High Human Impact Research Articles

Pervasive changes in algal indicators since pre-industrial times: A paleolimnological study of changes in primary production and diatom assemblages from ~200 Canadian lakes

Anthropogenic stressors affect lakes around the world, ranging in scale from catchment-specific pollutants to the global impacts of climate change. Canada has a large number and diversity of lakes, yet it is not well understood how, where, and when human impacts have affected these lakes at a national scale. The NSERC Canadian Lake Pulse Network sought to create the first nationwide database of Canadian lake health, undertaking a multi-year survey of 664 lakes spanning 12 ecozones across Canada. A key objective of the network is to determine where, by how much, and why have Canadian lakes changed during the Anthropocene. To address this objective, we compared sedimentary chlorophyll a and diatoms from modern and pre-industrial sediment intervals of ~200 lakes. The lakes spanned a range of sizes, ecozones, and degrees of within-catchment land use change. We inferred the quantity of chlorophyll a, its isomers and main diagenetic products using visible reflectance spectroscopy. We found widespread increases in primary production since pre-industrial times. Primary production increased, on average, across all ecozones, human impact classes, and stratification classes. Likewise, an increase in planktonic diatom taxa over time was detected in the majority of sampled lakes, likely due to recent climate warming. However, regional factors (ecozones) explained the most variation in modern diatom species assemblages as well as their temporal turnover. Furthermore, lakes with high human impact (i.e., higher weighted proportions of human land use in the catchment) exhibited greater taxonomic turnover than lakes with a low human impact class. The greatest diatom turnover was found in the agriculture-rich Prairies and the lowest in the sparsely populated Boreal Shield and Taiga Cordillera ecozones. Overall, our study highlights that drivers operating at different geographic scales (i.e., climatic and land-use changes) have led to significant alterations in algal indicators since pre-industrial times across the country.

Ecosystem Service Values in the Dongting Lake Eco-Economic Zone and the Synergistic Impact of Its Driving Factors.

Ecosystem service values (ESVs) are crucial to ecological conservation and restoration, urban and rural planning, and sustainable development of land. Therefore, it is important to study ESVs and their driving factors in the Dongting Lake Eco-Economic Zone (Dongting Lake). This paper quantifies the changes in ESVs in the Dongting Lake using land use data from 2000, 2005, 2010 and 2018. The eXtreme Gradient Boosting (XGBoost) model is used to study the effects of individual driving factors and the synergistic effects of these driving factors on ESVs. Our analysis suggests that: (1) From 2000 to 2018, the largest dynamic degree values in the Dongting Lake are in unused land types, followed by construction lands and wetlands. The ESVs of the Dongting Lake show an increasing trend, with those of forestlands being the highest, accounting for approximately 44.65% of the total value. Among the ESVs functions, water containment, waste treatment, soil formation and protection, biodiversity conservation and climate regulation contribute the most to ESVs, with a combined contribution of 76.64% to 76.99%; (2) The integrated intensity of anthropogenic disturbance shows a U-shaped spatial distribution, decreasing from U1 to U3. The driving factors in descending order of importance are the human impact index, total primary productivity (GPP), slope, elevation, population, temperature, gross domestic product, precipitation and PM2.5; (3) When the GPP is low (GPP < 900), the SHAP (SHapley Additive exPlanation) value of the high human impact index is greater than zero, indicating that an increase in GPP increases the ESVs in the Dongting Lake. This study can provide technical support and a theoretical basis for ecological environmental protection and ecosystem management in the Dongting Lake.

Human activities increase vigilance, movement and home range size of the endangered mountain nyala (Tragelaphus buxtoni) at the cost of foraging and resting

Behavioral responses in wildlife due to human activities may often go unnoticed but have significant effects on population viability. This is a particular concern with endangered species characterized by small population sizes. From June 2016 to May 2017, we measured the effects of human activities on daily the activity budget and home range size of mountain nyala ( Tragelaphus buxtoni ), an endemic antelope of the Ethiopian highlands. We tracked two groups of mountain nyala from two study sites that differ in the level of human activities; Adaba-Dodola Community Conservation Area (Adaba-Dodola CCA) and Arsi Mountains National Park (Arsi Mountains NP). Our results showed that the time spent on vigilance and movement was dramatically higher in Adaba-Dodola Community CCA, where human presence is significant, than in Arsi Mountains NP, whereas the opposite was true for time spent foraging and resting. In addition, mean home range size (95% KDE) was significantly larger for the Adaba-Dodola CCA group (13 ± 7.4 km 2 ) than for the Arsi Mountains NP group (6.3 ± 2.7 km 2 ) covering larger areas during the dry season (18.7 ± 6.9 km 2 ) than the wet season (4.9 ± 1.0 km 2 ). The finding that increased investment in vigilance and movement trade-off against the restorative behaviors of foraging and resting in human-disturbed areas have implications for conservation managements; specifically, it underscores the need to (i) establish the fitness consequences of behavioral changes, and (ii) monitoring behavioral change in the disturbed population with the aim of bringing it closer to the undisturbed baseline. The study highlights the importance of protected areas, limiting human activities and monitoring the behavioral change of endangered species in human-disturbed areas. • Mountain nyala spent more time on vigilance and movement at the cost of restorative behaviors in high human impact areas. • High human activities lead to significantly larger home range size of mountain nyala. • The study highlights the importance of limiting human activities and monitoring behavioral changes in endangered species.

Differential influence of human impacts on age‐specific demography underpins trends in an African elephant population

AbstractDiagnosing age‐specific influences on demographic trends and their drivers in at‐risk wildlife species can support the development of targeted conservation interventions. Such information also underpins understanding of life history. Here, we assess age‐specific demography in wild African elephants, a species whose life history is marked by long life and extreme parental investment. During the 20‐yr study, survival and its variation were similar between adults and juveniles in contrast to relationships found among many large‐bodied mammals. Prospective analysis on age‐specific Leslie matrices for females demonstrated survival is more influential than fecundity on λ, with sensitivity of both decreasing with age. Results aggregated by stage classes indicate young adults (9–18 yr) demonstrated the highest elasticity, followed by preparous juveniles (3–8 yr). Mature adults (36+ yr) had the lowest aggregate elasticity value. Retrospective analysis parameterized by data from the early and latter periods of the study, characterized by low then high human impact (faster and slower growth, respectively), demonstrated fecundity (particularly for adults; 19–35 yr) explained the greatest variation in λ observed during the period of low human impact, while survival (particularly juvenile and adult) was more influential during the high human impact period. The oldest females (mature adult stage) weakly influenced population growth despite demonstrating the highest fecundity and their behavioral importance in elephant society. Multiple regression models on survival showed the negative effects of human impacts and population size were the strongest correlates across sexes and ages. Annual rainfall, our metric for environmental conditions, was weakly informative. The presence of dependent young was positively correlated with survival for breeding females, suggesting condition‐based mortality filtering during pregnancy. Notwithstanding the stabilizing effect of high juvenile survival on elephant population growth, demographic processes in elephants were similar to those shaping life history in other large herbivores. Implications of the study results with respect to the conservation of elephants and analysis of demographic impact of poaching are discussed, along with the study's relevance to theories regarding the evolution of life history and parental care.

Modeling the 20th-century distribution changes of Microgyne trifurcata, a rare plant of the southern South American grasslands

Microgyne trifurcata is a rare native plant species from one of the areas with the highest human impact on the environment in southern South America. Its habitat, mostly grasslands suitable for agriculture, has been increasingly covered by crops since the late 1800s. Microgyne trifurcata provides an excellent case study to understand how different environmental variables have affected the distribution area of a rare species. This study aims to estimate the impact of topoclimatic and land-use changes in the distribution of Microgyne trifurcata throughout the twentieth century. We carried out recent past and present distribution modeling using the Ensembles of Small Models (ESM) methodology. In this spatio-temporal study, we included climatic, topographic, and land-use variables. We classified the occurrences into two periods of the twentieth century. The first dates from 1901 to 1940, and the second, from 1960 to 2000, when the main cropping changes of the area occurred. The projected area between 1960 and 2000 provides for this species new suitable habitats toward the northeast of the area of study. Our results highlight the importance of assessing the combined impacts of climate and land-use changes on species distributions over time. This study shows that the potential area of Microgyne trifurcata decreased and underwent fragmentation throughout the twentieth century when these variables combined are used to model its distribution. Our outcomes prompt future studies on the vulnerability of Microgyne trifurcata to outline conservation strategies.

Functional groups of hoverflies inSoutheast Europeacross different vegetation types

AbstractTo better understand the relationship between biodiversity and ecosystem functioning, it is increasingly accepted that the focus of study needs to shift from taxonomic identity to the diversity of functional traits displayed by species within a community. Such an approach allows species to be grouped according to particular functional characteristics. Increasingly viewed as an extremely important group of model organisms, hoverflies have been the focus of a variety of ecological studies. Based on data regarding selected functional traits of hoverflies registered in Southeast Europe, the main aims of our study were to define hoverfly functional groups according to the similarity of these traits, as well as to compare the representation of delineated hoverfly functional groups among these vegetation types. We used fuzzy clustering to classify 568 SE European hoverfly species into five functional groups. The principle trait separating these functional groups was larval feeding type, followed by size of species range, flight ability, number of generations, inundation tolerance, and tolerance to human impact. For 9 of 11 vegetation types, the dominant functional group was characterized by species with good flight ability, having high human impact tolerance and more annual generations. The remaining two vegetation types, South‐west Balkan sub‐Mediterranean mixed oak forests and Mediterranean mixed forests, showed disparate dominance patterns, indicating that richness of functional groups is dependent on vegetation. Further investigation of whether and how established conservation measures enable recovery of the functional richness affected by habitat disturbance would help elucidate the importance of functional diversity in preserving biodiversity.

First days at sea: depicting migration patterns of juvenile seabirds in highly impacted seascapes.

Increasing human activities have detrimental consequences on marine ecosystems and their impact can have cumulative effects. Within marine ecosystems, seabirds respond to ecosystem variability and face multiple human pressures, especially threatened species. In long-lived species, juveniles and immatures could represent up to 50% of the total population, but their migratory movements remain largely unknown. Here, we depict the migratory patterns of juvenile Balearic shearwaters Puffinus mauretanicus, the most threatened European seabird, using miniaturised satellite transmitters. At the end of the 2012 breeding season, five tagged juveniles left the breeding colonies of Eivissa Island (western Mediterranean) the first week of July. They moved westwards to reach the Atlantic Ocean between 3 and 13 days afterwards. Juveniles showed a two-phase migratory pattern: they first travelled slower close to the breeding colonies, and then moved towards their wintering areas in the Atlantic Ocean by rapid directional movements. Environmental cues (e.g.,marine productivity, water mass distribution, frontal systems) might have a prominent role in driving the migratory patterns of juvenile Balearic shearwaters, moving from warm and poor marine areas in the Mediterranean Sea to cooler and rich non-breeding grounds in the Atlantic Ocean. Based on observational findings, we observed certain spatial overlap of juvenile Balearic shearwaters with areas of high human impact, but the relationship between flying travel speed and both fishing effort and cumulative human impacts were not statistically significant. These results suggest that more research is needed to assess whether the movement patterns of migrating juveniles are affected by human activities. Therefore, understanding the at-sea spatial ecology of juveniles should be a priority for research and conservation due to the importance of this population component in long-lived species, as well as assessing their vulnerability to multiple anthropogenic pressures.

Nest site selection of White-tailed Hawks (Geranoaetus albicaudatus) on Texas barrier islands

The distribution of the White-tailed Hawk (Geranoaetus albicaudatus) in the United States is restricted to the prairies and savannas of the Gulf Coastal Plain of Texas. Although listed as a state threatened species, it remains one of the least studied raptors in North America. It appears to reach high densities on some Texas barrier islands despite the island vegetation communities being structurally simple and providing few nesting substrates. We compared vegetation and landscape characteristics for sets of White-tailed Hawk nest sites and random sites on 3 Texas barrier islands (Matagorda, Mustang, and North Padre) representing a gradient of low to high human presence and impact. We constructed model sets consisting of vegetation and landscape features measured at a random subsample of nest sites and random sites, then assessed model sets with logistic regression. Our best constructed model correctly differentiated 83% of nest sites from random sites on Matagorda Island, 70% on Mustang Island, and 50% on North Padre Island. Overall, it appears that the structure of nest substrates was important to White-tailed Hawk nest-site selection: shrubs categorized as densely structured with or without thorns accounted for 78% of nest substrates compared to only 13% of paired, random potential substrates. The most frequently selected nest substrates overall were yaupon (Ilex vomitoria; 43%) and Macartney rose (Rosa bracteata; 24%). If White-tailed Hawks are to be conserved on the barrier islands, a balance will need to be found between continued anthropogenic development, maintenance of habitat patches, and availability of suitable nesting substrates.

Multi-trophic level responses to environmental stressors over the past ~150 years: Insights from a lake-rich region of the world

Multiple stressors affect water quality and biodiversity in lakes worldwide. However, our understanding of which combinations of stressors are of greatest impact and how lakes have shifted from their pre-industrial baselines is fragmented. Questions remain regarding how multiple trophic groups are affected by global change stressors and whether region-specific differences need to be considered. Here, we apply multiple factor analyses together with latent variable modeling to quantify potential interactions within and among taxa that span multiple trophic levels (i.e. diatoms, cladocerans and chironomids) to improve our understanding of paleo-environmental dynamics from a suite of Canadian lakes spanning four ecozones: the Boreal Shield, the Mixedwood Plains, the Atlantic Highlands, and the Atlantic Maritimes. Across all ecozones, multi-trophic assemblages were distinguished in a multiple factor analysis along a land-use gradient, with mesotrophic/eutrophic diatoms and profundal chironomids tolerant of low bottom-water oxygen concentrations recorded in more disturbed sites. Functional units across three indicator groups formed distinct networks of co-responses to key environmental and land-use gradients, although cladocerans seemed to be driven by additional (i.e., residual) gradients. Applying a temporal beta-diversity approach between modern and pre-industrial assemblages, we detected significantly greater turnover of diatom functional groups in high versus low human impact sites (p = 0.03, n = 57), with similar but non-significant trends apparent with the chironomid and cladoceran groups. Ecozonal differences in temporal turnover were also evident in diatom (p = 0.003, n = 57) and chironomid functional groups (p = 0.04, n = 41). The ecozonal differences may be partially due to differential sensitivities of the pre-industrial assemblages and may also be driven by historical disturbances. Our work highlights how the magnitude and direction of ecological change vary across ecozones and can modify responses to human impacts, with a general trend of higher species turnover in sites with greater human disturbance.

Human‐induced reduction in mammalian movements impacts seed dispersal in the tropics

Seed dispersal is a key process affecting the structure, composition and spatial dynamics of plant populations. Numerous plant species in the tropics rely upon animals to disperse their seeds. Humans have altered mammalian movements, which will likely affect seed dispersal distances (SDD). Altered SDD may have a range of consequences for plant communities including reduced seedling recruitment and plant biomass, seed trait homogenization, altered gene flow and a reduced capacity to respond to environmental changes. Therefore, modelling the consequences of altered animal behaviour on ecosystem processes is important for predicting how ecosystems will respond to human impacts. While previous research has focused on the link between animal species extirpation and SDD, it remains unclear how changes in mammalian movement will impact SDD. Here we implemented a mechanistic modelling approach to examine how mammalian movement reductions impact SDD in the tropics. We combined allometric theory with a mechanistic seed dispersal model to estimate SDD via the movement of 37 large frugivorous mammals (&gt; 10 kg) in the tropics under different levels of human footprint, a global proxy of direct and indirect human disturbances. Our results suggest that assemblage‐level SDD reductions are estimated to be up to 80% across the tropics in response to human disturbance. This is particularly the case in areas with high human impact such as agricultural landscapes and suburban areas. The region with the largest reductions in SDD was the Asia‐Pacific with average reductions of 25%, followed by Central–South America (16%) and then Africa (15%). Our study provides insights into how human‐induced changes in movement behaviour of large mammals could translate into altered ecosystem functioning.

Relationships between macro-fungal dark diversity and habitat parameters using LiDAR

Despite the important role of fungi for ecosystems, relatively little is known about the factors underlying the dynamics of their diversity. Moreover, studies do not typically consider their dark diversity: the species absent from an otherwise suitable site. Here, we examined potential drivers of local fungal dark diversity in temperate woodland and open habitats using LiDAR and in-situ field measurements, combined with a systematically collected and geographically comprehensive macro-fungi and plant data set. For the first time, we also estimated species pools of fungi by considering both plant and fungi co-occurrences. The most important LiDAR variables for explaining fungal dark diversity were amplitude and echo ratio, which represent vegetation structure. These results suggest that the local fungal dark diversity is highest in production forests like plantations and lowest in more open forests and in open habitats with little woody vegetation. Plant species richness was the strongest explanatory factor overall and negatively correlated with local fungal dark diversity. Soil fertility showed a positive relationship with dark diversity in open habitats. These findings indicate that the local dark diversity of macro-fungi is highest in areas with a relatively high human impact (typically areas with low plant species richness and high soil fertility). Overall, this study brings novel insights into local macro-fungi dark diversity patterns, suggesting that a multitude of drivers related to both soil and vegetation act simultaneously to determine fungal dark diversity.

Ostrich population densities and temporal dynamics in coupled social-ecological systems: Suitable indicators for the ecological effectiveness of protected areas?

Assessing the ecological effectiveness of protected areas is a high priority in conservation biology and requires suitable indicators. Instead of using multiple species, single species can potentially be used as indicators to assess if conservation efforts are effective in maintaining species over time. Here, we assessed the suitability of ostrich (Struthio camelus massaicus) population densities and trends over time as indicators for the ecological effectiveness of four study areas (two national parks, a pastoral area, and a game-controlled area with manifold human impacts) in the Tarangire-Manyara ecosystem of northern Tanzania. Based on road transect surveys from 2011 to 2019, we estimated area- and season-specific population densities in a distance sampling framework and estimated temporal changes using generalized linear mixed models. Ostrich population densities and population trends over time were not associated with formal protection status. Ostriches in one national park occurred at highest densities and were constant over time, while densities were low in another national park and apparently declined over time. Ostriches in the pastoral area had the second-highest mean population density, while remaining constant over time. The study area with the highest human impact had lowest ostrich densities and a seemingly declining trend over time. Ostrich densities were positively correlated with time-matched population density estimates of nine out of ten ungulate species in the same study areas, suggesting that ostrich population densities broadly reflect those of large savanna mammals in this ecosystem. However, site-specific ostrich population trends over time were not closely correlated with trends of common large mammal species. Therefore, ostrich population densities appear as suitable management indicators to assess the broad ecological effectiveness of protected areas. However, ostrich population trajectories do not appear suitable as indicator surrogate to monitor trends of mammal populations over time.

Local Human Impacts Disrupt Relationships Between Benthic Reef Assemblages and Environmental Predictors

Human activities are changing ecosystems at an unprecedented rate, yet large-scale studies into how local human impacts alter natural systems and interact with other aspects of global change are still lacking. Here we provide empirical evidence that local human impacts fundamentally alter relationships between ecological communities and environmental drivers. Using tropical coral reefs as a study system, we investigated the influence of contrasting levels of local human impact using a spatially extensive dataset spanning 62 outer reefs around inhabited Pacific islands. We tested how local human impacts (low versus high determined using a threshold of 25 people km−2 reef) affected benthic community (i) structure, and (ii) relationships with environmental predictors using pre-defined models and model selection tools. Data on reef depth, benthic assemblages, and herbivorous fish communities were collected from field surveys. Additional data on thermal stress, storm exposure, and market gravity (a function of human population size and reef accessibility) were extracted from public repositories. Findings revealed that reefs subject to high local human impact were characterised by relatively more turf algae (>10% higher mean absolute coverage) and lower live coral cover (9% less mean absolute coverage) than reefs subject to low local human impact, but had similar macroalgal cover and coral morphological composition. Models based on spatio-physical predictors were significantly more accurate in explaining the variation of benthic assemblages at sites with low (mean adjusted-R2 = 0.35) rather than high local human impact, where relationships became much weaker (mean adjusted-R2 = 0.10). Model selection procedures also identified a distinct shift in the relative importance of different herbivorous fish functional groups in explaining benthic communities depending on the local human impact level. These results demonstrate that local human impacts alter natural systems and indicate that projecting climate change impacts may be particularly challenging at reefs close to higher human populations, where dependency and pressure on ecosystem services are highest.

Biodiversity and conservation of terricolous lichens and bryophytes in continental lowlands of northern Italy: the role of different dry habitat types

In dry habitats of European lowlands terricolous lichens and bryophytes are almost neglected in conservation practises, even if they may strongly contribute to biodiversity. This study aims at (a) testing the role of heathlands, acidic and calcareous dry grasslands for lichen and bryophyte diversity and conservation in lowland areas of northern Italy characterized by high human impact and habitat fragmentation; (b) detecting the effect of environmental drivers and vegetation dynamics on species richness and composition. Lichens, bryophytes, vascular plants, and environmental variables were recorded in 287 circular plots for 75 sites. Our results indicate that heathlands, acidic and calcareous dry grasslands host peculiar terricolous lichen and bryophyte communities that include several species of conservation concern. Thus, each habitat provides a complementary contribution to lichen and bryophyte diversity in continental lowland landscapes. Furthermore, in each habitat different factors drive species richness and composition with contrasting patterns between lichens and bryophytes. In terms of conservation, our results indicate that management of lowland dry habitats should act at both local and landscape scales. At local scale, vegetation dynamics should be controlled in order to avoid biodiversity loss due to vegetation dynamics and wood encroachment. At the landscape scale, patches of all the three habitats should be maintained to maximize regional diversity.

The global costs and benefits of expanding Marine Protected Areas

Marine ecosystems and the services they provide contribute greatly to human well-being but are becoming degraded in many areas around the world. The expansion of Marine Protected Areas (MPAs) has been advanced as a potential solution to this problem but their economic feasibility has hardly been studied. We conduct an economic assessment of the costs and benefits of six scenarios for the global expansion of MPAs. The analysis is conducted at a high spatial resolution, allowing the estimated costs and benefits to reflect the ecological and economic characteristics and context of each MPA and marine ecosystem. The results show that the global benefits of expanding MPAs exceed their costs by a factor 1.4–2.7 depending on the location and extent of MPA expansion. Targeting protection towards pristine areas with high biodiversity yields higher net returns than focusing on areas with low biodiversity or areas that have experienced high human impact.

Densities and drivers of sea turtle populations across Pacific coral reef ecosystems.

Sea turtle populations are often assessed at the regional to sub-basin scale from discrete indices of nesting abundance. While this may be practical and sometimes effective, widespread in-water surveys may enhance assessments by including additional demographics, locations, and revealing emerging population trends. Here, we describe sea turtle observations from 13 years of towed-diver surveys across 53 coral islands, atolls, and reefs in the Central, West, and South Pacific. These surveys covered more than 7,300 linear km, and observed more than 3,400 green (Chelonia mydas) and hawksbill (Eretmochelys imbricata) sea turtles. From these data, we estimated sea turtle densities, described trends across space and time, and modelled the influence of environmental and anthropogenic drivers. Both species were patchily distributed across spatial scales, and green turtles were 11 times more abundant than hawksbills. The Pacific Remote Island Areas had the highest densities of greens (3.62 turtles km-1, Jarvis Island), while American Samoa had the most hawksbills (0.12 turtles km-1, Ta’u Island). The Hawaiian Islands had the lowest turtle densities (island ave = 0.07 turtles km-1) yet the highest annual population growth (μ = 0.08, σ = 0.22), suggesting extensive management protections can yield positive conservation results. Densities peaked at 27.5°C SST, in areas of high productivity and low human impact, and were consistent with patterns of historic overexploitation. Though such intensive surveys have great value, they are logistically demanding and therefore have an uncertain budget and programmatic future. We hope the methods we described here may be applied to future comparatively low-cost surveys either with autonomous vehicles or with environmental DNA.

A millennium-long perspective of flood-related seasonal sediment yield in Mediterranean watersheds

Abstract Mediterranean mountains have been extremely vulnerable to land degradation and soil erosion due to climate factors (summer hydric stress, high storminess) and the long history of human pressure on these terrestrial ecosystems. The short-time span of instrumental monitoring datasets limits our ability to obtain a full depiction of the long-term drivers controlling flood intensity and frequency and soil erosion in Mediterranean watersheds. Here we have applied a novel methodology based on detailed microfacies analyses on annually-laminated (varved) lacustrine sediments to reconstruct floods and seasonal sediment yield and denudation rates in a mountainous Mediterranean watershed during the last 2775 years. The sediment yield reconstruction in this study agrees reasonably well with soil erosion rates from Pyrenean experimental watersheds supporting the validity of this methodology to assess the soil erosion and sediment production from a long-term perspective. The comparison with instrumental precipitation datasets demonstrates the different seasonal sensitivity of sediment yield to heavy rainfall magnitudes mostly depending on soil moisture conditions, soil and regolith erodibility and vegetation cover. During periods of reduced human impact in the watershed, the seasonal maxima in sediment production occurred in autumn, which corresponds to the season with more frequent and intense heavy rainfall in the region. The highest soil erosion rates occurred during periods with higher human impact in the watershed due to sustained burning, overgrazing and cereals cultivation that modified the seasonal sediment yield distribution, with the highest sediment production happening in winter. The most significant periods of increased sediment yield occurred during the Middle Ages (1168–1239 CE) and the 19th century (1844–1866 CE) due to an interplay between increased frequencies and magnitudes of heavy rainfall and intensive agropastoral activities in the lake's watershed. This study highlights the potential of seasonally-resolved archives to adequately evaluate the environmental drivers and mechanisms controlling flood dynamics and soil erosion at decadal to centennial time-scales in areas with strong seasonality.

Holocene succession patterns of land snails across temperate Europe: East to west variation related to glacial refugia, climate and human impact

Although Holocene mollusc succession has been described from many temperate European sites, no attempt to analyse diversity patterns across the continent from east to west has yet been done. Here, we assembled and quantitatively analysed 54 most representative Holocene successions categorized into five climatic and geomorphological regions. These were defined along a longitudinal transect across temperate Europe, i.e. West Carpathians, Bohemian Massif, West Continental, Atlantic France, and Atlantic England. We found a clear east-west gradient in the Holocene dynamic of land snail assemblages, correlating mainly with the changes in strictly forest species richness. Representation of these species increased towards the east in accordance with known position of glacial refugia in the Carpathian Mountains. The West Carpathians acted as a unique refugium, expressing the highest temporal stability of Holocene snail assemblages, with a sharp increase in strictly forest species richness already in the Early Holocene. In contrast, Atlantic regions, characterized by low elevation and low topographical heterogeneity, were always poor in number of strictly forest species with no or only shallow increase of their richness in the Holocene climatic optimum. Further reduction in the second half of the Holocene, along with the increase of strictly open-country species richness correlates with higher human impact on mollusc faunas in lowland and flat regions. These factors can explain the previously reported impoverishment of modern western European forest fauna and have apparently also contributed to regional diversity patterns throughout the Holocene. Among the regions, we found three types of successional trajectories in the composition changes of Holocene molluscs, mirroring the above mentioned east-west gradient, with the West Carpathians having the most distinctive fauna. Our results show that distance from glacial refugia, landscape topography, and also human impact importantly shaped the species richness dynamic and successional pathways of Holocene land-snail fauna across temperate Europe.

Time constraints imposed by anthropogenic environments alter social behaviour in longtailed macaques

Humans and their associated anthropogenic factors may strongly affect the demographics, activity and fragmentation of wild animal populations. Yet, the degree and nature of such impact on indicators of animals' social relationships remain largely under-investigated, despite the well-documented importance of strong social ties for an individual's health and fitness. Here, we examined whether interactions with humans may affect core aspects of social life in a primate species, by constraining the time available for individuals to engage in social interactions. Specifically, we predicted that individuals who spend more time monitoring or interacting with humans would reduce their time socializing with conspecifics (i.e. the time constraints hypothesis). Alternatively, human presence may result in increased levels of stress, leading to an increase in social behaviours that serve as a coping mechanism (i.e. the social stress hypothesis). We collected data between September 2016 and September 2017 on four groups of longtailed macaques, Macaca fascicularis, in Malaysia at two sites with differing levels of human impact. In support of the time constraints hypothesis, we found that at the site with moderate human impact, monkeys who monitored human activity more frequently engaged less often in grooming. In contrast, at the site with high human impact, we found evidence supporting the social stress hypothesis, as indicators of stress were positively associated with social interactions, although we could not link them to the presence of humans. Our results suggest that the nature of human impact on macaques' social behaviour is dependent upon the intensity of human activity and interaction with the macaques. These findings therefore provide insights into how humans may influence individual fitness and group social structure in animals living in an anthropogenic environment. More broadly, our results may lead to a better understanding of animal behaviour in anthropogenic environments, implementing conservation and population management strategies and mitigating human–wildlife conflict.

Human impact erodes chimpanzee behavioral diversity.

Chimpanzees possess a large number of behavioral and cultural traits among nonhuman species. The "disturbance hypothesis" predicts that human impact depletes resources and disrupts social learning processes necessary for behavioral and cultural transmission. We used a dataset of 144 chimpanzee communities, with information on 31 behaviors, to show that chimpanzees inhabiting areas with high human impact have a mean probability of occurrence reduced by 88%, across all behaviors, compared to low-impact areas. This behavioral diversity loss was evident irrespective of the grouping or categorization of behaviors. Therefore, human impact may not only be associated with the loss of populations and genetic diversity, but also affects how animals behave. Our results support the view that "culturally significant units" should be integrated into wildlife conservation.