RÉSUMÉ
The concurrent impact of anthropogenic and bioclimatic factors on biodiversity is a key focus in macroecology and biogeographical considerations in conservation programs within riverine ecosystems. However, there is still a lack of understanding about how multidimensional alpha and beta diversity measures respond to anthropogenic and bioclimatic drivers. Here, we assess the variations in taxonomic, phylogenetic, and functional alpha and beta diversity of riverine macroinvertebrate communities across different watersheds in China. Our results show significant declines in most facets of alpha diversity across watersheds with low environmental heterogeneity, reflecting the loss of species with unique traits and evolutionary legacies. Both functional and phylogenetic beta-diversity values reveal a decreasing pattern along low heterogeneity environments, whereas taxonomic beta-diversity shows a contrasting pattern, which highlights the influence of microhabitat variation. Moreover, our findings identify nutrient levels, organic matter, water quality indicators, climatic variation, and geographic and habitat characteristics as key determinants of diversity patterns that are indicative of broader water pollution challenges. These factors jointly influence functional and phylogenetic alpha diversity and contribute to spatial homogenization, which is reflected in decreased functional and phylogenetic beta diversity. These trends highlight the complex interactions of chemical and physical factors in shaping biodiversity characteristics across watersheds. Based on the null model, macroinvertebrate communities primarily show random patterns, whereas clustering and overdispersion were sporadically observed in specific communities. We propose that conservation and restoration efforts should be aimed at enhancing aquatic biomes by managing extreme environmental conditions and amplifying spatial spillover, thereby supporting the intrinsic dynamics within natural metasystems and thus preserving the multidimensional aspects of biodiversity.
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The lack of systematic approaches and analyses to identify, quantify, and manage the biotic transport of microplastics (MPs) along cross-ecosystem landscapes prevents the current goals of sustainable environmental development from being met. This Perspective proposes a meta-ecosystem framework, which considers organismal and resource flows among ecosystems to shed light on the research and management challenges related to both abiotic and biotic MP transport at landscape levels. We discuss MP transport pathways through species movements and trophic transfers among ecosystems and sub-ecosystems, and highlight these pathways in the mitigation of MP pollution. The integration of biotic pathways across landscapes prioritizes management actions for MP transport using diverse approaches such as wastewater treatment and plastic removal policies to mitigate contamination. In addition, our framework emphasizes the potential sink enhancement of MPs through habitat conservation and enhancement of riparian vegetation. By considering the mechanisms of meta-ecosystem dynamics through the processes of biotic dispersal, accumulation, and the ultimate fate of MPs, advances in the environmental impact assessment and management of MP production can proceed more effectively.
Sujet(s)
Écosystème , Microplastiques , Surveillance de l'environnement , Matières plastiquesRÉSUMÉ
Global ecosystems are facing anthropogenic threats that affect their ecological functions and biodiversity. However, we still lack an understanding of how biodiversity can mediate the responses of ecosystems or communities to human disturbance across spatial gradients. Here, we examined how existing, spatial patterns of biodiversity influence the ecological effects of small hydropower plants (SHPs) on macroinvertebrates in river ecosystems. This study found that levels of biodiversity (e.g., number of species) can influence the degrees of its alterations by SHPs occurring along elevational gradients. The results of the study reveal that the construction of SHPs has various effects on biodiversity. For example, low-altitude areas with low biodiversity (species richness less than 12) showed a small increase in biodiversity compared to high-altitude areas (species richness more than 12) under SHP disturbances. The increases in the effective habitat area of the river segment could be a driver of the enhanced biodiversity in response to SHP effects. Changes in the numerically dominant species contributed to the overall level of community variation from disturbances. Location-specific strategies may mitigate the effects of SHPs and perhaps other disturbances.
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Écosystème , Rivières , Humains , Biodiversité , AltitudeRÉSUMÉ
BACKGROUND: Climate change poses uncertainties in the effectiveness of classical biological control (CBC), and there is a lack of information on the establishment of natural enemy populations under present and future climatic conditions. The objective is to explore current traces of two alien predators (Neoseiulus californicus and Neoseiulus fallacis; introduced for the CBC program in the 1980s) and their future expansion under climate change in Taiwan. RESULTS: The results indicated that N. californicus was present in alpine orchards (e.g., Lishan and Meifeng) but N. fallacis was not found. Under current climate condition, most areas in Taiwan were deemed highly suitable for N. californicus, but not for N. fallacis, which may explain the outcomes of the CBC program. With intensifying climate change, the ranges of both species are projected to contract to varying extents in Taiwan but expand in some countries. CONCLUSION: The findings from this study can provide insights for evaluating and developing future CBC programs worldwide, and can help predict the implications of climate change on biological control efforts. © 2023 Society of Chemical Industry.
Sujet(s)
Mites (acariens) , Animaux , Espèce introduite , Changement climatique , Lutte biologique contre les nuisibles/méthodes , Comportement prédateurRÉSUMÉ
The family Termitidae is renowned for its diverse nesting behaviors, with the evolution of epigeal and arboreal nests hypothesized to increase desiccation stress due to greater exposure to air. However, these nests may also alleviate desiccation stress through humidity regulation. To explore the implications of acquiring epigeal and arboreal nests, we investigated desiccation tolerance traits in 16 Termitidae termite species with varying nest types and analyzed trait correlations. Principal component analysis revealed that termites constructing epigeal and arboreal nests exhibited reduced water loss rates and enhanced survival under desiccated conditions. Furthermore, termites building arboreal nests displayed a notably higher water content. Redundancy analysis demonstrated that nest types accounted for a substantial portion (57.2%) of the observed variation in desiccation tolerance. These findings support the hypothesis that epigeal and arboreal nests in termites are associated with increased desiccation stress and increased desiccation tolerance. These findings highlight the role of nest type in influencing desiccation tolerance mechanisms and water regulation strategies in termites.
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Isoptera , Animaux , Isoptera/physiologie , Dessiccation , Eau , Comportement de nidification , HumiditéRÉSUMÉ
BACKGROUND: Urbanization has led to the proliferation of high-rise buildings, which have substantially influenced the distribution of dengue vectors, such as Aedes aegypti (L.). However, knowledge gaps exist regarding the individual and combined effects of architectural and spatiotemporal factors on dengue vector. This study investigated the interrelationship between Ae. aegypti presence, building architectural features, and spatiotemporal factors in urban environments. RESULTS: The mosquito Ae. aegypti presence varied by location and seasons, being higher in outdoor environments than in indoor environments. Lingya (Kaohsiung City, Taiwan) had the highest mosquito numbers, particularly in basement and first floor areas. Ae. aegypti was found on multiple floors within buildings, and their presence was greater in summer and autumn. The XGBoost model revealed that height within a building, temperature, humidity, resident density, and rainfall were key factors influencing mosquito presence, whereas openness had a relatively minor impact. CONCLUSION: To effectively address the problems caused by urbanization, the three-dimensional distribution of Ae. aegypti, including their spatial distribution across heights and areas within the urban environment, must be considered. By incorporating these multiple factors, this approach provides valuable insights for those responsible for urban planning and disease management strategies. Understanding the interplay between architectural features, environmental conditions, and the presence of Ae. aegypti is essential for developing targeted interventions and mitigating the adverse impacts of urbanization on public health. © 2023 Society of Chemical Industry.
Sujet(s)
Aedes , Dengue , Animaux , Vecteurs moustiques , Vecteurs insectes , VillesRÉSUMÉ
Freshwater biodiversity undergoes degradation due to climate change. Researchers have inferred the effects of climate change on neutral genetic diversity, assuming the fixed spatial distributions of alleles. However, the adaptive genetic evolution of populations that may change the spatial distribution of allele frequencies along environmental gradients (i.e., evolutionary rescue) have largely been overlooked. We developed a modeling approach that projects the comparatively adaptive and neutral genetic diversities of four stream insects, using empirical neutral/ putative adaptive loci, ecological niche models (ENMs), and a distributed hydrological-thermal simulation at a temperate catchment under climate change. The hydrothermal model was used to generate hydraulic and thermal variables (e.g., annual current velocity and water temperature) at the present and the climatic change conditions, projected based on the eight general circulation models and the three representative concentration pathways scenarios for the two future periods (2031-2050, near future; 2081-2100, far future). The hydraulic and thermal variables were used for predictor variables of the ENMs and adaptive genetic modeling based on machine learning approaches. The increases in annual water temperature in the near- (+0.3-0.7 °C) and far-future (+0.4-3.2 °C) were projected. Of the studied species, with different ecologies and habitat ranges, Ephemera japonica (Ephemeroptera) was projected to lose rear-edge habitats (i.e., downstream) but retain the adaptive genetic diversity owing to evolutionary rescue. In contrast, the habitat range of the upstream-dwelling Hydropsyche albicephala (Trichoptera) was found to remarkably decline, resulting in decreases in the watershed genetic diversity. While the other two Trichoptera species expanded their habitat ranges, the genetic structures were homogenized over the watershed and experienced moderate decreases in gamma diversity. The findings emphasize the evolutionary rescue potential, depending on the extent of species-specific local adaptation.
Sujet(s)
Écologie , Écosystème , Biodiversité , Changement climatique , EauRÉSUMÉ
Microplastic pollution is an urgent threat to the biota of aquatic ecosystems and is generally recognized as a global issue. Identifying the sources of microplastics is acknowledged as the most effective approach for mitigating microplastic pollution. However, the factors that regulate the spatiotemporal dynamics of microplastics in urban river networks, such as microplastic sources and other variables, have not been studied together at the watershed scale, let alone regarding their impact on internal microplastics. Here, we define "internal microplastics" as microplastics in biota, either in the digestive system or internal organs of organisms. We estimated the effects of anthropogenic activities (land cover and wastewater treatment plants) and seasonality on the concentration of internal microplastics in midge larvae (Diptera: Chironomidae) in an urban river system at a watershed scale in Taiwan. Agricultural activities, but not industrial activities, had a significant negative nonlinear effect on microplastic concentration. However, seasonality was the most crucial factor, as the microplastic concentration was significantly lower during the wet season. Although the presence of a wastewater treatment plant significantly increased the microplastic concentration at downstream sampling sites, its effect appeared to be minor. We conclude that seasonality overrides the effects of anthropogenic activities on the variation in the concentration of internal microplastics in midge larvae in an urban river system.
Sujet(s)
Chironomidae , Polluants chimiques de l'eau , Animaux , Microplastiques/toxicité , Matières plastiques , Écosystème , Effets anthropiques , Surveillance de l'environnement , Polluants chimiques de l'eau/toxicité , Polluants chimiques de l'eau/analyse , LarveRÉSUMÉ
Both weather fluctuation and farming system influence the epidemiology of crop diseases. However, short-term experiments are difficult to mechanistically extrapolate into long-term ecological responses. Using a mechanistic model with Bayesian inference, long-term data spanning 10 years were used to construct relationships among weather fluctuation (temperature, relative humidity, wind, and rainfall), farming system (conventional and low-external-input farming), and crop disease in experimental rice fields in Taiwan. Conventional and low-external-input farming had similar influences on the disease incidence of rice blast. Temperature had a positive influence on the disease incidence only under high relative humidity. Rainfall positively affected the disease incidence until an optimum level of rainfall. Low-external-input farming, with a lower application of fertilizers and other sustainable nutrient management, achieved similar effects on the disease incidence to those achieved by conventional farming. This suggests that weather fluctuation may override the effect of the farming systems on fungal disease incidence in rice fields.
Sujet(s)
Mycoses , Temps (météorologie) , Théorème de Bayes , Humains , Incidence , Nutriments , Taïwan/épidémiologieRÉSUMÉ
Spatial biodiversity is a key issue in biogeography for the explorations of biological origin and diversification. However, seldom studies have addressed the temporal changes in spatial patterns of biodiversity. We explored the taxonomic and functional diversities of riverine macroinvertebrates in central China, with the elevational gradient, in different seasons in a normal climate year (i.e., no extreme anomalies in the annual precipitation or average annual temperature). The air temperature and streamflow discharge were decreased monotonically with the increase of elevation both in the dry and wet seasons. In addition, the total nitrogen had no significant change with the increase of elevational gradient in the dry season but showed a monotonically decreasing pattern in the wet season. The total phosphorus showed a monotonically decreasing pattern with the elevational gradient in the dry season but had no significant change in the wet season. The spatial pattern of taxonomic diversity of macroinvertebrates along the elevational gradient showed complex patterns, but the functional diversity had either the unimodal or monotonically decreasing pattern. In addition, the functional diversity with the elevational gradient had similar patterns between the dry and wet seasons. Further analysis of the elevational pattern in different seasons is an important basis for understanding the status quo of functional diversity and formulating countermeasures for biodiversity conservation.
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Microplastic pollution is no longer neglected worldwide, as recent studies have unveiled its potential harm to ecosystems and, even worse, to human health. Numerous studies have documented the ubiquity of microplastics, reflecting the necessity of formulating corresponding policies to mitigate the accumulation of microplastics in natural environments. Although anthropogenic activities are generally acknowledged as the primary source of microplastics, a robust approach to identify sources of microplastics is needed to provide scientific suggestions for practical policymaking. This review elucidates recent microplastic studies on various approaches for quantifying or reflecting the degree to which anthropogenic activities contribute to microplastic pollution. Population density (i.e., often used to quantify anthropogenic activities) was not always significantly correlated with microplastic abundance. Furthermore, this review argues that considering potential sources near sample sites as characteristics that may serve to predict the spatial distribution of microplastics in aquatic environments is equivocal. In this vein, a watershed-scale measure that uses land-cover datasets to calculate different percentages of land use in the watershed margins delineated by using Geographic Information System (GIS) software is discussed and suggested. Progress in strategies for quantifying anthropogenic activities is important for guiding future microplastic research and developing effective management policies to prevent microplastic contamination in aquatic ecosystems.
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This paper addresses sorbitan and sucrose ester in physical transformations of palm mid-fraction (PMF). Both emulsifiers influenced the crystallization properties of PMF, mainly due to emulsifier solubility, which affects its ability to interfere with the kinetics of solution-mediated phase transformations. DSC results corroborate the polymorphism analysis, indicating that the mechanism and rate of phase transformation depend on the chemical structure and amount of each emulsifier. The addition of sorbitan tristearate (STS) and sucrose stearate (S-370) increased the crystallization speed of the PMF and caused changes in the crystallization behavior. STS favored the ß'âß transition, while S-370 stabilized the ß'-form. We can conclude that the presence of emulsifiers dissimilar to the composition of PMF modified its physical structure, either by increasing the liquid fraction or by reducing molecular motion, facilitating or preventing polymorphic transformations.
Sujet(s)
Stéarate , Saccharose , Cristallisation , Hexose , Huile de palme , Saccharose/analogues et dérivésRÉSUMÉ
Most research on the ecological responses to extreme floods examines impacts at short time scales, whereas long-term datasets combining hydrological and biological information remain rare. Using such data, we applied time-series analysis to investigate simultaneous effects of a biotic factor (density dependence), an abiotic factor (extreme floods), and spatial synchrony in the population dynamics of three riverine insects. Spatial synchronization of population dynamics by extreme floods varied among species. These different responses to extreme floods could be explained by species-specific biological traits. Moreover, density dependence influenced the population dynamics under the context of extreme floods. Accordingly, quasi-extinction risks were highest for species that were simultaneously influenced by biotic and abiotic factors. An understanding of ecological responses to increasing hydrological extremes may be enhanced by recognizing long-term, climatic non-stationarity.
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Inondations , Rivières , Extinction biologique , Hydrologie , Dynamique des populationsRÉSUMÉ
The countervailing effects of disturbances (e.g., high mortality and enhanced recovery) on population dynamics can occur through demographic processes under rapidly increasing climatic extremes. Across an extreme-event gradient, we mechanistically demonstrated how dramatic changes in streamflow have affected the population persistence of endangered salmon in monsoonal Taiwan over a three-decade period. Our modeling indicated that the dynamics of the age-structured population were attributed to demographic processes, in which extensive mortality was characterized as a function of climatic extremes and vulnerability in the young stage of fish. In the stochastic simulations, we found that the extensive mortality and high proportion of large fish resulted from extreme flooding, which caused high values of postimpact population recovery. Our empirical evidence suggests that the magnitudes and timing of disturbance can explain the population persistence when facing climatic extremes and thereby challenges the understanding of the mechanistic drivers of these countervailing phenomena under changing environmental conditions.
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Poissons , Inondations , Animaux , Dynamique des populations , TaïwanRÉSUMÉ
Biological control commonly involves the commercialization and introduction of natural enemies. Phytoseiulus persimilis Athias-Henriot, a mite species widely used in the control of spider mites, was imported to Taiwan in the 1990s and was mass-reared and released into the field. However, none have been observed in comprehensive surveys of phytoseiid mites for over 30 years. In this study, the distribution of P. persimilis in Taiwan was predicted, and environmental variables that affect its distribution were analyzed. The mountainous region of southcentral Taiwan was determined to be suitable for the establishment of this species, whereas the four sites at which it was released in the 1990s, particularly those in southwestern Taiwan, exhibited low suitability. Notably, the minimum temperature of the coldest month was identified as a crucial limiting factor affecting the distribution of P. persimilis, indicating that a Mediterranean climate is more suitable for this species. To the best of our knowledge, this study is the first to predict the suitable distribution of exotic predatory mites in a biological control program. The present findings serve as a pivotal assessment framework for the commercialization and foreign introduction of natural enemies.
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Pest risk assessment is typically performed by expert taxonomists using a pest's biological data. However, the biological data or expert taxonomists may be difficult to find. Here, we used species distribution modelling to predict potential invasion in which phytophagous quarantine pests survive in Taiwan; the pests (unrecorded yet in Taiwan) included were three notorious quarantine whiteflies (Crenidorsum aroidephagus, Aleurothrixus trachoides, and Paraleyrodes minei) and three aphids (Nasonovia ribisnigri, Macrosiphum euphorbiae, and Viteus vitifoliae). In brief, maximum entropy modelling (MaxEnt) was used to predict the suitability of the pests' habitats under certain climatic conditions, and then receiver operating characteristic curve analysis was performed (to verify the prediction result). We then analysed environmental variables affecting the habitat suitability and matched them with Taiwan's crop cultivation areas for the assessment of potential invasion. We observed that the habitat suitability of the cultivation areas of host plants was low for C. aroidephagus, A. trachoides, and N. ribisnigri but was high for the remaining three species. Moreover, precipitation of coldest quarter negatively affected habitat suitability for C. aroidephagus, P. minei, N. ribisnigri, and M. euphorbiae. Seasonal temperature changes also negatively affected the habitat suitability for A. trachoides. This is the first study to demonstrate the use of species distribution modelling as the preliminary step for the pest risk assessment of these emerging pests with limited biological data before their invasion.
Sujet(s)
Lutte contre les nuisibles , Virus des plantes , Quarantaine , Produits agricoles , Écosystème , Géographie , Espèce introduite , Courbe ROC , TaïwanRÉSUMÉ
As the main primary producer in stream ecosystems, periphyton is the fundamental of stream ecosystems and plays an essential role in maintaining stream biodiversity. The central Hengduan Mountains is one of the famous global biodiversity hotspots. However, for stream biodiversity conservations, the fundamental information about the spatial pattern of stream periphyton and the determining factors in this region remains largely unknown. To fill this gap, we investigated the spatial pattern of periphyton biomass (measured by chlorophyll a) in four typical streams in the central Hengduan Mountains and analyzed the driving factors, with the perspective of watershed land use and instream water quality. The results of our study found that farmland area, instream dissolved silicate (DSi), and water temperature (WT) had significant negative relationships with the stream periphyton biomass in the central Hengduan Mountains. However, the dissolved inorganic phosphorus (DIP) and dissolved inorganic nitrogen (DIN) had non-significant effects on the periphyton biomass in our study. Further analysis showed that the correlation between the ratio of farmland in the catchment and the DSi is non-significant (r = 0.028, P = 0.698), suggesting that the changes in farmland area will not affect the concentration of dissolved silicate in the stream. This reveals that the stream periphyton biomass was co-determined by the watershed farmland area and instream DSi and WT, but not nitrogen or phosphorus. These results highlight the importance of farmland management and instream DSi for stream ecosystems in the central Hengduan Mountains. Our study investigated the spatial pattern of the stream primary producer in the central Hengduan Mountains region and identified the main determining factors, which could improve our understanding of the high mountain stream ecosystems.
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Rivières , Qualité de l'eau , Chine , Chlorophylle A , Écosystème , FermesRÉSUMÉ
The presence of microplastics (MPs) in the environment has generated global concerns. However, the explicit assessment of the effect of multiple anthropogenic activities on the existence of MPs in the freshwater system is scarcely reported. This study quantified anthropogenic activities and analyzed their relationship with MPs on a freshwater organism: the midge larvae (Diptera: Chironomidae). The study took place in an urban river and consisted of comparing the abundance and types of MPs. Our results highlight that, while industrial area was the most important variable contributing to the total MP concentration in midge larvae, residential area also influenced the concentration of microfibers in midge larvae. The impact of a residential area on the relative abundance of microfibers in each sample site was diluted by the proximity to an industrial area. In conclusion, we suggest that industrial areas are a potential source of MP pollution in river sediment, and midge larvae can be a good indicator of the MP concentrations in urban river systems. Quantifying anthropogenic activities can help discern their effects on MP concentration in a river system and promote management strategies.
Sujet(s)
Biotransformation/physiologie , Chironomidae/physiologie , Microplastiques/pharmacocinétique , Rivières , Animaux , Organismes aquatiques , Chironomidae/métabolisme , Villes , Surveillance de l'environnement , Comportement alimentaire/physiologie , Eau douce , Sédiments géologiques/composition chimique , Sédiments géologiques/parasitologie , Déchets industriels , Microplastiques/composition chimique , Microplastiques/toxicité , Rivières/composition chimique , Rivières/parasitologie , Taïwan , Polluants chimiques de l'eau/composition chimique , Polluants chimiques de l'eau/pharmacocinétique , Polluants chimiques de l'eau/toxicitéRÉSUMÉ
Agricultural intensification is one of the major threats to global biodiversity and ecosystem services. Sustainable management of agricultural lands can reduce these impacts, but few efforts have been made in the context of paddy rice fields, especially in simplified landscapes composed of large monocultures separated by fragments of natural lands, such as in Taiwan or elsewhere in Asia. In this study, during a pest control intervention, we examined the effects of management practices on insect communities under conventional and organic farming systems in the paddy fields of northern Taiwan in 2016. Our results showed that organic practices did not increase the species richness or abundance of the four insect groups (total, predators/parasitoids, pests, and other insects). In addition, the composition of the insect communities did not differ between organic and conventional farming systems. Both the abundance and richness of predator/parasitoid insects were similar between conventional and organic farming systems. The pest abundance in the organic systems could be suppressed by other unmeasured predators and integrated management practices, which showed similar levels to the conventional systems with pesticide applications. The results of this study suggest that farming systems may not influence insect biodiversity in simplified landscapes during pest-control intervention.
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The ability to prioritize habitats that have spatially varied contributions to species persistence can produce synergistic benefits for regional conservation efforts. However, conservation in spatially diverse landscape-networks requires considering dispersal asymmetry in the context of ecological connectivity and metapopulation persistence. By developing an approach based on metapopulation theory, this study prioritized the importance of habitat (as determined by the habitat quality and spatial position in networks) on metapopulation structure in mountainous streams. As a case study, we examined dispersal via overland and instream networks in a riverine mayfly Rhithrogena sp. cf. japonica in a mountain range of Southwest China. Compared to flow velocity, water depth, and instream nutrient-levels, water temperature was a key factor in determining local habitat suitability for R. sp. cf. japonica. Higher water temperature was linked to poor habitat suitability. Instream pathways were the main dispersal corridors compared with overland movement between tributaries for this mayfly. In basins on the east aspect of this mountain range, either monotonically increasing (i.e., never decreasing) or unimodal (i.e., with a single peak) patterns demonstrated the importance of riverine habitats that occur along elevational gradients. However, the importance of habitat appeared to show no definite patterns with elevation on the west aspect. In terms of metapopulation structure, local quality of habitat contributed more to the regional importance of habitat than its spatial position in the networks. The framework presented highlights that the importance of riverine habitats may be quite variable in species having directional dispersal networks across the fluvial landscape in mountainous areas. Results from this framework can serve as the basis to apply a mechanistic understanding to managing and protecting native populations through regional restoration actions.