Tree Composition Research Articles

Characterization of cocoa (Theobroma cacao L.) wood branches as a potential resource for paper production

For sustainable use of lignocellulosic resources, pruned tree branches of cocoa, one of the major evergreen tropical tree crops with significant economic importance worldwide, were investigated as a potential source of kraft pulp. This study determined the chemical composition, fiber dimensions, kraft pulp, and paper properties of the cocoa tree (Theobroma cacao L.) branches compared to the deciduous trees traditionally used in the paper industry. A handsheet of cocoa pulp showed promising results with narrow fiber length distribution, high paper density, and high mechanical strength. The yield of kraft pulp made from cocoa branches wood was lower. The tensile and burst indices of cocoa pulp handsheet were 2 and 2.5 times higher than that of hardwood traditionally used in the paper industry. These results suggest a potential use of cocoa (Theobroma cacao L.) tree branch wood for pulp production using the kraft process.

A biosecurity perspective on urban trees in public and private spaces and trees available from nurseries

Urban trees are of high importance for healthy urban ecosystems. However, some trees are invasive plants that may ‘escape’ from urban areas into natural environments. Furthermore, invasive forest pests often arrive and establish in urban environments before they spread to forest ecosystems. Therefore, knowledge of tree species composition in urban areas is important for the biosecurity of cities and surrounding forests. Despite this, urban tree inventories often lack information on trees on private properties. To assess the potential role of urban areas as a source of invasive trees as well as invasive pests of trees, we compared the species composition of urban trees in public and private spaces in several Swiss cities and in tree nurseries (henceforth: ‘nurseries’) in Switzerland. We analysed the various data sets we compiled regarding invasive tree species, and examined how many trees are potential hosts for invasive quarantine pests of trees. We found no statistically significant difference in tree species composition in public and private urban areas, but the proportion of non-native trees was higher in private than in public spaces. Tree species available in nurseries and those present in cities were not significantly different, with larger urban tree inventories having a greater overlap with the species available in nurseries. Five of eight tree species considered invasive whose sale was banned since September 2024 were still on sale ten months before the ban came into force. All eight tree species were present in urban tree inventories. Importantly, between 91 % and 97 % of all urban trees in public and private spaces were suitable hosts for at least one quarantine forest pest. Given the pivotal role that urban trees play for the health of urban and peri-urban ecosystems, knowledge of tree species composition is essential from a biosecurity perspective. Our findings suggest that the combination of public urban tree inventories and trees available from nurseries can provide an estimate of the composition of private urban trees and can be useful for invasive species monitoring.

Variation of shade tree composition and carbon stock of smallholder coffee agroforestry systems along an elevation gradient in Khun Mae Kuang Forest area, northern Thailand

Variation of shade tree composition and carbon stock of smallholder coffee agroforestry systems along an elevation gradient in Khun Mae Kuang Forest area, northern Thailand

Clonality in black locust (Robinia pseudoacacia L.) and implications for seed production

Key messageThe strong clonal growth of black locust (Robinia pseudoacacia L.) not only influences the stand structure of natural or artificially established stands, but also the genetic composition of seed harvested from such clonal stands. For the commercial production of genetically diverse seeds, the stand structure should be taken into account or, at best, seeds harvested from seed orchards should be used.ContextBlack locust is characterised by intensive asexual reproduction through the formation of root suckers. By this means clonal structures can develop within black locust stands, in which ramets of a single clone can dominate extensive areas.AimsWe want to analyse to what extent clonal structures within black locust stands negatively influence the genetic composition and diversity in seed harvested in such stands. We discuss how a potential reduction in genetic diversity can be reduced by measures taken during harvesting and whether the harvesting of seed orchards may be a better alternative.MethodsWe compare the genetic composition and diversity of parent trees and seed harvested from a clonal black locust stand with a seed orchard in which multiple ramets of selected clones were arranged in a randomised design.ResultsWithin the clonal stand, parent contributions to the seed lot analysed proved to be strongly uneven. Selfing rates were high and large full-sib families dominated within the seed lot. Although the relatively strong pollination from unknown pollen donors, probably located outside of the stand, prevented a massive loss of alleles, high selfing rates and the formation of large full-sib families led to an unequal distribution of alleles within the progeny. Within the seed orchard—even though it had a lower number of clones than expected—the randomised design promoted a more diverse pollination pattern.ConclusionWe conclude that for black locust, seed orchards have the greater potential to ensure a balanced genetic composition of harvested seed lots. If economic considerations make it necessary to harvest seed stands, this should only be done in a considered manner and, if possible, with knowledge of the clonal structures of the stand.

Influence of wildfires severity on tree composition and structure in Aberdare Afromontane Forest Ranges, Kenya

Wildfires strongly impacts on the forest ecosystems, with poorly understood consequences on the composition, diversity and structure within Afromontane forests of Eastern Africa. The impacts of wildfire on vegetation were investigated one year after the fire occurrence season. The burn severity was evaluated using Sentinel-2 satellite derived spectral index known as dNBR (difference Normalized Burn Ratio). This was used to delineate wildfire into low and high severity classes. We investigated the effects of wildfires using 36 plots of 15m radius distributed in high and low burn severities while others were laid in unburnt areas. Our findings indicated that tree height, basal area and density were significantly different along severity classes (p = 0.003, p=0.007 and p<0.000 respectively). However, diameter at breast Height was not significant along severity classes (p=0.185). The most ecologically important species based on Important Value Index (IVI) within the fire affected areas were Juniperus procera, Nuxia congesta, Olea europaea subsp. cuspidata, Protea kilimandscharicum and Scurtia myrtina. Among the five dominant tree species, the density of Protea kilimandscharicum and Olea europaea subsp. cuspidata were significant along the fire severities (p<0.05). Interaction of vegetation zones and wildfire severity indicated that only height was significant (p= 0.000) while all the other tree variables and species diversity index were insignificant; DBH (p=0.053), basal area (p=0.606), tree density (p=0.389), Shannon Weiner diversity index (p=0.843), Simpson dominance index (p=0.490) and Pielou's evenness index (p=0.248). Whereas this study was on a short-term post-fire effects on vegetation, it has shown remarkable findings which can guide restoration and management of fire affected landscapes. The study recommends evaluation of long-term regeneration and recovery to guide integrated fire management within Afromontane Forest Ecosystems.

Diverging Elevational Patterns of Tree vs. Epiphyte Species Density, Beta Diversity, and Biomass in a Tropical Dry Forest.

There is evidence to suggest that vascular epiphytes experience low competition for resources (light, water, and nutrients) compared to terrestrial plants. We tested the hypothesis that low resource competition may lead to higher nestedness among vascular epiphyte assemblages compared to trees. We studied the species composition and biomass of epiphytes and trees along an elevation gradient in a tropical dry forest in SW Ecuador. Both life-forms were inventoried on 25 plots of 400 m2 across five elevation levels (550-1250 m). Tree species density and total species richness increased with elevation, whereas basal area and biomass did not show significant trends. Epiphyte species density and richness both increased strongly with elevation, in parallel to biomass. Plot-level compositional changes were similarly strong for both life-forms. We attribute elevational increases in the species richness of trees and epiphytes to increasing humidity, i.e., more mesic growth conditions. We attribute the more pronounced elevational increase in epiphyte biomass, species density, and richness-the latter coupled with a higher degree of nestedness-to the greater moisture dependency of epiphytes and relatively low direct competition for resources. Our study provides a first comparison of elevational trends in epiphyte and tree diversity and biomass for a tropical dry forest.

Rocky outcrops form islands of high and unique tree biodiversity within an ocean of grass in Serengeti National Park

AbstractAfrican savannahs are characterised by a high plant diversity, partly resulting from a high turnover in community compositions across space. However, it is poorly understood what is driving this spatial turnover in plant communities. Here, we investigate to which extent the presence of rocky outcrops (also called kopjes) explains the community composition of trees in an African savannah, and how we can understand the responses of tree species to rocky outcrops by their functional traits. Along a precipitation gradient, we visited 24 sites in Serengeti National Park (Tanzania). At each site, we characterised tree communities, as well as their functional traits, in both a kopje and an adjacent open savannah plot (matrix plot). We found that kopjes harboured elevated tree abundances and species richness. Their dominant trees were more often evergreen, had a higher specific leaf area, a lower leaf nitrogen content and a lower spine density, than dominant trees in the savannah matrix. Differences in tree communities between kopjes and savannah matrix plots were generally the largest at sites with low precipitation. Our results indicate that kopjes are strong drivers of tree biodiversity, possibly due to locally increased soil moisture and low fire frequencies. The uniqueness of kopje tree communities may have important implications for higher trophic levels and ecosystem functioning.

Individual canopy tree species maps for the National Ecological Observatory Network.

The ecology of forest ecosystems depends on the composition of trees. Capturing fine-grained information on individual trees at broad scales provides a unique perspective on forest ecosystems, forest restoration, and responses to disturbance. Individual tree data at wide extents promises to increase the scale of forest analysis, biogeographic research, and ecosystem monitoring without losing details on individual species composition and abundance. Computer vision using deep neural networks can convert raw sensor data into predictions of individual canopy tree species through labeled data collected by field researchers. Using over 40,000 individual tree stems as training data, we create landscape-level species predictions for over 100 million individual trees across 24 sites in the National Ecological Observatory Network (NEON). Using hierarchical multi-temporal models fine-tuned for each geographic area, we produce open-source data available as 1 km2 shapefiles with individual tree species prediction, as well as crown location, crown area, and height of 81 canopy tree species. Site-specific models had an average performance of 79% accuracy covering an average of 6 species per site, ranging from 3 to 15 species per site. All predictions are openly archived and have been uploaded to Google Earth Engine to benefit the ecology community and overlay with other remote sensing assets. We outline the potential utility and limitations of these data in ecology and computer vision research, as well as strategies for improving predictions using targeted data sampling.

Features of the introduced species composition and state in the arboreta of Dzhanybek research station in the Northern Pre-Caspian Semi-Desert

The results of studying introduced species diversity and state under rainfed conditions at the Research station of the Institute of Forest Science of the Russian Academy of Sciences have been presented. The station is located in the clay semi-desert of the Northern Pre-Caspian region between the Volga and Ural rivers. The collections of two arboreta were examined. The first arboretum was established in 1953 on hydromorphic meadow-chestnut soils of large mesodepressions, and the second – in 1974 on solonetzic automorphic soils. The arboreta were originally established with an idea of complete elimination of irrigation. In recent decades, tending and silvicultural treatments were discontinued for a number of reasons. An annotated list of tree and shrub species includes 77 species belonging to 25 families and 44 genus. In the arboretum on the large mesodepression, the number of species surviving for more than half a century is 35% in relation to the number of “core” introduced species. Mostly, the species are represented by the families Rosaceae, Caprifoliaceae, Elaeagnaceae, Fagaceae, Fabacea, Oleaceae, Salicaceae, Sapindaceae, Ulmaceae. Some specimens older than 70 years are in satisfactory condition and produce viable volunteer regrowth. The main stages of their acclimatization, in relation to age, and changes in growing conditions, as affected by plants themselves as well as climate, are distinguished. In arboretum on solonetzic soils, the survival of species is 50%. The composition of tree and shrub vegetation of an unused pond, where spontaneous vegetation formed an intrazonal willow-oleaster-poplar community of quasi-riparian type, and of the overgrowing fallow land, where a specific “savannah-like” landscape was formed, have been studied. This allowed to identify the species whose life strategy contributes to their successful colonization of human-disturbed habitats and, in some cases, manifestation of the features of naturalization and invasiveness. The most promising species for landscaping, parks and other plantings in such harsh natural and climatic conditions were also determined.

Origin-specific differences in the durability of black locust (Robinia pseudoacacia) wood against wood-destroying basidiomycetes

Global climate change is accompanied by a change in tree composition in many regions. In Europe, the distribution areas of many species are expanding towards the north so that, among others, black locust (Robinia pseudoacacia), which is native to the USA and has long been established in south-eastern Europe, is also becoming increasingly important in central and northern Europe. Many other tree species are known to have different properties between their original and new locations, including the biological durability of the wood. Hence, the resistance of black locust wood against decay fungi was studied concerning origin-specific differences. Wood was sampled from seven different origins in Europe and original habitats in the United States. Fungal incubation experiments were conducted, wood extractives were analysed, and different anatomical characteristics were quantified such as ring width, vessel size distribution and the presence of tyloses. In addition to differences in durability between juvenile and mature wood, origin-specific differences within the mature heartwood were attributed to extractive contents and the percentages of earlywood vessels containing tyloses. Based on parameters that contributed at least 20% to mass loss, susceptibility to fungal decay was modelled with multiple regressions.

Higher tree species richness and diversity in urban areas than in forests: Implications for host availability for invasive tree pests and pathogens

Urban and forest trees provide valuable ecosystem services. However, they are increasingly threatened by invasive forest pests and pathogens. Trees in urban areas are often the first potential hosts non-native tree-feeding insects and tree pathogens (“pests”) encounter after introduction in a novel region. If the trees encountered are suitable hosts, these pests can establish and become invasive – eventually also in surrounding forests. Here, we compared tree species and genus composition between urban areas and surrounding forests and examined the implications for host availability for forest pests and potential effects on invasibility. We compiled and standardised 26 urban tree inventories, containing ∼ 500.000 individual trees. We used multivariate analyses to compare urban tree composition with forest tree composition from forests surrounding each municipality (10 km radius), derived from the Swiss National Forest Inventory. With > 1300 different tree species, species richness of urban trees was 17 times higher than species richness in surrounding forests. Linear models and multivariate analyses revealed that host availability for forest quarantine pests is significantly higher in urban areas than in forests, with large differences in host suitability for different quarantine pests between urban and forest tree assemblages. This indicates that differences in species composition in urban and forest trees can result in increased host availability, possibly facilitating the establishment of quarantine forest pests.

Seasonal dependence of deterministic versus stochastic processes influencing soil fungal community composition in a lowland Amazonian rain forest

The contribution of deterministic versus stochastic processes to the spatio-temporal assembly of soil microbial communities in tropical forests requires quantification so that responses to climate change may be accurately projected. Here we report the spatio-temporal composition of soil fungal communities in a topographically homogeneous forest area in central Amazonia. Soil fungal communities have a greater turnover in space than over time. Stochastic processes are inferred to dominate in the rainy season and deterministic processes in the dry season. Our study highlights the importance of spatial heterogeneity in the absence of environmental gradients and its relationship with seasonal patterns that modulate spatial heterogeneity and contribute to environmental determinism versus stochasticity for fungal community assembly. This baseline may serve to assess deviations in community patterns caused by changes in biotic interactions with above-ground vegetation, such as those resulting from shifts in taxonomical/functional composition of trees driven by climate change.

INDICATION OF ENVIRONMENTAL CONDITIONS ACCORDING TO THE DENDROFLORA COMPOSITION IN DIFFERENT ZONES OF THE PRYRICHKOVYI PARK IN POLTAVA

The dendroflora of the Pryrichkovyi Park in Poltava and the correspondence of woody plant species composition to environmental conditions were studied by analyzing the amplitude of the leading environmental factors.Twelve species of deciduous trees have been identified, the representatives of seven genera of six families of the order Angiospermae, or Magnoliophyta. The highest Margalef index was calculated in zone 1, and the highest dominance index in zone 3. In all three park zones, 6 species of trees are represented – 2 Acer sp., 2 Populus sp., Salix alba, and Tilia cordata. The Sørensen-Czekanovsky index indicates the greatest similarity in the species composition of trees between zones 1–2 and 2–3 and the least similarity between zones 1 and 3.The lowest light index (Lc) was calculated for zone 2, where the tree density is the highest. The high-light-tolerant species – Robinia pseudoacacia and Betula pendula – grow in zone 1 (with a high recreational load). The soil moisture range (Hd) tolerance is the greatest for Populus tremulae, which is common in all three park zones. The lowest soil aeration index (Ae) in zone 1 is explained by its greatest compaction due to recreational load. The soil acidity index (Rc) increases in zone 3, where willows and poplars grow.Analysis of the ecological amplitudes of certain indicators confirms that environmental conditions in all park zones are favorable for the majority of presented tree species. Therefore, the analysis of the environmental amplitudes is recommended to use when assessing new species for planting. The data obtained make it possible to continue the study of the condition of the most common tree species and resistance to natural and anthropogenic factors of their damage and injury, in particular, recreation, vehicle emissions, phytophagous insects, and pathogens.

The Added Value of Urban Trees (Tilia tomentosa Moench, Fraxinus excelsior L. and Pinus nigra J.F. Arnold) in Terms of Air Pollutant Removal

The serious densification of human settlements necessitates an increase in the role and importance of green infrastructures in the overall functioning of urban ecosystems. Accordingly, the aim of the present study was to (1) assess the efficiency of air pollutant removal (potentially toxic elements) of three common ornamental trees (Tilia tomentosa Moench, Fraxinus excelsior L. and Pinus nigra J.F. Arnold) and (2) model the air quality regulatory services (removal of PM10, PM2.5 and NO2). Three different approaches were applied—enrichment factor (EF) and metal accumulation factor (MAI) per tree species, as well as simulation modeling for the whole urban forest. The MAI values of the three studied species were found to be very similar, in the range of 22.35 to 23.08, which suggests that these species could be a good choice for planting in urban areas with worsened air quality. The highest EF values were observed for U (3–18), followed by As (1.6–2.56) and Sr (0.87–2.46). The potential of urban forests in countering air pollution was highlighted by three simulated scenarios for PM10, PM2.5 and NO2 removal. The highest removal efficiency was calculated for evergreen species, followed by the mixed composition of deciduous (90%) and evergreen trees (10%), and the scenario with wholly deciduous trees had the lowest one. The contribution of nature-based solutions in meeting air quality standards and enhancing resilience in urban areas was clearly demonstrated. The functional complementarity of the different functional tree groups (coniferous, evergreen and deciduous broad-leaved species) was proven to be crucial for the support of both functional stabilities of the phytocenosis under diverse climatic conditions and during the change of seasonal cycles in the vegetation.

Impact of forest management on structure, composition, biomass and carbon stock in Chir-pine (P. roxburghii) forest, Western Himalaya

This study performs a comparative analysis of tree composition, biomass, and carbon stock across different management regimes namely, Van Panchayat forest (VP), Reserve forest (RF), and Civil & Soyam forest (C&SF) in the state of Uttarakhand, with a focus on P. roxburghii (Chir-pine) forests. Collectively, these management regimes cover approximately 60 % of the forest area in the state. In this assessment, a total five tree species (Pinus roxburghii, Quercus leucotrichophora, Myrica esculenta, Acacia catechu, and Pinus wallichiana) were identified across the management regimes. The Pinus roxburghii emerged as the dominant species across all management regimes, with relative density of 92.79, 94.39, and 92.31 % in Van Panchayat forest, Reserve forest, and Civil & Soyam forest respectively. However, co-dominant species are varying across the sites. The total tree biomass and carbon stock were notably higher in Van Panchayat forest (236.31 & 112.25 t ha−1) compared to Reserve forest (224.85 & 106.80 t ha−1) and Civil & Soyam forest (193.58 & 91.95 t ha−1). These findings suggest that Van Panchayat forests exhibit a superior status in terms of density, biomass, and carbon stock as compared to Reserve and Civil & Soyam forests. Pinus roxburghii emerges as a crucial species, underscoring its ecological significance in the region. These findings underscore the critical role of effective forest management practices in fostering sustainable biomass accumulation and carbon sequestration in the Himalayan Chir-pine forests. Thus, it helps to mitigate the impacts of climate change and biodiversity conservation, and sustainable management of forests.

The composition of trees from Straseni forest compared with the productive potential

In the present article it is studied the composition of stands by species and their correspondence with the productive potential offered, in the conditions of the central area of the Republic of Moldova, located in the Straseni district, Straseni forest entity. The most valuable natural and fundamental trees were preserved here. The main species is present – the Quercus petrea, followed by the Quercus robur. Deviation of current compositions from optimal ones is the resoult of of poor forest management in the past. Accurately establishing the reason for the deviation from the optimal compositions will ensure the comparisons also made according to climatic conditions. The species structure of the volume reflects the ability to capitalize on the natural conditions of the territory where it is installed.

Regional uniqueness of tree species composition and response to forest loss and climate change

The conservation and restoration of forest ecosystems require detailed knowledge of the native plant compositions. Here, we map global forest tree composition and assess the impacts of historical forest cover loss and climate change on trees. The global occupancy of 10,590 tree species reveals complex taxonomic and phylogenetic gradients determining a local signature of tree lineage assembly. Species occupancy analyses indicate that historical forest loss has significantly restricted the potential suitable range of tree species in all forest biomes. Nevertheless, tropical moist and boreal forest biomes display the lowest level of range restriction and harbor extremely large ranged tree species, albeit with a stark contrast in richness and composition. Climate change simulations indicate that forest biomes are projected to differ in their response to climate change, with the highest predicted species loss in tropical dry and Mediterranean ecoregions. Our findings highlight the need for preserving the remaining large forest biomes while regenerating degraded forests in a way that provides resilience against climate change.

Оценка экосистемных услуг зеленых насаждений г. Йошкар-Олы

In many parts of the world, urban green spaces are being explored as a source of ecosystem services. Their role in the provision of regulation of and, support of ecosystem services and even in the provision of cultural services is considered. At the same time, species assessment of the composition and vital condition of trees that provide ecosystem benefits in an urbanized environment is becoming increasingly relevant. The purpose of this study was to assess the contribution of the most common species of woody plants in urban greening to the provision of ecosystem services. The research was carried out in Yoshkar-Ola, in different functional areas of the city: residential, recreational and industrial, where the assortment of trees was studied and their vital condition was assessed. For the most common tree species, the potential supply of providing ecosystem services was determined on a ten-point scale, taking into account adverse effects (so-called «ecosystem disservices»). It was established that Betula pendula, Tilia cordata, Sorbus aucuparia were the predominant species in the landscaping of the city, their share in the studied plantings reached 36–64%. Of the introduced species, Acer negundo, Picea pungens, and Thuja occidentalis are the most common in the landscaping of the city. Most of the trees of different functional zones belonged to the 1st and 2nd categories of life condition (healthy and with signs of slight oppression). Strongly weakened trees accounted for no more than 12% of the total number, and dying plants were rare. Betula pendula makes a significant contribution to the provision of ecosystem services in Yoshkar-Ola. Tilia cordata, Picea pungens and Sorbus aucuparia – do so mainly due to their high carbon storage capacity, phytoncide and aesthetic value. Acer negundo is considered to be a dangerous urban explerent and, despite its regulating and maintaining ecosystem services, its distribution in the urban environment should be limited.

Determinants of spatial distribution of trees outside forests along urban-rural gradients: A review

Urbanization can create uncertainty for biodiversity. Understanding the spatial distribution of trees along urban-rural gradients is crucial for sustainable land management and the conservation of biological diversity. However, limited information is available on the factors influencing the distribution of trees outside forests along urban-rural transition gradients. This paper uses the Preferred Reporting items for Systematic Reviews and Meta-Analyses (PRISMA) to review how distance from urban centers, land use types, socio-economic disparities, and community attitudes and perceptions impact the spatial distribution of trees outside forests along urban-rural gradients. The review indicates that the species composition, diversity, density, and spatial arrangement of trees outside forests vary along the urban-rural gradient. The most commonly cited factors influencing this distribution are respondents' attitudes and perceptions of trees, socio-economic factors, and land use variations. Distance from the urban center was the least cited factor. However, there is significant variation in how different factors impact this distribution from study to study. Therefore, further research is needed to better understand the factors driving changes in the diversity of trees outside forests in various urban-rural contexts and to determine whether variations exist across different settings.

Local factors influence the wild bee functional community at the urban-forest interface

IntroductionUrban forests provide necessary habitat for many forest-associated bee species amidst development and fragmentation. These forest fragments provide a variety of important floral and non-floral resources for bees that encompass a diversity of functional guilds characterized by size, diet breadth, nesting, sociality, origin, and seasonality. The relative importance of forest edge vs. interior habitats to these organisms is not well understood.MethodsHere, we compare bee communities between forest edge and interior locations at eight locations in Athens, GA, USA. We also explore the effects of stand structure, tree composition, ground cover type, and the presence of snags and downed wood on these organisms.ResultsWe found bee abundance and richness to be higher at the forest edge than interior with distinct community compositions at both locations. Canopy cover, invasive shrub cover, ground cover, and tree diversity influenced the observed community composition. We also determined that the most impactful functional traits influencing bee community structure in urban forest fragments were nesting substrate, origin (native or exotic to North America), sociality, and diet breadth.DiscussionOur findings will help establish the effects of local forest characteristics on the community composition, diversity, and abundance of wild bees and further our knowledge of the conservation value of urban forests for preserving wild bee communities.