Mixture Of Species Research Articles

Compactness Property of the Linearized Boltzmann Collision Operator for a Mixture of Monatomic and Polyatomic Species

The linearized Boltzmann collision operator has a central role in many important applications of the Boltzmann equation. Recently some important classical properties of the linearized collision operator for monatomic single species were extended to multicomponent monatomic gases and polyatomic single species. For multicomponent polyatomic gases, the case where the polyatomicity is modelled by a discrete internal energy variable was considered lately. Here we consider the corresponding case for a continuous internal energy variable. Compactness results, stating that the linearized operator can be decomposed into a sum of a positive multiplication operator, the collision frequency, and a compact operator, bringing e.g., self-adjointness, is extended from the classical result for monatomic single species, under reasonable assumptions on the collision kernel. With a probabilistic formulation of the collision operator as a starting point, the compactness property is shown by a decomposition, such that the terms are, or at least are uniform limits of, Hilbert–Schmidt integral operators and therefore are compact operators. Moreover, bounds on—including coercivity of—the collision frequency are obtained for hard sphere like, as well as hard potentials with cutoff like, models, from which Fredholmness of the linearized collision operator follows, as well as its domain.

Bi-cropping of castor bean and nutri-millets optimizes system productivity, energy efficiency, and carbon footprint in rainfed alfisols of semi-arid tropics

Intercropping enhances diversity, productivity, resilience, and soil health. To achieve these benefits of the intercropping system, drilling patterns and species mixture play a key role. Therefore, to optimize the productivity, profitability, energetics, and carbon footprint of the castor-based millet intercropping system, a field experiment was conducted for two consecutive kharif seasons (2020 − 2021 and 2021 − 2022) at the University of Agricultural Sciences, Bangalore, Karnataka (India). The results revealed that all the crops under monoculture outperformed their intercropping system for seed and stalk/stover yield. Among the different cropping systems, castor + finger millet (2:4) showed highest castor equivalent yield (CEY; 1911 kg ha−1) due to excellent land utilization efficiency (LUE; 106%), land equivalent ratio (LER; 1.13), land equivalent co-efficient (LEC; 0.32) compared to other cropping systems. Castor + finger millet (2:4) was even found superior in terms of monetary returns. Finger millet monoculture showed the highest energy consumption (10,770 MJ ha−1), energy output (96,507 MJ ha−1), and also net energy gain (85,737 MJ ha−1) compared to other cropping systems. However, it was comparable with castor + finger millet (2:4) despite its modest energy consumption (10,530 MJ ha−1). Castor monoculture showed the highest carbon (C) emission (2045 kg CO2-eq. ha−1) and also C output (1760 kg CE ha−1). While, net C gain (1210 kg CE ha−1), C efficiency (3.39 kg kg−1 CE), and C stability index (2.39) were highest in the castor + finger millet intercropping system. Consequently, the adoption of a castor + finger millet (2:4) intercropping system will be a viable alternative for achieving enhanced system productivity, and energy efficiency with lower C-footprints under semi-arid regions.

Consequences of tree species mixture for growth and damage based on large-scale inventory data in Finland

Interest in growing mixed species stands has increased in recent years, and the cultivation of mixed stands is promoted in silvicultural guidelines and forest certification systems. Mixtures of tree species have often increased biomass production, but the effect of species mixture on productivity has been small in studies conducted in the Nordic countries. However, several previous studies are based on temporary plots selected according to predefined criteria, usually removing possible effects of damage affecting forest growth. Sample-based forest inventories describe the actual development of forest resources and provide an opportunity to analyse the factors affecting forest growth. Using the data of the Finnish National Forest Inventory (NFI), we analysed the species mixture–productivity relationship that take place in real environmental and management conditions. We analysed pure and mixed species stands dominated by spruce and pine in southern Finland and compared their volume increment, growing stock, and damage, and present results separately for age classes 21–40, 41–60, and > 60 years. Mixed stands were more common in the 1920 s because of historical forms of land use, but tree species composition in the current forests is quite different, and the stands are conifer-dominated. Slight and moderate broadleaved species mixture did not notably affect the volume growth of coniferous stands on average, while it varied somewhat from case to case. Instead, the growth of pine- and spruce-dominated stands was related to the amount of growing stock, site fertility, and stand age, regardless of the level of broadleaved species mixture. In addition, the results showed an increasing proportion of damaged stands with an increasing proportion of broadleaved trees. Our results at regional level confirm the results of previous Nordic studies conducted at stand level that slight and moderate mixtures of broadleaved trees in coniferous stands have no or only a low reducing effect on wood production.

Mixture of winter cover crops reduces surface runoff and sediment production under no‐tillage system for Oxisols

AbstractOne of Brazil's efficient soil and water conservation practices is the no‐tillage system (NTS). Nonetheless, erosion during rainfall still causes soil and water losses in this system. Therefore, this study aimed to assess surface runoff in different cultivation systems and sediment production during rainfall events. In macro‐plot 1 (non‐terraced catchment [NTC]), we adopted the NTS management with up‐ and down‐slope farming without including mechanical runoff control practices, which most regional producers use. In macro‐plot 2 (best management practices [BMPs]), we optimized crop rotation by incorporating a mixture of cover crop species in autumn and implemented contour farming practices. In macroplot 3 (terraced catchment [TC]), we adopted the same soil management practices as the NTC macroplot, including mechanical runoff control using broad‐based terraces. We used rainfall data to create hyetographs, hydrographs, and sedimentographs, aiming to evaluate the impact of management practices on surface runoff and sediment production. The surface runoff was reduced by 81% (BMPs) and 88% (TC) compared to the NTC system. There was also a reduction in suspended sediment concentration, around 33% (BMPs) and 63% (TC), compared to the NTC system. Despite conservation systems have shown effectiveness in reducing surface runoff and sediment production, monitoring these systems during periods not influenced by the La Niña phenomenon is necessary to assess the impact of rainfall events on soils with conservation practices in extreme events. The study findings provide guidance and recommendations for agricultural producers and field technicians globally, offering criteria for selecting optimal soil and water management practices in no‐till systems. This promotes a conservation‐oriented approach to agriculture.

The seeds of Plantago lanceolata comprise a stable core microbiome along a plant richness gradient

BackgroundSeed endophytic bacteria are beneficial to plants. They improve seedling growth by enhancing plant nutrient uptake, modulating stress-related phytohormone production, and targeting pests and pathogens with antibiotics. Seed endophyte composition can be influenced by pollination, plant cultivar, and soil physicochemical conditions. However, the effects of plant community richness on seed endophytes are unknown. To investigate the effects of increasing plant species richness on the diversity and composition of the seed microbiome, we made use of a well-established long-term biodiversity experiment in Germany (The Jena Experiment). We sampled seeds from different Plantago lanceolata blossoms in a plant diversity gradient ranging from monoculture to 16 species mixtures. The seeds were surface sterilized to remove seed surface-associated bacteria and subjected to a metabarcoding approach to assess bacterial community structure.ResultsOur data indicate a very stable core microbiome, which accounted for more than 90% of the reads and was present in all seeds independent of the plant richness level the seeds originated from. It consisted mainly of reads linked to Pseudomonas rhizosphaerae, Sphingomonas faeni and Pirellulla spp. 9% of the obtained reads were not part of the core microbiome and were only present in plots of specific diversity levels. The number of unique ASVs was positively correlated with plant richness. Interestingly, most reads described as non-core members belonged to the same genera described as the core microbiome, indicating the presence of different strains or species with possibly different functional properties important for seed performance.ConclusionOur data indicate that Plantago lanceolata maintains a large seeds core microbiome across the plant richness gradient. However, the number of unique ASVs increases alongside the plant community richness, indicating that ecosystem biodiversity also mitigates diversity loss in seed endophytes.

Polarization Conforms Performance Variability in Amorphous Electrodeposited Iridium Oxide pH Sensors: A Thorough Surface Chemistry Investigation

Electrodeposited amorphous hydrated iridium oxide (IrOx) is a promising material for pH sensing due to its high sensitivity and the ease of fabrication. However, durability and variability continue to restrict the sensor’s effectiveness. Variation in probe films can be seen in both performance and fabrication, but it has been found that performance variation can be controlled with potentiostatic conditioning (PC). To make proper use of this technique, the morphological and chemical changes affecting the conditioning process must be understood. Here, a thorough study of this material, after undergoing PC in a pH-sensing-relevant potential regime, was conducted by voltammetry, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). Fitting of XPS data was performed, guided by raw trends in survey scans, core orbitals, and valence spectra, both XPS and UPS. The findings indicate that the PC process can repeatably control and conform performance and surface bonding to desired calibrations and distributions, respectively; PC was able to reduce sensitivity and offset ranges to as low as ±0.7 mV/pH and ±0.008 V, respectively, and repeat bonding distributions over ~2 months of sample preparation. Both Ir/O atomic ratios (shifting from 4:1 to over 4.5:1) and fitted components assigned hydroxide or oxide states based on the literature (low-voltage spectra being almost entirely with suggested hydroxide components, and high-voltage spectra almost entirely with suggested oxide components) trend across the polarization range. Self-consistent valence, core orbital, and survey quantitative trends point to a likely mechanism of ligand conversion from hydroxide to oxide, suggesting that the conditioning process enforces specific state mixtures that include both theoretical Ir(III) and Ir(IV) species, and raising the conditioning potential alters the surface species from an assumed mixture of Ir species to more oxidized Ir species.

Coupled-cluster theory for trapped bosonic mixtures.

We develop a coupled-cluster theory for bosonic mixtures of binary species in external traps, providing a promising theoretical approach to demonstrate highly accurately the many-body physics of mixtures of Bose-Einstein condensates. The coupled-cluster wavefunction for the binary species is obtained when an exponential cluster operator eT, where T = T(1) + T(2) + T(12) and T(1) accounts for excitations in species-1, T(2) for excitations in species-2, and T(12) for combined excitations in both species, acts on the ground state configuration prepared by accumulating all bosons in a single orbital for each species. We have explicitly derived the working equations for bosonic mixtures by truncating the cluster operator up to the single and double excitations and using arbitrary sets of orthonormal orbitals for each of the species. Furthermore, the comparatively simplified version of the working equations are formulated using the Fock-like operators. Finally, using an exactly solvable many-body model for bosonic mixtures that exists in the literature allows us to implement and test the performance and accuracy of the coupled-cluster theory for situations with balanced as well as imbalanced boson numbers and for weak to moderately strong intra- and interspecies interaction strengths. The comparison between our computed results using coupled-cluster theory with the respective analytical exact results displays remarkable agreement exhibiting excellent success of the coupled-cluster theory for bosonic mixtures. All in all, the correlation exhaustive coupled-cluster theory shows encouraging results and could be a promising approach in paving the way for high-accuracy modeling of various bosonic mixture systems.

Geographical and environmental patterns of Carpathian land snail faunas in a region of high endemicity

The land snail faunas of limestone gorges of Romanian Carpathians were sampled to test the effect of geographic and environmental factors on the malacofauna richness and composition. A total of 134 sites within 28 limestone gorges were surveyed during 2011–2019 using a combined strategy of visual search and litter/topsoil analysis. Environmental variables such as geographic location, altitude, climate, microhabitat type, dominant vegetation, tree cover and width of the gorge were recorded to detect the relationship with species richness and composition. While the numbers of species, their identities and their abundance varied greatly among samples, both presence and absence data and quantitative multivariate analyses showed that region and climate or altitude (both strongly associated with region) accounted for far more variation than differences in tree cover and dominant microhabitat. Nevertheless, the effects of different habitat preferences were evident. The mixture of species with very restricted ranges within this Pleistocene refugium and those that have spread widely during the Holocene raise questions about the meaning of region when related to local richness and composition.

Cost‐effectiveness of management strategies in a nucleation experiment in a tropical dry forest

Cost‐effective, large‐scale strategies are needed to restore degraded ecosystems worldwide. Applied nucleation is one technique that can accelerate succession in tropical forests. However, the effectiveness of irrigation and fertilization in the context of large‐scale applied nucleation in tropical dry forests (TDFs) has not yet been tested. To this end, we established a large‐scale experiment in southwestern Colombia on abandoned pastures. We planted 11,382 seedlings of 11 native species coupled with six management treatments that varied in the amounts of fertilizer and water. We monitored survival, height, and resprouting ability seedlings over 2 years. We also estimated the cost of seedling production, planting procedures, management, and monitoring, and assessed their cost‐effectiveness using seedling survival as an indication of effectiveness. After 2 years, 73% (8,266) of seedlings planted survived, and species survival ranged from 5 to 99%. Individuals that received the lowest amount of fertilizer (25 g of Nitrogen, Phosphorus, and Potassium [NPK]) with additional irrigation had the highest survival rates (>76%). Final height ranged from 52 to 330 cm across species. Seedlings that received the highest amount of fertilizer (50 g of NPK) without additional irrigation had the highest mean final height (174 ± 9.0 cm). The control was cheapest ($7313/ha) and the most cost‐effective method in terms of seedling survival. Our findings suggest that the best way to establish cost‐effective, large‐scale restoration projects in TDFs is to plant native species mixtures of locally adapted species without fertilization and irrigation and to invest in long‐term monitoring.

Dissimilarity in root traits and spatial distribution promotes the productivity of Piper nigrum L. and tree species in mixture systems

Background and aimsClarifying why species mixtures produce greater biomass compared to monocultures is important for understanding the effect of biodiversity in natural and agricultural systems. At present, it remains unclear whether differential root traits and spatial distribution between the liana and tree species can promote productivity of mixtures. MethodsA 4-month glasshouse experiment and a 3-year field trial were conducted to examine the influence of root traits and the vertical and horizontal root distribution on productivity of independently supported liana Piper nigrum (Pn) and five other species. In the glasshouse experiment, Pn was grown in monoculture or mixed with one of five species: Coffea arabica, Areca catechu, Artocarpus heterophyllus, Camellia oleifera, and Coffea canephora. In the field trial, the Pn/Ac system and each monoculture were tested. ResultsCompared with monoculture, all Pn and mixture systems showed a positive net effect and a high complementarity effect on shoot biomass. The variation in complementarity effect was mainly associated with dissimilarity in the multidimensional root space trait and a few specific individual traits (root phosphatase activity and mycorrhizal colonization) between Pn and the neighbors. In the field, Pn in the mixture increased proportion of root length in the 20–40 cm soil layer and allocated less root length in the space shared between Pn and Ac, thus achieving spatial separation of roots and promoting the final yield. ConclusionThese findings suggest that the dissimilarity in root traits and spatial distribution may be an important mechanism for promoting the productivity of mixtures of liana and tree species.

Long-term exposure to PM2.5 species and all-cause mortality among Medicare patients using mixtures analyses

BackgroundThe relationship between long-term exposure to PM2.5 and mortality is well-established; however, the role of individual species is less understood. ObjectivesIn this study, we assess the overall effect of long-term exposure to PM2.5 as a mixture of species and identify the most harmful of those species while controlling for the others. MethodsWe looked at changes in mortality among Medicare participants 65 years of age or older from 2000 to 2018 in response to changes in annual levels of 15 PM2.5 components, namely: organic carbon, elemental carbon, nickel, lead, zinc, sulfate, potassium, vanadium, nitrate, silicon, copper, iron, ammonium, calcium, and bromine. Data on exposure were derived from high-resolution, spatio-temporal models which were then aggregated to ZIP code. We used the rate of deaths in each ZIP code per year as the outcome of interest. Covariates included demographic, temperature, socioeconomic, and access-to-care variables. We used a mixtures approach, a weighted quantile sum, to analyze the joint effects of PM2.5 species on mortality. We further looked at the effects of the components when PM2.5 mass levels were at concentrations below 8 μg/m3, and effect modification by sex, race, Medicaid status, and Census division. ResultsWe found that for each decile increase in the levels of the PM2.5 mixture, the rate of all-cause mortality increased by 1.4% (95% CI: 1.3%–1.4%), the rate of cardiovascular mortality increased by 2.1% (95% CI: 2.0%–2.2%), and the rate of respiratory mortality increased by 1.7% (95% CI: 1.5%–1.9%). These effects estimates remained significant and slightly higher when we restricted to lower concentrations. The highest weights for harmful effects were due to organic carbon, nickel, zinc, sulfate, and vanadium. ConclusionsLong-term exposure to PM2.5 species, as a mixture, increased the risk of all-cause, cardiovascular, and respiratory mortality.

Developing crown width model for mixed forests using soil, climate and stand factors

Abstract The tree crown is a useful measure of tree vigour and is highly relevant to a tree's environmental adaptability. Crown allometry depends on environmental and stand conditions. Several studies have focussed on the effects of climate change and competitive intensity on the crown, but the regulatory role of soil resources and diversity on crown allometry and carbon allocation has been neglected. Data from 20,994 trees in 232 mixed forests collected between 2011 and 2019 were located near four major mountain ranges in northeast China. The proposed crown width model includes the stand developmental stage, soil, climate, competition intensity, species mixture, species diversity, structural diversity and their interactions. We observed that the cross‐species allometric scaling exponent does not conform to the universal scaling law. Our results showed that crown width increased with increasing soil bulk density, quadratic mean diameter and coefficient of diameter variation but decreased with increasing de Martonne aridity index, basal area, Simpson index and species mixture. The interaction between quadratic mean diameter and soil bulk density had a significant negative effect on crown width. The influence of a particular factor within the interaction term on crown width was modulated by the gradients of other factors. Furthermore, soil bulk density contributed more to crown width modelling than the aridity index, and structural diversity had a greater effect on crown width than species diversity. Synthesis. Our results provide new insights into the environmental variability of crown allometry in mixed forests under global change, which is critical for improving regional and global estimates of forest biomass and carbon stocks.

Productivity and Vegetation Structure Evolution of Complex Mixtures of Perennial Forage Grasses and Leguminous Species, in the Conditions of the Center of Moldova, Romania

Research in our country on the number of species needed to set up temporary grasslands has highlighted the productive and structural superiority of complex mixtures of more than two species. Although for the composition of mixtures is intended to use species and varieties as well as possible adapted to the environment, annual climatic variations sometimes influence the behaviour of the species and therefore productivity. The need to reduce doses of chemical fertilizers in the exploitation of temporary grasslands requires finding solutions to saturate the multiple ecological niches of temporary grassland ecosystems. These can be achieved by using a mix of a larger number of species adapted to the pedo-climatic conditions specific to the cultivation area, as well as by using an appropriate ratio between these species. The purpose of the study was to follow the productivity and evolution of the vegetation structure in some crop mixtures, in different conditions of fertilization. The research was conducted under the conditions of the Center of Moldova from Romania at ARDS Secuieni - Neamţ, during the 2018-2021 period,. The production of dry matter according to the type of mixture and the doses of fertilizers used the percentage of participation of perennial grasses and leguminous species in the vegetation structure, as well as its quality was analysed. From the analysis of the obtained data, the highest feed production (24.82 Mg·ha-1 DM) was obtained in the variant fertilized with N80P40 and sown with the mixture consisting of 70% grasses (Festuca arundinacea 30% + Dactylis glomerata 20% + Festuca pratensis 20%) and 30% leguminous (Medicago sativa 20% + Trifolium pratense 10%). At the first cut, in the mixture of 70% grasses (Festuca arundinacea 30% + Dactylis glomerata 20% + Festuca pratensis 20%) and 30% leguminous (Medicago sativa 20% + Trifolium pratense 10%), the participation percentage of grasses in the vegetation structure varied from 57% in the non-fertilized variant, to 61% in the variant fertilized with N80+40P40. The quality of the feed obtained was good for all variants studied.

Use of foreign mixtures of lawn grasses in greening of roadside areas in central Yakutia

Currently, in Yakutia, the construction of apartment buildings is rapidly developing, new neighborhoods are being created, roads, squares, etc. are being repaired, and this requires work on landscaping (sowing lawns, planting trees, shrubs and shrubs, perennial and annual flowers). Lawns are the most common type and an integral part of landscaping in urban areas. To improve environmental quality, in recent years, when arranging lawns, attention has been paid to sanitary, hygienic, reclamation and aesthetic functions, in addition to minimizing the costs of growing and maintaining lawns - by choosing the right grass. When using grass mixtures of foreign species of lawn grasses, certain conditions are required; the types of lawn grasses must have good adaptation to permafrost conditions, high winter hardiness, drought resistance, and survival, which is one of the positive features.

Developmental validation of the AGCU YNFS Y Kit: A new 6-dye multiplex system with 44 Y-STRs and 5 Y-InDels for forensic application.

With the widespread use of the Y chromosome in genetics, a lot of commercially available Y chromosome kits were developed, validated, and applied to forensic science practice. The AGCU YNFS Y Kit is a new Y chromosome system containing forty-four preferred Y short tandem repeats (Y-STRs) and five common Y-InDels. In this study, the AGCU YNFS Y system was validated to verify its performance by following the guidelines of the Scientific Working Group on DNA Analysis Methods (SWGDAM). A series of validation experiments included the following parameters: PCR-based studies, sensitivity studies, species specificity studies, stability studies, mixture studies, precision studies, stutter calculation, mutation and statistical analysis, population study, and case samples and degradation studies. The results suggested that appropriately changing PCR amplification conditions did not affect genotyping; the kit had good sensitivity for trace amounts of DNA (0.0625 ng), mixtures of multiple male individuals (minor: major = 1: 9), and three PCR inhibitors (more than 250 μM hematin, 250 ng/μL humic acid and 50 ng/μL tannic acid). The maximum standard deviation of allele size did not exceed 0.1552 reflecting the high accuracy of the system. By this, 87 DNA-confirmed pairs of father-son pairs were also analyzed for mutations. A total of 18 loci were mutated, with mutation rates ranging from 11.5×10-3 to 34.5×10-3 (95% CI 7.2×10-3-97.5×10-3, DYS627 and DYF404S1). In the population study, the haplotype diversity of 87 unrelated individuals was 0.9997, and discrimination capacity was 0.9885. Degradation studies have demonstrated that UV-C light exposure for up to 120 hours has no effect on male blood and semen-vaginal secretion mixtures. However, complete typing could no longer be obtained after 48 hours of UV exposure in single male saliva and in male saliva and female blood mixed samples. Collectively, the AGCU YNFS Y Kit is sensitive and accurate and can play its application value in forensic science practice.

Cluster dynamics of heterometallic trinuclear clusters during ligand substitution, redox chemistry, and group transfer processes.

Stepwise metalation of the hexadentate ligand tbsLH6 (tbsLH6 = 1,3,5-C6H9(NHC6H4-o-NHSiMe2tBu)3) affords bimetallic trinuclear clusters (tbsL)Fe2Zn(thf) and (tbsL)Fe2Zn(py). Reactivity studies were pursued to understand metal atom lability as the clusters undergo ligand substitution, redox chemistry, and group transfer processes. Chloride addition to (tbsL)Fe2Zn(thf) resulted in a mixture of species including both all-zinc and all-iron products. Addition of ArN3 (Ar = Ph, 3,5-(CF3)2C6H3) to (tbsL)Fe2Zn(py) yielded a mixture of two trinuclear products: (tbsL)Fe3(μ3-NAr) and (tbsL)Fe2Zn(μ3-NAr)(py). The two imido species were separated via crystallization, and outer sphere reduction of (tbsL)Fe2Zn(μ3-NAr)(py) resulted in the formation of a single product, [2,2,2-crypt(K)][(tbsL)Fe2Zn(μ3-NAr)]. These results provide insight into the relationship between heterometallic cluster structure and substitutional lability and could help inform both future catalyst design and our understanding of metal atom lability in bioinorganic systems.

Forest land management and the role of ecological silviculture on the sustainability of Greek forests

One of the challenges faced by current forestry practice is how to effectively respond to the great environmental and global changes to achieve biodiversity conservation and the demands for timber and other non-wood forest products. Worldwide forestry suggests that the approach of ecological silviculture can provide efficient tools for facing these challenges. The applied forest land management during the last seven decades in Greece relies on the principles of sustainability set by ecological silviculture through time. Greek silviculturists adopted these principles many years ago by setting the following priorities and perspectives for applied Greek forestry: the protection of all Greek forests, the systematic rehabilitation of degraded forests (e.g., conversion of coppices to high forest), the promotion of tree species mixture, the improvement of the horizontal and vertical structure of all forest ecosystems, the exclusive use of species natural regeneration, the application of selective felling prohibiting any of clear-cutting, the extensive use of low impact harvesting practices, the retention of a small number of old trees for promoting biodiversity, the protection of all rare and endangered flora and fauna species, and establishment forest protected areas. In this study, three modern indicators were used to evaluate the results of the above silvicultural ecological approach to Greek forests after a period of seven years of forestry practice based on these principles.

Effect of silvicultural treatments on forest diversity and structure in temperate forests under management in Durango, Mexico

<p>The present study evaluated the effect of silvicultural treatments on the diversity and structure of species in temperate forest ecosystems in the Municipality of Pueblo Nuevo in the State of Durango, Mexico; it was carried out to know if forest use modifies the diversity, mixture of species, spatial distribution, and dimensional differentiation of individuals in these ecosystems. The evaluation was carried out by comparing 10 plots with management history, which were measured before the application of the treatment and five years later. The diversity indices of Shannon, Simpson and Margalef were compared, as well as indices of structure of mixture of species, spatial distribution, and dimensional differentiation. According to the silvicultural treatments applied, the values of the indices do not present significant differences in their evaluations (p> 0.05), which indicates that forest use does not modify the diversity and structure of species of the tree stratum of this plant community.</p>

A CRISPR-based strategy for targeted sequencing in biodiversity science.

Many applications in molecular ecology require the ability to match specific DNA sequences from single- or mixed-species samples with a diagnostic reference library. Widely used methods for DNA barcoding and metabarcoding employ PCR and amplicon sequencing to identify taxa based on target sequences, but the target-specific enrichment capabilities of CRISPR-Cas systems may offer advantages in some applications. We identified 54,837 CRISPR-Cas guide RNAs that may be useful for enriching chloroplast DNA across phylogenetically diverse plant species. We tested a subset of 17 guide RNAs invitro to enrich plant DNA strands ranging in size from diagnostic DNA barcodes of 1,428 bp to entire chloroplast genomes of 121,284 bp. We used an Oxford Nanopore sequencer to evaluate sequencing success based on both single- and mixed-species samples, which yielded mean chloroplast sequence lengths of 2,530-11,367 bp, depending on the experiment. In comparison to mixed-species experiments, single-species experiments yielded more on-target sequence reads and greater mean pairwise identity between contigs and the plant species' reference genomes. But nevertheless, these mixed-species experiments yielded sufficient data to provide ≥48-fold increase in sequence length and better estimates of relative abundance for a commercially prepared mixture of plant species compared to DNA metabarcoding based on the chloroplast trnL-P6 marker. Prior work developed CRISPR-based enrichment protocols for long-read sequencing and our experiments pioneered its use for plant DNA barcoding and chloroplast assemblies that may have advantages over workflows that require PCR and short-read sequencing. Future work would benefit from continuing to develop invitro and in silico methods for CRISPR-based analyses of mixed-species samples, especially when the appropriate reference genomes for contig assembly cannot be known a priori.

Exploring the influence of tree species richness on vertical structure variability in young plantations using terrestrial laser scanning

Forest structure spatially varies at the landscape-scale (between-plot) but also local-scale (within-plot). Both scales of structural variability have significant impacts on forest ecosystem functioning and stability. However, we still have a limited understanding of how tree species richness affects the spatial structural variability. In this study, we disentangled within- and between-plot variability in stand structural variables depending on tree species richness level. Terrestrial laser scanning (TLS) technology, capable of developing forest vertical structure in 3D detail, was applied in the FORBIO tree diversity experiment at three sites in Belgium. One site was 9-year old (Hechtel-Eksel) and other two sites were 11-year old (Zedelgem and Gedinne). Each site included five different sets of one, two, three, and four tree species mixtures with one replica. At each plot, four single scan locations were used. Six stand structural variables were quantified based on TLS vertical plant profiles. We hypothesized that within-plot structural variability would increase with species richness, but that the between-plot structural variability would decrease with species richness. Our study revealed notable differences in structural variability between monocultures and mixtures across all sites examined. However, the relationship between tree species richness and structural variability patterns is site-dependent. Specifically, at the Zedelgem site, we observed increased within-plot variability and decreased between-plot variability with species richness, supporting the hypothesis that species richness drives stand structural variability. However, the hypothesized pattern was not as strong at the Hechtel-Eksel and Gedinne sites. Moreover, the various structural variables displayed contrasting responses to changes in species richness. These findings indicated the potential influence of tree species richness on within- and between-plot structural variability in young plantations, particularly in favorable site conditions with well-adapted species pools. Hence, afforestation measures would benefit from planting multiple tree species to initiate structurally complex stands by considering species richness level.