Habitat Resources Research Articles

Divergence of vessel diameter explains interspecific variation in hydraulic safety to salinity in the Sundarbans mangrove ecosystem

Abstract Despite their crucial role in providing ecosystem services and livelihood support in 124 countries, mangroves are facing challenges from warming, altered seasonal precipitation and sea level rise (SLR) in the face of climate change. Variation in intra‐ and interspecific hydraulic traits and related xylem anatomy may allow trees to adapt to changing environmental conditions, yet little is known about adaptive plasticity in mangroves. We examined (i) xylem and hydraulic trait variation across three (low, medium and high) salinity zones in three widespread mangrove species (Exocecaria agallocha, Xylocarpus moluccensis and Heritiera fomes) with distinct shade tolerance characteristics in the Bangladesh Sundarbans, (ii) associations of xylem and hydraulic traits, and (iii) habitat (regulator, resource and forest structure) effects on vessel diameter due to its strong influence on hydraulic conductivity variation. Although potential conductivity (KP) and leaf‐specific conductivity (KL) showed species‐specific variation, a notably greater conductivity was found in the low‐salinity zone (LSZ), which had lower vessel wall reinforcement (t/b)2. Xylem and hydraulic traits exhibited mostly strong phylogenetic signals, whereas pairwise relationships between traits were phylogenetically independent. The study species had distinct hydraulic characteristics, where vessel diameter (D) was strongly related to the variation in KP and KL. Furthermore, the study species exhibited a weak trade‐off between hydraulic efficiency and safety. A greater percentage of smaller vessel diameters in light‐demanding E. agallocha indicates greater hydraulic safety against cavitation under stressful conditions than in shade‐tolerant H. fomes, followed by X. moluccensis. Although species characteristics place broad bounds on xylem traits, the combined effects of salinity, nutrient availability and tree size modulate vessel diameter, which leads to hydraulic conductivity variation. The contrasting safety in terms of vessel diameter in mangroves suggests an important role in adaptation to salinity and species distribution. The results also provide insight into salinity‐induced growth reduction and mortality in mangroves. Read the free Plain Language Summary for this article on the Journal blog.

Sanctuary for migrating and wintering waterfowl: Synthesis and insights for waterfowl management and conservation planning

AbstractWaterfowl use a diversity of resources (e.g., food, structure, sanctuary) to meet energetic, social, and other life‐history demands during the non‐breeding period. Waterfowl often seek areas with limited human disturbance (i.e., sanctuary) during autumn and winter when hunting seasons are open perhaps to reduce exposure to mortality risks, minimize energy expenditure, and increase foraging efficiency, all of which should enhance survival and subsequent fitness. Prior studies of sanctuary use by waterfowl have mostly focused on patterns of abundance and behavior, with many documenting differential diel movements of marked birds in and around sanctuaries. Although reduced mortality risk is likely associated with sanctuary use, much less is known about the potential effects on energy expenditure, body condition, reproductive consequences at the individual level, and seasonal distribution with respect to viewing and harvest potential. We consider these aforementioned factors among the most significant gaps in our understanding of the function of sanctuary in waterfowl management. As waterfowl hunter recruitment, retention, and reactivation have become a major initiative of many natural resource agencies and a core principle of the North American Waterfowl Management Plan, we discuss the potential role of sanctuary relative to these efforts. Herein, we review historical aspects of waterfowl sanctuary, introduce hypotheses about its potential role in habitat resource management and conservation planning during autumn and winter, discuss our knowledge of the effects of sanctuary on waterfowl, and share insights to inform decisions about the role of sanctuary in waterfowl management given currently available evidence and remaining uncertainties. Our review describes the existing evidence for the biological and social outcomes of sanctuary, draws some conclusions about the role of sanctuary in natural resource management given the available evidence, and outlines potential research opportunities to help us make informed decisions regarding sanctuary implementation for waterfowl.

Environmental influences on the size and recruitment of inland Cisco populations in three Minnesota Sentinel lakes

AbstractObjectiveCisco Coregonus artedi are a pelagic coldwater fish that are widely distributed throughout many lakes across Canada and the northern Midwest and play an important role as forage for large piscivores. Cisco are sensitive to oxythermal stress caused by a combination of warm epilimnetic temperatures and hypolimnetic hypoxia during peak stratification periods and are at risk from stressors such as climate change and land use changes. We hypothesized that interannual variability in the amount of oxythermal habitat and prey resources were associated with observed differences in size structure and recruitment success of different Cisco populations. This study evaluated the relationship between characteristics of three inland (non‐Laurentian Great Lakes) Cisco populations, including maximum size and age‐0 density, with environmental and biological factors such as pelagic oxythermal habitat, zooplankton availability, and Cisco density and biomass over a 7‐year time series.MethodsTargeted, standardized, annual pelagic sampling was conducted from 2013 to 2019 using hydroacoustic sonar and vertical gill nets to sample Cisco, vertical net tows to sample zooplankton, and temperature and dissolved oxygen profiles to measure oxythermal habitat. Linear regression and mixed‐effect models were developed for two selected response variables: upper 95th percent total length (mm) and standardized age‐0 density (fish/ha‐m3).ResultCyclopoid copepod densities explained the most variability in the observed size differences, while age‐1+ Cisco biomass best explained the variability in the age‐0 density response variable. Additionally, the number of growing degree‐days at dissolved oxygen of 3.0 mg/L explained variability in both response variables.ConclusionResults from this study document the importance of zooplankton prey, oxythermal habitat, and internal population dynamics on Cisco size and recruitment. This information provides fisheries managers with insights on the characteristics of inland lake systems that influence variability in Cisco populations and how this effects the vulnerability of this relatively important forage species on gape‐limited predatory fish.

The influence of fire and termites on tree hollow development in an Australian tropical savanna

Tree hollows are important habitat resources for wildlife globally. In the tropical savannas of northern Australia, the abundance of tree hollows is influenced by both fire and termites. With the regular application of prescribed fire in these ecosystems, it is important to understand the implications of fire management on important habitat resources – especially when applied over the long-term. This study uses a long-term fire experiment (18 years of applied fire treatments) with targeted termite and tree hollow surveys to investigate how the proportion of stem hollowing and abundance of hollow entrances are affected by termites and different long-term fire regimes. We used sonic tomography in a novel application to non-destructively estimate tree stem hollowing. Trunk diameter was identified as the strongest predictor of both stem hollowing and hollow entrance abundance, with larger trees having a greater proportion of the stem hollowing and greater number of hollow entrances. The proportion of stem hollowing tended to be greater closer to the base of the tree, and the number of hollow entrances was greater in Eucalyptus miniata than E. tetrodonta. While the proportion of stem that was hollowed did not influence the number of hollow entrances, the presence of any hollowing at 1.3 m was associated with more hollow entrances. We did not detect an effect of fire activity on stem hollowing or the abundance of hollow entrances at the individual tree level, and it may be that these effects are only detectable at the stand level due to changes in tree demographics with varying fire regimes. As large trees tend to have more hollow entrances, management to promote habitat for wildlife should focus on fire regimes that avoid the loss of large trees in the landscape.

Complex interactive responses of biodiversity to multiple environmental drivers.

There remains considerable doubt, debate, and confusion regarding how biodiversity responds to gradients of important environmental drivers, such as habitat size, resource productivity, and disturbance. Here we develop a simple but comprehensive theoretical framework based on competition-colonization multispecies communities to examine the separate and interactive effects of these drivers. Using both numerical simulations and analytical arguments, we demonstrate that the critical trade-off between competitive and colonization ability can lead to complex nonlinear, zig-zag responses in both species richness and the inverse Simpson index along gradients of these drivers. Furthermore, we find strong interactions between these drivers that can dramatically shift the response of biodiversity to these gradients. The zig-zag patterns in biodiversity along ecological gradients, together with the strong interactions between the drivers, can explain the mixed findings of empirical studies and syntheses, thereby providing a new paradigm that can reconcile debates on the relationships between biodiversity and multiple drivers.

Avian abundance and diversity in three urbanized university campuses at different elevations in Northern Mindanao, Philippines

ABSTRACT This study investigates the impact of urbanization and elevation on avian diversity across three university campuses in the Philippines. Urbanization, a significant driver of global environmental change, negatively affects biodiversity by altering natural habitats. Birds, frequently used as bioindicators, are vital subjects for studying urban impacts due to their visibility and sensitivity to environmental changes. This research compares the abundance of bird families across campuses at different elevations, revealing significant variations influenced by urban structure, vegetation, and resource availability. Line transect, point count, and mist-netting methods were employed to survey the birds in the study area following established methods. The family Pycnonotidae is most abundant in the low-elevation urban campus (University of Science and Technology of Southern Philippines - Cagayan de Oro), while families like Nectariniidae and Cuculidae are more prevalent in the high-elevation campus (USTPClaveria). These findings underscore the importance of habitat diversity and resource availability in supporting avian communities. The study highlights the potential of urbanized university campuses to serve as refuges for biodiversity if managed appropriately. Enhancing habitat complexity, maintaining green spaces, and ensuring diverse food resources are crucial for sustaining bird populations. The results emphasize the need for targeted conservation efforts within urban campuses to preserve and promote avian diversity in increasingly urbanized landscapes.

GPS telemetry facilitates the identification of forage plant species for endangered Carnaby’s cockatoos (Zanda latirostris) at inland breeding sites and post-breeding dispersal locations in Western Australia

Carnaby’s cockatoos (Zanda latirostris) are an endangered species that has experienced major loss of habitat over the past century. Proponents seeking land clearing approval that may impact Carnaby’s cockatoos need to provide detailed habitat assessment. However, the current forage species list is outdated and generally restricted to the Swan Coastal Plain rather than the Carnaby’s full distribution range. This study provides an updated forage list, including the Swan Coastal Plain and much of the Carnaby’s breeding and non-breeding areas outside this region. Carnaby’s cockatoos were captured and satellite tagged, at five breeding sites in the wheatbelt and Great Southern areas in Western Australia (between 2017 and 2022). Spatial data collected from the tags facilitated the identification of forage plants used by Carnaby’s cockatoos. A total of 44 ‘new’ native plant species were identified as Carnaby’s cockatoo forage species, including five genera that have not previously been recorded. The updated forage list will inform proponents and regulators on the potential use of habitat patches by Carnaby’s cockatoos, aiding the referral process and enabling the protection and conservation of important and diminishing habitat resources.

Predicting Potential Distribution of Teinopalpus aureus Integrated Multiple Factors and Its Threatened Status Assessment.

The accurate prediction of the niche and the potential distribution of a species is a fundamental and key content for biodiversity related research in ecology and biogeography, especially for protected species. Biotic interactions have a significant impact on species distribution but are often overlooked by SDMs. Therefore, it is crucial to incorporate biotic interaction factors into SDMs to improve their predictive performance. The Teinopalpus aureus Mell, 1923 is endemic to high altitudes in southern East Asia, renowned for its exceptional beauty and rarity. Despite the significant conservation value, its spatial distribution remains unclear. This study integrated climate data, host plants, and empirical expert maps to predict its potential distribution. The results indicated that utilizing the species richness of host plants as a surrogate for biotic interactions was a simple and effective way to significantly improve the predictive performance of the SDMs. The current suitable distribution of T. aureus and its host plants is highly fragmented, primarily concentrated in the Nanling and Wuyi Mountains, and consisting of numerous isolated small populations. Given climate change, their distribution is significantly shrinking, increasing the threatened level in the future. Especially for the population of T. aureus hainani Lee, the likelihood of extinction is extremely high. Abiotic factors not only directly affect the distribution of T. aureus but also indirectly impact it through the host plants. This was evident in the delayed response of T. aureus to climate change compared to its host plants, which is called the "hysteresis effect" caused by biotic interactions. Overall, we tentatively suggest regarding T. aureus as a vulnerable species. In the future, multiple measures could be taken to indirectly protect the feeding and habitat resources of T. aureus by conserving host plants, thereby enhancing its survival prospects.

Investigation of the impact of diverse climate conditions on the cultivation suitability of Cinnamomum cassia using the MaxEnt model, HPLC and chemometric methods in China

Cinnamomum cassia Presl. is a subtropical plant that is used for food and medicine. Climate change has changed the suitable habitats of medicinal plants, which might have repercussions for the efficacy of herbal remedies. In this study, the potential distribution in each period of Cinnamomum cassia was predicted and the quality in different suitable habitats was evaluated. According to the results, (1) precipitation, temperature, and soil are the primary environmental variables influencing C. cassia distribution. (2) The high-suitable habitats of current climate scenarios were predominantly located in the southern regions (Guangdong and Guangxi etc.) of China, with an area of 706,129.08 km2. Under future climate scenarios, suitable habitats will increasingly move northward, with a greater concentration south of the Yangtze River, particularly in the 2090s SSP585 scenario, the total area of newly extended suitable habitat reaches 312,963.53 km2. (3) HPLC and FTIR, combined with chemometrics, can be effective methods for identifying different suitable habitats of C. cassia. The content of trans-cinnamaldehyde (0.85%) is significantly higher in the high suitability habitat compared to the medium-low suitability habitat (0.30%). Our findings can offer valuable guidance for the identification of suitable C. cassia cultivation areas in China, as well as for the evaluation of C. cassia resource quality and the rational use of resources in different suitable habitats.

Cover crops dismantle keystone ant/aphid mutualisms to enhance insect pest suppression and weed biocontrol

Abstract Cover crops are multifunctional tools that mitigate environmental impacts of agriculture, enhance resilience to weather extremes and suppress weeds and arthropod pests. Cover crops provide non‐crop food and habitat resources that attract natural enemies of pests, but their outcomes for pest management are less clear in regions where keystone mutualisms between red imported fire ants and aphids dominate. Here, we manipulate ant exclusion treatments and cover crop treatments (living mulches and terminated cover crops) that vary in food/habitat resources and examine responses of ants, aphids, other herbivores and predators in a cotton agroecosystem. Living mulches reduced both ants and aphids in the crop canopy by 97% and 93%, respectively, relative to bare soil treatments, and terminated cover crops reduced them as well by a lesser degree (~50%). Non‐aphid herbivores occurred in low densities system‐wide and increased in living mulches, whilst native predators had variable responses to cover crops and ant exclusion. Cover crops had no effect on prey removal in the crop canopy, but living mulches tripled rates of weed seed biocontrol, relative to bare soils. Cover crops elicited a shift in fire ant foraging from cotton foliage downward to the soil‐surface, preventing competitive exclusion by keystone ant/aphid mutualists that dominate crop monocultures. Cover crops altered the system‐wide impacts of fire ants: reducing ecosystem disservices (i.e. aphid tending) and enhancing ecosystem services (i.e. weed seed biocontrol). These results provide incentives for cover crop adoption as a regenerative practice in large‐scale commercial agriculture.

Mangroves Invaded by Spartina alterniflora Loisel: A Remote Sensing-Based Comparison for Two Protected Areas in China

Mangroves are one of the world’s most productive and ecologically important ecosystems, and they are threatened by the widespread invasion of Spartina alterniflora Loisel in China. As few studies have examined the spatial pattern differences of S. alterniflora invasion and the nearby mangroves in different latitudes, we chose the Zhangjiang Estuary and the Dandou Sea, two representative mangrove–salt marsh ecotones in the north and south of the Tropic of Cancer, as the study areas for comparison. The object-based image analysis and visual interpretation methods were combined to construct fine-scale mangrove and S. alterniflora maps using high-resolution satellite imagery from 2005 to 2019. We applied spatial analysis, centroid migration, and landscape indexes to analyze the spatio–temporal distribution changes of mangroves and S. alterniflora in these two ecotones over time. We used the landscape expansion index to investigate the S. alterniflora invasion process and expansion patterns. The annual change rates of mangrove and S. alterniflora areas in the Zhangjiang Estuary showed a continuous growth trend. However, the mangrove areas in the Dandou Sea showed a fluctuating trend of increasing, decreasing, and then increasing again, while S. alterniflora areas kept rising from 2005 to 2019. Spartina alterniflora showed larger annual change rates compared with mangroves, indicating rapid S. alterniflora invasion in the intertidal zones. The opposite centroid migration directions of mangroves and S. alterniflora and the decreasing distances between the mangrove and S. alterniflora centroids indirectly revealed the fierce competition between mangroves and S. alterniflora for habitat resources. Both regions saw a decrease in mangrove patch integrality and connectivity. The integrality of mangrove patches in the Zhangjiang Estuary was always higher than those in the Dandou Sea. We observed the growth stage (2011–2014) and outbreak stage (2014–2019) of S. alterniflora expansion in the Zhangjiang Estuary and the outbreak stage (2005–2009) and plateau stage (2009–2019) of S. alterniflora expansion in the Dandou Sea. The expansion pattern of S. alterniflora varies in time and place. Since the expansion of S. alterniflora in the outbreak stage is rapid, with a large annual change rate, early warning of S. alterniflora invasion is quite important for the efficient and economical removal of the invasive plant. Continuous and accurate monitoring of S. alterniflora is highly necessary and beneficial for the scientific management and sustainable development of coastal wetlands.

The impact of plant-derived fire management prescriptions on fire-responsive bird species.

In fire-prone regions, the occurrence of some faunal species is contingent on the presence of resources that arise through post-fire plant succession. Through planned burning, managers can alter resource availability and aim to provide the conditions required to promote biodiversity. Understanding how species occurrence changes at different spatial and temporal scales after fire is essential to achieve this goal. However, many fire prescriptions are guided primarily by the responses of fire-sensitive plants when setting tolerable fire intervals. This approach assumes that maintaining floristic diversity will satisfy the requirements of fauna. We surveyed bird species in two semi-arid vegetation types across an environmental gradient in south-eastern Australia. We conducted four surveys at each of 253 sites across a 75-year chronosequence of time since fire and used generalized additive mixed models to examine changes in the occurrence of birds in response to time since fire. Model predictions were compared to plant-derived fire prescriptions currently guiding fire management in the region. Time since fire was a significant predictor for 18 of 28 species modeled, in at least one vegetation type, over a gradient of 1.3° of latitude. We detected considerable variation in the responses of some species, both between vegetation types and geographically within a vegetation type. Our evaluation of plant-derived fire prescriptions suggests that the intervals considered acceptable for maintaining floristic diversity may not be sustainable for populations of birds requiring longer unburnt vegetation, with 6 of the 12 species assessed attaining a mean occurrence probability of 20.3% by the minimum tolerable fire interval, and 57.3% by the maximum tolerable fire interval, in their respective vegetation types. Our findings highlight the potential vulnerability of fire-responsive bird species if fire prescriptions are applied in a manner that fails to account for the slow development of habitat resources needed by some species, and the variation detected within the responses of species. This highlights the need for species-specific data collected at an appropriate spatial scale to inform management plans.

Longitudinal survey of hepatitis E virus in extensively raised pigs in Spain

Hepatitis E virus (HEV) is an emerging zoonotic virus of public health concern, of which pigs, wild boar and red deer are the main reservoirs. The European Food Safety Authority (EFSA) has recently prioritized the development of monitoring programs of HEV at different stages of the pig food chain, including outdoor pig farming. Pigs managed under these extensive production systems frequently share habitat and natural resources with wild boar and red deer during fattening stages and cross-species transmission of HEV among these species has previously been suggested. In this context, we aimed to (I) to evaluate the risk of HEV circulation within the production phases of extensively raised pigs and at the domestic-wildlife interface, and (II) to identify the genotypes circulating within these hosts. A total of 1452 pigs from seven different pig farms were longitudinally sampled during the breeding, rearing, and fattening production phases. In addition, 138 and 252 sympatric wild boar and red deer, respectively, were analysed. Anti-HEV antibodies were found in 1245 (85.7 %) out of the 1452 Iberian pigs sampled. The seroprevalence was 30.4 % in the breeding phase, 95.4 % in the rearing phase and 97.0 % in the fattening phase. Statistically significant differences (P < 0.05) were found among the three production phases. The seroprevalence was significantly higher (P < 0.001) in fattening pigs compared to those found in sympatric wild boar (31.9 %) and red deer (2.0 %). Three (1.0 %) out of the 293 serum pools analysed were positive for viral RNA. One of them was identified in pigs at the rearing phase (genotype 3 f) and two in wild boar (genotypes 3 f and 3 m). The high seroprevalence detected in extensively raised pigs, together with the detection of the zoonotic HEV-3 f and HEV-3 m subtypes in sympatric domestic and wild swine, highlights the risk of zoonotic transmission and the need to establish surveillance programs and control measures, particularly in breeding and rearing phase, in these epidemiological scenarios.

Data-driven evolutionary programming for evaluating the mechanical properties of concrete containing plastic waste

Plastic waste (PW) has emerged as a global environmental concern due to its detrimental impact on ecosystems and human health. Traditional concrete heavily relies on natural aggregates like sand, gravel, and crushed stone, whose extraction leads to environmental degradation, including habitat destruction and resource depletion. Recently, the use of PW in concrete has gained attention as a sustainable alternative to these conventional aggregates. By incorporating PW as a partial replacement for natural aggregates, the construction industry can reduce its reliance on finite resources while also addressing the issue of PW. However, despite its potential environmental benefits, the incorporation of PW into concrete has primarily been explored through experimental studies, which are often time-consuming and resource-intensive. Therefore, this study aims to optimize the utilization of waste plastic in concrete through machine learning (ML) techniques, specifically Multi-Expression Programming (MEP) and Gene Expression Programming (GEP). A comprehensive literature review was conducted to compile a database for evaluating the compressive strength (CS) and tensile strength (TS) of PW concrete. The most influential parameters, such as plastic (P), gravel (G), water (W), cement (C), sand (S), and age (A), were considered as inputs in the models' development. The models developed were thoroughly evaluated using multiple statistical measures. Additionally, sensitivity analysis was conducted to discern and highlight influential factors that have a significant impact on the predicted outcomes. The findings indicate that both MEP (CS_R2 = 0.88, and TS_R2 = 0.89) and GEP (CS_R2 = 0.87, and TS_R2 = 0.88) models performed well, with MEP demonstrating slightly superior performance. Sensitivity analysis highlights the significant influence of cement (25.63 % and 24.53 %) and plastic (22.4 % and 23.44 %) on concrete strength properties. Furthermore, the equations provided by GEP and MEP models are simple to use from a practical perspective. Overall, this study contributes to sustainability efforts by promoting the incorporation of waste materials in concrete mixtures, thereby reducing reliance on cement.

Climate and land use/land cover changes increasing habitat overlap among endangered crested ibis and sympatric egret/heron species

Climate and land use/land cover (LULC) changes have far-reaching effects on various biological processes in wildlife, particularly interspecific interactions. Unfortunately, interspecific interactions are often overlooked when assessing the impacts of environmental changes on endangered species. In this study, we examined niche similarities and habitat overlaps between wild Crested Ibis and sympatric Egret and Heron species (EHs) in Shaanxi, China, using Ecological niche models (ENMs). We aimed to forecast potential alterations in habitat overlaps due to climate and LULC changes. The results showed that although EHs possess a broader niche breadth compared to the Crested Ibis, they still share certain niche similarities, as indicated by Schoener’s D and Hellinger’s I values exceeding 0.5, respectively. Notably, despite varying degrees of habitat reduction, the shared habitat area of all six species expands with the changes in climate and LULC. We suggest that with the climate and LULC changes, the habitats of sympatric EHs are likely to suffer varying degrees of destruction, forcing them to seek refuge and migrate to the remaining wild Ibis habitat. This is primarily due to the effective conservation efforts in the Crested Ibis habitat in Yangxian County and neighboring areas. Consequently, due to the niche similarity, they will share and compete for limited habitat resources, including food and space. Therefore, we recommend that conservation efforts extend beyond protecting the Crested Ibis habitat. It is crucial to control human activities that contribute to LULC changes to safeguard the habitats of both Crested Ibis and other sympatric birds.

Metabolic Allometric Scaling of Unicellular Organisms as a Product of Selection Guided by Optimization of Nutrients Distribution in Food Chains

One of the major characteristics of living organisms is metabolic rate — the amount of energy produced per unit of time. When the mass of organisms increases, the metabolic rate also increases (as a power function of mass), but usually slower than mass. This effect is called metabolic allometric scaling. Its causes are considered unknown. The effect has important implications for individual and population organismal development. It was shown in the first part of this study, presented in a separate paper, that in the case of multicellular organisms, this effect is a consequence of natural selection and optimization of nutrient distribution between the species of a food chain, sharing resources of a common habitat. Here, in the second part that studies unicellular organisms, we discover that the same principle of natural selection guided by optimization of nutrient distribution between the species of a food chain defines also metabolic allometric scaling of unicellular organisms. To find that, we consider the metabolic properties of Amoeba proteus, fission yeast Schizosaccharomyces pombe, Escherichia coli, Bacillus subtilis, Staphylococcus. The sharing of nutrients is optimized in such a way that bigger microorganisms have progressively bigger nutrient influx per unit of surface. This evolutionary arrangement secures the stability of a food chain by providing certain metabolic advantages for bigger organisms. Accounting for this regular increase of nutrient influx with mass increase, we obtained allometric exponents and their ranges close to experimental values, thus proving that metabolic allometric scaling of both multicellular and unicellular organisms is defined by the same fundamental evolutionary principle of optimized sharing of nutrients between the species of a food chain.

Slow recovery in trophic structure of restored wetlands in Northeast China

Restoration measures have been widely implemented in wetland ecosystems globally to bend the curve of biodiversity loss and restore associated ecological functions. However, assessments of the effectiveness of wetland restoration have predominantly focused on the recovery of taxonomic composition, while few studies have assessed the effectiveness of these efforts from a food web perspective. Here, we incorporated stable isotope approach to investigate trophic structure in natural and restored wetlands in Northeast China. The investigated consumers, including zooplankton, macroinvertebrates, and fish, exhibited lower δ15N and higher δ13C values in restored wetlands than in natural wetlands. Natural wetlands exhibited higher trophic positions and a wider range of trophic levels compared to restored wetlands. Primary consumers in natural wetlands relied more on particulate organic matter (POM, 42.9 % ± 24.1 %), while those in restored wetlands were more dependent on substrate organic matter (SOM, 42.3 % ± 23.9 %). Compared to natural wetlands, isotopic richness was significantly lower in restored wetlands, with smaller isotopic variation (SEAs) in basal resources, aquatic invertebrates, and fish. Our findings reveal that the recovery of trophic structures in restored wetlands lags behind that of taxonomic composition. Future restoration efforts should prioritize enhancing habitat heterogeneity and resource availability to support a diverse range of trophic levels. Monitoring trophic dynamics is essential for assessing the progress of wetland restoration and should be integrated into monitoring schemes.

Individual dietary specialization and intraspecific morphological divergence of an endemic fish species: the case of Glanidium ribeiroi in the Iguassu ecoregion

ABSTRACT Because of the importance of information about endemic species and global biodiversity ecoregion, we tested the hypothesis that individuals of Glanidium ribeiroi (endemic species in the Iguassu ecoregion) are specialists and that this specialization decreases with increasing body size, especially concerning the size of the mouth and head, which can be limiting for the quantity and size of prey consumed by smaller individuals. Fish sampling was conducted monthly using gill nets and longlines from 2013 to 2016 in the main channel of the Iguaçu River and two tributaries. We observed the consumption of aquatic insects by smaller individuals and seeds, unidentified fish, and Decapoda by larger individuals. Individual dietary specialization was high and related to head width. The morphological traits of smaller-sized individuals were related to displacement and movement (larger peduncle), and the larger-sized individuals were related to high performance in the exploitation and prey acquisition (larger head and mouth, dorsal eyes, longer intestines). Our results highlight the importance of assessing individual variations within a population, favoring an understanding of population dynamics. In addition, morphological differences may imply differences in the use of habitat and food resources between individuals of larger and smaller body sizes and influence individual specialization.

Landscape changes of alpine grasslands in the Zhari Namco basin of the central‐southern Qiangtang plateau, 2001–2021

AbstractThe alpine grasslands of the Qiangtang Plateau face significant ecological risks due to extensive human activities, particularly in areas along lakeshores and riverbanks, where overgrazing has caused severe degradation and salinization of the grasslands. Conducting fieldwork in such environments presents significant challenges for long‐term community‐scale landscape ecological research. In this study, the habitat characteristics of dominant plant communities in the alpine basin of Zhari Namco were quantified from three perspectives: topography, hydrology, and fractional vegetation cover. Using Aster GDEM and Landsat imagery, five grassland types were mapped for 2001–2021. Based on the spatial variables of area, shape, and distance, 13 landscape indices were selected to observe spatiotemporal changes. The results revealed several key findings: (1) The patch structure of the zonal vegetation Stipa purpurea steppe has undergone a pattern of dispersion‐aggregation‐dispersion in the past 20 years, yet the core habitat area remains unchanged by more than 52%, indicating fundamental stability in the southern Qiangtang alpine grassland; (2) Using the minimally grazed Kobresia pygmaea meadow as a reference, other communities exhibit stability similar to or approaching it, but with significant differences in aggregation level. The gradual expansion of grazing and economic activities has been a driving factor; and (3) Water conservation projects have diversified the use of water resources in river and lakeside habitats. Stipa purpurea + Carex moorcroftii steppe and Carex swamp meadow exhibit optimal carrying capacity, making them the only areas with relatively high sustainability. The study underscores that the current ecological benefits are a result of effective management. However, without proper management, the region could trend towards landscape fragmentation, becoming the most vulnerable zone in the watershed. Therefore, it is essential to strengthen retrospective analysis of grazing intensity and trend analysis of habitat changes to provide a scientific basis for local economic development and grazing management.

Distribution pattern and driving factors of mite communities in karst cave ecosystems.

Mites are among the most abundant invertebrates in subsurface ecosystems, and their community assemblages and distributions are often significantly influenced by the diversity of habitat resources. The cave ecosystem encompasses drastic changes in nonbiological factors, such as changes in lighting conditions from bright to extraordinarily dark and habitat gradients of surface plant resources from abundant to scarce or even disappearing, providing an ideal unique environment for evaluating the assembly mechanism of soil animal communities. Nevertheless, there still needs to be a sufficient understanding of the biodiversity patterns and drivers of mite communities across environmental gradients in karst caves. We conducted a comprehensive survey on the composition and diversity of soil mites in three photometric zones (dark, twilight, and light) of a typical karst cave and its adjoining extractive environments (forest scrub and farmland). Our research aimed to investigate the ecological relationships of mite communities between above- and below-ground habitats and the effects of abiotic factors on mite communities. We collected 49 families, 86 genera, and 1284 mites. In the external cave environment, we captured 1052 mites from 72 genera and 45 families; in the internal cave environment, we captured 232 mites from 46 genera and 29 families. The abundance, richness of genera, and diversity parameters of the mite community decreased from the cave entrance to the cave interior with decreasing light intensity. Oribatid mites dominated the mite community. Protoribates and Scheloribates were the dominant genera, along with Tectocepheus and 11 other genera, which primarily distinguished the mite communities among different habitats. Forty endemic taxa were found in the external cave environment, compared to 14 endemic taxa in the internal cave environment. The mite community showed a strong preference for the cave ecosystem habitat. Temperature, humidity, and soil nitrogen content significantly influenced the distribution pattern of mite communities (VIP > 0.8, p < 0.05).