Key Ecological Factors Research Articles

Social and ecological dimensions are needed to understand human‐wildlife conflict in subsistence farming context

Abstract This study explores the social, economic and environmental dimensions of human‐wildlife conflict (HWC) in four districts of Bhutan. Looking beyond the common unidimensional approach to the evaluation of HWCs, it documents the multifaceted nature of HWCs through a social‐ecological system (SES) lens. We carried out a mixed method analysis of HWC based on 96 interviews consisting of qualitative and quantitative data and eight focus group discussions conducted in four districts representing four regions of Bhutan. Our case study finding reveals that HWC scenarios are complex and there is spatial variation in both social and ecological factors that contribute to HWC. In some areas, ecological aspects such as the composition and behaviour of wildlife species exacerbate the conflict, while in other regions the co‐occurrence of wildlife and livestock in the same ‘wild’ landscape drives HWC. The socio‐economic dimensions of HWC are largely driven by attitudes, tolerance, and behaviour of individuals underpinned by multiple factors. We propose that the SES approach improves our understanding of key social, economic and ecological factors, their interactions, and the feedback that either exacerbates or ameliorates HWC in contested landscapes. Read the free Plain Language Summary for this article on the Journal blog.

Fate and drivers of mariculture-derived microplastics from ponds to mangrove forests

Due to the combined influences of marine and terrestrial disturbances, the sources of microplastics (MPs) in mangrove ecosystems are complex and diverse. Previous studies have inferred the possible involvement of mariculture activities as a potential source of mangrove MPs based on the characteristics of MPs. However, the direct contributions of mariculture-derived MPs to mangrove MPs remain largely unknown. In this study, we systematically investigated the fate of MPs in the discharge of mariculture wastewater by quantifying the source contributions of mariculture-derived MPs to rivers and mangroves. The majority of detected MPs were transparent fibers, with their composition primarily comprising materials commonly used in mariculture activities such as polyvinylpyrrolidone (PVP), polyethylene terephthalate (PET), and nylon. The partial least squares path model elucidated the relationships among the composition of MPs in ponds, rivers, and mangroves, indicating that ponds exert a substantial direct effect on mangroves, particularly significant in the sediments (63.68%). Water turbidity, sediment carbon content, and sediment particle size are key ecological factors influencing the abundance of mariculture-derived MPs. This study provides compelling evidence regarding the sources of mangrove MPs and novel insights into mitigating the dissemination of MPs.

Study on the key ecological factors for the reproduction of Gymnocypris eckloni in the upper reaches of the Yellow River.

The development of hydroelectric projects has adversely affected the reproductive activities of downstream fish species. To facilitate the natural reproduction of fish and restore spawning grounds post-dam construction, it is imperative to explore the ecological factors crucial for their reproduction. Currently, various research methods with different advantages and limitations are employed for this purpose. Using identified spawning locations and periods as clues, we quantitatively investigate the flow velocity, water depth, water temperature, and riverbed substrate required for spawning. The results are validated using habitat simulation methods, aiming to establish a more scientific approach to explore ecological factors affecting fish reproduction. This study provides a more scientific, systematic, and detailed report on the ecological factors required for the spawning of Gymnocypris eckloni: flow velocity ranging from 0.19 to 0.97 m/s, water depth from 0.28 to 1.12 m, water temperature between 11.4 and 15.2°C, and predominantly gravel substrate. The reliability of the results was verified in another spawning ground, with good verification results. This research provides crucial data for the bio-mimetic reproductive technology of Gymnocypris eckloni and the restoration of spawning grounds for natural fish reproduction post-dam construction. It addresses the lack of suitable ecological factor data for protective fish species in the upper reaches of the Yellow River. The method exhibits strong scientific, accurate, and implementable characteristics.

Ecological determinants of leishmaniasis vector, Lutzomyia spp.: A scoping review.

Leishmania spp. are zoonotic parasites transmitted by phlebotomine sand flies, including those of the Lutzomyia genus, which can cause leishmaniases in both humans and dogs. Lutzomyia spp. are established in many countries in South and Central America and some areas of the southern United States, with suspected potential of these vectors to undergo further range expansion due to climate change. A scoping review was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses Extensions for Scoping Reviews (PRISMA-ScR) guidelines to describe the current state of knowledge on the key ecological factors associated with Lutzomyia spp. survival, reproduction and establishment. The following electronic databases were searched for eligible studies published from 1 January 1990, to the date of search, 26 April 2023: CAB Direct (CABI), MEDLINE (via Ovid), Biological Sciences Database and Environmental Sciences Database. Primary research articles that were available in English and focused on ecological factors associated with Lutzomyia spp., such as climatic and habitat factors, geographic range, seasonality and temporality, and host abundance, were eligible for inclusion in the study. Following de-duplication, a total of 167 studies were included in Level 1 screening, 64 studies were included in Level 2 screening and 31 studies met the criteria for data extraction. Study locations included Argentina, Brazil, Colombia, Peru, Venezuela, the United States, Mexico and Canada, with some studies including multiple regions. A total of 31 different Lutzomyia spp. were assessed across these studies, with most (51.6%) of the studies focused on Lutzomyia longipalpis. Eligible studies investigated factors such as seasonality (n = 5), temperature (n = 19), precipitation (n = 13), humidity (n = 2), vegetation presence or requirements (n = 13), ecotypes (n = 7), and/or community type (i.e., urban, suburban, rural) (n = 5). Lutzomyia spp. activity was found to be higher during the rainy season, and peak when temperatures were between 20 and 25°C. Lutzomyia spp. were also found to preferentially reside in tropical or subtropical forests, which are characterised by their lack of a distinct dry season and high precipitation. This scoping review summarised the current state of the literature on the ecological factors associated with the survival, activity and reproduction of Lutzomyia spp. While there appears to be some consensus in the literature regarding some ecological requirements (such as seasonality, temperature and habitat features), overall, there is a lack of published research in this topic. This poses a significant challenge for future studies, which aim to predict the future distribution of Lutzomyia spp. in the context of climate and land use changes. Additional ecological research is urgently needed on Lutzomyia spp. given their relevance to both human and animal health.

Allometry and ecology shape eye size evolution in spiders

Eye size affects many aspects of visual function, but eyes are costly to grow and maintain. The allometry of eyes can provide insight into this trade-off, but this has mainly been explored in species that have two eyes of equal size. By contrast, animals possessing larger visual systems can exhibit variable eye sizes within individuals. Spiders have up to four pairs of eyes whose sizes vary dramatically, but their ontogenetic, static, and evolutionary allometry has not yet been studied in a comparative context. We report variable dynamics in eye size across 1,098 individuals in 39 species and 8 families, indicating selective pressures and constraints driving the evolution of different eye pairs and lineages. Supplementing our sampling with a recently published phylogenetically comprehensive dataset, we confirmed these findings across more than 400 species; found that ecological factors such as visual hunting, web building, and circadian activity correlate with eye diameter; and identified significant allometric shifts across spider phylogeny using an unbiased approach, many of which coincide with visual hunting strategies. The modular nature of the spider visual system provides additional degrees of freedom and is apparent in the strong correlations between maximum/minimum investment and interocular variance and three key ecological factors. Our analyses suggest an antagonistic relationship between the anterior and posterior eye pairs. These findings shed light on the relationship between spider visual systems and their diverse ecologies and how spiders exploit their modular visual systems to balance selective pressures and optical and energetic constraints.

Invertebrate sounds from photic to mesophotic coral reefs reveal vertical stratification and diel diversity.

Although mesophotic coral ecosystems account for approximately 80% of coral reefs, they remain largely unexplored due to their challenging accessibility. The acoustic richness within reefs has led scientists to consider passive acoustic monitoring as a reliable method for studying both altiphotic and mesophotic coral reefs. We investigated the relationship between benthic invertebrate sounds (1.5-22.5kHz), depth, and benthic cover composition, key ecological factors that determine differences between altiphotic and mesophotic reefs. Diel patterns of snaps and peak frequencies were also explored at different depths to assess variations in biorhythms. Acoustic recorders were deployed at 20m, 60m, and 120m depths across six islands in French Polynesia. The results indicated that depth is the primary driver of differences in broadband transient sound (BTS) soundscapes, with sound intensity decreasing as depth increases. At 20-60m, sounds were louder at night. At 120m depth, benthic activity rhythms exhibited low or highly variable levels of diel variation, likely a consequence of reduced solar irradiation. On three islands, a peculiar peak in the number of BTS was observed every day between 7 and 9 PM at 120m, suggesting the presence of cyclic activities of a specific species. Our results support the existence of different invertebrate communities or distinct behaviors, particularly in deep mesophotic reefs. Overall, this study adds to the growing evidence supporting the use of passive acoustic monitoring to describe and understand ecological patterns in mesophotic reefs.

Tectorotularia hexagona (Polychaeta, Serpulidae) co-existing with Rhynchostreon suborbiculatum (Bivalvia, Gryphaeidae) in a river-dominated marginal marine environment of Cenomanian–Turonian age in Slovakia: An example of Late Cretaceous amensalism or competition?

The mutual relationship and co-occurrence of the tube-dwelling polychaete Tectorotularia hexagona and the oyster Rhynchostreon suborbiculatum in an instance of fluctuating marginal marine environment, represented by the Orlové Sandstone in the Western Carpathians (Pieniny Klippen Belt), is recorded. As a consequence of climate change during the Cenomanian and early Turonian, changes over time in key ecological factors (e.g., decrease in freshwater inflow and increase in temperature and water mass salinity) led to critical trophic alterations in the marginal marine system studied. The environmental change from polyhaline/eutrophic to euhaline/lower nutrient conditions led to a reduction in the pioneer palaeopopulation of R. suborbiculatum, and Tectorotularia hexagona and other stenohaline marine recliners took over the ecological niches originally occupied by the oyster. In this respect, the relationship between T. hexagona and R. suborbiculatum may be considered a Late Cretaceous example of competition between two groups of sessile-benthic recliners. In the present work, two different tube morphologies of T. hexagona from Hôrka are described, and the tube microstructure of this species is documented for the first time. In addition, the material from Hôrka is compared with that from the type locality, Essen in Germany, and ‘Hamulus’ hexagonus and Tectorotularia ‘westfalica’ are considered to constitute one and the same species. The wider ecological and systematic context of this serpulid species is discussed as well.

Identification of geographic, climatic, and soil factors dominating Stevia rebaudiana yield and quality

Raising crop yields and quality through plant ecological research has become an important approach to sustainably improving crop products. Stevia rebaudiana is widely introduced and cultivated around the world because of the continuous increase in demand for steviol glycosides. When selecting regions or plots suitable for high-yield and high-quality cultivation, it is necessary to understand the main ecological factors that contribute to the formation of S. rebaudiana yield and quality. In this study, sampling plots from different geographic and climatic regions in Xinjiang and Jiangsu were selected for S. rebaudiana cultivation. The geographic, climatic and soil ecological factors were analyzed based on a PLSR (partial least squares regression) model to discover the potentially influential factors in the yield and quality formation of the crop. The results suggest that not all geographic and climatic ecological factors contributed to yield formation; however, these factors, such as latitude, altitude and annual sunshine duration, had high or moderate influences on the concentration of each steviol glycoside and total steviol glycoside. Soil organic matter (OM), total potassium (TK), available potassium (AK), zinc (Zn), and catalase (CAT) had high or moderate effects on the concentrations of each steviol glycoside and total steviol glycoside. However, the other soil factors showed variability in the extent to which they drove the steviol glycosides. The study contributes to a more profound understanding of the ecological driving mechanisms of S. rebaudiana yield and quality formation. The yield or steviol glycoside concentrations of sweetleaf may be improved by modifying certain key ecological factors.

Light Intensity: A Key Ecological Factor in Determining the Growth of Pseudolarix amabilis Seedlings

The notable absence of juvenile Pseudolarix amabilis trees in forest understories suggests their vulnerability to ecological niche competition, leading to limited survival prospects. This study examines the key factors limiting the growth of P. amabilis seedlings by investigating the effects of five ecological factors: light intensity, rainfall, groundwater level, soil type, and type of fertilization, on the growth of one-year-old P. amabilis seedlings. Our results demonstrate that increasing the light intensity promotes plant growth by augmenting the leaf count, leaf biomass, plant height, stem biomass, root biomass, and total biomass. Further analysis reveals that increased light intensity influences biomass allocation, reducing the specific leaf area and leaf–stem biomass ratio, and favoring root and stem growth over leaf investment. Rainfall, groundwater level, fertilization type, and rhizosphere soil type primarily influence root growth by impacting the soil’s physicochemical properties. Specifically, rising groundwater levels lower the soil temperature and increase the soil moisture, total potassium content, and soil pH, leading to reductions in root biomass, plant height, net height increment, leaf number, and total biomass. When groundwater levels reach 21 cm and 28 cm, submerging the surface soil layer, root biomass decreases by 1.6 g/plant (−51.6%) and 2.3 g/plant (−74.2%), respectively. Further analysis reveals a gradual decrease in the root–shoot ratio above the 14 cm groundwater level, while the specific leaf area and leaf–stem biomass ratio remains unaffected, indicating stronger belowground root stress compared to aboveground stem and leaf components. The results highlight light intensity as the key ecological factor determining the growth of P. amabilis seedlings. These findings underscore the importance of considering light intensity in the management of natural stands, the cultivation of artificial forests, and the nursery cultivation of endangered P. amabilis.

Can artificially induced habitat complexity alter macroinvertebrates diversity? A case study from a freshwater wetland ecosystem

Habitat complexity can enhance the resilience of wetlands against environmental stressors such as extreme weather events, pollution, and habitat loss. The introduction of artificial induced complexity (AIC) can play a significant role in reshaping the macroinvertebrate communities within wetland ecosystems by enhancing habitat quality in protected areas. Therefore, this study was designed to examine the variation of macroinvertebrates community structure in artificially induced complex sanctuary site (SS), partially protected (PP) and open sites (OS) from July 2019-April 2020. AIC in the sanctuary sites was established through the installation of cemented hexapods and ring pipes. Over the study period, a total of 665 macroinvertebrates were gathered, with 55.55% originating from SS, 31.14% from PP, and 18.21% from OS sites. The community consists mainly of Lymnaea acuminatatea and Tubifex tubifex, with the most abundant species being Limnodrillus hoffmeisteri and Branchiura sowerbyi. A notable positive impact of AIC was evident in the increased total abundance and diversity indices of macroinvertebrate communities. The Analysis of Similarity (ANOSIM) revealed significant distinctions in community structures among various intervention types, which was further corroborated by a non-metric multidimensional scaling (nMDS) plot. Similarity of Percentage Analysis (SIMPER) highlighted that Limnodrillus hoffmeisteri made the most significant contribution to the dissimilarity observed among the different intervention types. Canonical Correspondence Analysis (CCA) revealed a close association between the structure of the macroinvertebrate community and three key ecological factors: periphyton biomass, macrophyte cover, and sediment properties. These findings could offer a more effective approach for managers and policymakers engaged in the conservation of macroinvertebrates and the sustainable management of fisheries resources within wetland ecosystems.

Soil moisture regime in lowland forests – quantity and availability of water

Abstract Water is one of the key ecological factors that has a great impact to development and productivity of lowland species such as Quercus robur. This paper deals with water regime influence to site conditions of these species and how actually changeable soil moisture affects Q. robur. Studied area includes a protective embankment built on the river bank in order to eliminate flooding effect, which means that all needs for water these associations provide from rainfalls and groundwater. Water regime was monitored during two critical years (extremely dry and extremely wet) on four soil types – Planosol, Fluvisol and Gleysol that belong to hydromorphic (three experimental plots) and Chernozem which belongs to automorphic soils (three experimental plots), respectively. It was studied the distribution of rainfalls and groundwater during the growing seasons and how it affects total and available water amount in the soil. The main focus should be given to available water, because it is located in capillary pores and plants can utilize it. Bearing in mind rainfalls makes just 15–20% of the total water amount in the soil it is much more significant to evaluate its proportion in available water. Based on obtained results, we can deduce that much more suitable site conditions for Q. robur are present on hydromorphic soils due to much greater proportion of groundwater.

Ecological Interactions and Livelihood Sustainability: a Study on the Impact of Local Pond Ecosystems in Malda District

This research delves into the dynamic interplay between ecological interactions and livelihood sustainability, focusing on the local pond ecosystems in Malda District. Ponds, integral components of the landscape, contribute significantly to both environmental health and community well-being. Recognizing the intricate web of relationships within these ecosystems is essential for devising effective conservation and management strategies. The primary objectives of this study are to assess the direct and indirect impacts of local pond ecosystems on the livelihoods of communities in Malda District, analyze the key ecological factors influencing pond health, and evaluate the effectiveness of existing conservation and management practices. Field investigations revealed a positive correlation between well-maintained pond ecosystems and enhanced agricultural productivity, water availability, and biodiversity conservation. Moreover, the study identified the interconnectedness between ecosystem health and human well-being, emphasizing the role of ponds in supporting local livelihoods. Challenges, such as pollution and climate change, were also observed, underscoring the need for sustainable management practices and community involvement in pond governance. In conclusion, this research underscores the pivotal role of local pond ecosystems in fostering ecological sustainability and securing livelihoods in Malda District. The findings advocate for the integration of local ecological knowledge into conservation strategies, with a focus on community engagement. This research contributes valuable insights for informed decision-making, policy formulation, and community-based initiatives to ensure a harmonious coexistence between human activities and the environment.

Appraisal of river sediments in southwestern Nigeria with a special focus on trace metals: Occurrence, seasonal variation, sources, and health risks

Metal toxicity can negatively affect aquatic biodiversity. In this study, eight trace metals (TMs) (Cd, Cr, Cu, Fe, Mn, Ni, Pb, and Zn) were determined in 72 sediment samples collected from six major rivers in Southwestern Nigeria between the dry and wet seasons of 2019 and 2021by inductively coupled plasma optical emission spectrometry (ICP-OES). Pollution indices such as enrichment factor, geo accumulation index, pollution load index, and potential ecological risk index were evaluated. At both seasons, the mean TM concentrations (mg/kg) followed a similar trend in decreasing order as Cu (589.32 ± 582.00) > Fe (269.52 ± 127.09) > Zn (162.68 ± 103.14) > Mn (61.89 ± 29.87) > Pb (10.09 ± 5.34) > Cd (8.59 ± 2.20) > Cr (8.72 ± 2.60) > Ni (3.16 ± 1.55) across locations and seasons. Distinctive distribution profiles characterized individual metals coupled with significant seasonal shifts in concentration (p < 0.05). Comparison with recommended national limits for Cd, Cu, Fe, Ni, Pb, and Zn suggested potential human and ecosystem health risks for the local population, while all the metals are above US EPA residential criteria. Cd displayed considerable, or very high ecological risks across all locations and seasons. Overall, Cd was considered a key potential ecological risk factor. Data revealed more anthropogenic than natural sources influenced sediment-bound TMs based on principal component analysis (PCA) and positive matrix factorization (PMF). The findings in this report provide fundamental information that would allow more effective monitoring through the establishment of critical policies and measures to reduce TMs levels in the environment.

PrEP discontinuation, cycling, and risk: Understanding the dynamic nature of PrEP use among female sex workers in South Africa.

PrEP cycling among women is thought to be safe when there are distinct "seasons of risk." However, cyclical PrEP use over short periods may be associated with increased risk of HIV acquisition. We aimed to characterize key social ecological factors contributing toward PrEP cycling among female sex workers (FSW) in the context of high HIV risk. Semi-structured, in-depth interviews were conducted with 36 FSW at risk for HIV acquisition and 12 key informant (KI) service providers in eThekwini (Durban), South Africa from January-October 2020. FSW identified key factors driving temporary discontinuation of PrEP including relocation, lack of information on or difficulty coping with side effects, and delays in accessing PrEP. In many cases, FSW were motivated to restart PrEP once barriers were overcome. In contrast, KIs emphasized the importance of individual adherence to PrEP and reliance on personal risk assessments when counselling FSW on cycling decisions. FSW and KI perspectives highlight a disconnect between providers' recommendations on the potential for cyclical use of PrEP during periods of minimal risk and actual drivers among FSW causing temporary PrEP discontinuation. Further interventions supporting safe PrEP cycling are needed to ensure decisions around cycling are deliberate and guided by changes in HIV risk rather than external factors.

Ecological regulation network of quality in American Ginseng: Insights from macroscopic-mesoscopic-microscopic perspectives

The environment profoundly influences the growth, development and constituents of plants. Nonetheless, a lack of comprehensive studies at various scales hinders our understanding of how environmental factors impact the quality of American ginseng. This study employed an integrated approach, considering macroscopic-mesoscopic-microscopic perspective, to reveal the ecological variables impacting the quality of American ginseng. From the macroscopic perspective, the MaxEnt model revealed that American ginseng is suitable for growth in temperate regions. The temperature seasonality and warmest quarter emerged as crucial bioclimatic factors that influence the distribution of American ginseng. Taking the mesoscopic perspective, the ginsenosides were significantly positively correlated with available phosphorus (AP) and soil water content (SWC), and significantly negatively correlated with ammonium nitrogen (NN), available potassium (AK), and microbial biomass carbon (MBC). From the microscopic perspective, a total of 16 microorganisms, including 14 bacteria and 2 fungi, were identified to have a significant impact on the synthesis of ginsenosides through 16 S and internally transcribed spacer (ITS) rRNA amplicon sequencing combine with machine learning. Notably, this is the first time to construct an ecological network for regulating the quality of American ginseng and identify the key ecological factors, which can serve as valuable references for targeted breeding and domestication of American ginseng. These findings not only established a theoretical foundation for the future investigation of biological fertilizers, but simultaneously provided crucial insights for cultivating high-quality medicinal plants.

Contribution de Louis Pasteur à la sécurité microbiologique des aliments/Louis Pasteur's contribution to the microbiological safety of food

We should thank Louis Pasteur for the essential concepts of medical microbiology, but some 30 years before he achieved the status of benefactor of humanity with the vaccination-treatment of rabies, one of the two pionneers of bacteriology (with the German Robert Koch) published his first observations on fermentations. His famous publication on lactic acid fermentation in 1857 established the concepts of the microbial ecology of food. This work on ferments and their activities led to modern biotechnology, but the ideas contained therein also laid the scientific foundation for food preservation techniques to ensure food quality and safety. Key ecological factors such as acidity, temperature and microbial competition were identified, as well as fundamental characteristics such as biological variability and the predictability of the evolution of microbial ecosystems

What are the main factors that are thought to impact upon the implementation of a whole school approach to student mental health and wellbeing in schools? A systematic review

Increased availability of evidence-informed, school-based, prevention and intervention programmes in the area of mental health and wellbeing promotion has contributed to a shift in research priorities from efficacy to implementation and dissemination. A central issue for school psychology research in moving research to practice is to ensure high quality implementation of both the intervention programmes and the support system that sustains it. The purpose of this review is to identify, appraise and synthesise research evidence using an implementation science framework in order to identify key contextual and ecological factors (facilitators and barriers) that impact upon the implementation process of whole school approaches to mental health and wellbeing promotion. Nine studies that met inclusion criteria were synthesised and critically appraised. A total of eighty-seven facilitators and sixty-seven barriers were extracted across the nine studies. Limitations of findings and methodologies relative to the review questions are outlined and discussed.

Tree Species Classification in Subtropical Natural Forests Using High-Resolution UAV RGB and SuperView-1 Multispectral Imageries Based on Deep Learning Network Approaches: A Case Study within the Baima Snow Mountain National Nature Reserve, China

Accurate information on dominant tree species and their spatial distribution in subtropical natural forests are key ecological monitoring factors for accurately characterizing forest biodiversity, depicting the tree competition mechanism and quantitatively evaluating forest ecosystem stability. In this study, the subtropical natural forest in northwest Yunnan province of China was selected as the study area. Firstly, an object-oriented multi-resolution segmentation (MRS) algorithm was used to segment individual tree crowns from the UAV RGB imagery and satellite multispectral imagery in the forests with different densities (low (547 n/ha), middle (753 n/ha) and high (1040 n/ha)), and parameters of the MRS algorithm were tested and optimized for accurately extracting the tree crown and position information of the individual tree. Secondly, the texture metrics of the UAV RGB imagery and the spectral metrics of the satellite multispectral imagery within the individual tree crown were extracted, and the random forest algorithm and three deep learning networks constructed in this study were utilized to classify the five dominant tree species. Finally, we compared and evaluated the performance of the random forest algorithm and three deep learning networks for dominant tree species classification using the field measurement data, and the influence of the number of training samples on the accuracy of dominant tree species classification using deep learning networks was investigated. The results showed that: (1) Stand density had little influence on individual tree segmentation using the object-oriented MRS algorithm. In the forests with different stand densities, the F1 score of individual tree segmentation based on satellite multispectral imagery was 71.3–74.7%, and that based on UAV high-resolution RGB imagery was 75.4–79.2%. (2) The overall accuracy of dominant tree species classification using the light-weight network MobileNetV2 (OA = 71.11–82.22%), residual network ResNet34 (OA = 78.89–91.11%) and dense network DenseNet121 (OA = 81.11–94.44%) was higher than that of the random forest algorithm (OA = 60.00–64.44%), among which DenseNet121 had the highest overall accuracy. Texture metrics improved the overall accuracy of dominant tree species classification. (3) For the three deep learning networks, the changes in overall accuracy of dominant tree species classification influenced by the number of training samples were 2.69–4.28%.

Seasonal patterns in the structure of the fish larvae assemblages in the lower Amazon River

Abstract This study assessed the phenology and functional structure of parental stocks of fish larvae, and evaluated how the species modulate their reproductive activities as a function of natural hydrological regimes in the lower Amazon River, Brazil. Larvae were collected using conical plankton nets monthly over two hydrological cycles between January and December 2013, and between May 2017 and April 2018. The collections were conducted around an alluvial island located near the municipality of Santarém, Pará, Brazil. After identification, individuals were classified into four functional groups (e.g., life‐history strategy, feeding habits, type of migration, and swimming‐performance/microhabitat‐use in the water column) based on species traits. The relationships between seasonal hydrology, environmental variables and larval assemblage structure were evaluated using multivariate analyses. A total of 31,347 fish larvae were collected, from nine taxonomic orders, 26 families, 40 genera and 53 species. The larval assemblages showed highly variable taxonomic and functional composition between different phases of the hydrological cycle (rising water, high water, receding water and low water) and were strongly influenced by environmental variables. Fish reproductive phenology in the lower Amazon is complex and distributed among the hydrological phases. The different ecological characteristics allow the species to withstand specific environmental conditions during each phase. Changes in the structure of larval assemblages indicate that hydrological variability is a key ecological factor influencing the reproductive dynamics of fish and reflects adaptive strategies used to reduce interspecific competition for space and food, maximising recruitment. The variation of fish reproduction across the hydrological cycle that we observed is a result of different ecological characteristics enabling species and functional groups to adapt to environmental conditions of each phase.

Leaf litter decomposition rates: influence of successional age, topography and microenvironment on six dominant tree species in a tropical dry forest

Litter decomposition is a central process in forest ecosystems because of its role in carbon and nutrient cycling and maintaining soil fertility. Decomposition is affected by plant traits, soil and microenvironmental conditions, topography, and vegetation structure, which varies with successional age. However, it is unclear how all these factors affect leaf decomposition of dominant tree species in tropical dry forests (TDFs). The objective of this study was to compare the decomposition rates of six dominant tree species: three legumes (Caesalpinia gaumeri,Lysiloma latisiliquum,Piscidia piscipula) and three non-legumes (Bursera simaruba,Gymnopodium floribundum,Neomillspaughia emarginata) in five successional age categories (8–10, 15–22, 23–30, 65–84, &amp;gt; 85 years-old) and two topographic conditions (flat and sloping sites) in a TDF, and to analyze the association with leaf traits (toughness, N, C and total phenols content) soil properties (bulk density, organic carbon, pH, clay), microenvironmental (litter and soil moisture, leaf area index), and vegetation variables (basal area, aboveground biomass, tree diameter, tree height). Litterbags were placed in 30–400 m2circular plots distributed in forests of the Yucatan, Mexico, and collected on six occasions spread over 230 days (540 samples per species).L. latisiliquumandC. gaumerihad the highest decomposition rates (as well as leaf nitrogen concentration and the lowest leaf toughness). Conversely,G. floribundumhad the lowest decay rate. Decomposition rate reached high values at intermediate successional ages, suggesting that soil fertility recovers rapidly after disturbance, although onlyL. latisiliquumshowed significant differences among stand age categories. Decomposition rate was consistently higher at flat sites than on slopes but the difference was significant only forL. latisiliquum. The soil, vegetation structure and microenvironmental variables that contributed most to explaining variation in decay rates varied among species. Decomposition tended to increase with soil moisture and clay content, and to decrease with soil organic carbon and pH suggesting susceptibility to climate change and soil erosion, particularly in sloping areas. Our results highlight the importance of analyzing species-specific responses, especially for dominant species, which likely contribute most to leaf litter decomposition, and to consider key ecological factors that influence this key process.