Similar Tree Research Articles

Phylogenomics and plastome evolution of Lithospermeae (Boraginaceae)

BackgroundLithospermeae is the largest tribe within Boraginaceae. The tribe has been the focus of multiple phylogenetic studies over the last 15 years, with most focused on one genus or a few genera. In the present study, we newly sequenced 69 species of Lithospermeae and relatives to analyze the phylogenomic relationships among its members as well as the evolution of the plastid genome.ResultsThe phylogeny of Lithospermeae resolved from the plastid genome and nrDNA cistron is generally congruent with prior studies, but is better resolved and supported. Increasing character sampling across the plastid genome results in gradually more similar trees to that from the entire plastid genome. Overall, plastid genome structure was quite consistent across Lithospermeae. Codon Usage Bias (CUB) analyses demonstrate that across Lithospermeae plastid genomes were rich in AT and poor in GC. Mutation may play a greater role than selection across the plastid genome of Lithospermeae. The present study is the first to highlight the CUB characteristics of Lithospermeae species, which can help elucidate the mechanisms underlying patterns of molecular evolution and improve the expression levels of exogenous genes by codon optimization.ConclusionsThis study provides a comprehensive phylogenomic analysis of Lithospermeae, significantly enhancing our understanding of the phylogenetic relationships and plastid genome evolution within this largest tribe of Boraginaceae. By utilizing an expanded genomic sampling approach, we have achieved increased resolution and support among the evolutionary relationships of the tribe, in line with but improving upon previous studies. The analyses of plastid genome structure revealed consistency across Lithospermeae, with a notable CUB. This study marks the first investigation into the CUB of Lithospermeae species and sets the stage for further research on the molecular evolution of plastid genomes across Boraginaceae.

TCα-PIA: A Personalized Social Network Anonymity Scheme via Tree Clustering and α-Partial Isomorphism

Social networks have become integral to daily life, allowing users to connect and share information. The efficient analysis of social networks benefits fields such as epidemiology, information dissemination, marketing, and sentiment analysis. However, the direct publishing of social networks is vulnerable to privacy attacks such as typical 1-neighborhood attacks. This attack can infer the sensitive information of private users using users’ relationships and identities. To defend against these attacks, the k-anonymity scheme is a widely used method for protecting user privacy by ensuring that each user is indistinguishable from at least k−1 other users. However, this approach requires extensive modifications that compromise the utility of the anonymized graph. In addition, it applies uniform privacy protection, ignoring users’ different privacy preferences. To address the above challenges, this paper proposes an anonymity scheme called TCα-PIA (Tree Clustering and α-Partial Isomorphism Anonymization). Specifically, TCα-PIA first constructs a similarity tree to capture subgraph feature information at different levels using a novel clustering method. Then, it extracts the different privacy requirements of each user based on the node cluster. Using the privacy requirements, it employs an α-partial isomorphism-based graph structure anonymization method to achieve personalized privacy requirements for each user. Extensive experiments on four public datasets show that TCα-PIA outperforms other alternatives in balancing graph privacy and utility.

Successful development of European tree frog (Hyla arborea Linnaeus, 1758) populations in the south-west and west of Luxembourg following reintroduction

In this article, we provide a comprehensive overview of our European tree frog reintroduction, from the sourcing and captive-rearing of donor animals, through reintroduction and population development, to the current status of the project. Before the start of the project, only one isolated population remained in the east of the country. Starting with two initial reintroductions (2012 to 2014), two tree frog populations have developed over the past decade and we have managed to save the species from extinction on the national level. While both populations have been expanding rapidly in recent years, they show noticeable differences regarding initial development and spread. Further reintroductions to reinforce these populations were carried out from 2019 to 2024. In total, more than 7,000 juveniles and tadpoles were released over the entire duration of the project, resulting in ca. 830 calling males at 61 sites in 2024. Our long-term annual monitoring provides detailed data on population development and spread, which are presented and discussed. In addition, comparisons with similar tree frog reintroduction projects in other countries are made and logistical and epidemiological aspects of the reintroduction project are highlighted. Finally, we give an outlook on practical implications for conservation management, upcoming challenges and future focal points of the project.

Removal of Airborne Particulate Matter by Evergreen Tree Species in Dhaka, Bangladesh

Urban air quality stands as a pressing concern in cities globally, with airborne particulate matter (PM) emerging as a significant threat to human health. An investigation was carried out to examine the potential of four prevalent evergreen roadside tree species grown at different locations in Dhaka to capture PM using their leaves. The distribution of PM by mass and quantity in Dhaka are presented for the first time for Bangladesh and these results will also be applicable to countries with similar climates and tree species. Separate gravimetric analyses were carried out to quantify PM in three different size ranges (0.2-2.5 μm, 2.5-10 μm, and 10-100 μm) accumulated on surfaces and trapped within waxes by using the rinse and weigh method. The method is validated for the first time through SEM-EDX analysis, which confirmed that the increase in weight from chloroform-rinsed leaves was exclusively attributable to particle deposition on the filter. The chemical composition of the deposited PM2.5 was analyzed quantitatively by determining the concentration of twenty-five trace elements employing ICP-MS. SEM-EDX analysis revealed the significance of leaf microstructural traits in effectively capturing PM. Significant variations in the deposition of PM were found among different species for two PM categories (surface PM and wax-embedded PM) and three size fractions (large, coarse, and fine) (one-way ANOVA; p<0.05). The quantity of wax retained on the foliage of trees documented in these locations also varied (p<0.05). Among the species studied, Ficus benghalensis demonstrated a greater ability to retain PM. Mangifera indica was identified to be the most efficient collector of wax-related PM and appears to be the ideal species for traffic-heavy areas distinguished by high concentrations of organic compounds from vehicle emissions.

Classification and Mapping of Fuels in Mediterranean Forest Landscapes Using a UAV-LiDAR System and Integration Possibilities with Handheld Mobile Laser Scanner Systems

In this study, we evaluated the capability of an unmanned aerial vehicle with a LiDAR sensor (UAV-LiDAR) to classify and map fuel types based on the Prometheus classification in Mediterranean environments. UAV data were collected across 73 forest plots located in NE of Spain. Furthermore, data collected from a handheld mobile laser scanner system (HMLS) in 43 out of the 73 plots were used to assess the extent of improvement in fuel identification resulting from the fusion of UAV and HMLS data. UAV three-dimensional point clouds (average density: 452 points/m2) allowed the generation of LiDAR metrics and indices related to vegetation structure. Additionally, voxels of 5 cm3 derived from HMLS three-dimensional point clouds (average density: 63,148 points/m2) facilitated the calculation of fuel volume at each Prometheus fuel type height stratum (0.60, 2, and 4 m). Two different models based on three machine learning techniques (Random Forest, Linear Support Vector Machine, and Radial Support Vector Machine) were employed to classify the fuel types: one including only UAV variables and the other incorporating HMLS volume data. The most relevant UAV variables introduced into the classification models, according to Dunn’s test, were the 99th and 10th percentile of the vegetation heights, the standard deviation of the heights, the total returns above 4 m, and the LiDAR Height Diversity Index (LHDI). The best classification using only UAV data was achieved with Random Forest (overall accuracy = 81.28%), with confusion mainly found between similar shrub and tree fuel types. The integration of fuel volume from HMLS data yielded a substantial improvement, especially in Random Forest (overall accuracy = 95.05%). The mapping of the UAV model correctly estimated the fuel types in the total area of 55 plots and at least part of the area of 59 plots. These results confirm that UAV-LiDAR systems are valid and operational tools for forest fuel classification and mapping and show how fusion with HMLS data refines the identification of fuel types, contributing to more effective management of forest ecosystems.

Is the Current Systematic Subdivision of the Subfamily Neanurinae (Collembola, Neanuridae) Still Valid? Testing the Monophyly and Phylogenetic Relationships of Currently Established Tribes of the Neanurinae.

The subfamily Neanurinae is the largest in the family, with almost 800 described species. These springtails differ significantly from all other Collembola in their morphology, behaviour, and natural habitats. A systematic division of the Neanurinae into tribes was proposed more than 30 years ago by Cassagnau (1989), but it has not yet been tested using cladistic methods. Recent studies, both phylogenetic analyses of individual tribes or genera and descriptions of new taxa, suggest that the currently recognised tribes may not be monophyletic. The phylogenetic relationships among major lineages of the Neanurinae were explored by analysing a dataset of 101 discrete morphological characters. Bayesian and maximum parsimony analyses yielded similar tree topologies. The relationships among the Neanurinae were not resolved in any of the analyses, except for the support for the monophyly of the tribe Lobellini. The results indicate that the taxonomic characters used in the classification of Neanurinae are shared among members of the different tribes, which may have resulted in a classification with little phylogenetic basis. The article discusses the phylogenetic significance of morphological characters, including those recognised as key to the evolution and history of Neanurinae.

Sub-national scale mapping of individual olive trees integrating Earth observation and deep learning

The olive tree holds great cultural, environmental, and economic significance in the Mediterranean region. In particular, Morocco has been making dedicated investments over $10 billion since 2008 to fuel the transition from cereal to olive production. Understanding the spatial extent of this large-scale land conversion is critical for a variety of socioeconomic purposes. In response to this demand, we conducted a study to map individual olive trees in northern Morocco using satellite imagery and deep learning techniques at a sub-national scale. This study utilized cloud-free, very-high-resolution DigitalGlobe imagery collected between 2018 and 2022 to identify each individual olive tree in six northern Morocco provinces. We compared various deep learning models, including both transformer-based and CNN-based models, to generate patch-level spatial constraints and pixel-level tree identification. We found that transformer-based models outperformed CNN-based models in both tasks. Additionally, spatially constraining the pixel-level results improved olive tree mapping accuracy to varying degrees, depending on the initial performance of the model. The evaluation of the olive map generated from this study shows high accuracy in both surveyed and unsampled regions. This research represents the first-of-its-kind individual olive tree mapping at the sub-national scale that can help monitor the large-scale land conversions such as about 110,000 ha of olive plantings in the six Moroccan provinces studies here. Meanwhile it demonstrates a cost-effective and efficient prototype approach that can be adapted to identify similar tree crop expansion occurring in other parts of the world.

Stress experienced by professionals from basic health units in the context of the COVID-19 pandemic

OBJECTIVE: To understand stress at work among professionals in Basic Health Units, in the context of the COVID-19 pandemic. METHOD: Qualitative, exploratory and descriptive study. Data collection took place through semi-structured interviews and systematic observation. The 20 study participants were professionals from two Basic Health Units (UBS) in a municipality in the state of Bahia. The data was analyzed using IRAMUTEQ (word cloud and similarity tree) and content analysis. RESULTS: It was found that the experience of stress is something present and striking in the daily lives of health professionals at UBS due to their proximity to users and the responsibility of taking care of their health. They tend to experience frustration, instability, physical and emotional exhaustion and suffering due to the pressures of the service and the weaknesses of the health system. Fear during the COVID-19 pandemic brought anguish experienced in the work, social and family environment due to the difficulty of carrying out daily activities. They faced situations of lack of respect and empathy, risk of contamination, work overload, physical exhaustion, discrimination and isolation. FINAL CONSIDERATIONS: The stress of UBS health professionals was linked to the experience of overload in work activities, which was intensified with the biosafety measures adopted.

Adaptive Space Search-based Molecular Evolution Optimization Algorithm.

In drug development process, a significant portion of budget and research time are dedicated to the lead compound optimization procedure in order to identify potential drugs. This procedure focuses on enhancing the pharmacological and bioactive properties of compounds by optimizing their local substructures. However, due to the vast and discrete chemical structure space and the unpredictable element combinations within this space, the optimization process is inherently complex. Various structure enumeration-based combinatorial optimization methods have shown certain advantages. However, they still have limitations. Those methods fail to consider the differences between molecules and struggle to explore the unknown outer search space. In this study, we propose an adaptive space search-based molecular evolution optimization algorithm (ASSMOEA). It consists of three key modules: construction of molecule-specific search space, molecular evolutionary optimization, and adaptive expansion of molecule-specific search space. Specifically, we design a fragment similarity tree in molecule-specific search space, and apply a dynamic mutation strategy in this space to guide molecular optimization. Then we utilize an encoder-encoder structure to adaptively expand the space. Those three modules are circled iteratively to optimize molecules. Our experiments demonstrate that ASSMOEA outperforms existing methods in terms of molecular optimization. It not only enhances the efficiency of the molecular optimization process, but also exhibits a robust ability to search for correct solutions. The code is freely available on the web at https://github.com/bbbbb-b/MEOAFST. Supplementary data are available at Bioinformatics online.

Phylogeny of Transferable Oxazolidinone Resistance Genes and Homologs.

Oxazolidinone resistance, especially transmissible resistance, is a major public health concern, and the origin of this resistance mechanism is not yet resolved. This study aims to delve into the phylogenetic origin of the transmissible oxazolidinone resistance mechanisms conferring cross-resistance to other drugs of human and veterinary importance. The amino acid sequences of the five cfr ribosomal methylases and optrA and poxtA were used as queries in searches against 219,549 bacterial proteomes in the NCBI RefSeq database. Hits with >40% amino acid identity and >80% query coverage were aligned, and phylogenetic trees were reconstructed. All five cfr genes yielded highly similar trees, with rlmN housekeeping ribosomal methylases located basal to the sister groups of S-adenosyl-methionine-dependent methyltransferases from various Deltaproteobacteria and Actinomycetia, including antibiotic-producing Streptomyces species, and the monophyletic group of cfr genes. The basal branches of the latter contained paenibacilli and other soil bacteria; they then could be split into the clades [cfr(C):cfr(E)] and [[cfr:cfr(B)]:cfr(D)], always with different Bacillaceae in their stems. Lachnospiraceae were encountered in the basal branches of both optrA and poxtA trees. The ultimate origin of the cfr genes is the rlmN housekeeping ribosomal methylases, which evolved into a suicide-avoiding methylase in antibiotic producers; a soil organism (Lachnospiraceae, Paenibacilli) probably acted as a transfer organism into pathogenic bacteria. In the case of optrA, the porcine pathogenic Streptococcus suis was present in all branches, while the proteins closest to poxtA originated from Clostridia.

Drought induces moderate, diverse changes in the odour of grassland species

Plants react to drought stress with numerous changes including altered emissions of volatile organic compounds (VOC) from leaves, which provide protection against oxidative tissue damage and mediate numerous biotic interactions. Despite the share of grasslands in the terrestrial biosphere, their importance as carbon sinks and their contribution to global biodiversity, little is known about the influence of drought on VOC profiles of grassland species. Using coupled gas chromatography-mass spectrometry, we analysed the odorants emitted by 22 European grassland species exposed to an eight-week-lasting drought treatment (DT; 30% water holding capacity, WHC). We focused on the odorants emitted during the light phase from whole plant shoots in their vegetative stage. Emission rates were standardised to the dry weight of each shoot. Well-watered (WW) plants (70% WHC) served as control. Drought-induced significant changes included an increase in total emission rates of plant VOC in six and a decrease in three species. Diverging effects on the number of emitted VOC (chemical richness) or on the Shannon diversity of the VOC profiles were detected in 13 species. Biosynthetic pathways-targeted analyses revealed 13 species showing drought-induced higher emission rates of VOC from one, two, three, or four major biosynthetic pathways (lipoxygenase, shikimate, mevalonate and methylerythritol phosphate pathway), while six species exhibited reduced emission rates from one or two of these pathways. Similarity trees of odorant profiles and their drought-induced changes based on a biosynthetically informed distance metric did not match species phylogeny. However, a phylogenetic signal was detected for the amount of terpenoids released by the studied species under WW and DT conditions. A comparative analysis of emission rates of single compounds released by WW and DT plants revealed significant VOC profile dissimilarities in four species only. The moderate drought-induced changes in the odorant emissions of grassland species are discussed with respect to their impact on trophic interactions across the food web. (294 words)

Revegetated riparian areas are dominated by weeds, and lack structural diversity and natural recruitment: lessons for restoration practice

Riparian areas can be highly biodiverse and provide critical ecosystem services. However, they are frequently subject to anthropogenic impacts such as land clearing, agricultural use, and urban development. Restoration of riparian areas via revegetation commonly improves the health of waterways and surrounding areas, but vegetation outcomes are rarely assessed. Our study compared 10 to 14‐year‐old revegetation to remnant vegetation in riparian areas of south‐eastern Australia to determine if species composition, vegetation structure, and ecosystem function (plant recruitment) differed. We also assessed if the amount of surrounding native vegetation, browsers (including deer, rabbits, and macropods), or soil characteristics influenced native woody plant recruitment at revegetated sites. While native and exotic woody species richness did not differ, native woody plants were less abundant and exotic woody plants twice as abundant at revegetated sites. The ground layer of revegetated sites was dominated by weeds, whereas remnant sites largely comprised native herbaceous plants and leaf litter. Tree heights and tree canopy cover were similar in revegetated and remnant areas, although shrubs and ferns were lacking in revegetation. Native woody plant recruitment was lower at revegetated sites and was negatively associated with browser presence. Our results suggest that while revegetation may have similar species richness and tree cover as remnant areas, weeds often dominate and important structural components such as shrubs and ferns, and ecological processes such as plant recruitment, are lacking. Better consideration of all vegetation strata, reduced browsing pressure and weed control are likely to achieve better revegetation outcomes.

Delayed response of bryophytes to wind disturbance and salvage logging in hemiboreal mixed forests

Climate change accompanied by altered natural disturbance regimes threatens the resilience of boreal and hemiboreal forests. Bryophytes, an important part of plant biomass and diversity, fulfill numerous important functions in forests, thus markedly contributing to the resilience of these ecosystems. We studied abundance, richness, diversity and community composition of bryophyte species 20–21 years after wind disturbance in moderately damaged, heavily damaged and heavily damaged and subsequently salvage-logged stands; overmature forest stands with similar tree species composition were included in the study as a reference group. The community characteristics were linked with treatment and accompanying environmental variables. Altogether, 108 bryophyte taxa (81 mosses and 27 liverworts) were identified in study plots. We found that bryophytes responded to windthrow severity level and salvage logging in terms of species richness, diversity, and composition; diversity of microhabitats was the most important environmental variable explaining the variation in diversity metrics. Besides exhibiting greater overall species richness, uncleared wind-disturbed plots contained more bryophyte species with high conservational value as well, compared to salvage-logged and control plots. The largest number of bryophyte taxa was associated with deadwood substrates. Ordination analysis further emphasized the importance of deadwood substrate for liverworts. In order to fulfill the objective of biodiversity conservation, wind-disturbed forests should be left to recover naturally, to ensure a favorable status of all naturally occurring species and to improve the status of endangered and rare species. Retaining a proportion of surviving and/or wind-damaged trees while salvaging might also alleviate the unfavorable environmental conditions for bryophyte species while “lifeboating” some species through the following successional stages.

A study on molecular taxonomy of South Indian species Selaginella sweared by DNA barcoding using rbcL

In this study, genetic polymorphisms using DNA barcoding has been performed on selected ten species of Selaginella collected form Tamil Nadu and the Hills of Kerala. The main aim of this study was to estimate a phylogenetic and evolutionary relationship between selected species of Selaginella using DNA barcoding. The genomic DNA of selected species of Selaginella was isolated and were examined for DNA polymorphisms. The method described by Sanger has been used to sequence the PCR rbcL products. The phylogenetic analysis was carried out using four methods viz., minimum evolution, neighbor joining, UPGMA and maximum parsimony. For the studied species, the PCR amplification result was good, the molecular weight range from 500 to 600 base pairs and the amplicons were sequenced. The obtained sequences were aligned, annotated and submitted in GenBank. The phylogenetic analysis of studied Selaginella species using minimum evolution, NJ and UPGMA methods showed similar trees whether maximum parsimony tree displayed varied tree. The sequence alignment results illustrated that the sequence of S. involvens, S. intermedia, S. inaequalifolia, S. wightii and S. tenera were distinct from the other studied Selaginella species viz., S. brachystachya, S. repanda, S. radicata, S. bryopteris and S. delicatula. The cladistics tree also explains the relationship between S. delicatula with and without cones. This concludes that rbcL data is most valuable for inferring phylogenetic relationship between closely related species. DNA barcoding using rbcL gene was applied to distinguish the inter-specific variation among the selected Selaginella species.

The intensity of forest management affects the nest cavity production of woodpeckers and tits in mature boreal forests

Cavities made by birds are an important microhabitat for many taxa in forests. Long-term dynamics of cavity patterns and the effect of forest management on cavities are, however, largely unknown. We studied cavity production, measured as nest cavity production rates (CPR = no. of new cavities/km2/year), of woodpeckers and tits in forests with different management intensity in southern Finland, based on a data from 37 years. Forests were divided into managed, seminatural and natural stands. The data covered 56 forest stands with the total area of 1690 ha. Stands were inventoried annually for new cavities. The total numbers of woodpecker and tit cavities were 2238 and 329, respectively. There were large differences in CPRs between forest stands with different management intensity. For woodpeckers, the CPR was highest in natural forests (5.7) and lowest in managed forests (1.5). For the tit species, the respective numbers were 0.9 and 0.3. The CPRs of different cavity-making bird species and cavity tree characteristics (e.g. tree condition and species) were consistent, suggesting that different cavity-makers benefit from similar forest and tree characteristics. The results also suggest that forests managed with currently prevailing methods limit the production of cavities. To promote cavities, the results from this and other studies suggest that managed forests should include more features of natural forests, such as more diverse tree species and within-stand structural variability distribution (tree-level heterogeneity), larger amount of decayed wood, more retention trees and snags and longer rotation periods.

First report of the complete mitochondrial genome of 3 beetles (Coleoptera: Scarabaeidae) harming Gastrodia elata (Asparagales: Orchidaceae).

Gastrodia elata Blume, a valuable traditional Chinese medicine with significant clinical and nutritional importance, is a fungal heterotrophic orchid. We present the first report of the mitochondrial genome structure and characteristics of 3 Scarabaeidae pests affecting G. elata: Sophrops peronosporus Gu & Zhang, Anomala rufiventris Kollar & Redtenbacher, and Callistethus plagiicollis Fairmaire. Each mitogenome contained 13 protein-coding genes (PCGs), 22 transfer RNAs (tRNAs), 2 ribosomal RNAs (rRNAs), and a control region, with no gene rearrangements observed. All 21 tRNAs, except trnS1 that lacks a dihydrouridine, had a stable cloverleaf secondary structure. Maximum likelihood and Bayesian inference analyses based on the 13 PCGs produced 2 topologically similar phylogenetic trees, both of with high nodal support. Larvae of these Scarabaeidae pests cause substantial damage by gnawing on the tubers and roots of G. elata, leading to reduced yield and compromised quality. These findings contribute to phylogenetic studies of Scarabaeidae, expand knowledge of G. elata pests, and offer valuable reference materials for their identification and control.

Progressing towards Estimates of Local Emissions from Trees in Cities: A Transdisciplinary Framework Integrating Available Municipal Data, AI, and Citizen Science

Urban tree cadastres, crucial for climate adaptation and urban planning, face challenges in maintaining accuracy and completeness. A transdisciplinary approach in Kaiserslautern, Germany, complements existing incomplete tree data with additional precise GPS locations of urban trees. Deep learning models using aerial imagery identify trees, while other applications employ street view imagery and LIDAR data to collect additional attributes, such as height and crown width. A web application encourages citizen participation in adding features like species and improving datasets for further model training. The initiative aims to minimize resource-intensive maintenance conducted by local administrations, integrate additional features, and improve data quality. Its primary goal is to create transferable AI models utilizing aerial imagery and LIDAR data that can be applied in regions with similar tree populations. The approach includes tree clusters and private trees, which are essential for assessing allergy and ozone potential but are usually not recorded in municipal tree cadastres. The paper highlights the potential of improving tree cadastres for effective urban planning in a transdisciplinary approach, taking into account climate change, health, and public engagement.

Phylogenetic Determination of Chenopodium quinoaBased on the Chloroplast Genes rbcL and matK

Chenopodium quinoa is an Andean species of great interest because of its excellent nutritional quality and great adaptability to different environmental conditions. In addition, the high phenotypic diversity has caused difficulties in the correct taxonomic identification, and there are few studies on the phylogenetic relationships of quinoa in Colombia. Therefore, the objective of this research was to determine the phylogenetic relationships of quinoa with the matK and rcbL chloroplastid genes to characterize the genetic diversity in Colombian quinoa. Evolutionary analyses were performed using nucleotide substitution rates, pattern, base composition, and phylogeny construction. The rbcL gene presented approximately 1344 bp, and matK had 646 bp, which were translated into 434 and 215 amino acids, respectively. The nucleotide composition of the genes showed high percentages of similarity and identity with the Chenopodium quinoa sequences registered in GenBank and BOLD. Similar phylogenetic trees were obtained with the rbcL and matK genes, and both concatenated sequences grouped the accessions into clades. The results showed that Colombian quinoa has low rates of genetic differentiation that may be due to the domestication processes of the species, the lack of certified seeds, and the constant exchange of seeds between farmers in the principal producing areas of the Andean region.

Invasion by Callery pear (Pyrus calleryana) does not affect understory abundance or diversity in early-successional meadows

AbstractTrait differences between invasive plants and the plants in their recipient communities moderate the impact of invaders on community composition. Callery pear (Pyrus calleryana Decne.) is a fast-growing, stress-tolerant tree native to China that has been widely planted for its ornamental value. In recent decades, P. calleryana has naturalized throughout the eastern United States, where it spreads rapidly and achieves high abundance in early-successional environments. Here we compare the impacts of low-density, establishment-phase P. calleryana to those of functionally similar native trees on the understory community diversity and total cover of three early-successional meadows in Indiana’s Eastern Corn Belt Plains. In contrast to our prediction that P. calleryana would have greater negative effects on the total abundance and diversity of the understory plant community compared with native tuliptree (Liriodendron tulipifera L.), American sycamore (Platanus occidentalis L.), or non-tree control plots, we found that these low-density populations of P. calleryana had no significant impact on total cover, species richness, or diversity indices for the understory community compared with the native trees and non-tree control plots. Likewise, the studied populations of P. calleryana had no significant impact on the native, introduced, woody, or native tree subsets of the understory community. These results indicate that in young, low-density populations situated in early-successional meadows, the trait differences between P. calleryana and functionally similar native trees are not of a great enough magnitude to produce changes in community composition. Going forward, complementary research on the impacts of P. calleryana on community composition and ecosystem processes in areas with long-established, dense invasions or invasions in more sensitive ecosystems would allow us to more fully understand how this widespread invader disrupts its host ecosystems.

Structural Analysis of Social Representations of COVID-19 Among Health Professionals

The COVID-19 pandemic has had significant repercussions, particularly among healthcare professionals who have faced drastic changes in their work routines, increased exposure to risk, the precariousness of services, and experiences of loss and anxiety. This study aimed to analyze the structure of social representations of COVID-19 among health professionals in Ceará, located in Northeastern Brazil. A qualitative study was conducted using the Theory of Social Representations and included nursing professionals (nurses, nursing technicians, and assistants), physicians, and physical therapists who were 18 years of age or older. The sample consisted of 1317 participants who were selected using convenience sampling. Due to restrictive measures, data collection was carried out remotely through a questionnaire created using Google Forms. Out of the 1317 participants, 737 (55.5%) were nurses, 191 (14.4%) were nursing technicians, 254 (19.1%) were physicians, and 145 (11%) were physical therapists. Additionally, 1123 (84.6%) of the participants were women, with a mean age of 34 ± 8.9 years. A total of 6635 words were elicited during the study, with 1316 different evocations. The central core of the social representations was composed of the terms “fear,” “anxiety,” and “anguish.” The similarity tree analysis revealed that “fear” (n = 802) served as the organizing structure, with 18 associated terms and five cores: “death” (n = 502), “sadness” (n = 203), “anguish” (n = 185), “anxiety” (n = 171), and “insecurity” (n = 144). The structural analysis of the social representations of COVID-19 among health professionals indicated that fear, anxiety, and anguish formed the central axis, highlighting the prevalence of negative emotions. This finding was supported by the presence of terms such as death, isolation, sadness, insecurity, and pain in the first periphery of the representation.