of water and the configuration of the surrounding habitat were the elements that best explained the variation in beta diversity. However, the surrounding habitat had a predominant role in the differences between communities. The level of exposed soil was the component that best acted on the turnover component of beta diversity followed by urbanization, which highlights the impact of human presence on anuran diversity. In other words, we observed that anthropogenic changes caused changes in species composition in the evaluated ponds. Among water parameters, only phosphate was relevant for the configuration of communities. Phosphate peaks may result from sewage or fertilizer contamination, not infrequent in the region despite the low human density and the small-scale agriculture economy. Even though they are anthropogenic environments, artificial ponds can help maintain the anuran communities, but their effectiveness will depend on the presence of forest remnants and water quality.

Characterization of winter PM2.5 source contributions and impacts of meteorological conditions and anthropogenic emission changes in the Sichuan Basin, 2002–2020

In this study, the Weather Research and Forecasting (WRF) model and Community Multiscale Air Quality–Integrated Source Apportionment Method (CMAQ–ISAM) were utilized, which were integrated with the Multiresolution Emission Inventory for China (MEIC) emission inventory, to simulate winter PM2.5 concentrations, regional transport, and changes in emission source contributions in the Sichuan basin (SCB) from 2002 to 2020, considering variations in meteorological conditions and anthropogenic emissions. The results indicated a gradual decrease in the basin's winter average PM2.5 concentration from 300 μg/m3 to 120 μg/m3, with the most significant decrease occurring after 2014, reflecting the actual impact of China's air pollution control measures. Spatially, the main pollution area shifted from Chongqing to Chengdu and the western basin. The sources of PM2.5 at the eastern and western margins of the basin have remained stable and have been dominated by local emissions for many years, while the sources of PM2.5 in the central part of the basin have evolved from a multiregional co-influenced source during the early period to a high proportion of local emissions; except for boundary condition sources, residential sources were the main PM2.5 sources in the basin (approximately 29.70 %), followed by industrial sources (approximately 14.11 %). Industrial sources exhibited higher contributions in Chengdu and Chongqing and gradually stabilized with residential sources over the years, while residential sources dominated in the eastern and western parts of the basin and exhibited a declining trend. Meteorological conditions exacerbated pollution in the whole basin from 2008 to 2014, especially in the west (21–40 μg/m3). The eastern basin and Chongqing exhibited more years with alleviated meteorological pollution, including a 40+ μg/m3 decrease in Chongqing from 2002 to 2005. Reduced anthropogenic emissions alleviated annual pollution levels, with a greater reduction (> −20 μg/m3) after 2011 due to pollution control measures.

Drought evaluation using various evapotranspiration models over semi-arid river basins

ABSTRACT Multivariate drought indices including various hydrological processes into account can be more valuable under climatic and anthropogenic changes. Standardized Precipitation Evapotranspiration Index (SPEI) and Standardized precipitation Actual Evapotranspiration Index (SPAEI) are the drought indices used to estimate drought index, considering precipitation, and evapotranspiration (ET) into account. Many studies used empirical, machine learning, and process-based model estimates of ET for the calculation of drought indices of SPEI and SPAEI. However, the sensitivity of ET estimates on drought characteristics at the catchment scale is highly complex. The present study aimed to include and analyze the sensitivity of various approaches of empirical (Budyko, Penman–Monteith, Hargreaves, and Turc), modeled (SWAT), and remote sensing (MODIS) in the drought characterization using SPEI and SPAEI. The present methodology was tested on a dry-sub-humid river catchment of India, the Tunga-Bhadra River catchment for the period of 2000–2012. The performance of statistical indicators (Nash–Sutcliffe Efficiency and R2) for SPEI values by various empirical methods of Potential Evapotranspiration (PET) (i) Penman–Monteith (ii) Hargreaves against remote sensing PET were 0.93 and 0.95, respectively, which are high in comparison with SWAT simulated PET-based SPEI values, which shows NSE values of 0.85 against remote sensing PET-based SPEI.

Future trends of marine fish biomass distributions from the North Sea to the Barents Sea

Climate warming is one of the facets of anthropogenic global change predicted to increase in the future, its magnitude depending on present-day decisions. The north Atlantic and Arctic Oceans are already undergoing community changes, with warmer-water species expanding northwards, and colder-water species retracting. However, the future extent and implications of these shifts remain unclear. Here, we fitted a joint species distribution model to occurrence data of 107, and biomass data of 61 marine fish species from 16,345 fishery independent trawls sampled between 2004 and 2022 in the northeast Atlantic Ocean, including the Barents Sea. We project overall increases in richness and declines in relative dominance in the community, and generalised increases in species’ ranges and biomass across three different future scenarios in 2050 and 2100. The projected decline of capelin and the practical extirpation of polar cod from the system, the two most abundant species in the Barents Sea, drove an overall reduction in fish biomass at Arctic latitudes that is not replaced by expanding species. Furthermore, our projections suggest that Arctic demersal fish will be at high risk of extinction by the end of the century if no climate refugia is available at eastern latitudes.

Bringing the Anthropocene Down to Size, or, How Can We Understand a Gigaton?

This contribution takes on the incomprehensibility of human transformation of the Earth’s surface, framing it as a “Constructocene” dominated by architecture and infrastructure. Based on an idea first proposed by Jan Zalasiewicz, it then looks at the Anthropocene Square Meter as a way of making human impact tangible. Using the model as a storytelling device, it then walks through four narratives of vast and heavy anthropogenic material change.

ONE HEALTH MULTIMODAL SURVEILLANCE IN TIME OF CHANGE: LESSONS NOT LEARNT FROM CASE STUDY OF A/H5N1 SPILLOVER TO MAMMALS IN GDAŃSK METROPOLITAN AREA

This case study of A/H5N1 spillover to mammals in the Gdańsk area underlines the complexities of managing emerging One Health threats in significant political and economic aspects. We compared the relatively successful rapid regional response with the utterly lost battle in communication and cooperation, emphasising the need for improved interdisciplinary regional and international cooperation and robust surveillance systems in an era of anthropogenic and natural change.

Home range and seasonal movement of Nanorana vicina (Stoliczka, 1872) (Anura: Dicroglossidae) in Himalayan streams, India

The spatial movement pattern is a poorly known aspect of amphibian ecology, especially in the Indian Himalayan region. Thus, we studied the home range and movement of Nanorana vicina,, an obligate stream frog endemic to the Western Himalayas. We radio-tagged 16 individuals and tracked their movement for an average of 63 days in two streams of Binog Wildlife Sanctuary, Uttarakhand. Our results showed that the highest mean movement of a tagged frog was 5.9 ± 3.26 meters (m) in 13 days during monsoon. Most of the movements (90 %) were restricted within the stream. Movement varied significantly across seasons, with the highest movement during the monsoon (2.71 ± 0.46 m) and the lowest during the post-monsoon (0.78 ± 0.14 m). The Dunn's Test revealed that post-monsoon movement was significantly lower than in both pre-monsoon and monsoon periods. The minimum convex polygon showed a range of 1.61 m2 to 43.16 m2 and 15.78 m2 to 684.99 m2 for 50% and 90% MCP, respectively. No significant difference was found in the weights of frogs before tagging and after removing tags (n = 10, p > 0.05). Himalayan streams are subjected to rapid anthropogenic and climate-induced changes. Less vagile and highly philopatric species, such as N. vicina, might be much more vulnerable to such changes. Thus, the study highlights the importance of the stream and the riparian zone for the conservation of this stream frog.

Reduced Runoff in the Upper Yangtze River Due To Comparable Contribution of Anthropogenic and Climate Changes

Reduced Runoff in the Upper Yangtze River Due To Comparable Contribution of Anthropogenic and Climate Changes

Carbon isotope trends across a century of herbarium specimens suggest CO2 fertilization of C4 grasses.

Increasing atmospheric CO2 is changing the dynamics of tropical savanna vegetation. C3 trees and grasses are known to experience CO2 fertilization, whereas responses to CO2 by C4 grasses are more ambiguous. Here, we sample stable carbon isotope trends in herbarium collections of South African C4 and C3 grasses to reconstruct 13C discrimination. We found that C3 grasses showed no trends in 13C discrimination over the past century but that C4 grasses increased their 13C discrimination through time, especially since 1950. These changes were most strongly linked to changes in atmospheric CO2 rather than to trends in rainfall climatology or temperature. Combined with previously published evidence that grass biomass has increased in C4-dominated savannas, these trends suggest that increasing water-use efficiency due to CO2 fertilization may be changing C4 plant-water relations. CO2 fertilization of C4 grasses may thus be a neglected pathway for anthropogenic global change in tropical savanna ecosystems.

Interactive Effects of Temperature, Aridity, and Plant Stoichiometry on Insect Herbivory: Past and Present.

AbstractThe influence of climate on deep-time plant-insect interactions is becoming increasingly well known, with temperature, CO2 increases (and associated stoichiometric changes in plants), and aridity likely playing a critical role. In our modern climate, all three factors are shifting at an unprecedented rate, with uncertain consequences for biodiversity. To investigate effects of temperature, stoichiometry (specifically that of nitrogen), and aridity on insect herbivory, we explored insect herbivory in three modern floral assemblages and in 39 fossil floras, especially focusing on eight floras around a past hyperthermal event (the Paleocene-Eocene Thermal Maximum) from Bighorn Basin (BB). We find that higher temperatures were associated with increased herbivory in the past, especially among BB sites. In these BB sites, non-N2-fixing plants experienced a lower richness but higher frequency of herbivory damage than N2-fixing plants. Herbivory frequency but not richness was greater in BB sites compared with contemporaneous, nearby, but less arid sites from Hanna Basin. Compared with deep-time environments, herbivory frequency and richness are higher in modern sites, suggesting that current accelerated warming uniquely impacts plant-insect interactions. Overall, our work addresses multiple aspects of climate change using fossil data while also contextualizing the impact of modern anthropogenic change on Earth's most diverse interactions.

Fungal composition associated with host tree identity mediates nutrient addition effects on wood microbial respiration.

Fungi are key decomposers of deadwood, but the impact of anthropogenic changes in nutrients and temperature on fungal community and its consequences for wood microbial respiration are not well understood. Here, we examined how nitrogen and phosphorus additions (field experiment) and warming (laboratory experiment) together influence fungal composition and microbial respiration from decomposing wood of angiosperms and gymnosperms in a subtropical forest. Nutrient additions significantly increased wood microbial respiration via fungal composition, but effects varied with nutrient types and taxonomic groups. Specifically, phosphorus addition significantly increased wood microbial respiration (65%) through decreased acid phosphatase activity and increased abundance of fast-decaying fungi (e.g., white rot), while nitrogen addition marginally increased it (30%). Phosphorus addition caused a greater increase in microbial respiration in gymnosperms than in angiosperms (83.3% vs. 46.9%), which was associated with an increase in Basidiomycota:Ascomycota operational taxonomic unit abundance in gymnosperms but a decrease in angiosperms. The temperature dependencies of microbial respiration were remarkably constant across nutrient levels, consistent with metabolic scaling theory hypotheses. This is because there was no significant interaction between temperature and wood phosphorus availability or fungal composition, or the interaction among the three factors. Our results highlight the key role of tree identity in regulating nutrient response of wood microbial respiration through controlling fungal composition. Given that the range of angiosperm species may expand under climate warming and forest management, our data suggest that expansion will decrease nutrient effects on forest carbon cycling in forests previously dominated by gymnosperm species.

Using Radiometric and Categorical Change to Create High-Accuracy Maps of Historical Land Cover Change in Watersheds of the Great Lakes Basin

Great Lakes Basin landscapes are undergoing rapid land cover and land use (LCLU) change. The goal for this study was to identify changes in land cover occurring in the Great Lakes Basin over three time periods to provide insights into historical land cover changes occurring on a bi-national watershed scale. To quantify potential impacts of anthropogenic changes on important yet vulnerable Great Lakes Wetland ecosystems, the historical changes in land cover over time are assessed via remote sensing. The goal is to better understand legacy effects on current conditions, including wetland gain and loss and the impacts of upland ecosystems on wetland health and water quality. Three key time periods with respect to Great Lakes water level changes and coastal wetland plant invasions were mapped using Landsat-derived land cover maps: 1985, 1995, and 2010. To address change between the three time periods of interest, we incorporate both radiometric and categorical change analysis and open-source tools available for assessing time series data including LandTrendr and TimeSync. Results include maps of annual land cover transition from 1985 to 1995 and 1995 to 2010 basin-wide and by ecoregion and an assessment of the magnitude and direction of change by land cover type. Basin-wide validated change results show approximately 776,854 ha of land changed from c.1980–1995 and approximately 998,400 ha of land changed from c.1995–2010. Both time periods displayed large net decreases in both deciduous forest and agricultural land and net increases in suburban cover. Change by ecoregion is reviewed in this study with many of the change types in central plains showing change in and out of agriculture and suburban land covers, the mixed wood plain ecoregion consisted of a mixture of agricultural, suburban, and forestry changes, and all top five change types in the mixed wood shield consisted of various stages of the forestry cycle for both time periods. In comparison with previous LCLU change studies, overall change products showed similar trends. The discussion reviews why, while most changes had accuracies better than 84%, accuracies found for change from urban to other classes and from other classes to agriculture were lower due to unique aspects of change in these classes which are not relevant for most change analyses applications. The study found a consistent loss in the deciduous forest area for much of the time studied, which is shown to influence the aquatic nitrogen implicated in the expansion of the invasive plant Phragmites australis in the Great Lakes Basin. This underscores the importance of LCLU maps, which allow for the quantification of historical land change in the watersheds of the Great Lakes where invasive species are expanding.

The spatiotemporal profile and adaptation determine the joint effects and interactions of multiple stressors

BackgroundBiodiversity is declining worldwide as ecosystems are increasingly threatened by multiple stressors associated with anthropogenic global change. Stressors frequently co-occur across scales spatially and temporally, resulting in joint effects that are additive or non-additive, i.e., antagonism or synergism. Forecasting and counteracting threats from intensifying stressors requires improved mechanistic understanding of joint effects, which is currently relatively low. To date, research on multiple stressors has been biased toward simplified scenarios, emphasized classification of interactions over realized joint effects, and mostly ignored adaptation (i.e., phenotypic plasticity or evolving life-history traits) of organisms. To investigate if more a realistic scenarios design incorporating complex spatiotemporal stressor profiles and adaption change joint effects and interactions of multiple stressors compared to simplified scenarios, we modified a spatially explicit meta-population model for a generic freshwater insect. We used the model to simulate different, hypothetical spatiotemporal profiles of a continuous and a discrete stressor and evaluated their joint effects and interactions. Agricultural land use represented the continuous stressor impacting meta-population patch quality and network connectivity and related scenarios implied different trajectories. Climatic events represented the discrete stressor impacting all patches simultaneously by temporary mortality events, with related scenarios implying different event severity. Adaptation mitigated the effects of climatic events based on previous events.ResultsExcluding adaptation, we found that at higher levels of the discrete stressor (i.e., strong and frequent climatic events) it strongly dominates the joint effects, while at a low level (i.e., weak and infrequent climatic events) of the discrete stressor, the continuous stressor (i.e., land use) dominates. Yet, the continuous stressor always defined the interaction type, with decreasing land use stress leading to antagonism, and increasing land use stress leading to synergism. Adaptation reduced joint effects under decreasing land use stress, yet had little compensatory influence under increasing land use stress. Moreover, adaptation changed interaction sizes inconsistently across the different land use and climate scenarios, with change depending on the climate scenario. Here, interactions decreased in the moderate scenario but increased in the severe and intense scenarios.ConclusionsWe highlight that realistic stressor scenarios accounting for potential adaptation are critical for a mechanistic understanding of how species respond to global change. To our knowledge, this is the first modeling study to show that stressor interactions depend on complex spatiotemporal stressor profiles and adaptation, following general principles.

Seabirds show foraging site and route fidelity but demonstrate flexibility in response to local information

BackgroundFidelity to a given foraging location or route may be beneficial when environmental conditions are predictable but costly if conditions deteriorate or become unpredictable. Understanding the magnitude of fidelity displayed by different species and the processes that drive or erode it is therefore vital for understanding how fidelity may shape the demographic consequences of anthropogenic change. In particular, understanding the information that individuals may use to adjust their fidelity will facilitate improved predictions of how fidelity may change as environments change and the extent to which it will buffer individuals against such changes.MethodsWe used movement data collected during the breeding season across eight years for common guillemots, Atlantic puffins, razorbills, and black-legged kittiwakes breeding on the Isle of May, Scotland to understand: (1) whether foraging site/route fidelity occurred within and between years, (2) whether the degree of fidelity between trips was predicted by personal foraging effort, and (3) whether different individuals made more similar trips when they overlapped in time at the colony prior to departure and/or when out at sea suggesting the use of the same local environmental cues or information on the decisions made by con- and heterospecifics.ResultsAll species exhibited site and route fidelity both within- and between-years, and fidelity between trips in guillemots and razorbills was related to metrics of foraging effort, suggesting they adjust fidelity to their personal foraging experience. We also found evidence that individuals used local environmental cues of prey location or availability and/or information gained by observing conspecifics when choosing foraging routes, particularly in puffins, where trips of individuals that overlapped temporally at the colony or out at sea were more similar.ConclusionsThe fidelity shown by these seabird species has the potential to put them at greater risk in the face of environmental change by driving individuals to continue using areas being degraded by anthropogenic pressures. However, our results suggest that individuals show some flexibility in their fidelity, which may promote resilience under environmental change. The benefits of this flexibility are likely to depend on numerous factors, including the rapidity and spatial scale of environmental change and the reliability of the information individuals use to choose foraging sites or routes, thus highlighting the need to better understand how organisms combine cues, prior experience, and other sources of information to make movement decisions.

Characterizing spatio-temporal variations of dimethyl sulfide in the Yellow and East China Sea based on BP neural network

Dimethyl sulfide (DMS), an organic volatile sulfide produced from Dimethylsulfoniopropionate (DMSP), exerts a significant impact on the global climate change. Utilizing published literature data spanning from 2005 to 2020, a BP neural network (BPNN) model of the surface seawater DMS in the Yellow and East China Sea (YECS) was developed to elucidate the influence of various marine factors on the DMS cycle. Results indicated that the six parameters inputted BPNN model, that include the time (month), latitude and longitude, sea-surface chlorophyll a (Chl-a), sea-surface temperature (SST), and sea-surface salinity (SSS), yielded the optimized simulation results (R2 = 0.71). The optimized estimation of surface seawater DMS in the YECS were proved to be closely aligned with the observed data across all seasons, which demonstrated the model’s robust applicability. DMS concentration in surface seawater were found to be affected by multiple factors such as Chl-a and SST. Comparative analysis of the three environmental parameters revealed that Chl-a exhibited the most significant correlation with surface seawater DMS concentration in the YECS (R2 = 0.20). This underscores the pivotal role of chlorophyll in phytoplankton photosynthesis and DMS production, emphasizing its importance as a non-negligible factor in the study of DMS and its sulfur derivatives. Furthermore, surface seawater DMS concentration in the YECS exhibited positive correlations with Chl-a and SST, while displaying a negative correlation with SSS. The DMS concentration in the YECS show substantial seasonal variations, with the maximum value (5.69 nmol/L) in summer followed in decreasing order by spring (3.96 nmol/L), autumn (3.18 nmol/L), and winter (1.60 nmol/L). In the YECS, there was a gradual decrease of DMS concentration from the nearshore to the offshore, especially with the highest DMS concentration concentrated in the Yangtze River Estuary Basin and the south-central coastal part off the Zhejiang Province. Apart from being largely composed by the release of large amounts of nutrients from anthropogenic activities and changes in ocean temperature, the spatial and temporal variability of DMS may be driven by additional physicochemical parameters.

GEOTOURIST OBJECTS AND ROUTESOF THE SIAN LOWLAND

The geomorphological, geological, and archaeological objects of the Sian Lowlandhave been studied, and their significance as potentially popular geotourist attractions has been substantiated. The Sian Lowlandis located in the northwestern part of the Ukrainian Carpathian Foreland and is a constituent geomorphological element of the Sian-Dniester interfluve. The lowland’s relief is smooth, characterized by the alternation of ridge-like elevations of the Vyshnia‒Vizhomlia, Vizhomlia‒Shklo, Shklo‒Zavadivkainterstreams and shallow trough-shaped river valleys with gently inclined non-terraced slopes and often waterlogged bottoms. The topography of the Vyshniaand Shklo valleys is varied with dunes concentrated in two strips – one stretches along the right side of the Vyshnia river valley through the villages of Malniv, Martyny, Sokolia, ArlamivskaVolia, Khorosnytsia and Zarichchia, and the other one is developed in the Shklo river valley between Krakivets and Yavoriv. The northeastern part of the Sian Lowland has undergone a significant anthropogenic transformation – the Shklo River channel has been regulated, and a complex of anthropogenic landforms and deposits has been formed within the boundaries of the Yavoriv mining district: karst processes and phenomena have been activated. Less large-scale anthropogenic changes have occurred in the lowland’s southern part, which is proposed to be covered by a geotourist route that will run through Rodatychi ‒ SudovaVyshnia ‒ Zarichchia‒Khorosnytsia ‒ ArlamivskaVolia ‒ Sulkivshchyna. The main geotourist attractions here are the following geological, geomorphological and archaeological objects: the preserved valley of glacial meltwater runoff between Rodatychi and SudovaVyshnaya, which is now drained by the Rakivriver, as well as the dunes spread in the valley and the archeological monument KniazhyiMist; eolian, fluvial landforms and deposits, outcrops of fluvioglacial accumulations and archaeological sites developed in the vicinity of the villages of Zarichchiaand Pisky:a complex of eolian and fluvial landforms and deposits, as well as archaeological sites, developed nearKhorosnytsia village; eolian landforms and deposits, an archaeological site near the village of ArlamivskaVolia; glacial accumulations, which were discovered in a quarry located east of the village of Sulkivshchyna (north of Mostyska). These settlements are connected to each other and to Lviv by the M-11 highway (Lviv‒Mostyska‒Shehyni) and/or the Lviv‒Shehynirailway line, which provides convenient access to the proposed geotourist attractions. The developed geotourist route also makes it possible to unite the so far separate Carpathian, Carpathian Foreland and Roztoczegeotourist routes into a single network. Key words: geotourist attractions; Sian Lowland; eolian deposits; dune; terrace; fluvial landform; archaeological site.

The effect of fluvial avulsion on the Holocene chronostratigraphic record and the agricultural signal of the world's largest coastal lagoonal system

This study identified the occurrence of Holocene chronology hiatuses in the sedimentary record of the Patos-Mirim system caused by river avulsion processes, as well as evidence of sharp anthropogenic changes in the surrounding region of the lagoon water bodies. The presence of chronology hiatuses demonstrates the importance of considering the disturbance effect of paleo-drainage processes on the paleoenvironmental resolution and expression of the sedimentary record of such coastal plains. Anthropogenic activities especially those related to agriculture and forestry have increased significantly during the great acceleration, resulting in modifications of both the landscape and the environmental conditions of the lagoon bodies. Such impacts were clearly reflected in the sedimentary record where abrupt changes in palynological trends, sedimentary DNA, isotopic and granulometric analyses were inferred. The climatic conditions combined with regressive sea level can explain the chronology hiatuses. Pollen analyses demonstrated changes in the landscape, particularly indicated by the shift from Cyperaceae to Poaceae dominance after the 1960 CE. Therefore, all proxies together demonstrate the modification in the landscape and changes in the environment, clearly influenced by anthropogenic action from unsustainable agricultural practices.

Wolverine population density and home range size in Arctic Alaska

AbstractUnderstanding the spatial requirements of exploited wildlife species, including population density and home range size, is important for wildlife management and conservation. Wolverines (Gulo gulo) are hunted and trapped across the Arctic, and are vulnerable to numerous, often interrelated, threats resulting from anthropogenic changes in their environment. Previous population density estimates for wolverines in the Arctic range tenfold, from the lowest to highest available for the species, limiting their utility outside the specific areas and times they were derived. The most recent density estimate in Arctic Alaska, USA, was produced 4 decades ago and was derived from a relatively small study area. We evaluated wolverine population density and home range size across the North Slope of Alaska during 2017–2022 using global positioning system (GPS)‐based collar data and spatial capture‐recapture models. Population density estimates were 2.0 individuals/1,000 km2 (95% credible interval = 1.3–3.5) in 2018 and 2.8 individuals/1,000 km2 (95% credible interval = 1.7–3.5) in 2021. Median home range sizes modeled with autocorrelated kernel density estimators and Ornstein‐Uhlenbeck foraging movement processes were 699 km2 (range = 158–2,895 km2) among 12 females and 2,332 km2 (range = 797–4,699 km2) among 10 males. These population density estimates are nearly 10 times lower than the previous estimate for Arctic Alaska. We recommend incorporating this information into management strategies to ensure sustainable harvest, particularly as the region's remote areas are more efficiently accessed by hunters and are being considered for transportation corridors supporting new industrial development.

52,000 years of woolly rhinoceros population dynamics reveal extinction mechanisms

The extinction of the woolly rhinoceros (Coelodonta antiquitatis) at the onset of the Holocene remains an enigma, with conflicting evidence regarding its cause and spatiotemporal dynamics. This partly reflects challenges in determining demographic responses of late Quaternary megafauna to climatic and anthropogenic causal drivers with available genetic and paleontological techniques. Here, we show that elucidating mechanisms of ancient extinctions can benefit from a detailed understanding of fine-scale metapopulation dynamics, operating over many millennia. Using an abundant fossil record, ancient DNA, and high-resolution simulation models, we untangle the ecological mechanisms and causal drivers that are likely to have been integral in the decline and later extinction of the woolly rhinoceros. Our 52,000-y reconstruction of distribution-wide metapopulation dynamics supports a pathway to extinction that began long before the Holocene, when the combination of cooling temperatures and low but sustained hunting by humans trapped woolly rhinoceroses in suboptimal habitats along the southern edge of their range. Modeling indicates that this ecological trap intensified after the end of the last ice age, preventing colonization of newly formed suitable habitats, weakening stabilizing metapopulation processes, triggering the extinction of the woolly rhinoceros in the early Holocene. Our findings suggest that fragmentation and resultant metapopulation dynamics should be explicitly considered in explanations of late Quaternary megafauna extinctions, sending a clarion call to the fragility of the remaining large-bodied grazers restricted to disjunct fragments of poor-quality habitat due to anthropogenic environmental change.