Low Species Diversity Research Articles

Observations on the Composition and Diversity of Ant Communities in Different Habitats in a Campus Ecosystem

Ants are more sensitive to ecosystem changes and their fast response to habitat alterations enable them as a useful tool for natural areas restoration efforts. A preliminary investigation was conducted to determine the diversity and distribution of ants from various habitats selected across the campus of Sree Narayana College, Thiruvananthapuram, Kerala State. A total of seventeen species belonging to four subfamilies, fourteen genera and 234 individuals were collected. The subfamily Myrmicinae is the most diverse followed by Formicinae, Ponerinae and Dolichoderinae. In the present study, Diversity Index, Dominance index and Evenness index of ant species were determined. Diversity varied from 0.49 to 0.82 indicating low diversity. Dominance index value ranged from 0.17 to 0.47 while Evenness index value from 0.63 to 0.92. The results showed low diversity and dominance of ant species in the campus area indicating the severity of human interference in the campus ecosystem.

Study on the biodiversity of macroinvertebrate in the Dayang River Basin during summer based on environmental DNA and morphological analysis

The health of the Dayang River ecosystem, critical freshwater resource for Dandong City, is intertwined with local water management and coastal development. In June 2023, we conducted a biodiversity survey in the Dayang River basin using a combined morphological and environmental DNA (eDNA) approach. We assessed both species and functional diversity of summer macroinvertebrates. A total of 81 macroinvertebrates species were identified, with some overlap in species detection between the methods. The trunk stream exhibited lower species diversity with uneven distribution across sites, whereas the tributaries displayed a more stable species composition. Functional diversity analysis mirrored this pattern, revealing lower functional diversity in the trunk stream, indicative of intense competition and niche occupation. Conversely, the tributaries displayed more uniform and complete functional diversity. This study highlights the differential influence of hydrological environments on macroinvertebrate communities during the summer season, with the trunk stream favoring certain species with specific habitat preferences and adaptations. Furthermore, it underscores the value of combining traditional morphological surveys and eDNA techniques for comprehensive biodiversity assessments.

Vegetation Restoration Effectiveness in Mianshan Abandoned Mine, Dongzhi County, China: Considering Habitat Diversity and Critical Drivers

Vegetation restoration in abandoned mines is crucial for ecosystem recovery and sustainable development. However, the assessment of restoration effectiveness and long-term sustainability through appropriate methods remains a significant challenge. This study aims to evaluate the vegetation restoration effectiveness of the Mianshan abandoned mine in Dongzhi County, China, three years after the completion of the restoration project, using the analytic hierarchy process (AHP) and fuzzy comprehensive evaluation (FCE) methods. Drone oblique photography and field survey transects were applied to determine vegetation growth and geological conditions across different habitats, including the base, terrace, and slope behind the terrace. An evaluation indicator system was developed to assess restoration effectiveness. Results indicated that the overall vegetation restoration was moderately effective, with vegetation coverage and recovery rate (restored-to-native vegetation coverage ratio) of 62.0% and 66.7%, respectively. The terrace habitat exhibited the highest, while the base and slope showed fair restoration effectiveness. Vegetation coverage was the highest on the terrace, but species diversity was the lowest. The base had lower coverage but greater species diversity, with more planted species and invasive species. The slope exhibited low coverage and species diversity, with poor growth of planted species. The terrace had more conservative species than the base and slope. Key factors influencing vegetation restoration effectiveness across habitats included topography (e.g., slope gradient), soil texture (clay or gravelly soil), soil moisture, species selection, and planting strategies. This study evaluated vegetation restoration effectiveness in the Mianshan mine using AHP and FCE methods, highlighting the influence of topography, soil conditions, and species selection on restoration outcomes across diverse habitats.

Biodiversity and relative abundance of benthic invertebrates in the intertidal of Taraba Sound, Magellan Region, Chile.

The Taraba Sound is situated north of the Strait of Magellan within the Chilean fjord and channel system. In this inlet, samples were collected at three beach levels (supralittoral, mesolittoral and infralittoral) along four transects perpendicular to the coastline. A total of 2,754 specimens were collected and identified, representing seven phyla and 24 operational taxonomic units (OTUs). The dominant components across the four beaches were bivalves and crustaceans, with Choromytiluschorus and Paramoeracf.fissicauda contributing significantly to zone similarity. Beaches 2 and 4, located adjacent to river mouths, had lower salinity and consequently lower species richness, abundance, diversity and evenness, particularly in the supra- and mesolittoral zones where freshwater influence is more pronounced. Our study represents the first comprehensive characterisation of intertidal benthic invertebrate biodiversity in the region. Its findings provide valuable baseline data for future research, especially considering the anticipated increase in aquaculture concession applications and the establishment of offshore sea farming centres in the region.

Atlantic Forest Regeneration Dynamics Following Human Disturbance Cessation in Brazil

The Brazilian Atlantic Forest (BAF) is one of the most important biodiversity hotspots and species-rich ecosystems globally. Due to human activities, it has been significantly reduced and fragmented. This study examined both biotic (floristic composition, diversity, and structure) and abiotic (topographic and soil) factors in BAF fragments undergoing varying levels and durations of human disturbance cessation: approximately 20 years (20 y), ~30 years (30 y), and over 40 years (>40 y). We aimed to understand the recovery dynamics of floristic composition, diversity, and structure in BAF fragments in relation to abiotic factors. Several statistical tools were employed to examine similarities/differences and relationships. Forests of the 30 y group exhibit significantly greater homogeneity in terms of floristic composition, while forests of the 20 y group are characterized by lower species abundance and diversity. The floristic composition was primarily influenced by soil features and the time of disturbance. Under “Environmental Protection Areas”, soil–vegetation recovery can occur more swiftly than usually observed for BAF. A significant BAF recovery was observed approximately 40 years after the end of human disturbance. A partial recovery featured 30 y disturbed areas, while in 20 y forests, recovery is in its early stages. Human-disturbed BAF can gradually rebound when effective management practices are implemented.

Diversity and availability of edible caterpillar host plants in the Luki biosphere reserve landscape in the Democratic Republic of the Congo

Edible caterpillars are an important food and economic resource for rural African people. However, they are subject to a number of threats; in particular, their host plants are threatened. The Luki Biosphere Reserve landscape is a region of the Democratic Republic of Congo where the practice of eating caterpillars is a recent phenomenon; however, rural communities have reported their scarcity. This study assessed the diversity and availability of host plants of the edible caterpillars in the Luki Biosphere Reserve (LBR) landscape. Botanical inventories were conducted in eleven ha plots of each of the following habitats: forest, savannah under protection, fallow, and inhabited areas, covering an area of 44 ha. The coverage-based rarefaction and extrapolation method and the iNEXT online software were used to calculate the true diversity of edible caterpillar host plants. The diameter structure of the edible caterpillar host plant species was assessed by counting the number of individuals in each diameter class. The results revealed that in the Luki Biosphere Reserve landscape, edible caterpillars rely on 15 main plant host species (Spondias mombin L., Petersianthus macrocarpus (P.Beauv.) Liben, Croton sylvaticus Hochst. ex Krauss, Hymenocardia acida Tul., Lannea welwitschii (Hiern) Engl., Macaranga spinosa Müll.Arg., Celtis mildbraedii Engl., Coelocaryon botryoïdes Vermoesen, Albizia gummifera (J.F.Gmel.) C. A. Sm, Bridelia atroviridis Müll.Arg, Ficus mucuso Welw. ex Ficalho, Funtumia elastica (P.Preuss) Stapf, Lannea welwitschii (Hiern) Engl., Milicia excelsa (Welw.) C.C. Berg., and Terminalia superba Engl. & Diels). The habitats exhibited low species diversity of the edible caterpillar host plants. Moreover, several of these species are becoming scarce or are locally threatened with extinction. The trend in the diametric structure is similar to species evolving in a disturbed environment.The results of this study suggest potential habitat instability linked to human activities that could lead to biodiversity loss and, thus, a decline in edible caterpillars in the LBR landscape. A better understanding of the unfavourable conditions that influence the nutritional support for the edible caterpillars would help promote appropriate strategies that can be applied in local development plans for community lands at a landscape scale.

Revised taxonomy of Synodontis catfishes (Siluriformes: Mochokidae) from the Lake Tanganyika basin reveals lower species diversity than expected

Abstract Synodontis Cuvier, 1816 is a species-rich group of African catfishes. Prior to this analysis, 13 species of Synodontis were recognized from Lake Tanganyika and its tributaries, composing the only extant lacustrine radiation of the genus, with a unique origin of obligate brood parasitism among all fishes. Species differentiation and phylogenetic relationships of this group remained largely unresolved. Herein, the taxonomy of Synodontis in the Lake Tanganyika basin is revised, including redescriptions of all species and an updated identification key. Genetic (mitochondrial and nuclear genomic markers) and morphological data suggest a lower species diversity than previously recognized, supporting the distinction of 10 Synodontis species in the lake basin. Based on our findings, we recognize Synodontis grandiops, Synodontis ilebrevis, and Synodontis lucipinnis as junior synonyms of Synodontis multipunctatus, Synodontis polli, and Synodontis petricola, respectively. No recent material of Synodontis dhonti and Synodontis tanganyicae (with Synodontis lacustricolus as a synonym) was available. Morphometric/meristic data suggest their close relationship to Synodontis granulosus. Sequencing of historical specimens inferred S. tanganyicae as sister to S. granulosus but with a 1.7% divergence based on mitochondrial data. In contrast to previous studies, phylogenomic data support the lacustrine assemblage of Synodontis in Lake Tanganyika as monophyletic.

Accumulation of road salt in a calcareous fen: Kampoosa Bog, western Massachusetts.

Road salt poses a threat to the quality of soils and water resources. Wetlands located in salt contaminated areas are at risk of experiencing lower plant and animal species diversity. Therefore, it is critical to understand how modifications to salt application rates and hydrological events impact wetland water quality. Here, we use chloride mass flux, discharge, groundwater chloride concentration, meteorological, and salt application data from 2012-2020 to estimate chloride accumulation and outflux rates in the Kampoosa Bog subwatersheds, located in Stockbridge and Lee, Massachusetts, and bordered by major highways (Interstate-90 and U.S. Route 7). We also investigate the correlation between wetland size and chloride retention rate. During the 2018-2019 period, mean annual chloride application rates in the major watershed increased from 363000 kg/year (2012-2017) to 479000 kg/year. This led to a net chloride accumulation (KB100 subwatershed: 339000 kg; KB150 subwatershed: 188000 kg) and increased groundwater chloride concentrations in the fen. Chloride outflux from these subwatersheds was primarily driven by discharge. We found that the relationship between wetland percent cover and chloride retention is complex. Although the percent wetland cover is greater in the KB100 main wetland region compared to the KB150 subwatershed, high precipitation in 2018 resulted in similar chloride retention efficiencies (~26%). During the drier year (2019), chloride retention was higher in the wetland region due to its gentle slopes which promote water accumulation and consequently higher evaporation rates which lowers discharge and chloride outfluxes. The chloride steady-state concentration analysis also suggests that there is potential for chloride accumulation to continue because the watershed has not yet reached steady-state chloride concentrations. Without major modifications to salting practices, chloride concentrations will continue increasing and potentially promote the re-growth of invasives (Phragmites) and continued growth of salt tolerant species (Typha angustifolia/xglauca) that diminish plant diversity.

Effects of weed management on soil metagenomic composition in cultivated chickpea fields

Abstract Non-chemical methods, including mechanical and manual weed management are important for improving crop yields and preserving soil microbial diversity. In Tunisia, chickpea cultivation uses a combination of these methods to suppress weeds. This study aimed to evaluate the impact of weeding practices on chickpea (Cicer arietinum L. cultivar REBHA) yield and soil microbial diversity. Field experiments were conducted at the Technical Center for Biological Agriculture in Essaida, Tunisia, using six plots with manual and no weeding treatments. Chickpea yield was measured, and soil samples were collected for metagenomic analysis. Floristic surveys identified 13 weed species, with Chenopodium album L., Rumex acetosa L., and Urtica dioica L. being the most dominant. Seed yield ranged from 23.2 to 26.2 qls/ha in non-weeded plots and from 25.1 to 30.1 qls/ha in weeded plots, showing an increase in yield (11.75%) with manual weeding.
Soil metagenomics revealed changes in bacterial community composition between the two treatments. The dominant phylum was Pseudomonadota, whose relative abundance increased from 24.88% in non-weeded plots to 34.76% in weeded plots. Alpha diversity indices showed lower species richness and diversity in weeded soils, with 62000 OTUs in weeded plots compared to 43202 OTUs in non-weeded plots. Betaproteobacteria and Alphaproteobacteria exhibited higher OTU counts in weeded soils. The Simpson diversity index was lower in non-weeded soils (0.025) than in weeded soils (0.075), indicating a more irregular microbial distribution in non-weeded plots. Thus, manual weeding improved chickpea yield and altered the soil bacterial community, increasing diversity in key microbial taxa. This study highlights the complex interaction between weed management practices and soil microbial ecosystems, which may influence crop productivity.

I want to climb to the tops of trees! Factors facilitating the development of ivy vines in central European forests

Abstract Lianas, which are considered to form tree-related microhabitats, are known as important elements of tropical forests; however, their ecological function and relationships with host trees (phorophytes) in temperate forests are poorly known. This gap in knowledge stems from a low species diversity and abundance of lianas in temperate forests. An exception is common ivy (Hedera helix), which is widely distributed and is currently increasing its abundance in temperate forests. In this study, we examined the relationships between ivy vines with features of their phorophytes, using Central European upland mixed forests as an example. We assess the presence and density of ivy within 69 study plots, established in the forest interior and ecotone. We use generalized linear mixed-effects models to assess drivers of ivy’s presence and its density, while accounting for the tree diameter at breast height, bark roughness, and the canopy light transmittance. We show that ivy is able to grow on nearly all tree species, although it prefers phorophytes with rough bark and a large diameter. Large generative individuals (ivy vines that produce fruits) were found mostly on veteran trees (usually oaks, alders, or pines). For its growth, ivy requires tree phorophytes with only a moderate transparency of light through the tree crowns, which is likely related to evergreen leaves that enable ivy vines to also develop during leaf-off periods. The features of phorophytes preferred by ivy indicate that the vine finds optimal conditions for development in old patches of tree stand, often in areas inaccessible or unprofitable for forest management. We propose using large and fruiting ivy vines as indicators of old-growth forests that deserve protection, which would be in line with the current policy of sustaining and restoring close-to-natural forests in Europe.

Shedding light on some dark branches: The under‐appreciated diversity of gymnosome pteropods and their coiled thecosome prey in the Neotropics

AbstractHoloplanktonic organisms are thought to have enormous populations sizes, expansive geographic ranges, and low species diversity. Previous work suggests that pelagic gastropods are no exception to this generalization. However, most of these data are derived from temperate species, whereas the bulk of pteropod diversity occurs in the tropics. Here, we present DNA barcode data for COI focused on the under‐studied limacinoid, gymnosome, and pseudothecosome pteropods collected from the coastal waters of Panama. We applied four molecular species delimitation approaches to determine the number of operational taxonomic units (OTUs) identifiable from our sequences and all data available from Barcode of Life Database (BOLD) and GenBank and compared these to the Barcode Index Number generated by the BOLD. Assemble Species by Automatic Partitioning (ASAP), Poisson Tree Processes (PTP), Bayesian Poisson Tree Processes (bPTP), and Generalized Mixed Yule Coalescent (GMYC) methods generally gave congruent results and suggest that pteropod diversity in the tropics is significantly underrepresented both in DNA sequence databases and in the number of named OTUs. Of 42 specimens collected and sequenced, we recovered 16 OTUs, only one of which belonged to an OTU already represented in sequence databases. Neighbor‐joining trees including the previously published sequences show that in all three groups morphospecies can include genetically divergent lineages. Many very divergent (>15% from nearest neighbor) taxa are also still represented by only a single sequence, suggesting that there is a large amount of cryptic or pseudo‐cryptic diversity still to be described. To aid this future endeavor, we include some preliminary 16S data derived from new pteropod‐specific primers.

Ecological condition of seagrass meadows around sea-based tin mining activities in the waters of Bangka Belitung Islands, Indonesia

Bangka Belitung islands have long been major tin producers, impacting the environment, including coastal ecosystems. Tin extraction from the seabed increases water turbidity and alters chemical composition, adversely affecting seagrass meadows. This study investigated the ecological condition of seagrass meadows around sea-based tin mining activities on the islands. We mapped seagrass habitat extent and calculated the Seagrass Ecological Quality Index (SEQI) at five locations reflecting varying environmental impacts of tin mining. Satellite imagery from Landsat 7 ETM+ (2000) and Sentinel L2A (2022) was used, showing higher mapping accuracy during low tide. Our analysis revealed that seagrass meadows near mining sites had low species diversity and significant habitat decline over the past two decades (82.79 %). SEQI values were lower, and Total Suspended Solid (TSS) levels were higher near mining operations. This study underscores the detrimental effects of tin mining on seagrass meadows, urging stringent regulations, rehabilitation, and continuous monitoring for sustainability.

Variation in Relative Abundance of Small Mammal Species Caught in Two Different Ecosystems and Implicated in the Spread of Emerging Pathogens in Mali

Background: Small rodents and insectivores are potential reservoirs of many pathogens transmissible to humans, such as bacteria, parasites and viruses responsible for epidemics in sub-Saharan Africa, particularly in West Africa. Few studies on small mammal species in West Africa are available. Our previous findings from a study investigating emerging pathogens in two localities in Mali has determined the prevalence of pathogens in small mammals (rodents and insectivores). We used the data collected from this small mammal population with different eco-climatic characteristics to test hypothesis that small mammal distribution in different eco-climatic settings could explain the diversity and frequency of pathogens they carry. Methods: Sessions of trapping were carried out in December 2016 in Faladjè and Bougouni with “Besançon tous services” (BTS) wire mesh traps baited with peanut butter and/or onion. All animals captured were identified morphologically. Results: Out of 123 small rodents and insectivores captured over 674 trap-nights, 75 (60.97%) were from Faladjè and 48 (39.02%) from Bougouni. Of these, six species of small rodents belonged to the family Muridae (Mastomys erythroleucus, Mastomys natalensis, Rattus rattus, Praomys daltoni, Gerbilliscus gambianus, Taterillus gracilis) and two species of insectivores associated with the genus Crocidura spp. belonged to the family Soricidae and Erinaceidae (Crocidura cf olivieri and Atelerix cf albiventris), respectively. There is low species diversity within these two areas, but the variation in relative abundance is significant (binomial test, p ˂ 0.05) between Faladjè and Bougouni. Mastomys erythroleucus was the most dominant species (57.33%, 43/75) in Faladjè, while R. rattus dominated (37.5%,18/48) in Bougouni. Conclusions: These two species of small mammals potentially involved in the transmission of bacteria, parasites and pathogenic viruses to humans are differently present in two distinct eco-climatic areas in Mali.

Metagenomic Study Reveals Phage–Bacterial Interactome Dynamics in Gut and Oral Microbiota in Pancreatic Diseases

Individuals with pancreatic-related health conditions usually show lower diversity and different composition of bacterial and viral species between the gut and oral microbiomes compared to healthy individuals. We performed a thorough microbiome analysis, using deep shotgun sequencing of stool and saliva samples obtained from patients with chronic pancreatitis (CP), pancreatic ductal adenocarcinoma (PDAC), and healthy controls (HCs).We observed similar microbiota composition at the species level in both the gut and oral samples in PDAC patients compared to HCs, among which the most distinctive finding was that the abundance of oral-originated Fusobacterium nucleatum species did not differ between the oral and the gut samples. Moreover, comparing PDAC patients with HCs, Klebsiella oxytoca was significantly more abundant in the stool samples of PDAC patients, while Streptococcus spp. showed higher abundance in both the oral and stool samples of PDAC patients. Finally, the most important finding was the distinctive gut phage–bacterial interactome pattern among PDAC patients. CrAssphages, particularly Blohavirus, showed mutual exclusion with K. oxytoca species, while Burzaovirus showed co-occurrence with Enterobacteriaceae spp., which have been shown to be capable of inducing DNA damage in human pancreatic cells ex vivo. The interactome findings warrant further mechanistic studies, as our findings may provide new insights into developing microbiota-based diagnostic and therapeutic methods for pancreatic diseases.

Investigation of gut microbiota disorders in norovirus infected children patients based on 16s rRNA sequencing

Background Norovirus is the leading cause of sporadic viral gastroenteritis cases and outbreaks. Gut microbiota plays a key role in maintaining immune homeostasis. We aimed to investigate the composition and functional effects of gut microbiota in children infected with norovirus. Methods Stool samples were collected from 31 children infected with norovirus and 25 healthy children. The gut microbiota was analyzed by 16S rRNA gene sequencing, followed by composition, correlation network, functional and phenotype prediction analyses. Results Gut microbiota in children infected with norovirus was characterized by lower species richness and diversity. Veillonella is the dominant gut microbiota specie in norovirus infection. Blautia was significantly lower in norovirus infection. There was a positive correlation between Faecalibacterium, Blautia, Subdoligranulum, Eubacterium_hallii_group, Fusicatenibacter, Agathobacter, Roseburia and Dorea. Functionally, secondary metabolites biosynthesis, transport and catabolism, selenocysteine lyase and peroxiredoxin were the most significantly higher functional compositions of gut microbiota in norovirus infection. However, sn-glycerol-1-phosphate dehydrogenase and fermentation were the most significantly lower functional compositions in norovirus infection group. Phenotype analysis showed that Contains_Mobile_Elements had the highest level of phenotypes in the gut microbiota of norovirus infection. Conclusion Norovirus infection may lead to dysregulation of the gut microbiome in children.

Influence of bark chemistry on distribution of epiphytic mosses on basal trunk of <i>Cryptomeria japonica</i>

Epiphytic mosses are integral parts of forest community structure in the Darjeeling Hills of the Eastern Himalayan region with remarkable contributions to the ecosystem functionality. The study was framed to assess the richness and spatial distribution of epiphytic mosses growing on the basal trunk of Cryptomeria japonica (Thunb. ex. L.) D.Don, and also to evaluate the explanatory host traits for shaping the moss assemblage. Field measurements and sampling were performed near Lamahatta village within Darjeeling district on 270 microplots placed on tree trunks. A total of twelve mosses represented by the members of Dicranales and Hypnales were recorded. Low species diversity was observed with dominance and maximum cover of Syrrhopodon confertus. Canonical correspondence analysis predicted a distinct combination of chemical requirements for local colonization of each moss. The results also demonstrated influence of bark acidic inputs on abundance and co-existence of bryophytes. The outcome can be potentially helpful in depicting the community structure of non-vascular epiphytes, which may further be considered while developing forest management strategies.

Understanding the mechanism of microplastic-associated antibiotic resistance genes in aquatic ecosystems: Insights from metagenomic analyses and machine learning

The pervasive presence of microplastics (MPs) in aquatic systems facilitates the transmission of antibiotic resistance genes (ARGs), thereby posing risks to ecosystems and human well-being. However, owing to variations in environmental backgrounds and the limited scope of research subjects, studies on ARGs in MPs lack unified conclusions, particularly regarding whether different types of MPs selectively promote ARG enrichment. Analysing large-scale datasets can better encompass broad spatiotemporal scales and diverse samples, facilitating a more extensive exploration of the complex ecological relationships between MPs and ARGs. The present study integrated existing metagenomic datasets to conduct a comprehensive risk assessment and comparative analysis of resistance groups across various MPs. In addition, we endeavoured to elucidate potential associations between ARGs and bacterial taxa, as well as MP structural features, using machine learning (ML) methods. The findings of our research highlight the pivotal role of MP type in shaping plastispheres, accounting for 9.56 % of the biotic variation (Adonis index) and explaining 18.59 % of the ARG variance. Compared to conventional MPs, biodegradable MPs, such as polyhydroxyalkanoates (PHA) and polylactic acid (PLA), exhibit lower species uniformity and diversity but pose a higher risk of ARG occurrence. These ML approaches effectively forecasted ARG abundance by using the bacterial taxa and molecular structure descriptors (MDs) of MPs (average R2tra = 0.882, R2test = 0.759). Feature analysis showed that MDs associated with lipophilicity, solubility, toxicity, and surface potential significantly influenced the relative abundance of ARGs in the plastispheres. The interpretable multiple linear regression (MLR) model, particularly notable, elucidated a linear relationship between bacterial genera and ARGs, offering promise for identifying potential ARG hosts. This study offers novel insights into ARG dynamics and ecological risks within aquatic plastispheres, highlighting the importance of comprehensive MP monitoring initiatives.

Morphological and Molecular Characterization of Trichoderma Isolates from Vegetable Crop Rhizospheres in Nepal

Background Trichoderma spp. hold significant potential as biocontrol agents in agriculture due to their antagonistic properties against plant pathogens. The study aimed to characterize and identify Trichoderma isolates from rhizospheric regions of vegetable crops. Methods In this study, Trichoderma isolates were collected from rhizospheric soil samples of vegetable crops from different ecological zones and were selected for comprehensive morphological and molecular characterization. The isolates were visually assessed for colony color, growth pattern, aerial mycelium presence, phialide and conidial morphology, and chlamydospore presence. Molecular analysis was employed based on ITS and tef-1α sequences. Diversity indices were also computed for different ecological zones. Results The morphological characteristics and phylogenetic trees for both regions provided a clear species resolution, with four main clades: Harzianum, Viride, Brevicompactum and Longibrachiatum with 12 species T. harzinaum, T. afroharzianum, T. lentiforme, T. inhamatum, T. camerunense, T. azevedoi, T. atroviride, T. asperellum, T. asperelloides, T. koningii, T. longibrachiatum and T. brevicompactum and nine species as a new country record. Diversity indices indicated that high mountain regions displayed the highest species diversity and evenness (H = 1.724 [0.28], J = 0.84, D = 0.28), followed by hilly regions (H = 1.563 [0.28], J = 0.72, D = 0.28). Plains, on the other hand, exhibited lower species diversity (H = 1.515, J = 0.66, D = 0.33). The calculated species abundance values showed that plains (E = 2.11), mid-hills (E = 1.95), and high mountains (E = 1.99) each had their unique diversity profiles. Notably, T. afroharzianum and T. asperellum were predominant. Conclusions Overall, the study unveiled a rich diversity of Trichoderma species in different agricultural zones of Nepal. These findings shed light on the ecological distribution and diversity of Trichoderma spp., which could have significant implications for sustainable agriculture and biological control strategies.

Meloidogyne hapla dominates plant‐parasitic nematode communities associated with kiwifruit orchards in Portugal

AbstractKiwifruit, Actinidia spp., is an important crop worldwide and its cultivation has been increasing in Portugal. Kiwifruit plants are susceptible to plant‐parasitic nematodes (PPNs), including Meloidogyne spp. M. hapla and M. incognita have been reported to affect kiwifruit in major production regions worldwide, although information is lacking on the distribution and identity of PPNs associated with kiwifruit orchards in Portugal. Moreover, research is scarce on the drivers of PPN communities in this crop. Our primary objective was to investigate the diversity, density and distribution of PPNs within kiwifruit orchards of Portugal and to elucidate the influence of environmental factors on their community composition. Additionally, we aimed to evaluate population densities and identity of Meloidogyne spp. Nematodes were extracted from composite soil and root samples collected from orchards. Analysis of soil nematode communities suggested bacterial‐driven decomposition and high nutrient enrichment in these soils. Sixteen different genera of PPNs were detected, with Meloidogyne spp. as the dominant genus, mostly represented by a single species, M. hapla. PPN communities exhibited low richness, and β‐diversity analysis indicated a high degree of similarity among them. Additionally, their composition was significantly influenced by soil and climatic parameters. We found that 37 out of 40 kiwifruit orchards in Portugal were infested by root‐knot nematodes. The unexpectedly low species diversity, dominated by M. hapla, merits further research to establish underlying factors for its high incidence in this crop and to assess the impact of these nematodes on kiwifruit performance and productivity.

Sparse large trees in secondary and planted forests highlight the need to improve forest conservation and management

Large trees are essential for carbon storage and biodiversity conservation. While an increasing number of studies have focused on large trees in primary forests, little is known about them in secondary and planted forests. We surveyed 86,936 trees in secondary forests and 91,294 trees in planted forests in Zhejiang, China, to investigate the distribution patterns and determinants of large trees in these forests. We found a mean density of large trees (DBH ≥ 30 cm) of 15 ± 13 stems ha−1 in secondary forests and 11 ± 9 stems ha−1 in planted forests. Moreover, the mean density of trees with DBH ≥ 60 cm was 0.36 stems ha−1, indicating that large trees are particularly rare in secondary and planted forests. These large trees were primarily occurred in secondary forests that living in high-elevation area with less human exploitation and colder and wetter climates, and in planted forests with higher species richness and lower tree density. In addition, the density of large trees in these forests significantly increased with tree species richness and decreased with increasing tree density. These results indicate that the sparse large trees were the legacy of historical human activities in the studied area, but currently, the development of large trees is still limited by the improper forest structure characterized by low species diversity and high tree density. To better conserve large trees, there is an urgent need for enhanced conservation policies for secondary forests, such as establishing forest parks for forests with large trees, and implementing near-natural forest management practices for planted forests, which include planting mixed native tree species and maintaining moderate tree density.