How sympatric species with similar ecological requirements partition resources to reduce competition is a key question in community ecology. We tested whether forest musk deer (Moschus berezovskii) and Siberian roe deer (Capreolus pygargus) exhibit resource differentiation despite their sympatric distribution. This study was conducted in the Huanglong Mountains, China, using fecal DNA metabarcoding and microhabitat surveys. The largest numbers of fecal detection sites for both ungulate species were recorded in deciduous broad-leaved forest. Fecal detection sites attributed to forest musk deer had larger trees and higher herb species richness than those attributed to Siberian roe deer. Although the measured microhabitat characteristics at fecal detection sites showed substantial overlap between the two species, the observed overlap differed significantly from the null expectation. Dietary analyses revealed they collectively consumed 173 plant genera. Tree taxa had the highest relative read abundance in forest musk deer samples (62.18%), while shrub taxa dominated Siberian roe deer samples (51.94%). Siberian roe deer exhibited a significantly broader trophic niche than forest musk deer. Overall dietary overlap between the two ungulates was significantly different from random expectation. Species identification based on fecal morphology achieved only 70.40% accuracy. These findings support dietary differentiation and reveal interspecific differences in microhabitat characteristics measured at fecal detection sites, whereas habitat-specific use, selection, or preference could not be inferred. Additionally, we emphasize the necessity of molecular confirmation in sympatric ungulate studies. Protecting frequently detected dietary plants such as Morus and Quercus may benefit forest musk deer, whereas the potential importance of large trees and understory structure should be evaluated through standardized use-availability studies.
Coastal marine ecosystems have declined worldwide, threatening the biodiversity and human livelihoods they support. The range of threats is unclear for understudied marine ecosystems such as Pinnidae shellfish beds, a family of large semi-infaunal bivalves that form marine habitats on sedimentary seafloors globally. These bivalves support diverse marine communities and have long held commercial and cultural importance. Although Pinnidae populations have declined globally in recent decades, scientific knowledge remains fragmentary and skewed toward a single species, leaving no global overview of the threats they face. We conducted the first systematic literature review on the drivers of decline across the Pinnidae family globally, synthesizing 107 publications. We identified 24 drivers, grouped into pathogens, human impacts on water quality or physical disturbance, abiotic factors, and invasive species. Nearly half the literature identified pathogens as the primary driver (48.6%) – though this literature was almost entirely focused on Pinna nobilis – followed by human impacts (40.1%) and abiotic factors (24.3%) (note that papers could address multiple drivers). Pathogens, abiotic factors, and human damage accounted for the highest mortality. However, only 12 of the 55 Pinnidae species were represented in the literature, with most research (77.5%) focused on P. nobilis in the Mediterranean. For the other 11 species, abiotic factors emerged as the main driver, while pathogens were the least reported threat (8.3%). Most non-P. nobilis research occurred in Japan, Mexico, New Zealand, and China. Our review highlights major knowledge gaps across the family. Targeted research and conservation action are needed to identify and manage the drivers of decline to protect Pinnidae populations from increasing extinction risk.
Over the past two millennia, baobabs (Adansonia digitata L.) have dispersed across the globe via ancient trade routes that linked Africa to other parts of the world. Some of these introductions are over 1500 years old and thus surviving populations can be regarded as archaeophytes. One such population of baobabs, has become naturalised in the Dhofar Mountains of southern Oman. This study aimed to describe the structure and historical trends of this population, and to determine its origin. We found that the population exhibited a bell-shaped size-class distribution, comprising 18% juvenile and 82% adult trees, a size-class distribution slope of -0.01, a permutation index of 15 and fluctuating quotients. These results indicate an unstable population with past episodic recruitment and mortality, and that in recent years regeneration has been poor with the population is in decline. DNA sequence comparisons indicated that east Africa was the most probable origin of the population. However, overgrazing by domestic animals and infestation of mango stem-borer (Batocera rufomaculata) have raised conservation concerns. We therefore recommend that current planting initiatives and protection measures be continued and that the area is fenced from domestic animals and further research be conducted into biological control mechanisms to manage B. rufomaculata infestations.
Biodiversity loss continues to accelerate globally, with Protected Areas (PAs) serving as key tools for conservation. However, spatially explicit evidence on mammal distributions within many tropical PAs remains limited. This study addressed this gap by integrating systematic field surveys with species distribution modelling to map mammalian habitat suitability and richness in Inani National Park (INP), a coastal protected area in southeastern Bangladesh. Using transect surveys and camera trapping conducted in INP from November 2022 to November 2023, we recorded 23 mammal species, of which 19 were modelled by MaxEnt v3.4.4 using 1,124 georeferenced occurrence records. Habitat suitability was predicted using environmental variables including land cover, vegetation productivity (NDVI), topography, and distance to water bodies. Model performance was strong across all species (AUC = 0.801–0.855), indicating robust predictive reliability. Results showed that mammal distributions were primarily driven by land cover and proximity to streams and khals, while topographic variables played a minor role. Species richness was highest in riparian corridors and shrub with scattered tree habitats, particularly in the southern and western parts of the park. Agricultural and settlement areas supported very low suitability and richness, indicating strong habitat filtering in human-modified landscapes. Overall, INP supports a spatially structured mammal community, with semi-natural vegetation and riparian systems acting as key biodiversity refuges. These results provide the first fine-scale, multi-species distribution maps for the park and a baseline for long-term monitoring. They highlight the need to maintain habitat heterogeneity and protect riparian corridors to sustain mammal diversity under increasing anthropogenic pressure.
In the rapidly urbanizing Yangtze River Delta (YRD), natural habitats have been extensively modified into fragmented patches. The remnant hilly regions serve as critical biodiversity refuges, yet how mammalian communities respond to varying degrees of landscape fragmentation in this megacity cluster remains poorly understood. To address this gap, we conducted a systematic camera-trapping survey (December 2023–December 2024) across a fragmentation gradient in the northern YRD, encompassing three mountain ranges representing distinct isolation contexts: the Ningzhen Mountains (highly isolated urban islands), the Maoshan Mountains (intermediate isolation), and the Yili Mountains (relatively continuous habitat connected to the southern Tianmu range). Based on 31,893 effective camera-days across 100 sites, we recorded 12 native terrestrial mammal species. A pronounced south-to-north decline in species richness (Yili: 11 > Maoshan: 9 > Ningzhen: 8) and Shannon diversity was observed, consistent with increasing isolation along the fragmentation gradient. PERMANOVA confirmed significant compositional differences among ranges (R² = 0.207, p = 0.001). Redundancy Analysis (RDA) indicated that 22.2% of variation in community structure was explained by environmental predictors; domestic predator abundance, distance to built-up areas, and road proximity emerged as the primary significant drivers. Diel activity analysis of four generalist species further revealed that peak activity times shifted 5–7hours deeper into the night in Ningzhen relative to the reference Yili Mountains, suggesting that temporal plasticity represents an additional dimension of the anthropogenic filtering process. Our findings indicate that landscape fragmentation acts as a selective filter suppressing sensitive species while generating localized refuges for adaptable taxa (e.g., water deer, Hydropotes inermis, in Ningzhen). These results highlight the need for spatially stratified conservation strategies: prioritizing internal habitat quality for isolated urban islands while maintaining structural connectivity for continuous ranges to sustain the resilience of the YRD's ecological network.
The dhole (Cuon alpinus Pallas, 1811) is a highly social apex predator, but its behavioral plasticity remains poorly understood. We tested whether differences in environmental conditions and prey distribution between open and closed habitats drive divergent behavioral strategies in dholes, focusing on activity rhythms, group size, and behavioral diversity. Based on behavioral plasticity theory in social carnivores, we predicted that dholes in open habitats would show stronger seasonal shifts in activity rhythms, larger group sizes, and higher behavioral diversity than those in closed habitats. From January 2020 to November 2025, we systematically deployed 823 camera traps across the main distribution areas of dholes in China. Using a posture–act–environment (PAE) coding framework, we constructed the first comprehensive ethogram for the species, including 14 postures, 29 environments, and 82 acts, which were further organized into 12 primary and 78 secondary behaviors. Cross-habitat comparisons showed that open dholes formed larger groups (2.45 ± 0.14 vs. 1.74 ± 0.09 individuals) and exhibited stronger seasonal shifts in activity rhythms (Δ_open = 0.60 vs. Δ_closed = 0.90), but showed no significant difference in behavioral diversity. Generalized linear models indicated that group size was an important factor explaining variation in behavioral diversity across habitats. These results support the hypothesis that dholes in open habitats exhibit stronger behavioral plasticity and suggest that they respond to environmental heterogeneity and resource variation by adjusting activity timing, grouping strategy, and behavioral composition.
Urbanisation influences bat communities, yet the impacts in small settlements, particularly those that occur in mountain regions, remain poorly understood. We investigated how a human-modified mountain landscape influences bat species richness and activity along an urbanisation gradient in South Tyrol, northern Italy. Passive acoustic surveys across 32 sites recorded bat activity from 2019–2023. Environmental variables quantifying urban characteristics, habitat composition and configuration were measured at different spatial scales. We used generalised linear models and mixed models to assess the impact of settlement- and landscape-scale variables on bat species richness and activity. Bat activity and community composition did not differ significantly between villages, cities, or industrial sites, although species richness was significantly higher at villages compared to industrial sites. Small woody vegetation and proximity to forests positively influenced total bat activity, feeding activity, and Pipistrellus pipistrellus activity, whereas the number of forest patches surrounding settlements showed a negative correlation with total bat activity. At the species level, P. pipistrellus indicated a negative association with artificial light and larger forests surrounding settlements, while Pipistrellus kuhlii/P. nathusii showed a positive association with the presence of major rivers. Small settlements in mountain landscapes appear important but overlooked habitats for bat communities. Nevertheless, even highly urbanised areas, such as cities and industrial sites can support bat communities in mountain landscapes by providing settlement-scale vegetation and heterogeneous forest structure at the surrounding landscape-scale.
Camera trap images have been used to identify individual mammals that have unique pelage patterning, but details on how identification was achieved are often omitted, limiting reproducibility. Developing standardised frameworks for individual identification of mammals would greatly enhance rigour and consistency. The numbat (Myrmecobius fasciatus) is one such species where individual identification has been conducted, but details on how this was done were limited. Using images from four camera trap surveys conducted on an agricultural property in southwestern Australia, this study assessed the extent of variation and reliability of pelage features, and the extent to which putative individuals can be reidentified over time in the numbat. We also examined how individual identification can be used to track numbat movements and site fidelity relative to den logs in remnant vegetation. We successfully identified individual numbats using 16 phenotypic variables. Left and right flank stripe number and dorsal stripe patterning exhibited the greatest inter-individual variation and were consistently discernible in a high proportion of images. Putative individuals could be redetected after 2.5 years, providing circumstantial evidence of pelage pattern stability in adult numbats. We further demonstrated that distinct groups of individuals preferentially used different remnant vegetation patches and den logs. Our results explicitly define features best used for identification of individual numbats and highlight the importance of remnant vegetation and high den log availability for sustaining diverse numbat populations. This research illustrates the importance of developing systematic frameworks for establishing photo identification as a tool for examining mammal ecology.
Habitat compression increasingly confines Persian leopards (Panthera pardus tulliana) to the cores of protected areas, where refuge effects influence their spatial distribution and density. Understanding these patterns is crucial for effective habitat management, prey conservation, and mitigating intra- and interspecific competition. This study assessed Persian leopard density in Kiasar National Park and Dodangeh Wildlife Refuge across the cold and warm seasons, functioning as core habitats within the surrounding Hyrcanian–Alborz landscapes. Using camera traps and closed-population capture–recapture models over 12 months, we estimated seasonal leopard abundance and converted abundance estimates to density using a half mean maximum distance moved (HMMDM)-buffered effective sampling area. Camera traps recorded 18 individual Persian leopards (10 males and 8 females). HMMDM-based density estimates were 2.43 leopards/100km² in the cold season and 3.36 leopards/100km² in the warm season. Most individuals showed higher activity during the cold season. Our findings provide baseline information on Persian leopards in Kiasar National Park and Dodangeh Wildlife Refuge, highlighting these areas as relatively dense refuges for leopards in northern Iran. Individuals appear to concentrate in these areas, especially during the warm season, potentially due to habitat compression associated with livestock and human activities. To mitigate these pressures and their ecological consequences, expanding protected area boundaries, prioritizing prey-rich habitats, and maintaining continuous ranger patrols are essential, as they reduce habitat compression, lower intra- and interspecific competition, and enhance leopard survival.
Laos has historically supported a rich megafauna assemblage, much of which has been lost in modern times. We compiled and analyzed historical and contemporary evidence (ca. 1850–2026) to reconstruct trajectories, assess current status, and identify recovery prospects for Laos’s megafauna, focusing on rhinoceroses, tigers (Panthera tigris), and elephants (Elephas maximus). Javan (Eurhinoceros sondaicus) and Sumatran (Dicerorhinus sumatrensis) rhinoceroses occurred historically in Laos, with credible records continuing until approximately 1990, although the later records do not allow species-level attribution or determination of when each species disappeared. Both are now extirpated from the country. Tigers remained widespread into the early 2000s, but declined rapidly, with the last verified images from 2013; they are now considered extirpated, although limited potential for recovery may remain through recolonization or reintroduction. Asian elephants persist, but only an estimated 300–400 individuals remain across approximately 24 putative population units, 88% of which reportedly contain fewer than 20 individuals. Their demographics, connectivity, and long-term viability remain uncertain, although Nakai–Nam Theun and Nam Pouy are the two largest populations and likely have better persistence prospects than others. Reducing mortality and maintaining or restoring connectivity could improve prospects for smaller populations. Hunting for food and the wildlife trade—facilitated by widespread firearms, weak deterrence, and expanding infrastructure—have contributed to widespread faunal depletion and “empty forests.” Accelerating development may increase access, trade, and demand for wildlife products, but could also create opportunities for coordinated transboundary protection and enforcement. Recovery remains possible for some of Laos’s megafauna, but opportunities are rapidly narrowing.
Understanding the ecological mechanisms that underpin distribution patterns is critical for the effective management of marine species exhibiting cannibalism. This study evaluated the extent to which prey- density proxies improves distribution models of a cannibalistic predator relative to models based solely by oceanographic covariates. Specifically, we incorporated conspecific juvenile density as a proxy for potential intraspecific prey availability, allowing us to examine whether documented cannibalism has a detectable spatial signature in the distribution of larger individuals. Using seasonal bottom trawl survey data for Harpadon nehereus (Bombay duck) collected in the coastal East China Sea from 2016 to 2021, we developed three model formulations: (1) a Predator-Environmental (PE) model including abiotic predictors (temperature, salinity, sea level) with year as a temporal effect; (2) a Predator-Prey (PP) model including biotic predictors, using proxies for conspecific juvenile and alternative prey; and (3) a combined Predator-Biophysical (PB) model incorporating both abiotic and biotic variables. Model performance improved markedly when prey variables were included, and the combined model performed best across all seasons. Conspecific juvenile was a consistently positive predictor of larger individual distribution and generally provided greater explanatory value than alternative prey index. The association between conspecific juveniles and larger individuals also persisted after accounting for measured environmental conditions, year effects, and repeated sampling among stations, indicating that their spatial correspondence was not attributable solely to shared responses to the measured environment. Abiotic effects varied seasonally. In summer, temperature showed a unimodal relationship with larger individual density, with an apparent upper response point near 26.5°C within the study region. Seasonal predictions indicated that larger individuals were concentrated mainly in shallow inshore shelf waters and shift southward to offshore waters during winter. Collectively, these results support a detectable cannibalism-related spatial association and show that models based solely on abiotic covariates may overlook ecologically important variation associated with conspecific juveniles availability. Incorporating biologically informed indicators of intraspecific prey availability, alternative prey, and environmental conditions may improve the ecological interpretation of distribution models and support seasonally informed management of cannibalistic fish populations.
It is increasingly acknowledged that shifts in climate may lead to mismatches in the distribution of interacting species. However, the influence of biotic interactions on the distribution of insect species in tropical biomes, and the potential for climate change to disrupt these interactions, remain largely unexplored. We investigated the impacts of climate change on the distribution of six monophagous butterfly species endemic to South America’s Atlantic Forest, one of the most species-rich Global Biodiversity Hotspots. We compiled occurrence data from museum specimens and online sources to predict the distribution of the butterflies and their respective host plants using an ensemble modelling technique. We project that five of the six butterfly species and all host plant species will experience range contractions under a pessimistic climate scenario, with range losses of up to 79% for one butterfly (A. chalciope). Among areas projected to be climatically suitable for both butterflies and their host plants in the future, only around half are formally protected. Additionally, land-use constraints are substantial: ~25–80% of climatically suitable areas for the butterflies and their hosts consist of converted landscapes likely unsuitable for the species. Our results show that accounting for biotic interactions and land use can substantially reduce climate-based estimates of species distributions. If these findings extend to other specialised species interactions that have not yet been surveyed, they indicate that specialist species may be at greater risk from climate change than previously thought. Our study highlights the importance of incorporating biotic interactions and habitat suitability in biogeographical, ecological and conservation research.
Estuarine wetlands develop pronounced habitat heterogeneity along land-sea gradients, yet the differentiated responses of aquatic communities among vegetation habitats and their environmental drivers remain poorly understood. Focusing on four typical habitats in the Liaohe Estuary wetland — Phragmites australis wetland (PA), Suaeda salsa-Phragmites australis wetland (SP), Suaeda salsa wetland (SS), and mudflat wetland (MF) — this study systematically analyzed the community structure, biodiversity, density, and biomass of phytoplankton, zooplankton, benthic macroinvertebrates, and fish, as well as their responses to environmental factors. The results showed that aquatic communities in the Liaohe Estuary exhibited ordered succession and habitat specificity along the land-sea gradient. Salinity was the key driver shaping aquatic community patterns, its effects differed among different aquatic communities, suppressing phytoplankton diversity while promoting fish diversity. Dissolved oxygen showed a stronger bidirectional regulatory effect, being significantly positively correlated with fish community characteristics but significantly negatively correlated with phytoplankton community characteristics. Different vegetation types displayed marked functional differentiation and habitat complementary, SP sustained phytoplankton and benthic macroinvertebrate diversity, SS supported a highly even fish community, MF served as a key habitat for zooplankton and consumer communities, and PA maintained high primary-producer diversity, jointly sustaining the overall biodiversity of the Liaohe Estuary wetland. These findings indicate that the structural and functional stability of the Liaohe Estuary wetland ecosystem depends on the integrity of the land-sea continuum, as well as on environmental gradients.
Incidental capture (bycatch) in fisheries poses a significant threat to many marine mammals, including cetaceans. The harbour porpoise (Phocoena phocoena) is a small cetacean that ranges throughout temperate waters in the northern hemisphere which is specifically threatened by passive gear, such as set gillnets. Here, we investigate spatiotemporal patterns in bycatch rates (number of bycaught harbour porpoises bycaught per net-kilometre-day) in the Swedish gillnet fishery, and for the first time we assess harbour porpoise bycatch along the Swedish south coast. Despite that harbour porpoise population abundance is presumed to be higher on the Swedish west coast than along the Swedish south coast, bycatch rates were higher along the southern than the western coast. Although the distribution area of the critically endangered Baltic proper subpopulation includes the southern Baltic Sea, recorded bycatch events in this area occur during the second half of the year when these individuals are expected to have moved further north in the Baltic Sea. Hence, the porpoises bycaught along the Swedish south coast are more likely belonging to the endangered Belt Sea subpopulation, rather than the critically endangered Baltic Sea subpopulation. Our estimates also indicate a declining trend in the number of bycaught individuals, likely reflecting reduced gillnet fishing effort over time, as annual variation in bycatch rate could not be estimated due to data limitations. Overall, our results enhance the understanding of spatiotemporal patterns in harbour porpoise bycatch in the transition zone between the North Sea and the Baltic Sea, providing novel knowledge that may support management actions for this highly sensitive species.
Environmental conditions are a key aspect in shaping space-use and habitat selection of large herbivores. However, how weather extremes, such as prolonged periods of low precipitation, impact habitat selection processes in temperate ecosystems remains understudied. Understanding these dynamics is increasingly urgent, as climate change is expected to intensify the frequency and duration of low-precipitation periods. This study aimed to assess how selection of wet habitats by the European bison (Bison bonasus), the largest European herbivore with high water requirements, changed under varying precipitation levels in summer. Using GPS data of 22 European bison in the Polish part of the Białowieża Primaeval Forest, we tested the effect of sex and precipitation on the selection of the wettest habitats within individual bison summer ranges by means of a step-selection analysis, and predicted selection under different precipitation levels. Our results showed that female bison showed a stronger selection for wet habitats than males, but we found no difference between the sexes for precipitation-dependent selection. Precipitation influenced habitat selection, but primarily among individuals whose summer ranges included a greater availability of wet habitats. Bison occurring in the wettest part of the forest increased their selection of wet habitats under low precipitation levels, whereas no such selection was observed for periods of high precipitation. In contrast, bison occupying drier habitat ranges showed no selection for wet habitats, regardless of precipitation. Overall, these findings suggest that the relationship between habitat selection and precipitation depends on the wetness of the summer ranges occupied by bison. Our findings expand our understanding of how large herbivores respond to environmental variability in temperate forests, suggesting the importance of wet habitats for these animals in the context of climate change.
Mediterranean mountain ecosystems host a unique and highly endemic flora, yet they are increasingly threatened by global change, including the spread of invasive plant species. While elevational gradients are known to structure biodiversity and invasion patterns, the combined role of anthropogenic disturbance and environmental heterogeneity across spatial scales remains insufficiently understood. In this study, we assessed patterns of plant invasion and its association with total species richness, J’Pielou evenness and plant diversity (Shannon-Wiener and Simpson indices) across six mountain roads spanning broad environmental gradients in the southern Iberian Peninsula. We surveyed plant communities both along roadsides and in adjacent natural vegetation and evaluated the relative importance of broad scale environmental gradients (captured by elevation), spatial variation among roads, soil microhabitat conditions and anthropogenic influence, in shaping plant invasive species occurrence, and plant species richness, evenness and diversity indices. Our results show limited plant invasive species occurrence, with invasive species largely confined to roadsides. Plant invasion occurrence was positively associated with Shannon diversity, whereas no significant effects were detected for dominance or evenness, a pattern consistent with an early stage of invasion. Elevation emerged as a key driver of both invasion occurrence and species richness, while soil microhabitat conditions, particularly soil moisture and temperature, played a central role in shaping evenness and diversity. Road proximity significantly increased both invasion probability and species richness. These findings highlight the need for complementary assessments of diversity and prioritize roads for monitoring and early management to safeguard plant biodiversity in Mediterranean mountain landscapes.
Global climate change threatens biodiversity, in part due to its effects on species distributions and habitat suitability. The ability to predict future impacts and discern variability in rates of change is critical for conservation planning. Here, we quantified the relative influence of climate and tree species metrics on contemporary and future patterns of incidence (i.e., an index of broad-scale habitat conditions and a metric of habitat suitability) associated with forest-breeding birds across the eastern USA and assessed trends in decadal trajectories of future projections. We hypothesized that potential future tree species distributions will modify decadal trajectories of bird species habitat suitability predicted by climate change, with differential outcomes associated with tree species remaining static or shifting dynamically over time. We used North American Breeding Bird Survey data and randomForest models to evaluate the incidence of 100 forest bird species and quantify the pace of predicted change based on climate alone and in conjunction with static and lagged tree distributions. For 90 forest bird species, our results showed that future tree species distributions altered either the overall trajectory (n = 83) or timing (n = 50) of changes in projections of habitat suitability expected from climate effects only. In particular, maintaining contemporary tree species distributions into the future moderated climate-associated declines in habitat suitability for 78 bird species. Decadal trajectories emphasized the importance of timing, with the greatest declines occurring for 16-30 bird species within the first three decades of the century, depending on the future scenario. Ultimately, these findings underscore the importance of climate-informed, time-sensitive conservation plans for forests and the birds breeding within them.
The effects of land-use composition and spatial configuration on biodiversity have been widely assessed in agroecosystems, yet whether complementary dimensions of diversity respond similarly to these landscape attributes remains unclear. This limitation is particularly evident for vertebrate taxa that are difficult to survey at landscape scales, including small mammals, which play key roles in agroecosystems. Here, we used barn owl (Tyto alba) pellet analysis to investigate how landscape structure shapes multiple dimensions of small mammal diversity in Mediterranean agroecosystems in northeastern Portugal. We characterized small mammal assemblages at 40 nest sites using morphological identification and quantified diversity with Hill numbers (q = 0, 1, 2), capturing complementary dimensions of diversity, from species richness to dominance-weighted diversity. We then related variation in landscape composition and configuration to small mammal diversity metrics using generalized linear mixed models. Species richness (q0) showed the strongest response to landscape variables, declining with increasing olive grove cover and shape complexity of olive groves and urban areas, while increasing with shrubland cover and chestnut woodland patch density. Abundance-weighted diversity metrics showed weaker and more differentiated responses, with diversity of order q1 (common species) showing a unimodal relationship with agricultural cover and a declining trend with increasing shape complexity of agricultural land, and q2 (dominant species) declining at high levels of agricultural cover, while showing a declining trend with its shape complexity and a positive trend with wetland density. Overall, our results reveal contrasting responses among richness, common-species and dominant-species diversity to landscape composition and configuration, highlighting the value of integrating multiple diversity measures in agroecosystem assessment and management.
The Ailao Mountains in Yunnan contain China’s largest contiguous area of subtropical mid-mountain, humid, evergreen broad-leaved forests, which serve as a core carbon sink for the region. This study characterized the community structure of these forests and assessed changes in species diversity, biomass, and carbon sequestration potential using long-term monitoring data collected in 2010, 2015, and 2020. The key findings were as follows: (1) The canopy layer exhibited a stable community structure, with Castanopsis wattii, Lithocarpus xylocarpus, and Schima noronhae consistently ranking as the top three species by importance value from 2010 to 2020. Species composition in the understory changed frequently, although dominant species maintained stable positions. Carbon stocks of major tree species either varied slightly among years or increased steadily, with the most significant increases occurring between 2015 and 2020. (2) Species diversity across all strata showed an overall upward trend between 2010 and 2020, indicating a more diverse community composition. (3) Carbon stocks in forest communities continued to grow; their carbon sink capacity increased, and the total carbon stock of the entire forest community in the Ailao Mountains is approximately 1.75 × 107 Mg C. These findings support a pivotal role for mid-mountain humid evergreen broad-leaved forests in the Ailao Mountains in maintaining the regional carbon balance. However, constraints on seedling regeneration warrant further attention to safeguard long-term carbon sink capacity.
The modeling of ecological risks to aquatic ecosystems often introduces additional analytical steps by relying on proxy indicators for clustering analyses, which can increase uncertainty and may not accurately capture the actual risks to ecosystems. In response, we have developed a model in which ecological risk responses are directly clustered. This modeling approach was applied to the Pinglu Canal during its operational period. First, we identified eight aquatic ecological risk response bundles (AERRBs) through clustering analysis, revealing distinct spatial patterns of ecological risk responses. Next, a Bayesian Network (BN) was developed to model the causal relationships among the risk sources, receptors, and responses, offering a dynamic adaptive framework for understanding and managing risks. By adjusting the response nodes in the BN based on the characteristics of each risk response bundle, we simulated risk changes under various scenarios, enabling targeted risk management strategies in the canal. The main conclusions are as follows. (1) Bundles 3, 6, and 8 account for 43.54%, 16.57%, and 20.94% of the total area of the Pinglu Canal, respectively, making them the most prominent AERRBs. (2) The Xijin Reservoir zone is dominated by bundles 6 and 8. The cross-ridge section of the Pinglu Canal is dominated by bundle 3 in K30–K37 and bundle 8 in the other sections. The main ecological conservation zone was dominated by bundle 2 in the main waterway, and bundle 3 in the ecological conservation and drinking water source protection zones. The densely populated zone was predominantly influenced by bundles 5 and 6, whereas the concentrated wetland distribution zone was influenced by bundles 6 and 7. (3) The aggregation of aquatic ecological risks represented by AERRBs, combined with the causal inference functionality of BN, facilitated the management of different ecological risk sources and receptors in key canal sections. Moreover, this method, which integrates the spatial distribution pattern of ecological risk responses and causal analysis, is also applicable to the aquatic ecological risk management of canals worldwide.
