Tree Population Structure Research Articles

Genetic variation and population structure of the rice accessions maintained in the AfricaRice genebank using DArTseq

AbstractUtilizing the full potential of rice collections mainly depends on an in‐depth exploration and understanding of the vast diversity in its germplasm. The AfricaRice genebank holds the largest collection of rice germplasm originating from the African continent. In the present study, we comprehensively characterized a collection of 9013 accessions, including Oryza barthii A. Chev., Oryza glaberrima Steud., Oryza longistaminata A. Chev. & Roehr., Oryza sativa L. ssp. indica, and Oryza sativa L. ssp. japonica, for genetic diversity and population structure using genotyping‐by‐sequencing through DArTseq analysis. We identified 27,718 high‐quality single nucleotide polymorphism markers after the genotypic data were filtered. Based on the analyses, the collection has extensive genetic diversity, and the average genetic distance of the entire set was 0.267 (range 0.001–0.469), with 45.1% of pairs of accessions being highly distant and 40.1% moderately distant from each other. Neighbor‐joining tree, principal component, and Bayesian population structure analyses clustered the 9013 accessions into six groups, based roughly on their taxonomic and biological status. The first, second, and third groups consisted of accessions belonging to O. glaberrima, O. barthii, and O. longistaminata, respectively. The fourth, fifth, and sixth groups were improved‐indica, japonica, and traditional‐indica accessions, respectively. The highest value of genetic variance proportion (PhiPT) was found in the species group followed by groups based on cluster analysis and on Bayesian population structure at K = 6. These results allow us to better understand the genetic diversity present in 9013 rice accessions maintained in the AfricaRice genebank and offer a valuable tool for pre breeding, breeding, and further genetic applications.

Genetic diversity and population structure of superior shea trees (Vitellaria paradoxa subsp. paradoxa) using SNP markers for the establishment of a core collection in Côte d'Ivoire.

The shea tree is a well-known carbon sink in Africa that requires a sustainable conservation of its gene pool. However, the genetic structure of its population is not well studied, especially in Côte d'Ivoire. In this study, 333 superior shea tree genotypes conserved in situ in Côte d'Ivoire were collected and genotyped with the aim of investigating its genetic diversity and population structure to facilitate suitable conservation and support future breeding efforts to adapt to climate change effects. A total of 7,559 filtered high-quality single nucleotide polymorphisms (SNPs) were identified using the genotyping by sequencing technology. The gene diversity (HE) ranged between 0.1 to 0.5 with an average of 0.26, while the polymorphism information content (PIC) value ranged between 0.1 to 0.5 with an average of 0.24, indicating a moderate genetic diversity among the studied genotypes. The population structure model classified the 333 genotypes into three genetic groups (GP1, GP2, and GP3). GP1 contained shea trees that mainly originated from the Poro, Tchologo, and Hambol districts, while GP2 and GP3 contained shea trees collected from the Bagoué district. Analysis of molecular variance (AMOVA) identified 55% variance within populations and 45% variance within individuals, indicating a very low genetic differentiation (or very high gene exchange) between these three groups (FST = 0.004, gene flow Nm = 59.02). Morphologically, GP1 displayed spreading tree growth habit, oval nut shape, higher mean nut weight (10.62g), wide leaf (limb width = 4.63cm), and small trunk size (trunk circumference = 133.4cm). Meanwhile, GP2 and GP3 showed similar morphological characteristics: erect and spreading tree growth habit, ovoid nut shape, lower mean nut weight (GP2: 8.89g; GP3: 8.36g), thin leaf (limb width = 4.45cm), and large trunk size ( GP2: 160.5cm, GP3: 149.1cm). A core set of 100 superior shea trees, representing 30% of the original population size and including individuals from all four study districts, was proposed using the "maximum length sub-tree function" in DARwin v. 6.0.21. These findings provide new knowledge of the genetic diversity and population structure of Ivorian shea tree genetic resources for the design of effective collection and conservation strategies for the efficient use of inbreeding.

Factors driving tree community structure in traditional home gardens in the Mayan forest

Introduction'Peasant populations in tropical areas use Traditional Home Gardens (THG) as a key resource for their homes. THG supports significant plant biodiversity, most directly related to asset production, including locally rare species related to food, fuelwood, cultural, ornamental, shade, and wind barriers. Previous studies have considered factors driving tree diversity in THG; however, few have evaluated the biological, environmental, and management factors that shape tree diversity. Our objective in the present study was to identify the drivers of the tree community in THG across a precipitation gradient, evaluating biological, environmental and management factors. MethodsWe visited forty-eight THG distributed across the precipitation gradient spanning around 300 km The tropical Mayan Forest in the Yucatan Peninsula, Mexico., where tree inventory and identification were obtained from specimens with a diameter at breast height > 5 cm. Interviews were conducted with owners about the history of THG. Metadata were captured and analyzed for 19 putative determinants of tree population structure. Differences in tree diversity by individual THG and region were determined statistically. Modeled interaction networks were determined based on a co-occurrence matrix. ResultsTHG tree abundances are mainly explained by the relative abundance of not deliberately established individuals, the organic carbon content in the soil, and surrounding forest integrity. Management history of THG by peasants, including factors such as irrigation, TGH area, and fertilization, showed smaller but significant differences. Tree distribution is at a lower degree influenced by the precipitation gradient in the Yucatan Peninsula, which shows different abundances even for species established by THG owners. ConclusionsOur results suggest that biological and environmental factors may shape tree abundance and distribution over anthropic activities in THG. We identified rare, region-specific, and indicator species by region and modeled interaction networks that show coincidences with the empirical knowledge of THG owners.

Demographic change and loss of big trees in resprouting eucalypt forests exposed to megadisturbance

AbstractAimIncreased tree mortality linked to droughts and fires is occurring across temperate regions globally. Vegetation recovery has been widely reported; however, less is known about how disturbance may alter forests structurally and functionally across environmental gradients. We examined whether dry forests growing on low‐fertility soils were more resilient to coupled extreme drought and severe fire owing to lower tree mortality rates, higher resprouting success and persistence of juveniles relative to wetter forests on more fertile soils.LocationFire‐tolerant eucalypt forests of temperate southeastern Australia.Time period2020–2023.Major taxa studiedEucalyptus, Corymbia, Angophora.MethodsDemographic surveys of tree mortality and regeneration in all combinations of dry/wet forest, fertile/less fertile substrates exposed to extreme drought and fire were conducted. We used Bayesian regression modelling to compare tree mortality, diameter, response traits, population structure and occurrence of fire scars between substrates/forest types.ResultsOverall mortality (20%–33%) and topkill (34%–41%) were within historically reported ranges for various forests and soil types. However, we observed an atypical trend of increased mortality and topkill in the largest trees, particularly when they had structural damage from past fires. Trees in wet forests on more fertile soils had the highest levels of mortality. Numbers of persistent resprouting juveniles were highest in dry forests on low‐fertility soils. Dry forests growing on low‐fertility soils appear more resilient to compound disturbances due to lower rates of mortality and higher rates of juvenile persistence. Wet forests on more fertile soils may experience greater demographic change due to higher mortality of small and large trees.Main conclusionsMesic forests on relatively fertile soils were found to be at relatively high risk of demographic change from compound disturbances. Combined, fire and drought are likely to reduce the number of large trees in affected areas, with consequences for forest carbon cycling and storage.

Species Composition and Diversity of Plants along Human-Induced Disturbances in Tropical Moist Sal Forests of Eastern Ghats, India

Plant biodiversity data are prerequisites for the sustainable management of a forest. We used quantitative ecological tools to determine the species composition, diversity (richness and evenness), population structure, distribution patterns, and regeneration status of trees in a Tropical Moist Sal Forest of Eastern Ghats, India. For this purpose, a field inventory was conducted during 2020–2022 in sixteen 1.0 ha forest stands along a human-induced disturbance gradient. A total of 161 species (61 trees, 40 shrubs, 60 herbs) belonging to 77 families and 143 genera were recorded in the 16.0 ha of forest area. The results revealed a significant (p < 0.01) decrease in the tree and shrub species density, basal area, species richness, and diversity along the gradient of disturbance. However, in the case of herbs, the Shannon–Weiner diversity index increased significantly (p < 0.01) with increasing disturbance levels. Irrespective of forest types and disturbance levels, the tree diameter class (10–30 cm) accounted for the highest stem density in the forest. A mixed trend was found in the case of the basal area; the >41 cm diameter class constituted the highest basal area in the Pure Sal Forest while the 10–30 cm class was in the Moist Deciduous Forest without Sal. Tree species richness was found higher in lower diameter classes. Disturbances impacted the distribution pattern of trees; in the Pure Sal Forest, the contagious distribution of trees were 61.54%, 40%, and 12.5% in undisturbed, low-disturbed, and moderately disturbed sites, respectively. The percent of trees showing random and regular distribution increased with the increased level of disturbance in all forest types. The number of tree species having good regeneration decreased with the increased disturbance intensity in all forest types. Frequent grazing, repeated forest fires, and poor soil seed banks at the Moderately Disturbed site were the main reasons for the poor/no regeneration of Pterocarpus marsupium, Adina cordifolia, Terminalia bellerica, and some other economical species. Significant changes in structural attributes of the tree community revealed the impact of human-induced disturbances in the Moist Sal Forests of Eastern Ghats. The disturbance mosaics promoted the growth of many invasive weed species and lianas, depleting the number of valuable species in the forest. This study suggests the adaption of sustainable biodiversity conservation approaches through the active participation of the tribal so that the remnants the Moist Sal Forests of Eastern Ghats can be controlled to prevent further degradation.

Temporal changes in genetic diversity reveal small-scale invasion dynamics of the eastern redcedar (Juniperus virginiana var. virginiana) in the Lakeside Daisy State Nature Preserve in Ohio

AbstractEastern redcedar (Juniperus virginiana L. var. virginiana; hereafter ERC) is a native species currently invading open areas and grasslands outside of its original range in the United States. We studied ERC’s invasion patterns in the Lakeside Daisy State Nature Preserve (LDSNP), a short grass prairie located on the Marblehead Peninsula in Ohio, examining the changes in the genetic diversity and structure of the encroaching population. We investigated the relative importance of long-distance dispersal versus diffusion in the invasion of this short grass prairie by ERC. We use eight microsatellite marker loci to infer gene flow from external sources versus within-population recruitment. We found that the older trees in this preserve were less than 50 yr old, indicating that the population was established between 1970 and 1980. When we grouped trees into five age categories of 10-yr increments, we found that the allelic diversity, as indicated by the average number of alleles per locus, increased as the age of the trees decreased. We also found that not all loci were in Hardy-Weinberg equilibrium, probably due to the arrival of new variants in the preserve. Moreover, heterozygosity remained high, with an excess of heterozygotes in all age groups (F = −0.163 ± 0.046). Principal coordinate analysis showed two distinct groups of trees in the LDSNP. Analysis of the cryptic population structure of the ERC trees using STRUCTURE revealed four ancestral clusters in the ERC population. All ancestral clusters are present in all age groups, suggesting that all trees sampled are derived from an admixed population. Furthermore, the high observed heterozygosity and lack of inbreeding in this dioecious species maintained all ancestral clusters over time. Overall, our findings indicate that ERC encroachment of the LDSNP results from multiple and reiterated gene flow events from the edge of the range through animal-mediated seed dispersal.

Tree species diversity and population structure in Tropical dry deciduous forest of Sri Lankamalleswara Wildlife Sanctuary, Southern Eastern Ghats, India.

Tree species diversity and population structure in Tropical dry deciduous forest of Sri Lankamalleswara Wildlife Sanctuary, Southern Eastern Ghats, India.

POTENTIAL OF COLI FRUIT AS ANIMAL FEED IN MOA DISTRICT SOUTHWEST MALUKU

This study aims to determine the distribution area and population of Koli trees on Moa Island and to determine the amount of fruit and mesocarp juice in one production. This research used a survey method, simple random interviews of 30 respondents and direct observation at the research location. Research variables: Respondent profile: age, gender, education level and occupation. Coli tree population structure. Calculating the production of cauliflower and mesocarp fluid. The results of the study: Respondents' age was 23-64 years old, male sex (100%), education level of respondents: Elementary school graduates (SD) 70%, respondent's main occupation: farmer 93.33%, sideline: breeder 80.00%. Koli tree production area/sample village: 16,000m2/1.6Ha consisting of 4 lanes, area of each lane 4,000m2/0.4Ha, consisting of 4 plots, area of each plot: 1,000 m2/0.1Ha, number of coli trees per plot : 8 trees, number of koli trees in the production land area/village: 8×4×4=128 trees. Coli fruit production for 1 harvest is 20 bunches × 20 fruit = 400 fruit/tree, multiplied by the number of koli trees from one village: 400×128 = 51,200 fruit harvested 2/year: 51,200×2 = 102,400 fruit/village/year, liquid mesocarp/fruit: 260grams and 446grams. Mesocarp fluid/village: 446 gram×102,400 fruit = 45,670,400 gram/45,670.4 Kg/45.7 Ton (large fruit), 260 gram×102,400 fruit = 26,624,000 gram/26,624 Kg/26.62 Ton (small fruit). 1 year mesocarp fluid production in 3 sample villages is 79.86-137 tons/year.

Understanding the Phyllanthus and Terminalia chebula Species Population Change, Dependency and Sustainability: A Study in Malai Mahadeshwara Hills Wildlife Sanctuary, Southern India

Non-Timber Forest Products (NTFPs) are vital sources of livelihood for forest-dependent communities across the globe. This study examined the NTFPs species (Phyllanthus emblica, P. indofischeri, and Terminalia chebula) population change determined by the dependency, disturbances, and accessibility in the dry tropical forest of Malai Mahadeshwara (MM) Hills wildlife sanctuary. The long-term monitoring population data were analyzed across three time periods; 2000-01, 2010-11, and 2020-21. The participatory research methods were used to assess the dependency and accessibility which influence the population structure. The multi-factor linkage approach was used to identify the significant drivers of population decline. The results indicated that grazing, fire, hemi-parasite infection, and Lantana invasion influenced the tree population structure and regeneration of study species. This study has also indicated variations and changes in the interrelationship among factors that have a significant role in shaping NTFPs species population structure. Multiple factor analysis determined that grazing, fire, and lantana have significant impacts on population structures, regeneration, and fruit production of NTFPs species. The study recommended that forest managers should consider a site-specific adaptive approach and multiple factors models and inclusive management tools provisioned in recent policies like the Biological Diversity Act -2002 and Forest Rights Act-2006 would hold great potential for developing sustainable use and co-management practices.

Some of the Mechanisms for Coexistence of Tree Species Diversity in Tropical Forests: A Review of Effects of Tree Density Dependence

Tree communities contribute to maintenance of species diversity in tropical forests. Coexistence of many tree species is not without competition. Therefore, coexistence of tree species and size diversities occur sequentially or simultaneously in tropical natural forests. Understanding coexistence and competition mechanisms of tree species requires knowledge of interactions within and between species. However, many conservation efforts and strategies failed due to inability to identify and maintain functional coexistence mechanisms among tree species in the forest. Also, most trees died because of pressure on their habitats and not because of limiting growth resources. Hence, species identity, minimum distance and size of the neighbouring trees which are responsible for coexistence of competing trees in most tropical forests have not been explicitly reviewed. Therefore, this review evaluated some of the density dependent mechanisms for coexistence of tree species alpha diversity in tropical forests. Many interactive mechanisms are responsible for coexistence tree species in tropical forests. Inter- and intra-specific competitions are the most significant and both facilitate positive and negative density dependence. Therefore, switching from negative to positive density dependence may occur in some situations. Positive and negative density effects regulate species abundance and coexistence through conspecific and heterospecific structures. Aggregates of conspecific and heterospecific neighbours constitute forest spatial structure. Negative density interactions are mutually exclusive and basically ranged from effect of species identity of neighbours, distance to neighbours and tree size of the neighbours to reference trees in the community structures. Some mechanisms shorten distances for heterospecific than conspecific interactions. Conspecific structures improved survival and growth of rare tree species. Interactive mechanisms in tree community and population structures facilitate species diversity and size inequality, respectively.

Structure and regeneration status of tulu lafto forest, Horo Guduru Wollega Zone, West Ethiopia

Ethiopia, with its wide altitudinal gradient is known for its rich biodiversity. But the natural vegetation in the country is highly threatened by alarming deforestation rate. This study was conducted to examine tree population structure and the natural regeneration of indigenous tree species in Tulu Lafto Forest which is located in Horo Guduru Wollega Zone of Oromia National Regional State, Western Ethiopia. Seventy-five quadrats of 400 m2 were systematically laid following an altitudinal gradient. In all the quadrats, diameter at breast height (dbh) and height of all woody plants with a dbh of 2.5 cm and above were measured and recorded. Seedlings and saplings of all woody species were also counted. In the forest, 145 woody species in 118 genera and 55 families were recorded. Although the overall population structure of the forest is an inverted J pattern, some selected tree species revealed irregular population distribution patterns. Seedling and sapling density analysis also showed some tree species have poor regeneration. Hence, species with irregular population distribution patterns and those that are missing from the juvenile phase (seedlings and saplings) require urgent conservation measures.

Impacts of Industrialization on Plant Species Composition, Diversity, and Tree Population Structure in Tropical Moist Deciduous Forest in Bangladesh

Industrial activities have various effects on biodiversity, posing significant threats to forest ecosystems. The current study describes the species composition, taxonomic diversity, and stand structure at Bhawal Sal forest, Gazipur, Bangladesh, as they are affected by industrialization. To achieve the goal, 30 different categorized industries within the forest were considered sampling points and three distance gradient sites viz. Site-1 = Adjacent to industries (0 m), Site-2 = 160 m distance and Site-3 = 320 m distance from industries were designated as treatments. A total of 90 quadrate plots (10 m × 10 m) were taken randomly, of which 30 plots were from each site. Through forest inventory, 46 species (24 trees, 8 shrubs, 5 climbers, and 9 saplings) were recorded from three sites. The study revealed that the stand density and basal area of mature trees (257 stems ha−1 and 8.06 ± 0.60 m2·ha−1) at Site-1 were significantly lower due to diverse industrial operations than other sites. Statistically, all the biodiversity indices of mature trees; Shannon–Wiener’s index (1.72), Simpsons index (0.82), Margalef’s index (1.38), Pielou’s evenness Index (0.39) was found to be lower at proximity to industries. The lowest species richness (12) of all plants was recorded from Site-1. However, the diameter and height distributions of Site-1 comprised young (10–20 cm·dbh) to medium-sized (20.1–30 cm·dbh) trees, while the medium to large sized (>30 cm·dbh) trees was contained at Site-3 in this study. The population structure of tree species at Site-1 also showed a fluctuating curve. Overall, this study highlights that plant ecosystems and tree population structure have declined tremendously due to industrialization. Hence, the current research could be significant for developing the management framework for the disturbed deciduous forest.

Phytodiversity complex of trees and shrubs in Federal University Birnin Kebbi, Kebbi state, Nigeria

Plant biodiversity in the dry ecosystem of the savanna is constantly under threat of extinction, thereby contributing to the ongoing climatic crisis. The systematic compilation of plant species growing in any region is an important tasks of ecological research centered on conservation. In the present study, a comprehensive and systematic inventory of the diversity and population structure of trees and shrubs growing on the Ungwar Jeji campus of Federal University Birnin Kebbi Northwestern Nigeria was provided. The data was collected using a standard 50 × 50 quadrat with 156 total sample plots stratified into plantation area (PA), undisturbed area (UA), building area (BA), and drive/walkways area (DA). Diversity indices were computed using PAST 3.17 software. The campus is richly endowed and diverse in species as revealed by the Margalef's species richness value of 4.753 and the Diversity Index Value (Shannon_ H′) of 2.51, respectively. The inventory recorded 39 species belonging to 17 families of trees (66.67%) and shrubs (30.77%). Fabaceae has the most species (30.77%), while the least families recorded 1 species (2.5%) each. Azadirachta indica and Acacia podalyriifolia recorded an IVI of 55.4 and 99.62 making them the most important tree and shrub species respectively. Ficus platyphylla (2.82%) is the least. Most of the species encountered are of least concern (89.19%) except for Vitellaria paradoxa, which is Vulnerable (2.70%) according to the IUCN Red List version 2021–2. This preliminary inventory is useful for the planning and implementation of a sustainable conservation strategy on the campus. DNA conservation of the species is recommended.

Spatial Distribution and Species Association of Dominant Tree Species in Huangguan Plot of Qinling Mountains, China

The spatial distribution pattern and population structure of trees are shaped by multiple processes, such as species characteristics, environmental factors, and intraspecific and interspecific interactions. Studying the spatial distribution patterns of species, species associations, and their relationships with environmental factors is conducive to uncovering the mechanisms of biodiversity maintenance and exploring the underlying ecological processes of community stability and succession. This study was conducted in a 25-ha Qinling Huangguan forest (warm-temperate, deciduous, broad-leaved) dynamic monitoring plot. We used univariate and bivariate g(r) functions of the point pattern analysis method to evaluate the spatial distribution patterns of dominant tree species within the community, and the intra- and interspecific associations among different life-history stages. Complete spatial randomness and heterogeneous Poisson were used to reveal the potential process of community construction. We also used Berman’s test to determine the effect of three topographic variables on the distribution of dominant species. The results indicated that all dominant species in this community showed small-scale aggregation distribution. When we excluded the influence of environmental heterogeneity, the degree of aggregation distribution of each dominant species tended to decrease, and the trees mainly showed random or uniform distribution. This showed that environmental heterogeneity significantly affects the spatial distribution of tree species. Dominant species mainly showed positive associations with one another among different life-history stages, while negative associations prevailed among different tree species. Furthermore, we found that the associations between species were characterized by interspecific competition. Berman’s test results under the assumption of complete spatial randomness showed that the distribution of each dominant species was mainly affected by slope and convexity.

Woody species diversity, structural composition, and human use of church forests in central Ethiopia

Church forests on the premises of Ethiopian Orthodox Churches have been recognized as refugia of tropical plant biodiversity within the predominantly agricultural landscape matrix. Understanding the species composition, population structure, and human use of trees in forested areas is crucial for sustainable conservation efforts. We investigated these features in mixed natural-planted church forests in central Ethiopia. Three forests associated with churches for 37–50 years were surveyed to assess: (i) the diversity and population characteristics of woody species depending on the age of the church forest, (ii) the use of trees by humans, and (iii) church forests’ contribution to the conservation of threatened species. Vegetation and ethnobotanical data were collected via forest inventory of 24 plots sized 0.04 ha and through a rapid rural appraisal conducted in 120 households. Thirty woody species, twenty-eight indigenous species, and two exotic species were identified. The three church forests were floristically different, with only four tree species in common. Most indices of diversity and population structural parameters of woody species were higher in older than in younger church forests, presumably due to a longer tradition of forest conservation. All church forests presented inverse J-shaped size-class distributions, indicative of populations with good recruitment potential. Woody species were mainly used for medicine, construction wood, and firewood. Eighteen threatened species were recorded; however, few conservation activities besides social taboos were revealed in the examined forests. Our findings highlight the role of church forests in the conservation of woody species diversity, and the need to strengthen current strategies to support long-term biodiversity conservation.

Dynamics of Tree Population Structure After Disturbance of Araucaria Forest Remnants

This study aimed at evaluating and compare the changes from 2012 to 2016 in the structure and floristic composition of a remnant Araucaria Forest. The entry and mortality rates were 2.2% year-1 and 6.9% year-1, respectively. Among the most represented species, those with the greatest yearly increases in their numbers were Sebastiania brasiliensis, Eugenia uniflora, and Allophylus sp. Average mortality density was 498 ind ha-1, and was particularly high for the following species: Casearia decandra (representing 32.3% of total mortality), Eugenia sp. (27.2%), Cinnamodendron dinisii (24.5%), and Lithraea brasiliensis (25.2%). The pioneer species represented 8.33% of income and 29.17% mortality, and secondary species composed 33.33% and 62.50% of income and mortality, respectively. Climax species accounted for 8.33% of income and did not contribute to mortality. The high tree mortality observed in the present study can be attributed, among others factors, to the effects of natural disturbance that occurred in the period.

The influence of tree population structure on regeneration potential in the sacred forests of Assam, India

The influence of tree population structure on regeneration potential in the sacred forests of Assam, India

Nationwide Assessment of Population Structure, Stability and Plant Morphology of Two Mimusops Species along a Social-Ecological Gradient in Benin, West Africa

Understanding tree species autecology and population structure supports effective conservation actions. Of particular importance are multipurpose trees that provide non-timber forest products (NTFPs). We assessed the population structures and morphologies of two species of NTFP trees in the genus Mimusops across bioclimatic zones in Benin by sampling 288 plots within 11 forests. Structural characteristics were compared between species, forests and zones. Correlations were also observed between Mimusops tree regeneration density, tree features and ecological characteristics. The density of trees ≥5 cm and of regeneration and mean tree height were higher for M. andongensis (within more protected forest) than M. kummel (in forests with access to people), while the highest mean diameter was observed for M. kummel. Tree and regeneration densities and mean height were greatest in the humid zone of Benin, whilst the largest mean diameter was obtained in the sub-humid zone. The results showed significant correlations between regeneration density and soil properties for M. andongensis but not for M. kummel. The correlations between tree morphology and soil characteristics were weak for both species. Ecological characteristics, along with the species’ functional traits and pressures, are important factors related to the observed differences between the species. All diameter classes were represented, and the population seemed more stable in the more protected forest relative to other forests. Mimusops trees with a diameter of 5–15 cm represented more than 30% of this species in most forests; this suggests, for M. kummel, whose trees flower when quite small (≥6 cm dbh), that there are sufficient reproductive trees. Thus, as a long-lived species, its populations could be maintained even with low/episodic recruitment. However, we found no regeneration in many forests and climate change could threaten populations. Therefore, it is important to investigate regeneration growth and dynamics, seed production and germination of the species in relation to the biophysical conditions and disturbances experienced by Mimusops stands.

Insights on Genetic Diversity, Population Structure, and Linkage Disequilibrium in Globally Diverse Coconut Accessions Using Genotyping-by-Sequencing.

Genotyping-by-sequencing (GBS) has emerged as a cost-effective approach for genome-wide discovery of single-nucleotide polymorphism (SNP) markers and high-throughput genotyping. In this study, 96 coconut palms, representing 16 accessions from globally diverse origins, were genotyped using the GBS strategy. A total of 10,835 high-quality SNPs, which were identified after stringent filtering, were utilized to assess genetic diversity, population structure, and linkage disequilibrium (LD) analyses. The polymorphism information content (PIC) values of SNPs ranged from 0.1 to 0.4, with a large proportion of SNPs (8633 nos.; 79.7%) having a higher PIC in the range of 0.3-0.4. The genetic diversity analysis revealed the existence of a high level of variation in coconut accessions, with an average expected heterozygosity (He) value of 0.43. Unweighted neighbor-joining phylogenetic tree and Bayesian-based model population structure grouped coconut genotypes into four main clusters. The accessions are generally clustered based on their height (tall or dwarf), with a few accession clusterings based on geographical origins. Investigation of LD pattern in coconut indicated a relatively rapid LD decay with a short range (9 kb). The results obtained in this study will contribute to enhancing the capacity of coconut researchers to utilize genetic diversity for further genetic improvement. In addition, it would open up possibilities for performing genomic studies such as genome-wide association studies and genomic selection to accelerate the efficiency and speed of coconut genetic improvement.

Tree population structure, diversity, regeneration status, and potential disturbances in Abu Gadaf natural reserved forest, Sudan

Forests and forest trees have continuously been supporting human beings through the provision of food and food-associated materials, fodder and foraging sites for their livestock, and medicinal materials, as well as multiple ecological services. However, unbalanced utilization of these resources and the biotic and abiotic disturbances interrupt their sustainability and ecological functions. We studied the tree population structure, diversity, and regeneration status of tree species in the Abu Gadaf Natural Reserved Forest in 46 sample plots of 20 m x 50 m (1000 m2) distributed systematically throughout the reserve over a year. The study findings showed that highland sites have higher tree species richness (47 species) compared to lowland sites (31 species) and the highest contributors are Combretaceae (21.3%) and Fabaceae (19.2%) families. Moreover, seedlings in highland sites are twice that of lowlands, with a significant difference between the two sites (F1,46 = 138.4, p < 0.001). The same trend has been observed for saplings and adult trees (F1,46 = 143.2, p < 0.01; F1,46 = 126.7, p < 0.01, respectively). Likewise, all dendrometric parameters and diversity indices demonstrated significant differences between the sites across the reserve with lower values in the lowland sites and vigorous regeneration in the highland sites (T = 33.7, P < 0.001; T = 22.3, P = 0.001; T = 27.9, P = 0.042, respectively). The study concludes that over browsing by livestock and intensive illegal tree logging in the lowland sites have severely affected the tree population composition, which might consequently disturb the regeneration process and seedlings recruitment. A conservation action plan is urgently needed to protect vulnerable species, especially those with low importance value index.