Characteristics Of Tree Species Research Articles

Resilience impacts of a secondary disturbance: Meta‐analysis of salvage logging effects on tree regeneration

Abstract Intense controversy surrounds the compounded disturbance of salvage logging, which superimposes an anthropogenic disturbance on already disturbed ecosystems and thereby provides a litmus test of forest regeneration and resilience. We conducted meta‐analysis to assess whether salvage logging affects tree regeneration, and whether potential effect moderators (disturbance type and severity, logging intensity, time elapsed between disturbance and logging or since logging, forest type and age, regeneration syndrome and aridity) modify this overall effect. Thirty‐seven publications yielded 305 effect sizes for tree density and 135 for height. We found no significant effect of salvage logging on tree density or height. Also, most effect moderators were not significant. The effect size of salvage logging on tree density increased over time after logging, potentially indicating resilience to initial salvage logging impacts. Tree density in old (>100 years) disturbed forests was less negatively affected by salvage logging than in young (<50 years) and intermediate‐aged forests. Study site and phylogenetic relatedness improved model fit, indicating modulation by local ecological factors and tree species characteristics. Synthesis. Salvage logging does not produce generalised detrimental effects on tree regeneration. Potential impacts and their mitigation should be assessed upon knowledge of local conditions and species.

植被群落特征对城市生态系统服务的影响研究进展

生态空间（林地、灌木、草地、水体）所产生的生态系统服务极大的改善了人类的生存环境，在城市绿地破碎化日益严重、绿地质量逐渐降低、乡土植物逐渐减少、入侵风险逐渐加剧等生态背景下，如何维持稳定而持续增长的城市生态系统服务供给，一直困扰着当下从事城市生态学领域研究的学者和城市管理者。植被群落作为城市绿地系统的基本组成单元，在绿地破碎化趋势下，可作为研究内容来探讨城市生态系统服务维持或提升策略；植被群落泛指城市中常见的、具有明显边界的、按照一定分布规则的植物群落单元，既包括道路绿地、居住区绿地、公园绿地等，也包括城市郊野自然林地。但对植被群落生态功能的研究也多停留在对某一生态问题的简单相关性研究，缺乏系统性和整体性。从微观层面的植被群落角度，整合相关文献研究，介绍了受植被群落特征影响的6种典型城市生态系统服务，综述了植被群落特征对这6种城市生态系统服务的影响机理，对植被群落特征因子进行总结、归类，从树种特性、垂直结构、水平结构、其他4个角度构建了"植被群落特征因子对城市生态系统服务影响关系表"。最后面向典型生态系统服务提升提出了城市低质量植被群落地区的营建和更新原则，以期为今后城市园林部门、规划部门制定城市绿地系统规划提供基础性技术支撑。;The ecosystem services generated by ecological spaces (woodlands, shrubs, grasslands, and water bodies) have greatly improved the human living environment. In the context of increasing fragmentation of urban green spaces, decreasing quality of green spaces, diminishing native plants and increasing risk of invasion, how to maintain a stable and sustainable increase in the supply of urban ecosystem services has been troubling scholars and urban managers. As a basic component of urban green space systems, vegetation communities can be used as a research component to explore strategies for maintaining or enhancing urban ecosystem services in the context of green space fragmentation; vegetation communities refer to common urban plant community units with distinct boundaries and according to certain distribution rules, including both road green space, residential green space and park green space, as well as natural woodland in the urban countryside. while studies on the ecological functions of vegetation communities were mostly confined to simple correlation studies of a certain ecological problem, lacking in a systematic and holistic approach. This paper introduces six typical urban ecosystem services that are influenced by vegetation community characteristics from the perspective of urban vegetation communities at the micro level, integrating relevant literature studies. This is followed by an overview of the mechanisms by which vegetation community characteristics affect these six urban ecosystem services, and a summary and categorisation of vegetation community characteristics factors. A table of relationships between vegetation community characteristics and urban ecosystem services was then constructed from four perspectives:tree species characteristics, vertical structure, horizontal structure and others. Finally, the principles for the establishment and renewal of urban low-quality vegetation communities are proposed for the enhancement of typical ecosystem services, with the aim of providing basic technical support for urban landscape departments and planning departments in their future planning of urban green space systems.

Measurement of moisture content and gamma radiation shielding characteristics of tree species grown in Punjab

Measurement of moisture content and gamma radiation shielding characteristics of tree species grown in Punjab

How do tree species characteristics affect the bacterial community structure of subtropical natural mixed forests?

The effects of tree species on bacterial community structure have attracted much attention, but few studies have been done in natural mixed forests. In this study, we selected 12 sampling sites in the subtropical natural mixed forest (mainly distributed by Chinese sweet gum, chestnut, Oriental oak, Masson pine, Chinese fir, etc.). The fermentation layer (OF) and humified layer (OH) were mixed as forest floor samples, and the topsoil samples (0–10 cm) were taken. Bacterial composition was studied by 16S rRNA gene sequencing. Coniferous canopy area ratio (Pc), broadleaved and shrubby canopy area ratio (Phwd), elevation, soil properties were tested. The objective is to reveal which soil properties are significantly affected by tree species characteristics, which soil properties significantly affect bacterial community structure, and whether the bacterial community structure is the same in forest floor and topsoil samples at the same sampling site. The results showed that: (1) Pc and Phwd could be used to represent tree species characteristics of natural mixed forests, and they significantly (P=0.05) affected the soil C/N ratio; (2) the soil C/N ratio was the main factor affecting the soil bacterial community composition, especially for the dominant heterotrophic bacteria (Acidothermus, Variibacter, Candidatus Solibacter, Acidibacter, and Bryobacter). The relative abundance (1.11–26.27%) of the dominant heterotrophic bacteria increases with an increase in the C/N ratio (6.33–10.76) within a certain range; (3) the dominant bacteria in topsoil samples were Nitrospira, Acidothermus, Arthrobacter, Bradyrhizobium, and Variibacter, while that in forest floor samples were Jatrophihabitans, Acidothermus, Burkholderia-Paraburkholderia, and Bradyrhizobium. Although the forest floor bacteria came from the topsoil at the same sampling site, the bacterial community structure had changed significantly. This study indicated that tree species drive the change of soil bacterial community by changing the soil C/N ratio, which may provide a new perspective for maintaining the stability of regional ecosystem structure.

Spatial distribution and interspecific associations of regenerating saplings in karst secondary forests.

A 140 m×120 m plot was set in a secondary forest with more than 30 years natural reco-very after abandonment in Ziyun Miao and Buyi Autonomous County, a typical karst area in Guizhou Province. We investigated the spatial distribution and interspecific associations of regenerating sapling population using spatial point pattern analytical method. There were 1291 saplings with 39 tree species. Betula luminifera, Platycarya strobilacea, Liquidambar formosana, Pinus massoniana and Populus davidiana were the dominant populations of regenerating saplings, accounting for 83.7% of the saplings and 77.8% of the total importance value. The spatial distributions of B. luminifera, P. strobilacea and L. formosana were strongly aggregated at a spatial scale of 0-60 m, while the spatial distributions of P. massoniana and P. davidiana were aggregated at small scale and randomly distributed at large scale. The spatial associations among those dominant populations were mostly positively correlated, with positive correlations of P. massoniana with L. formosana and P. davidiana at small scale but no associations at large scale. In conclusion, the spatial distributions and interspecific associations differed among the dominant sapling populations, due to the different biological characteristics of different tree species, habitats and uses of spatial resources. Most of the stands investigated were dominated by pioneering species, with poor stand quality and unstable community structure. A mixed forest dominated by P. massoniana and B. luminifera would be the next stage of succession. We recommended that measures of forest management should be adopted to accelerate vegetation restoration.

Effects of the morphological characteristics of plants on rainfall interception and kinetic energy

Forests play an important role in the water cycle and in the control of soil erosion. The canopy, as the first active surface of the forest, directly affects soil erosion by redistributing rainfall. However, the effects of the plant morphological characteristics of different tree species on rainfall interception and kinetic energy reduction have not been determined. We determined 116 globally important woody tree species and classified them based on the differences of plant life-forms, leaf textures and trichomes on leaves in the Guizhou karstic regions of China. The water adsorbed on the branches and leaves of these species was measured to explain rainfall interception. We further selected four representative species among the 116 species and measured rainfall interception, stemflow and throughfall, as well as the corresponding indices of plant morphological characteristics, under simulated rainfall. Results indicated that the adsorbed water showed considerable differences between tree species with different plant morphological characteristics. Tree species with trichomes on their leaves had the largest amount of adsorbed water compared to those with papery or leathery leaves and those without trichomes. Rainfall interception was significantly dependent on leaf area index (LAI), mean leaf area (MLA) and leaf shape factor (LSF), but stemflow and throughfall were dependent on diffuse non-interceptance (DIFN) under tree canopies. Tree canopies increased the numbers, volumes and kinetic energy of large raindrops. LAI, mean foliage tilt angle (MTA), MLA and LSF had differently significant impacts on drop size distribution (DSD), and the kinetic energy of rainfall under canopies, but DIFN did not any impacts on them. The results presented in this study quantitatively clarify the impacts of the morphological characteristics of different plants on adsorbed water of branches and leaves, linking rainfall interception of canopies and the redistribution and kinetic energy of rainfall.

Population estimates of non-native rose-ringed parakeets Psittacula krameri (Scopoli, 1769) in the Durban Metropole, KwaZulu-Natal Province, South Africa

Rose-ringed parakeets Psittacula krameri are one of the most widely distributed urban avian invader species present in ~ 35 countries with population sizes increasing. These parakeets were introduced to South Africa as part of the pet trade, and feral populations have established in several urban areas since and are of concern. We, therefore, conducted monthly surveys between August 2018 – December 2019 in the greater Durban Metropole, KwaZulu-Natal Province, to determine their population size and roosting sites. In addition, we recorded bird species that communally roosted with rose-ringed parakeets, and tree species characteristics that they used for roosting. We identified five main roost site areas with an overall mean (± SD) monthly population size of 1 783.3 ± 505.2 rose-ringed parakeets. There was an increase in rose-ringed parakeet numbers, particularly in August and December after their breeding. Most rose-ringed parakeets were recorded in the north, with fewer in the south of the metropole; and many were located around shopping centres and parks. A total of seven bird species communally shared roost sites with rose-ringed parakeets, with the non-native common myna Acridotheres tristis being the species that frequently shared roosts with parakeets. Three tree species were used as roosts, with the Natal mahogany Trichilia emetica and the giant palm Raphia australis, so being the preferred roost tree species. The results showed variations in the measured tree traits and the number of individual parakeets roosting per tree species. The population size of non-native rose-ringed parakeets showed persistent growth, and it is, therefore, suggested that control measures for this species are introduced before its population expands further.

Growth characteristics of tree species in natural stands of Gambari forest reserve, Southwestern Nigeria

Growth characteristics of tree species in natural stands of Gambari forest reserve, Southwestern Nigeria

Woody Species Colonization along Edge-Interior Gradients of Deciduous Forest Remnants in the Mae Khum Mee Watershed, Northern Thailand

This study investigated the environmental factors and tree species characteristics that are important for the colonization of edge-interior gradients, for later application to the restoration of edge-transition areas created by highland agriculture in deciduous forests in the Mae Khum Mee watershed, northwest Thailand. Three belt plots (100 × 10 m) were established at the transition from the forest edge to the interior of two deciduous forest types (mixed deciduous forest [MDF] and deciduous dipterocarp forest [DDF]), for a total of six belt plots. The species composition of canopy trees and regenerated seedlings and saplings was assessed, together with several environmental factors. We analyzed the relative importance of the physical environment and recruitment limitation was evaluated in relation to the regeneration traits of tree species. The results indicated that it was difficult for DDF and MDF species to effectively colonize the near-edge areas of the forests, primarily because the key factors related to seedling and sapling colonization (i.e., recruitment limitation, the physical environment, and factors related to forest structure) did not match the edge environment. Generalist species experienced much less recruitment limitation along the edge-interior gradients of both DDFs and MDFs. Generalists such as Pterocarpus macrocarpus, Dalbergia cultrata, and Vitex pinnata exhibited more successful establishment under conditions at the edges of both deciduous forests. These findings suggest that the natural regeneration of generalist species can be utilized as a first step in forest-edge restoration due to their facilitation of subsequent colonization by primary forest species.

Biomass Estimation, Nutrient Accumulation, and Stoichiometric Characteristics of Dominant Tree Species in the Semi-Arid Region on the Loess Plateau of China

The biomass estimation, nutrient stock, and stoichiometric characteristics are critical for understanding forest productivity and quality. To date, there is not enough comprehensive research on nutrient stock and stoichiometric characteristics of each tissue among different tree species in the semi-arid region on the Loess Plateau. So, six dominant tree species were selected to estimate the forest biomass by allometric equation and to analyze the effects of tissue and species on biomass allocation and nutrient stock by variance analysis in our study. Results showed that forest biomass, nutrient concentration, nutrient stock, and stoichiometric characteristics varied with tissue and species. Betula platyphylla and Pinus tabulaeformis had high total biomass while Populus davidiana had the least total biomass, and the biomass allocation of each tissue generally followed the order of stem > branch > root > foliage. The weighted mean concentrations of carbon (C), nitrogen (N), and phosphorus (P) changed from 432.67 g·kg−1 to 481.43 g·kg−1, from 6.15 to 8.30 g·kg−1, and from 0.43 to 0.74 g·kg−1, respectively. The relatively high nutrient stocks were observed in Pinus tabulaeformis and Betula platyphylla across organs and in stem across species. The C:N and C:P ratios were higher in stem and root than those in branch and foliage for each species, while the effects of tissue on N:P varied with species. Overall, the N:P ranged from 7.92 for stem (Larix principis-rupprechtii) to 22.18 for foliage (Populus davidiana). Therefore, Pinus tabulaeformis and Betula platyphylla can increase effectively nutrient fixation capacity in the semi-arid region on the Loess Plateau. Also, N or P limitation of tree growth in this region varied with species.

Effect of climatic factors on forest succession in the forest-steppe zone of the Republic of Tatarstan

The paper analyzes the effect of climatic factors on forest succession in the forest-steppe zone of the Republic of Tatarstan. A reliable relationship was revealed between a decrease of the oak forested area and extremely low frosts in 1939–1940, 1941–1942 and 1978–1979, and a decrease in the area of birch after the 2010 drought. Birch and oak are replaced by maple, linden and aspen. Insignificant amount of young trees and the predominance of ripe and overripe plantations of oak and birch will lead to the continuation of forest succession in the forest-steppe zone. Impossibility of reverse succession at this stage by natural rehabilitation is associated with the biological characteristics of these species. Oak and birch forest rehabilitation is only possible with measures to promote natural or artificial regeneration with due regard to the biological characteristics of tree species.

Influence of tree functional diversity and stand environment on fine root biomass and necromass in four types of evergreen broad-leaved forests

Positive effects of tree diversity on above-ground biomass have been well documented, whereas the relationships between tree functional diversity and fine root biomass and necromass remain unclear. This study explored the variation in fine root biomass and necromass among different evergreen broad-leaved forest types, the relative importance of the niche complementarity and the mass ratio hypotheses in driving biodiversity effects, as well as forest stand attributes and environmental factors causing variation in fine root biomass and necromass. We detected no significant differences between most forest types, and the prominently lower amount of fine root biomass and necromass in monsoon evergreen broad-leaved forests may be ascribed to the accelerated turnover rate caused by the elevated temperature. Conversely, the functional divergence showed marginally positive effects on fine root necromass, hence the effects of functional diversity may be negligible; however, community-weighted mean trait values, i.e. specific leaf area and leaf phosphorus concentration, demonstrated significantly negative effects on them. Basal area and stem density showed significant influence in regulating fine root biomass. The optimal GAM models explained 79.5% and 54.4% of the variation of fine root biomass and necromass, respectively. Our results suggest that fine root biomass and necromass may be determined by the functional characteristics of dominant tree species rather than collective functional diversity and closely linked to forest stand, topographic and edaphic factors.

Ethnobotanical survey of existing trees in the botanical garden of UFRRJ

Ethnobotany has as main objectives not only to rescue popular knowledge linked to scientific knowledge about the use of plant materials used by social groups with different customs and cultures, but also to contribute to the identification, registration and conservation of natural resources. Aiming at these assumptions, the present work aims to produce a survey of the ethnobotanical characteristics of eudicotiledonous tree species in the Botanic Garden of the Federal Rural University of Rio de Janeiro (UFRRJ). The analysis of the ethnobotanical characteristics was done through specialized bibliography and also through records of uses by the local community, using its own methodology for such survey. The tree species were evaluated in 18 categories: food, handicrafts, apiculture, cellulosic, energetic, forage, wood, medicinal, oilseed, ornamental, reforestation, repellent, tannin, technology, textile, dye, ritualistic and poisonous. Among the species with more useful properties, Genipa americana L., included in 16 categories, is evident. However, this survey shows that the Botanic Garden of UFRRJ has an important collection of useful species

Anatomy and dendrochronological potential of Moringa peregrina from the hyper-arid desert in Egypt

The annual growth and wood characteristics of tree species at southern Mediterranean countries, and its relationship with climate variables are recently two important topics for the researchers in this region. Although Moringa peregrina (Forssk.) Fiori is a key species in Africa due to its medicinal and economic values (e.g. as fuel, food and water purifier), little is known about its annual growth or its response to climate variables. In this study, we analyze its dendrochronological potential, macroscopic and microscopic wood structure, and correlation with climate. Wood discs were collected from two desert sites in Egypt: Saint Catherine (SC) and Hurghada (HG). Wood discs and micro-slides were prepared, and the distinctness and pattern of rings, vessels, and ray structure were examined microscopically. The ring boundaries of M. peregrina were distinct and marked by thick-walled and flattened fibers. For the HG site, the resulting ring-width chronology spans 16 years, from 2001 to 2016. A significant positive relationship was found between tree growth at HG and precipitation prior to the vegetation period (January-March). April temperature of the year prior to growth had a significant positive relationship with M. peregrina growth. In contrast, April and May-August temperatures of the current growing season had a significant negative relationship with tree growth. We could not develop a chronology for M. peregrina at SC site due to the presence of growth anomalies in the collected wood discs from the site. Consequently, we did not get a clear picture on the climate- annual growth relationship for M. peregrina trees at this site. At SC, M. peregrina trees respond to stressful environmental conditions by adjusting their anatomical structure to produce a high number of small vessels. Moreover, there was spatial variability in the architecture of ray parenchyma that reflected the degree of stress in both sites. The results of this study improve our understanding of the growth-climate relationship in sub-tropical trees and the potential role of ray parenchyma in stressed environments.

In-situ measurement of photosynthetic characteristics of dominant tree species based on canopy crane in a Korean pine broad-leaved forest in Changbai Mountain, northeastern China.

To better understand the eco-physiological characteristics of dominant tree species in Korean pine broad-leaved forests, and to provide fundamental data for modelling and predicting carbon dynamics of forest ecosystems, we measured leaf CO2 assimilation rate versus intercellular CO2 concentration curves of four canopy dominant tree species in a Korean pine broad-leaved forest, in situ, for the first time, using a canopy crane in the Changbai Mountain Forest Ecosystem Research Station. Several important photosynthetic parameters were fitted with the FvCB model. Photosynthe-tic rate (A), maximum carboxylation rate (Vc max) and stomatal conductance (gs) were lowest in Pinus koraiensis (Pk), while stomatal limitation on photosynthesis (Ls) was highest in Pk. There were significant variations of photosynthetic characteristics among the three broad-leaved tree species [i.e., Fraxinus mandshurica (Fm), Quercus mongolica (Qm) and Tilia amurensis (Ta)]. The rank of tree species with respect to area-based Vc max was: Fm (83.2 μmol·m-2·s-1) and Qm (89.3 μmol·m-2·s-1) > Ta (68.4 μmol·m-2·s-1) and Pk (68.8 μmol·m-2·s-1) (P<0.05), and their rank with respect to mass-based Vc max was: Fm (1.36 μmol·g-1·s-1) > Qm (1.03 μmol·g-1·s-1) > Ta (0.90 μmol·g-1·s-1) > Pk (0.42 μmol·g-1·s-1) (P<0.05). From July to September, A value significantly declined in Fm and Qm, but remained stable in Ta and Pk. By contrast, Vc max significantly decreased in all tree species from July to September. Our results indicated that seasonal variation of Vcmax should be taken into consideration in the modelling and predicting of forest ecosystem carbon dynamics in northeastern China.

Assessment of post-fire vegetation recovery in Southern Siberia using remote sensing observations

Wildfire is one of the main disturbances affecting forest dynamics, succession, and the carbon cycle in Siberian forests. The Zabaikal region in southern Siberia is characterized by one of the highest levels of fire activity in Russia. Time series of Landsat data and field measurements of the reforestation state were analyzed in order to estimate post-fire vegetation recovery. The results showed that the normalized burn ratio time series can be used to estimate forest recovery in the pine- and larch-dominated forests of the Zabaikal region. Multiple factors determine a forest’s recovery rate after a wildfire, including fire severity, tree species characteristics, topography, hydrology, soil properties, and climate. Assessing these factors is important if we are to understand the effects of fire on forest succession and to implement sustainable forest management strategies. In this work we used the field data and Landsat data to estimate post-fire vegetation dynamics as a function of several environmental factors. These factors include fire severity, pre-fire forest state, topography, and positive surface temperature anomalies. A regression model showed that fire frequency, fire severity, and surface temperature anomalies are the primary factors, explaining about 58% of the variance in post-fire recovery. High frequency of fire and positive surface temperature anomalies hamper the post-fire reforestation process, while more severe burns are followed by higher recovery rates. Further studies are necessary to consider other important factors such as soil properties, moisture, and precipitation, for better explanation of post-fire vegetation recovery.

Climate forcing of tree growth in dry Afromontane forest fragments of Northern Ethiopia: evidence from multi-species responses

BackgroundClimate-induced challenge remains a growing concern in the dry tropics, threatening carbon sink potential of tropical dry forests. Hence, understanding their responses to the changing climate is of high priority to facilitate sustainable management of the remnant dry forests. In this study, we examined the long-term climate-growth relations of main tree species in the remnant dry Afromontane forests in northern Ethiopia. The aim of this study was to assess the dendrochronological potential of selected dry Afromontane tree species and to study the influence of climatic variables (temperature and rainfall) on radial growth. It was hypothesized that there are potential tree species with discernible annual growth rings owing to the uni-modality of rainfall in the region. Ring width measurements were based on increment core samples and stem discs collected from a total of 106 trees belonging to three tree species (Juniperus procera, Olea europaea subsp. cuspidate and Podocarpus falcatus). The collected samples were prepared, crossdated, and analyzed using standard dendrochronological methods. The formation of annual growth rings of the study species was verified based on successful crossdatability and by correlating tree-ring widths with rainfall.ResultsThe results showed that all the sampled tree species form distinct growth boundaries though differences in the distinctiveness were observed among the species. Positive and significant correlations were found between the tree-ring widths and rainfall, implying that rainfall plays a vital role in determining tree growth in the region. The study confirmed the formation of annual growth rings through successful crossdating, thus highlighted the potential applicability of dendroclimatic studies in the region.ConclusionsOverall, the results proved the strong linkage between tree-ring chronologies and climate variability in the study region, which further strengthens the potential of dendrochronological studies developing in Ethiopia, and also has great implications for further paleo-climatic reconstructions and in the restoration of degraded lands. Further knowledge on the growth characteristics of tree species from the region is required to improve the network of tree-ring data and quality of the chronology so as to successfully reconstruct historic environmental changes.

Effect of site and provenance on the length of transfusion parenchyma of Douglas-fir needles

Douglas-fir has been the most common introduced conifer species in European plantations since 1825. The analysis of the characteristics of the introduced tree species by conducting genetic tests may predict the success of transfer of Douglas-fir seed of different provenances. The projection of the model of provenance test aims at providing information on adaptation to habitat and climate conditions in new ecosystems in Serbia. The original seed of Douglas-fir from North America was used for setting the experiment of different provenances at two sites in Serbia. The first experiment was set in a beech forest (Fagetum moesiacae montanum Jov. 1976) on district cambisol in the area of Juhor mountain in central Serbia, while the second one was set in Tanda near the town of Bor in eastern Serbia on the habitat of Hungarian and Turkey oak (Quercetum frainetto-cerris Rud. 1949) on eutric cambisol. Through the analysis of the anatomical structure of Douglas-fir needles this paper tends to determine whether there are statistically significant differences in the length of transfusion parenchyma of provenances located in different habitats. The important function of parenchyma in needles is the physiological process of water, organic and mineral matter flow. The effects of the sites where the experiments were set on the transfusion parenchyma of needles were determined by statistical analysis.

Fourier Dense Network to Conduct Plant Classification Using UAV-Based Optical Images

Plant classification is a science that is used to assess the quality of forest resources and has been studied extensively. In this paper, we proposed a novel convolutional neural network known as the Fourier Dense Network (FDN) which is a data-driven method to classify the optical aerial images of plants. To efficiently classify plants, the FDN learns and extracts the features of plants in time and frequency domains from the optical images captured using an unmanned aerial vehicle (UAV). In FDN, we designed a fast Fourier dense block (FF-dense block) that describes the features of the plants by using the magnitude and phase information in the frequency domain. Moreover, we used a transition layer to reduce the dimension of feature maps between two FF-dense blocks in the time domain. The primary contributions of this study are as follows: (1) an FF-dense block that considers frequency information and transfers the information into various layers of a block was designed; and (2) the characteristics between the time and frequency domains were repeatedly extracted and combined to more effectively describe the characteristics of tree species. To evaluate our study, we established a novel dataset comprising the UAV-based optical images of plants-vegetational optical aerial image dataset-for conducting plant classification and information retrieval. The dataset contains more than 21863 images of 12 plants. To the best of our knowledge, this is the largest publicly available dataset of the UAV-based optical images of plants. The experimental results demonstrated that the FDN can achieve state-of-the-art performance in terms of plant classification.

Factors of selection and quality of wood used for woodcraft in medieval Polish strongholds and early urban centres

AbstractThis paper discusses various aspects of the use of wood for crafts in the Middle Ages, based on xylological analyses of 4211 crafted items of everyday use discovered at 62 archaeological sites in Poland. Over 1500 items were identified in the authors’ own analyses, and the remaining taxonomic data were taken from the literature. The research showed that the main types of wood used at the time were Pinus sylvestris, Quercus sp., Fraxinus excelsior, Picea sp. vel Larix sp., Taxus baccata, Alnus sp., Abies alba and Euonymus sp. Nineteen other taxa were used to make a much smaller pool of objects.At most of the analysed sites a similar set of materials was used to produce the items, regardless of their age and location. The choice of wood was selective and was based on the characteristics of particular tree and shrub species. Large coopered vessels were primarily made of wood from Quercus sp., Pinus sylvestris and Taxus baccata. The manufacture of turned utensils usually involved Fraxinus excelsior, while stave bowls were made using only Pinus sylvestris and Picea/Larix (mainly Picea abies).To verify the local availability of the source taxa, we used pollen sequences from natural and anthropogenic sites in the vicinity of the places where the examined artefacts were found. The choice of wood was limited by the availability of the trees and shrubs. In north-western Poland the most important taxa used for woodworking in the Middle Ages were Pinus sylvestris, Quercus sp., Fraxinus excelsior and Fagus sylvatica; in the south, Picea/Larix and Abies alba were used most frequently. Some items made of Abies alba, Picea and Larix were imported from other parts of the country.We inferred two stages of the use of wood by medieval Polish craftsmen. In the first stage, from the mid-10th century to the late 12th century, they largely used deciduous taxa; the second stage, from the 13th to the 15th centuries, saw the increased use of conifers.We found that the medieval craftsmen chose high-quality wood without defects. Radial wood with the best technical parameters was preferred. Its share increased in the late Middle Ages; this can be attributed to the craftsmen’s increasing familiarity with carpentry techniques.