Anthropogenic Land Use Change Research Articles

Effect of land-use and land-cover change on mangrove soil carbon fraction and metal pollution risk in Zhangjiang Estuary, China

Land-use and land-cover change (LULCC) is the main cause of mangrove deforestation and degradation. However, the effect of LULCC on mangrove soil organic carbon (SOC) fractions and metal pollution risks, and the difference between the effects of those two soil evolutions are largely unknown. Here, we collected soil samples from natural systems (mangroves and mudflat), land-cover changes (Spartina alterniflora invasion), and anthropogenic land-use changes (cropland and culture pond) in Zhangjiang Estuary. We determined the soil aggregate fractions (macro-aggregate, micro-aggregate, and silt-clay fraction) and the associated carbon, and heavy metal dynamics. Our findings suggested that LULCC did not remarkably affect SOC contents, but changed the soil aggregate structures. LULCC significantly increased aggregate-associated carbon fractions, especially macro-aggregate carbon fraction. The large proportion of silt-clay fraction in natural systems was corresponding to a high percentage of mineral organic carbon, indicating that LULCC decreases the mangrove SOC stability. Land-cover change promoted the accumulation of SOC, nitrogen, and heavy metals compared with uninvaded mudflat. The heavy metal contents in mangrove soil were highest among all studied soils, expect for Cd, which suggested that mangrove soil had high metal accumulation. However, land-use changes could stimulate the mobility and dynamics of metals enriched in mangrove soils; these changes, especially in cropland, will also cause a large amount of exogenous Cd being exported into the adjacent aquatic environment. Thus, mangrove shifts metal pollutant from sink to source when affected by land-use changes. The contamination index demonstrated that heavy metals have posed ecological risks, especially for Cd in cropland. Compared with mangrove, land-use change was dominated by single-element pollution, but land-cover change showed low multiple-element complex pollution. These findings elucidate the effects of LULCC on mangrove SOC fraction and metal pollution risk, and are of great significance for designing the long-term management and conservation policies for mangrove managers.

Spatial variation of organic carbon sequestration in large lakes and implications for carbon stock quantification

Lakes are recognized as critical zones for carbon transformation and storage, and lacustrine sediments sequestrate considerable amounts of organic carbon (OC). Understanding sedimentation processes and OC burial patterns is crucial to clarifying lakes’ role in global carbon cycling. However, OC sedimentation may be quite spatially heterogeneous within an aquatic system, owing to the differences in OC production and sources, hydrodynamic conditions and underwater topography. The uncertainties in estimating OC sequestration in the world’s large lakes remain poorly constrained. This study takes the test case of two large lakes (50 and 249 km2) with different water depth and trophic status, using a multi-core paleolimnological technique, to identify the spatial variation in OC accumulation and its main influencing factors over the past century. Results of multi-core comparisons revealed similar temporal trends in major organic and nutrient parameters, suggesting coherent processes of whole-lake sedimentary environment changes for each lake. The OC preserved in sediments was primarily of autochthonous origin. However, OC standing stocks varied ∼3-fold spatially, and average OC accumulation rates ranged between 9.5–27.4 g m−2 yr−1 (post–1963 in oligo-mesotrophic deep-lake Lugu) and between 17.4–43.5 g m−2 yr−1 (post–1980 in eutrophic shallow-lake Erhai), respectively. These variations were primarily attributable to the spatial differences in aquatic primary production and terrestrial detritus supply relating to anthropogenic land-use change and phosphorus loading, rather than intra-lake sediment focusing-related transport and redistribution. The single central-core approach from Lugu Lake would overestimate whole-lake OC stock by 32% or underestimate the value by 48%, indicating spatial variability is an important source of uncertainty for OC stock quantification in similar large and/or morphometrically complex waterbodies. Therefore, spatial heterogeneity of OC accumulation in inland waters requires considerable research with well-placed multi-cores to provide a deeper understanding of carbon sequestration patterns and mechanisms.

Signals of Holocene climate transition amplified by anthropogenic land-use changes in the westerly–Indian monsoon realm

Abstract. The Indian summer monsoon (ISM) rainfall is the lifeline for people living on the Indian subcontinent today and was possibly the driver of the rise and fall of early agricultural societies in the past. The intensity and position of the ISM have shifted in response to orbitally forced thermal land–ocean contrasts. At the northwestern monsoon margins, interactions between the subtropical westerly jet (STWJ) and the ISM constitute a tipping element in the Earth's climate system because their non-linear interaction may be a first-order influence on rainfall. We reconstructed marine sea surface temperature (SST), supply of terrestrial material and vegetation changes from a very well-dated sediment core from the northern Arabian Sea to reconstruct the STWJ–ISM interaction. The Holocene record (from 11 000 years) shows a distinct, but gradual, southward displacement of the ISM in the Early to Mid-Holocene, increasingly punctuated by phases of intensified STWJ events that are coeval with interruptions of North Atlantic overturning circulation (Bond events). The effects of the non-linear interactions culminate between 4.6 and 3 ka BP, marking a climatic transition period during which the ISM shifted southwards and the influence of STWJ became prominent. The lithogenic matter input shows an up to 4-fold increase after this time period, probably related to the strengthened influence of agricultural activities of the Indus civilization, with enhanced erosion of soils. This anthropogenic land-use change is amplifying the impact of Bond events and adding to the marine sedimentation rates adjacent to the continent.

Spatiotemporal variability of water ecosystem services can be effectively quantified by a composite indicator approach

Ecological restoration will be promoted globally as a strategic solution supporting the relevant sustainable development goals including land degradation neutrality. However, this restorative approach is facing challenges from climate change and anthropogenic land-use change. One of these acute challenges is to balance ecological restoration and water ecosystem services particularly in dryland areas that are the most vulnerable to land degradation and climate change. Therefore, it is critical to understand the spatiotemporal variability of water ecosystem services in a changing environment on a regional scale. To gain this understanding, this paper formulates a composite indicator approach by integrating gross primary productivity (GPP) and waterbodies derived from remote sensing with key soil, climate, and topographic variables. The water ecosystem service index (WESI) was quantified in 10 watersheds of the Chinese Loess Plateau (CLP) region during 2000–2018 and found to be correlated positively with the surface runoff of these watersheds at high confidence levels. Then WESI is used in the whole CLP. The results of WESI indicate that about 90% of the CLP is low in water ecosystem services and about 45% of the CLP experienced significant increases for water ecosystem services under the impacts of large scale vegetation restoration, climate change, and land-use change. The WESI approach provides an efficient alternative to the complex modelling approaches that need much more ground based monitoring data. The WESI is useful for mapping the spatial pattern and temporal trends of regional water ecosystem services that are critical for ecological restoration and land-use planning in a changing environment.

Gaps, biases, and future directions in research on the impacts of anthropogenic land-use change on aquatic ecosystems: a topic-based bibliometric analysis.

Anthropogenic land use change (ALUC) satisfies human needs but also impacts aquatic ecosystems. Aquatic ecosystems are intrinsically linked with terrestrial landscapes, an association that is already recognized as a key factor to address future research and effective governance. However, the complexity and range of the impact of ALUC in aquatic ecosystems have been fundamental challenges and have implicitly routed the analysis to particular segments, drivers, management, or effects of the theme. In this study, we present an attempt to frame the subject in a broader context through a topic-based bibliometric analysis. Our aim is to identify possible biases and gaps in the current scientific literature and detect the main topics that have characterized the theme. Our results show an unequal distribution of articles by country when we analyzed the authors' affiliation and also a slight increase in contributions from social and economic disciplines, although they are still underrepresented. Moreover, we distinguish topics whose prevalence seems to change, especially those topics where the use of scenario analysis and multi-stressors are considered. We discuss the main biases and gaps revealed by our results, concluding that future studies on the impact of ALUC on aquatic ecosystems should better integrate social and economic disciplines and expand geographic frontiers.

Peridomestic conditions affect La Crosse virus entomological risk by modifying the habitat use patterns of its mosquito vectors.

Anthropogenic land-use change may affect the transmission risk for endemic vector-borne diseases such as La Crosse encephalitis. In this study, we applied a comparative ecological approach to evaluate differences in vector species abundance, gonotrophic status, and environmental variables among six residential habitats (historical case houses) and six paired adjacent forest patches in a La Crosse virus endemic area of North Carolina. A total of 93,158 container Aedes spp. eggs were obtained by ovistrips and 1,040 resting mosquito adults were collected by large-bore aspiration from 10 June through 8 October, 2010. At sites characterized by high densities of artificial containers, the totals of eggs and adult mosquitoes were higher in the peridomestic plots. At sites characterized by lower densities of artificial containers, the totals of eggs and adult mosquitoes were higher in the forested plots. Although Aedes triseriatus, the primary La Crosse virus vector, was more commonly found in forested habitat overall, in sites characterized by high density of artificial containers, it was found in higher abundance in the peridomestic habitat. Similarly, the proportion of gonotrophically active (parous and gravid) mosquitoes was higher in the peridomestic habitat for sites with highartificial container density. Our study suggests that La Crosse virus transmission risk may be higher at peridomestic habitats with higher densities of artificial containers and thus reinforces the importance of public health measures to improve source reduction efforts.

Land cover and weather jointly predict biometric indicators of phenotypic quality in a large herbivore

Body size and body mass are key indicators of individual phenotypic quality and predictors of important life-history traits such as survival and reproductive success. In wild herbivores, individual responses to changing environmental conditions influence morphometric traits over temporal scales and between populations. However, little research has assessed joint effects of weather and land use on body size/mass at finer, intra-population scale. We used data collected on female and juvenile red deer Cervus elaphus shot over a 17-year period (2001–2017) along two sides of a mountainous ridge largely differing in land cover and habitat productivity, to investigate how fine-scale land use patterns and weather influenced multiple morphometric indicators of phenotypic quality. Accounting for weather, body mass of all sex/age classes increased with increasing proportion of cultivated areas in the landscape and, for young females and calves, that increase was stronger or occurred only in the “low-quality” site. Other biometric traits such as mandible length and hind foot length showed the same pattern in young and calves, suggesting that body mass/size reflects individual responses especially in the early life-stage. Accounting for land use, body mass of adult females and calves was enhanced by increasing rainfall and decreasing temperature in spring-summer, i.e. favourable conditions for vegetation growth. This result also supports late gestation- and lactation-mediated effects of vegetation productivity on offspring quality. Additionally, in male calves, body mass and several other traits increased with decreasing severity of the previous winter, suggesting that quality of male offspring - but not that of females - could depend on winter conditions experienced in utero, likely due to higher maternal costs. Our findings emphasise how land cover and weather jointly affect indicators of phenotypic quality in a large mammal, helping to predict size responses of herbivores under the ongoing climatic- and anthropogenic land use-changes.

Environmental drivers of ichthyofauna community composition of the river ecosystems draining the Lake St. Lucia basin, South Africa

Within South Africa, the St. Lucia Basin, comprising the White Mfolozi, Black Mfolozi, Mfolozi Hluhluwe-Mkuze sub-basins, is an ecologically important region. However, the river ecosystems and their inherent biota, especially the ichthyofauna, are inadequately studied. Considering the anthropogenic land-use change currently occurring and the concomitant elevated resource-use, we sought to ascertain the composition of the fish species communities within the basin and the environmental drivers influencing the spatial shifts in these communities to provide baseline information. We collected data from 20 sites in the basin from 2016 to 2018. A total of 4 420 individuals representing 24 fish species, from eight families, were recorded. Using generalised linear modelling, species count data were fitted to sub-catchment factor variables and habitat variables. We observed significant differences in the structure of the ichthyofauna communities between the sub-catchments as well as the environmental drivers to be substrate, mean depth, mean velocity, overhanging vegetation and woody debris. The Hluhluwe sub-catchment was the most diverse, while the White Mfolozi was the least diverse. Continued unsustainable use of the basin's water resources and poor land management practices are likely to shift the ichthyofauna communities into uniform, species-depauperate communities, potentially leading to a loss in ecosystem services and functioning.

South African raptors in urban landscapes: a review

Globally, but especially in Africa, increasing human populations and anthropogenic land-use change are generally affecting diversity negatively. Urban environments in southern Africa typically comprise a mosaic landscape of anthropogenic infrastructure with some green spaces. These urban cities have a range of fauna that have persisted or increased in population density compared with areas that are more natural. We analysed the occurrence of diurnal and nocturnal raptors using South African Bird Atlas Project (SABAP2) data and reviewed literature. We found 66 raptor species occurred in South African cities. Thirty species had reporting frequencies greater than 10% in at least one of the 11 cities assessed, revealing impressive diversity of the raptor clade in South African cities. Five species were both abundant and widespread, occurring >10% in five or more cities each, of which three belong to the scavenger guild: Black-winged Kite Elanus caeruleus, African Fish Eagle Haliaeetus vocifer, Common Buzzard Buteo buteo vulpinus, Yellow-billed Kite Milvus aegyptius and Black Sparrowhawk Accipiter melanoleucus. However, only a few of these 66 raptors had been extensively studied in urban areas: the Black Sparrowhawk, African Crowned Eagle Stephanoaetus coronatus, Lanner Falcon Falco biarmicus and Peregrine Falcon Falco peregrinus. This lack of research is specifically severe, given that Africa is hosting a unique and diverse range of raptor species and that numbers and diversity of raptors have declined dramatically over the past decades across the continent. In fact, these four extensively studied species occurred in higher densities in urban areas than rural areas, which indicates that urban areas might create valuable opportunities for urban conservation, not least through public engagement.

Land Use Dynamics and Optimization from 2000 to 2020 in East Guangdong Province, China

Anthropogenic land-use change is one of the main drivers of global environmental change. China has been on a fast track of land-use change since the Reform and Opening-up policy in 1978. In view of the situation, this study aims to optimize land use and provide a way to effectively coordinate the development and ecological protection in China. We took East Guangdong (EGD), an underdeveloped but populous region, as a case study. We used land-use changes indexes to demonstrate the land-use dynamics in EGD from 2000 to 2020, then identified the hot spots for fast-growing areas of built-up land and simulated land use in 2030 using the future land-use simulation (FLUS) model. The results indicated that the cropland and the built-up land changed in a large proportion during the study period. Then we established the ecological security pattern (ESP) according to the minimal cumulative resistance model (MCRM) based on the natural and socioeconomic factors. Corridors, buffer zones, and the key nodes were extracted by the MCRM to maintain landscape connectivity and key ecological processes of the study area. Moreover, the study showed the way to identify the conflict zones between future built-up land expansion with the corridors and buffer zones, which will be critical areas of consideration for future land-use management. Finally, some relevant policy recommendations are proposed based on the research result.

Organic carbon burial in a large, deep alpine lake (southwest China) in response to changes in climate, land use and nutrient supply over the past ~100 years

Inland waterbodies play an important role in the global carbon cycle, acting both as carbon sources with organic carbon (OC) mineralization and as sinks with OC burial in sediments. Under recent impacts of global warming, anthropogenic land-use change and nutrient supply, however, there is a limited knowledge regarding OC dynamics in sediments of large, deep lakes especially in subtropical alpine regions. Here, we studied the patterns of OC burial and the potential regulating factors using multiple sedimentary proxies and observational records in Lugu Lake (southwest China) over the past ~100 years. Comparisons of 15 sediment cores in different areas of the lake reveal similar temporal trends in OC content and other sediment parameters, indicating coherent patterns of whole-lake sedimentary environmental change dominated by watershed human perturbation. Based on C/N ratios and δ13Corg analyses, the sediment OC has primarily been autochthonous in source. OC accumulation rates (OCAR) increased during 1880–1980, from ~14 to 43 g C m−2 yr−1 in a central core (LGS), mainly resulting from elevated primary production under increased phosphorus input and soil erosion. Subsequently, OCAR decreased considerably to ~15 g C m−2 yr−1, although the phosphorus supply and lake primary productivity remained high. We infer the OCAR decline likely resulted from increased organic matter decomposition and OC mineralization in the water column because of climate warming and lake-water thermal stratification. This phenomenon might mask the positive contribution of primary production to OC burial. Our findings suggest that the commonly observed synergistically positive effects of warming and eutrophication on sediment OC burial may be impaired in deep lakes, which needs further investigations across ecological, climatic and land-use gradients.

Bird and small mammal community composition and abundance in upland open habitats and early conifer forests

Anthropogenic land-use change, such as commercial afforestation, is a significant driver of shifts in ecological communities and species abundance. In this study, the consequences of afforestation of upland habitats for two distinct animal groups, birds and small mammals, were examined by comparing open moorland, early pre-thicket conifer forests (2–4 years post-replanting) and late pre-thicket conifer forests (6–8 years post-replanting) across 24 upland study sites in Ireland. Field data were collected using bird point counts, live trapping of small mammals and detailed vegetation surveys. A total of 17 bird species and four small mammal species were detected. Both groups showed contrasting patterns of abundance between moorland and pre-thicket forests, with bird density being higher in moorland, while small mammal abundance was higher in pre-thicket forests. Bird diversity was lowest in moorland and highest in late pre-thicket forests, while small mammal diversity was highest in moorland and lowest in late pre-thicket forests. Our study shows that afforestation can alter the abundance and community composition of bird and small mammal populations and that the consequences of land-use change associated with afforestation in upland areas vary across different taxa. Our findings have important implications for forest management practices and conservation of upland habitats and species.

Drivers of Timberline Dynamics in Rodna Montains, Northern Carpathians, Romania, over the Last 131 Years

Currently, there is little information regarding the recent spatiotemporal dynamics of upper timberline in the Carpathian Mountains. We reconstructed the temporal (1887–2018) and spatial dynamics of upper timberline in the Rodna Mountains (Eastern Carpathians) based on seven sets of maps and aerial photographs and explained its variability in relation to three main drivers: air temperature, land morphometry and anthropogenic pressure. The impact of natural drivers (temperature, morphometry) on timberline position was evaluated using a high-resolution digital elevation model, local and regional instrumental and modelled climate databases. The impact of anthropogenic factors on timberline position was documented from published sources such as local paleolimnological studies and historical documents. Results show that timberline rose on average with 113 ± 2 m on the northern slope of the Rodna Mts (currently reaching 1640 m above sea level (a.s.l.)) and with 182 ± 2 m on the southern slope (up to an elevation of 1539 m a.s.l.). Our results suggest that this pattern might be connected with the rising temperature over the recent decades. On the northern slope where land morphometry restricts anthropogenic activities, timberline reached the highest elevation. On the more accessible southern slope, anthropogenic land-use changes likely moderated timberline elevational rise under increasing temperatures.

Intestinal Helminths in Wild Rodents from Native Forest and Exotic Pine Plantations (Pinus radiata) in Central Chile.

Simple SummaryLand-use changes are one of the most important drivers of zoonotic disease risk in humans, including helminths of wildlife origin. In this paper, we investigated the presence and prevalence of intestinal helminths in wild rodents, comparing this parasitism between a native forest and exotic Monterey pine plantations (adult and young plantations) in central Chile. By analyzing 1091 fecal samples of a variety of rodent species sampled over two years, we recorded several helminth families and genera, some of them potentially zoonotic. We did not find differences in the prevalence of helminths between habitat types, but other factors (rodent species and season of the year) were relevant to explain changes in helminth prevalence. Given that Monterey pine plantations are one of the most important forestry plantations worldwide, and due to the detection of potentially zoonotic helminths, more research should be conducted in this study area and elsewhere in order to better understand the effect of pine plantations on parasites and pathogens in rodents and other wildlife hosts.Native forests have been replaced by forestry plantations worldwide, impacting biodiversity. However, the effect of this anthropogenic land-use change on parasitism is poorly understood. One of the most important land-use change in Chile is the replacement of native forests by Monterey pine (Pinus radiata) plantations. In this study, we analyzed the parasitism (presence and prevalence) of intestinal helminths from fecal samples of wild rodents in three habitat types: native forests and adult and young pine plantations in central Chile. Small mammals were sampled seasonally for two years, and a total of 1091 fecal samples from seven small mammal species were analyzed using coprological analysis. We found several helminth families and genera, some of them potentially zoonotic. In addition, new rodent–parasite associations were reported for the first time. The overall helminth prevalence was 16.95%, and an effect of habitat type on prevalence was not observed. Other factors were more relevant for prevalence such rodent species for Hymenolepis sp. and season for Physaloptera sp. Our findings indicate that pine plantations do not increase helminth prevalence in rodents compared to native forests.

Local and Landscape Compositions Influence Stingless Bee Communities and Pollination Networks in Tropical Mixed Fruit Orchards, Thailand

Stingless bees are vital pollinators for both wild and crop plants, yet their communities have been affected and altered by anthropogenic land-use change. Additionally, few studies have directly addressed the consequences of land-use change for meliponines, and knowledge on how their communities change across gradients in surrounding landscape cover remains scarce. Here, we examine both how local and landscape-level compositions as well as forest proximity affect both meliponine species richness and abundance together with pollination networks across 30 mixed fruit orchards in Southern Thailand. The results reveal that most landscape-level factors significantly influenced both stingless bee richness and abundance. Surrounding forest cover has a strong positive direct effect on both factors, while agricultural and urbanized cover generally reduced both bee abundance and diversity. In the local habitat, there is a significant interaction between orchard size and floral richness with stingless bee richness. We also found that pollinator specialization in pollination networks decreased when the distance to the forest patch increased. Both local and landscape factors thus influenced meliponine assemblages, particularly the forest patches surrounding an orchard, which potentially act as a key reservoir for stingless bees and other pollinator taxa. Preservation of forest patches can protect the permanent nesting and foraging habitat of various pollinator taxa, resulting in high visitation for crop and wild plants.

Increases in the seaward river flux of nutrients driven by human migration and land-use changes in the tide-influenced delta

Most large megacities are located on areas adjacent to tide-influenced deltas. However, contribution of megacities to seaward nutrient fluxes in tide-influenced deltas are poorly quantified in regional and global levels. We analyzed nutrient concentrations and water current data for a large and tide-influenced delta, the Changjiang (Yangtze River) since 1980. Concentrations, species ratios and fluxes of nutrients in tide-influenced delta has been found to differ dramatically from those at upstream. Over the period 2004 to 2015, the seaward nutrient fluxes of dissolved inorganic nitrogen and dissolved silica increased by 5%–10%, but dissolved inorganic phosphorus increased by 15%–20%, in the tide-influenced delta of the Changjiang. Consequently, the DIP/DIN decreases by 11% and DIP/DSi increases by 14% at the river mouth relative to those farther upstream the tidal limit. The legacy and/or recycled contribution accounts for 10%–30% of this increased nutrient flux, hence additional sources are predominantly those involving anthropogenic land-use changes. These findings have implications not only for the Changjiang but also for other riverine systems with respect to management strategy. Nutrient dynamics in tide-influenced deltas near urban areas should receive increased research and policy attention. By not considering nutrient sources in tide-influenced deltas, knowledge of the seaward fluxes and species ratios of nutrients from land sources is incomplete and can be biased, to the point that assessments of their impacts on adjacent marine environments may be inaccurate and mitigation policies therefore ineffective.

Terrain gradient variations in ecosystem services of different vegetation types in mountainous regions: Vegetation resource conservation and sustainable development

Natural vegetation plays a vital role in ecosystem services, while anthropogenic land-use change causes extensive damage to natural vegetation, decreasing ecosystem services, and impacting human well-being. Therefore, it is of great significance to establish protected areas and implement vegetation protection measures. Ecosystem services depend on the vegetation type and terrain, but this topic has not been considered in detail in policy implementations. In this study, the Integrated Valuation of Ecosystem Services and Trade-offs (InVEST) model was used to evaluate water yield, carbon storage, soil conservation, and water purification in the Chuan-Dian ecological shelter. Statistical methods were applied to analyze the differences in ecosystem services of different vegetation types and determine spatial variations in ecosystem services along terrain (altitude, slope, landform relief, and terrain niche) gradients. The results showed that ecosystem services differed for different vegetation types, and natural forests provided higher ecosystem services than other vegetation types, except for water yield. The rational allocation of forests, shrubs, and grasses and the implementation of organic agriculture and agroforestry systems are important measures to ensure sustainable economic and ecological development. We used the ordered weighted average method to select priority conservation areas based on ecosystem services. The priority conservation areas can play an important role in vegetation management in mountainous regions. This study provides new perspectives for vegetation protection and sustainable development in large-scale mountain areas.

Up in the air: Threats to Afromontane biodiversity from climate change and habitat loss revealed by genetic monitoring of the Ethiopian Highlands bat.

While climate change is recognized as a major future threat to biodiversity, most species are currently threatened by extensive human‐induced habitat loss, fragmentation and degradation. Tropical high‐altitude alpine and montane forest ecosystems and their biodiversity are particularly sensitive to temperature increases under climate change, but they are also subject to accelerated pressures from land conversion and degradation due to a growing human population. We studied the combined effects of anthropogenic land‐use change, past and future climate changes and mountain range isolation on the endemic Ethiopian Highlands long‐eared bat, Plecotus balensis, an understudied bat that is restricted to the remnant natural high‐altitude Afroalpine and Afromontane habitats. We integrated ecological niche modelling, landscape genetics and model‐based inference to assess the genetic, geographic and demographic impacts of past and recent environmental changes. We show that mountain range isolation and historic climates shaped population structure and patterns of genetic variation, but recent anthropogenic land‐use change and habitat degradation are associated with a severe population decline and loss of genetic diversity. Models predict that the suitable niche of this bat has been progressively shrinking since the last glaciation period. This study highlights threats to Afroalpine and Afromontane biodiversity, squeezed to higher altitudes under climate change while losing genetic diversity and suffering population declines due to anthropogenic land‐use change. We conclude that the conservation of tropical montane biodiversity requires a holistic approach, using genetic, ecological and geographic information to understand the effects of environmental changes across temporal scales and simultaneously addressing the impacts of multiple threats.

Habitat disturbance influences the skin microbiome of a rediscovered neotropical-montane frog

BackgroundThe skin microbiome serves as a first line defense against pathogens in vertebrates. In amphibians, it has the potential to protect against the chytrid fungus Batrachochytrium dendrobatis (Bd), a likely agent of amphibian declines. Alteration of the microbiome associated with unfavorable environmental changes produced by anthropogenic activities may make the host more susceptible to pathogens. Some amphibian species that were thought to be “extinct” have been rediscovered years after population declines in the late 1980s probably due to evolved Bd-resistance and are now threatened by anthropogenic land-use changes. Understanding the effects of habitat disturbance on the host skin microbiome is relevant for understanding the health of these species, along with its susceptibility to pathogens such as Bd. Here, we investigate the influence of habitat alteration on the skin bacterial communities as well as specifically the putative Bd-inhibitory bacterial communities of the montane frog Lithobates vibicarius. This species, after years of not being observed, was rediscovered in small populations inhabiting undisturbed and disturbed landscapes, and with continuous presence of Bd.ResultsWe found that cutaneous bacterial communities of tadpoles and adults differed between undisturbed and disturbed habitats. The adults from disturbed habitats exhibited greater community dispersion than those from undisturbed habitats. We observed a higher richness of putative Bd-inhibitory bacterial strains in adults from disturbed habitats than in those from undisturbed habitats, as well as a greater number of these potential protective bacteria with a high relative abundance.ConclusionsOur findings support the microbial “Anna Karenina principle”, in which disturbance is hypothesized to cause greater microbial dispersion in communities, a so-called dysbiosis, which is a response of animal microbiomes to stress factors that decrease the ability of the host or its microbiome to regulate community composition. On the positive side, the high richness and relative abundance of putative Bd-inhibitory bacteria may indicate the development of a defense mechanism that enhances Bd-protection, attributed to a co-occurrence of more than 30-years of host and pathogen in these disturbed habitats. Our results provide important insight into the influence of human-modified landscapes on the skin microbiome and health implications of Bd-survivor species.

Resistance of mound-building termites to anthropogenic land-use change

Humans pose a major threat to many species through land-use change in virtually every habitat. However, the extent of this threat is largely unknown for invertebrates due to challenges with investigating their distributions at large scales. This knowledge gap is particularly troublesome for soil macrofauna because of the critical roles many of these organisms perform as ecosystem engineers. We used a combination of high-resolution airborne Light Detection and Ranging and deep learning models to map the distribution of the ecologically important termite genus Macrotermes across a South African savanna land-use gradient, quantifying the effects of land-use change on patterns of mound densities, heights and spatial patterning. Despite significant anthropogenic alteration to landscapes, termite mounds persisted and shared a number of similarities to mounds in untransformed areas. Mean mound height was not substantially reduced in transformed landscapes, and over-dispersion of mounds at localized scales was conserved. However, mound densities were partially reduced, and height distributions in transformed areas differed to those in protected areas. Our findings suggest that mound-building termites persist even in areas of relatively high human disturbance, but also highlight important differences in termite distributions that could lead to reductions in ecosystem services provided by termites in human-modified landscapes. The persistence of at least half of mounds in human-modified landscapes could serve as starting points for savanna restoration.