Species Evenness Research Articles

Угруповання мишовидих гризунів на ділянках з різним ступенем ураження пожежами: чорнобильські полігони

As a result of climate change, forest fires are becoming a common factor in the dynamics of ecosystems in the forest zone of Ukraine, but the assessment of the consequences of this shift in the ecological situation is in the process of pilot studies. In the spring of 2020, a number of large ecosystem fires occurred in the Central Polissia region, which affected forests the most. Among other things, a large fire occurred in ecosystems located in the Exclusion Zone and the Zone of Unconditional (Mandatory) Resettlement, which was formed as a result of the Chornobyl accident. The ecosystems of the Chornobyl Radiological and Ecological Biosphere Reserve located within its boundaries were also affected by the fire. The consequences of this fire were assessed a year later, using mouse-like rodents as a model group. The purpose of the study was to assess and compare the communities of mouse-like rodents in areas that were affected by two degrees of fire damage—where there was a surface fire and those that were most affected (highland fire). Four polygons were created in the control-impact scheme. Each of the pairs of plots was identical in terms of typical forest vegetation conditions. Sherman traps were used for trapping. A total of 560 trap-days were processed, and 101 animals were captured. The presence of four species of rodents from the genera Apodemus, Sylvaemus, and Myodes was recorded, namely the striped field mouse, the yellow-necked wood mouse, the European wood mouse, and the bank vole. The main indicators of species diversity were calculated using information indices—species richness, evenness, and similarity. The surveys revealed both negative and positive changes in areas affected by fires. Areas characterised by relatively higher values of species diversity indices compared to the control had a high intensity of vegetation recovery. They belonged to areas with wet, relatively fertile (sugrud) and infertile (subor) forest types. The plots with low intensity of vegetation recovery had a depleted community structure and belonged to fresh and dry boreal forest. Based on this, it is possible to create a forecast of ecosystem restoration by assessing the type of forest vegetation conditions.

Effects of exclosures on mountain grassland floristic composition in Sidama, Ethiopia

This study was conducted to assess the effects of exclosure on mountain grassland’s species composition, richness, diversity and dominance in Sidama, Southern Ethiopia. Locally established exclosures aged between 10 and 12 years old were compared against adjacent open-grazed areas in Mollona-Meno Kebele for this study. The study was replicated at four sites. An exclosure was paired with adjacent open-grazed lands having a similar land area and slope. Both in the exclosures and adjacent open-grazed lands, 87 and 86 plant species were recorded, representing 20 families, respectively. A significantly higher difference was observed between exclosures and adjacent open-grazed lands in terms of herbaceous species abundance, diversity, evenness and density. Higher herbaceous species’ important value index (IVI) was recorded inside exclosures than in the open-grazed lands. The results suggested that the establishment of exclosures on degraded lands could support the restoration of degraded native herbaceous species which consequently enhanced ecosystem services.

Pollinator insects in the Mount Tumpa Forest Park, Manado, North Sulawesi, Indonesia

Abstract. Koneri R, Langoy MD, Nangoy MJ, Wakhid. 2024. Pollinator insects in the Mount Tumpa Forest Park, Manado, North Sulawesi, Indonesia. Biodiversitas 25: 2415-2426. This study aimed to analyze the diversity and distribution of pollinator insects in forest, forest edge, shrub, and agricultural land around the Mount Tumpa Forest Park, Manado, North Sulawesi, Indonesia, using the scan sampling method. Data analysis included species abundance, species dominance, richness index, diversity index, species evenness index, correlation between environmental factors, species diversity, and composition of pollinator insect species among habitats. Therefore, 17 families were reported, comprising 103 species and 3,665 individuals. The family with the highest number and most frequently encountered was Nymphalidae (25 species). Furthermore, the highest species richness and diversity indices were found in the forest edge habitat. Environmental factor analysis indicated that agricultural land habitat was characterized by high air temperature and low humidity. The species distribution found three patterns: clustered, regular, and random. The results showed that the forest edge habitat had the highest diversity due to complex vegetation structure and environmental factors supporting the survival of pollinator insects.

Short-Term Responses of Alpine Vegetation to the Removal of Dominant versus Sparse Species.

The mass ratio hypothesis posits that ecosystem functions are predominantly influenced by the dominant species. However, it remains unclear whether a species must be abundant to exert functional dominance. We conducted a removal experiment in an alpine grassland near Pudacuo National Park, Yunnan, China, to assess the community and ecosystem impacts of the removed species. We implemented four treatments as follows: exclusive removal of the most abundant species (Blysmus sinocompressus), exclusive removal of a sparse species with high individual biomass (Primula secundiflora), simultaneous removal of both species, and a control with no removals. Results showed that removing B. sinocompressus significantly reduced biomass production, supporting the mass ratio hypothesis, while removal of P. secundiflora had negligible effects. B. sinocompressus removal positively impacted community metrics like coverage, species evenness, and the Shannon diversity index, but not species richness, likely due to its spatial dominance. Conversely, P. secundiflora removal had minimal community impact, probably due to its limited influence on nearby species. This study underscores the proportionate roles of the dominant species in alpine grasslands, emphasizing that their community and ecosystem impacts are proportional to their abundance.

Fish biodiversity status and threats of Chinadi Beel in Bangladesh

This study examined the fish fauna of Chinadi Beel in Bangladesh in terms of diversity, quantity, and state of conservation. A pre-tested questionnaire and a direct catch evaluation survey were employed to conduct the study in the beel. In the examined beel, a comprehensive count of 3,360 fish specimens, encompassing 52 distinct fish species from 8 orders and 19 families, was documented. Cypriniformes was identified as the dominating order among the 8 orders examined, accounting for 51.49% of the total. Out of 52 fish species about 31 least concern (59.61%), 8 endangered (15.38%), 6 vulnerable (11.54%), 6 near threatened (11.54%) and 1 critically endangered (1.92%) species were observed according to the International Union for Conservation of Nature. The study utilized population diversity indices, specifically the Shannon-Weiner diversity index (H'), Margalef species richness (d), Pielou's evenness index (J'), and Simpson dominance index (c), to assess the species diversity, richness, and evenness of fish which value were found to be 2.50, 4.30, 0.90, and 0.30, respectively. Chinadi Beel has the capacity to function as a significant reservoir of fishing resources and a repository of genetic information for many fish species. However, the present study emphasized several anthropogenic and environmental issues, such as unregulated fishing, agricultural pollutants, illegal or harmful fishing, the construction of infrastructure for development, and climate change. Hence, it is highly recommended to implement ecosystem-based fisheries management that actively involves the local population in order to guarantee the long-term preservation of these water bodies.

Estructura comunitaria de peces, asteroideos y equinoideos en el Farallón de San Ignacio, arrecife situado en la “brecha faunística de Sinaloa”, México

Even though there is extensive research on the rocky reefs in the Gulf of California, some areas still have scarce information, such as the Farallón de San Ignacio, which is well known for its high biodiversity and its location in the biogeographic transition zone known as the "Sinaloa gap." Due to the limited information available for this site, the present study aimed to describe the composition and structure of asteroid and echinoid fish assemblages at the Farallón de San Ignacio. For this purpose, visual surveys were conducted in November 2016 using belt transects of 25 m long by 4 m wide for fish and 25 m long by 2 m wide for invertebrates, to estimate species abundance, richness, diversity, and evenness indices, and to compare them with other rocky reefs located at the same latitude on the western coast of the Gulf of California that were visited the same year. A total of 34 species were recorded, including two asteroids and four echinoids. The most abundant species were the fish Azurina atrilobata, the starfish Phataria unifacialis, and the sea urchin Diadema mexicanum. Despite the Farallón’s isolation, the complexity of its community structure is similar to that of other islands in the Gulf of California, although there were differences in species composition due to the high abundance of herbivorous species at this site.

Composition and diversity of 16S rRNA based skin bacterial microbiome in healthy horses

Characterization of microbiota structure on the skin of healthy horses is important for further development of modulation strategies to ensure optimal bacterial composition for physiological processes. This requirement is also supported by the relatively high incidence of dermatological diseases in horses and thus the need to manage them therapeutically. The taxonomic analysis of skin samples (n = 30) from five different body parts of clinically healthy Shetlands ponies females (neck, back, abdomen, pastern, muzzle) kept under homogeneous conditions (in open stalls with paddock, feed with dry hay, green grass ad libitum and granulated feed) was performed using amplification of V3—V4 region of the 16S rRNA gene. Results indicate that bacteria associated with healthy equine skin represent 18 phyla, 29 classes and 119 families. The most abundant phyla were Proteobacteria (30.8 ± 9.1%) followed by Actinobacteriota (20.4 ± 7.6%), Firmicutes (19.5 ± 10.1%), Bacteroidota (8.5 ± 5.0%) and Deinococcota (7.2 ± 14.8%). Among 229 genera identified, Corynebacterium (7.4 ± 6.5%) was the most abundant genus in skin sites of horses, followed by Deinococcus (7.1 ± 14.9%) and Macrococcus (5.0 ± 8.2%). Indices for the richness and diversity of species within bacterial populations for five regions of horses skin revealed no significant variations observed for species richness (Chao1, p-value 0.2001) but significant result for species evenness (Shannon, p-value 0.0049) with maximum on the neck and minimum on the back skin site. The clustering was seen across samples from different skin sites but also across samples collected from individual horses.

Weed Biology and Ecology Studies: Diversity, Dominance, Population and Weed Growth and Land Use Efficiency in Intercropping Corn (Zea mays l.) with Leguminous Crops in Dryland

The aim of the research is to examine the effect of intercropping corn with leguminous crops on weeds and land use efficiency. The experimental research method was designed using a randomized complete block design (RCBD) with three blocks. The treatments tested were monocrop planting patterns and intercropping between corn and leguminous crops. The results of the research showed that 16 weed species were found with high species diversity, evenness, dominance, and abundance, so that there were six dominant species that existed during plant growth. Peanuts and cowpeas are suitable for intercropping with corn because they can suppress the population and growth of weeds. Soybeans, green beans, and red beans are not suitable because they are not effective in suppressing the population and growth of weeds and compete with corn, so that corn yield losses due to competition are 38.20%–40.96% and due to weed competition, they reach 62.37%–63.77%. The best ecological and agronomic land use efficiency was obtained by intercropping corn with peanuts and cowpeas, with NKL values based on dry biomass weights of 1.90 and 1.89 (NKL > 1) and dry seed weights of 1.79 and 1.78 (NKL > 1).

One-year effects of stand age, pre-fire treatments, and hillslope aspect on recovery of plant diversity and soil properties in a Mediterranean forest burnt by a severe wildfire

Although several management options are adopted to redirect post-fire forest ecosystems towards less vulnerable and more resilient and functional communities, little is known about the interactions among tree stand age, pre-fire forest management, and slope aspects, and their consequences for plant species and soil properties recovery immediately after severe wildfires. To address this knowledge need, this study evaluates the post-fire changes in species richness and diversity (with a specific focus on regeneration mechanisms and life forms) of regenerating plants as well as the main physico-chemical and biological properties of burned soils with the reciprocal relations. Plant cover and diversity, and many soil properties have been monitored in forests of southeast Spain with mature, middle and young stands, presence of pre-fire treatments or not, and north and south hillslopes about one year after the fire. To this aim, the reciprocal relationships among soil properties and plants were evaluated adopting a combination of statistical techniques (PERMANOVA, Non-metric Multi-Dimensional Scaling, Distance-based Linear Modelling, Distance-based Redundancy Analysis, and Spearman correlation analysis). The damage to soil and vegetation was so high that both plants and pre-fire soil properties slowly recovered. Only a few life forms of vegetation (geophytes and herbaceous chamaephytes) were influenced by the stand age. If combined with soil aspect, stand age resulted in significantly lower germinating species in mature stands and lower resprouters in young stands, both on south hillslopes. Plant diversity was high, and the post-fire regeneration did not change the species richness and evenness. The post-fire changes in soil properties were limited, and only slight small differences in pH and betaglucosidase among stands of different age were found. No evident associations between soil properties and plant diversity were revealed by the low correlation coefficient. The low variance in plant cover and diversity, as well as in soil properties, resulted in a low accuracy of the dbRDA model to reproduce its variability among sites with different pre-fire characteristics.

Potential distribution and ecological impacts of Acmella radicans (Jacquin) R.K. Jansen (a new Yunnan invasive species record) in China

Background Acmella radicans(Jacquin) R.K. Jansen is a new invasive species record for Yunnan Province, China. Native to Central America, it has also been recently recorded invading other parts of Asia. To prevent this weed from becoming a serious issue, an assessment of its ecological impacts and potential distribution is needed. We predicted the potential distribution of A. radicans in China using the MaxEnt model and its ecological impacts on local plant communities and soil nutrients were explored.ResultsSimulated training using model parameters produced an area under curve value of 0.974, providing a high degree of confidence in model predictions. Environmental variables with the greatest predictive power were precipitation of wettest month, isothermality, topsoil TEB (total exchangeable bases), and precipitation seasonality, with a cumulative contribution of more than 72.70% and a cumulative permutation importance of more than 69.20%. The predicted potential suitable area of A. radicans in China is concentrated in the southern region. Projected areas of A. radicans ranked as high and moderately suitable comprised 5425 and 26,338 km2, accounting for 0.06 and 0.27% of the Chinese mainland area, respectively. Over the 5 years of monitoring, the population density of A. radicans increased while at the same time the population density and importance values of most other plant species declined markedly. Community species richness, diversity, and evenness values significantly declined. Soil organic matter, total N, total P, available N, and available P concentrations decreased significantly with increasing plant cover of A. radicans, whereas pH, total K and available K increased.ConclusionOur study was the first to show that A. radicans is predicted to expand its range in China and may profoundly affect plant communities, species diversity, and the soil environment. Early warning and monitoring of A. radicans must be pursued with greater vigilance in southern China to prevent its further spread.

Habitat loss and simplification lower arthropod richness but not diversity

AbstractHabitat loss is rarely truly random and often occurs selectively with respect to the plant species comprising the habitat. Such selective habitat removal that decreases plant species diversity, that is, habitat simplification or homogenization, may have two negative effects on other species. First, the reduction in plant community size (number of individuals) represents habitat loss for species at higher trophic levels who use plants as habitat. Second, when plants are removed selectively, the resulting habitat simplification decreases the diversity of resources available to species at higher trophic levels. It follows that habitat loss combined with simplification will reduce biodiversity more than habitat loss without simplification. To test this, we experimentally implemented two types of habitat loss at the plant community level and compared biodiversity of resident arthropods between habitat loss types. In the first type of habitat loss, we reduced habitats by 50% nonselectively, maintaining original relative abundance and diversity of plant species and therefore habitat and resource diversity for arthropods. In the second type of habitat loss, we reduced habitats by 50% selectively, removing all but one common plant species, dramatically simplifying habitat and resources for arthropods. We replicated this experiment across three common plant species: Asclepias tuberosa, Solidago altissima, and Baptisia alba. While habitat loss with simplification reduced arthropod species richness compared with habitat loss without simplification, neither type of habitat loss affected diversity, measured as effective number of species (ENS), or species evenness as compared with controls. Instead, differences in ENS and evenness were explained by the identity of the common plant species. Our results indicate that the quality of remaining habitat, in our case plant species identity, may be more important for multi‐trophic diversity than habitat diversity per se.

Assessment of biodiversity and seasonal dynamics of spiders in maize crops of Punjab, Pakistan

Spiders contribute significantly to natural pest control in agriculture. Here, we investigated the biodiversity, population dynamics and predatory activities of spiders in the maize-growing districts (Kasur and Lahore) of Punjab, Pakistan during 2018–2019. Various collecting methods including pitfall and yellow pan traps, manual hand-picking, beat sheet, and sweep nets were used to collect spiders on a biweekly basis. The collected 12,894 individuals represented 45 different species, 27 genera, and 13 families. The major families recorded were Araneidae (32.92%), Lycosidae (20.43%) and Salticidae (11.12%) comprising >64% of the overall abundance. Neoscona theisi (Araneidae) was found to be most dominant species (11.61%). Moreover, the species Macracantha hasselti (Araneidae) and Atypena formosana are reported for the first time from Pakistan. Besides, the estimated species diversity from both districts was 97%. The Margalef's index was highest in Kasur (D = 5.08) and lowest in Lahore (D = 4.95). The values of the Shannon-Wiener and species evenness indices were similar in Kasur and Lahore suggesting similar diversity levels and an even distribution. Spider abundance was highest in April and lowest in June and July. These findings will help to develop effective Integrated Pest Management strategies in maize growing areas across the world.

Tumor microbiome differences in early-onset versus average-onset pancreatic adenocarcinoma.

4016 Background: The rise in early-onset gastrointestinal cancers includes an increased risk of pancreatic adenocarcinoma (PDAC), but the underlying pathogenesis is incompletely understood. The tumor microbiome is an increasing focus of research given its impact on tumor pathogenesis and outcomes. We evaluated microbiome profiles in resected specimens from early-onset PDAC (eoPDAC) and average-onset PDAC (aoPDAC). Methods: PDAC specimens were selected consecutively from Cleveland Clinic and Roswell Park Cancer Institute biorepositories and categorized on age at diagnosis ( < 50 years defined as eoPDAC, and > 50 years as aoPDAC). The tissue microbiome was characterized using shotgun metagenomic sequencing. Alpha diversity, denoting the richness and evenness of microbial species within a specific sample, was compared using the Wilcoxon rank-sum test. The differential test of Beta-diversity distances (Bray Curtis distance), representing microbial taxonomic differences between the specimens was performed using Permutational MANOVA. All p-values were adjusted for multiple testing. Results: The study comprised 44 individuals with resected PDAC (24 eoPDAC and 20 aoPDAC). After quality checks, 63 tissue specimens were selected for analysis (13 tumor and 10 adjacent normal specimens for eoPDAC, 20 each of tumor and adjacent normal specimens for aoPDAC). eoPDAC tumor demonstrated significantly higher alpha diversity compared to adjacent normal tissue (P = 0.02) and aoPDAC (P = 0.0062) while aoPDAC did not (tumor vs normal alpha diversity P = 0.31). Beta diversity analysis demonstrated significantly different diversity of genera between all the groups (P < 0.05). Consistent with this finding, the majority of the species - 259/302 (85.8%) in eo vs aoPDAC comparison and 262/366 (71.6%) for eoPDAC vs normal comparison did not overlap. Differential abundance analysis revealed a significant variation of tumor microbiome in eoPDAC vs aoPDAC (P < 0.05). Prevalent bacterial genera (tumor specimens) are listed in the Table. eoPDAC tumor tissues were enriched in Enterobacter, Neisseria,and Escherichia genera, while aoPDAC tumor tissues were enriched in Klebsiella and Bacillus genera. Conclusions: eoPDAC has a distinct microbiome profile compared to aoPDAC. The correlation with several microbial genera associated with pancreatic diseases is a significant finding and warrants further exploration. This is relevant considering the rising incidence of eoPDAC of unknown etiology, and ongoing efforts to develop microbiome-based biomarkers for screening and treatment. [Table: see text]

Tillage and mulching influence weed community dynamics and crop productivity of Sesbania alley–based food–fodder systems in rainfed agro-ecosystems

Context or problemCrop yield in rain-fed agro-ecosystems is limited by low soil moisture availability and weeds. Objective or research questionThis study aimed to answer the questions- 1. Do tillage practices, mulching and Sesbania alley-based food-fodder cropping system affect weed dynamics under rainfed agro-ecosystem? and 2. Is the productivity of a Sesbania alley-based rainfed food-fodder system affected by tillage practice, mulching or crop sequence? MethodsA four-year field experiment was conducted with Sesbania alley-based food-fodder systems (sorghum – chickpea; sorghum – barley; sorghum – mustard), and three tillage practices (conventional tillage; minimum tillage during rainy season - zero tillage during winter season; conventional tillage during rainy season - zero tillage during winter season) with and without mulch. ResultsDuring the study period, conservation agricultural techniques resulted in a shift in weed flora in all Sesbania alley-based cropping systems. Grass, broadleaf, and total weed densities declined by 8–9%, 35–38%, and 11–13%, respectively, across diverse cropping systems from 2014 to 15; however, sedge population increased (13–29% increase) during the same period. Mulching practices considerably reduced sedge density compared to the without-mulch treatment in all the tillage combinations. The lowest total weed biomass was recorded for minimum tillage during the rainy season and zero tillage + mulching treatment (17 g m–2) during the winter season. Weed species abundance and dominance were greater in 2014, while the diversity and evenness of weed species were higher in 2016, which indicates a weed shift. Sesbania hedgerow + (sorghum-mustard) with conventional tillage during the rainy season and zero tillage during the winter season without mulching had the highest weed diversity index and evenness than that of other treatment combinations. The Sesbania dry matter (DM) yield was significantly higher by 13% and 11% in minimum tillage during the rainy season and zero tillage during the winter season with mulching compared to conventional tillage without mulch in 2015–16 and 2016–17, respectively. However, tillage and mulching had a significant effect on the grain and straw yields of winter crops. All the tillage practices with Sesbania mulching recorded higher grain and straw yields for winter crops compared to the un-mulched treatments. ConclusionsThe innovative Sesbania alley-based rainfed food-fodder system, along with reduced tillage and mulching, improved productivity and altered weed dynamics. Implications or significanceThe knowledge gathered on weed dynamics may aid in determining weed management tactics under conservation agricultural practices. Double cropping is possible without compromising fodder needs by employing suitable tillage and mulching procedures, as well as Sesbania alley-based cropping systems.

Community Structure Analysis of The Boroko and Binuanga Mangrove Areas North Bolaang Mongondow Regency, North Sulawesi Province

Mangrove forests are one of the potential coastal and marine natural resources that Indonesia has, as an abundant archipelagic country. The area of mangrove forests in Indonesia is approximately 3,490,000 ha or equivalent to 21% of the world's mangrove forests. This research aims to analyze the community structure of the Boroko and Binuanga mangrove areas, North Bolaang Mongondow Regency, North Sulawesi Province. The research uses a survey method with a quantitative descriptive approach, namely a method of collecting data directly at the research location. The survey method was used to collect data in the form of mangrove identification, species diversity, species evenness and species uniformity in the mangrove area at the research location. The types of mangroves found in the Boroko and Binuanga mangrove areas consist of 7 species, namely Rhizophora apiculata, Rhizophora mucronata, Ceriops tagal, Bruguiera gymnorrhiza, Avicennia alba, Lumnitzera littorea, and Sonneratia alba. The results of the analysis of the diversity index, species richness and evenness of mangrove species in Boroko and Binuanga villages obtained a diversity index (H') value of 1.29-1.34, species richness (DMg) 1.01-1.23 and species evenness (E ) 0.68-0.71. The diversity of mangrove species in Boroko and Binuanga Villages is in the medium category, the evenness index (E) shows that the evenness of mangrove plants is stable and based on the species richness index criteria the two research locations are in the low species richness category.

Impact of Parthenium hysterophorus L. on floristic diversity in Dhauladhar foothills of Himachal Pradesh.

Parthenium hysterophorus L. has become a weed of global concern owing to its fast expansion and invasive character. In order to study the status of this noxious weed and its impact on floristic diversity in Dhauladhar foothills, the study was conducted during the year 2021-2022 in culturable wastelands of Dhauladhar ranges in Kangra district of Himachal Pradesh, India. The impact of Parthenium hysterophorus L. on associated species at different altitudes and aspects was observed. Our observations depicted that Parthenium hysterophorus L. has been growing more vigorously in the northern aspect than the southern aspect with the density of 37.78m-2 and 21.62m-2, respectively. The highest density of this noxious weed was recorded in the altitudinal range of 600-1200m (34.32m-2) while it was not observed beyond 1805m above sea level. The invasion of Parthenium hysterophorus L. significantly affected the plant density of other species. The descending order of the species as per dominance was observed as Cynodon dactylon, Trifolium repens, Oxalis latifolia, Parthenium hysterophorus L., and Ageratum houstonianum. The average number of species and species density were observed more in non-invaded sites (9.35 and 27.67m-2) than in invaded sites (7.10 and 20.60m-2). Species abundance and plant cover were observed more in non-invaded sites (28.73 and 657.90 m2ha-1) than in invaded sites (22.70 and 322.30 m2ha-1). Species diversity, richness, and evenness were reported to decline in invaded sites (1.56, 0.95, and 0.81, respectively) with respect to the non-invaded sites (1.94, 1.16, and 0.88, respectively). The study highlights the significant concerns associated with the invasive weed within the plant communities. Understanding its invasive status holds considerable implications for local afforestation initiatives, forest management strategies, and conservation policies. Furthermore, this investigation lays a foundational groundwork for implementing effective measures to get rid of this alien weed.

Characterising different artisanal fishing gears catches that operate in distinct habitats to assess ichthyofauna assemblages in Bons Sinais estuary, Mozambique

Monitoring the ichthyofauna is crucial to detect changes in aquatic communities for fisheries management and conservation. This study aimed to identify the most effective gear for ichthyofauna studies in the estuary. Thus, the performance of the beach seine (active gear) and chicocota (fixed gear), common fishing gears used by artisanal fishers in the Bons Sinais estuary (BSE), were used to characterise fish assemblage structure. Monthly surveys were conducted at two fixed sample points of the BSE to assess the composition of the fish assemblage. The analysis revealed statistical differences in abundance, biomass, and the presence/absence of different species between gears regardless sampling months. At ecological level, differences among gears were explained by different modus operandi, technological features and also different sampling habitats where gears operate; beach seine is catching bottom-bound and littoral fish while Chicocota is sampling the pelagic assemblage of the mid-channels. The frequency of occurrence of the 13 most abundant species differed between gears. Both gears showed little size-selectivity, with the mean total length and mean body height of these species statistically differing between gears. A total of 92 fish species were identified. No statistical differences were observed among gears for species richness, diversity and evenness. Both fishing gears captured several local socio-economically important species in the BSE. In particular, 13 of the most important species accounted for more than 54% and 60% of the total abundance and biomass in beach seine and chicocota, respectively. The complementary use of fixed and active fishing gears for studying fish community structure in estuaries is recommended. This multi-gear sampling approach enhances the capacity to detect changes in fish communities and provides valuable data for fisheries management and conservation efforts.

Landscapes with higher crop diversity have lower aphid species richness but higher plant virus prevalence

Abstract Diversifying agricultural systems by growing more than one crop species in an area can decrease pest and disease pressure and increase crop yields. However, there is a lack of information on how crop diversity at larger spatial scales influences pest and disease pressure. Here, we investigated how landscape‐scale crop diversity affects aphid vector communities and prevalence of non‐persistently transmitted potato virus Y (PVY). To test the influence of landscape‐scale crop diversity on PVY prevalence and aphid communities, we conducted a field study during the 2020 and 2021 field seasons in the San Luis Valley, Colorado, where we quantified aphid communities and PVY incidence at multiple sites. We then determined the association between aphid species richness and abundance and PVY incidence with landscape variables (crop diversity metrics and percentage cover of crop species) within 1, 2 and 3 km buffers from study sites. Higher crop diversity (measured as Shannon Diversity Index) led to decreased aphid species richness at a 3 km buffer in the 2021 field season. We only detected a positive association between percentage of alfalfa crop cover and aphid species richness in 2020 and aphid abundance in 2021 within a 1 km buffer. Higher crop diversity led to increased PVY incidence at a 2 km buffer in 2021 and 3 km buffer in 2020 and 2021. At a 3 km buffer in 2021, we found a positive influence of crop species richness on PVY incidence and a negative influence of crop species evenness on PVY incidence. Also in 2021, we found a positive influence of percentage of potato (virus host) on PVY incidence and a negative influence of percentage of barley (virus non‐host) on PVY incidence. Synthesis and applications. In summary, we found that landscape‐scale crop diversity impacts plant virus prevalence at spatial scales of >1 km. This suggests that potato growers could reduce PVY prevalence by geographically isolating potato fields from other potato or other PVY hosts. Crop diversity had a negative influence on aphid vector communities, so growers could reduce risk of virus spread by aphid vectors by using certified potato seed in a diversified landscape.

Biodiversity of Trichoderma species of healthy and Fusarium wilt-infected banana rhizosphere soils in Tenerife (Canary Islands, Spain).

Banana (Musa acuminata) is the most important crop in the Canary Islands (38.9% of the total cultivated area). The main pathogen affecting this crop is the soil fungal Fusarium oxysporum f. sp. cubense subtropical race 4 (Foc-STR4), for which there is no effective control method under field conditions. Therefore, the use of native biological control agents may be an effective and sustainable alternative. This study aims to: (i) investigate the diversity and distribution of Trichoderma species in the rhizosphere of different banana agroecosystems affected by Foc-STR4 in Tenerife (the island with the greatest bioclimatic diversity and cultivated area), (ii) develop and preserve a culture collection of native Trichoderma species, and (iii) evaluate the influence of soil chemical properties on the Trichoderma community. A total of 131 Trichoderma isolates were obtained from 84 soil samples collected from 14 farms located in different agroecosystems on the northern (cooler and wetter) and southern (warmer and drier) slopes of Tenerife. Ten Trichoderma species, including T. afroharzianum, T. asperellum, T. atrobrunneum, T. gamsii, T. guizhouense, T. hamatum, T. harzianum, T. hirsutum, T. longibrachiatum, and T. virens, and two putative novel species, named T. aff. harzianum and T. aff. hortense, were identified based on the tef1-α sequences. Trichoderma virens (35.89% relative abundance) and T. aff. harzianum (27.48%) were the most abundant and dominant species on both slopes, while other species were observed only on one slope (north or south). Biodiversity indices (Margalef, Shannon, Simpson, and Pielou) showed that species diversity and evenness were highest in the healthy soils of the northern slope. The Spearman analysis showed significant correlations between Trichoderma species and soil chemistry parameters (mainly with phosphorus and soil pH). To the best of our knowledge, six species are reported for the first time in the Canary Islands (T. afroharzianum, T. asperellum, T. atrobrunneum, T. guizhouense, T. hamatum, T. hirsutum) and in the rhizosphere of banana soils (T. afroharzianum, T. atrobrunneum, T. gamsii, T. guizhouense, T. hirsutum, T. virens). This study provides essential information on the diversity/distribution of native Trichoderma species for the benefit of future applications in the control of Foc-STR4.

Temporal changes in species richness, composition and diversity of the forest stands over 36-year period, Western Himalaya, India

This study investigates the temporal changes in species richness, composition, and diversity in forest stands spanning a 36-year period in the Western Himalaya. Four forest stands (subtropical Sal-forest, subtropical Chir-pine forest, temperate Banj-oak forest, and temperate Mixed-oak Forest) studied in 1980–1981 were resurveyed using similar methods. Over the past 36 years, 19 new species have been recorded in the four stands; eight species planted and eleven species naturally introduced. Dominant species continue to dominate in the forest stands. However, their contribution to the total tree density has decreased over the year. Species diversity, richness, and evenness increased in all forests except the Sal stand. Three species were newly introduced in the Sal stand, seven in the Chir-pine stand, eight in the Banj-oak stand, and seven in the Mixed-oak stand. The highest similarity in species composition was observed in the Sal stand (59 %), followed by the mixed-oak stand (57 %), Chir-pine stand (50 %), and Banj-oak stand (47 %). The results indicate an increase in tree density across all sites, with the Mixed-oak forest exhibiting the highest increase in tree density due to least biotic pressure. The findings of this study, based on two-time composition datasets, provide valuable insights into forest dynamics, supporting biodiversity conservation and management planning.