Woody Vegetation Species Research Articles

Quantifying vegetation cover on coastal active dunes using nationwide aerial image analysis

AbstractCoastal active dunes provide vital biodiversity, habitat, and ecosystem services, yet they are one of the most endangered and understudied ecosystems worldwide. Therefore, monitoring the status of these systems is essential, but field vegetation surveys are time‐consuming and expensive. Remotely sensed aerial imagery offers spatially continuous, low‐cost, high‐resolution coverage, allowing for vegetation mapping across larger areas than traditional field surveys. Taking Aotearoa New Zealand as a case study, we used a nationally representative sample of coastal active dunes to classify vegetation from red‐green‐blue (RGB) high‐resolution (0.075–0.75 m) aerial imagery with object‐based image analysis. The mean overall accuracy was 0.76 across 21 beaches for aggregated classes, and key cover classes, such as sand, sandbinders, and woody vegetation, were discerned. However, differentiation among woody vegetation species on semi‐stable and stable dunes posed a challenge. We developed a national cover typology from the classification, comprising seven vegetation types. Classification tree models showed that where human activity was higher, it was more important than geomorphic factors in influencing the relative percent cover of the different active dune cover classes. Our methods provide a quantitative approach to characterizing the cover classes on active dunes at a national scale, which are relevant for conservation management, including habitat mapping, determining species occupancy, indigenous dominance, and the representativeness of remaining active dunes.

Tree vegetation viability of the Murmansk urban ecosystem

This paper aims to analyze the woody vegetation viability of northern territories. The research objectives were as follows: (1) to study the predominant species of woody vegetation in public gardens and alleys in Murmansk; (2) to identify groups and categories of trees quality conditions; and (3) to calculate the average coefficient of trees condition for the city. To conduct the research, we used the method guidelines for the stand viability assessment in July 2020, and we studied a total of seven sites (1,252 specimens of trees). According to the methodology, we identified three groups of trees conditions. We noted that the public green spaces in Murmansk are within the minimum norm for the cities in the tundra zone, with landscaped objects slightly below the normative values. The predominant trees in the studied public gardens and alleys are Sorbus species. The research showed that most trees are of satisfactory quality and belong to the “weakened category.” We recorded the following types of damage: frost cracks, bare trunk, insufficient leafage, small leaf plates, trunks’ bending and tilting. The main factors affecting the condition of woody vegetation in Murmansk are abiotic factors (wind, frost, heavy rain, hail, sharp temperature fluctuations). Biotic factors and human activity have a lesser impact. The city annually carries out sanitary work to cut down dead branches and give the landscaping objects aesthetic value. The novelty of the research is in the fact that the assessment of the trees in Murmansk in 2020 was carried out for the first time; the previous works are dated 2013–2017.

Functional Efficiency of the Woody Vegetation Species Composition in Urban Green Spaces

Functional Efficiency of the Woody Vegetation Species Composition in Urban Green Spaces

Natural Regeneration of Forest Stands after Ground Fires in the Rostov Region

Forest fires cause significant damage to protective plantations in the Rostov region. The largest area of forest fires in the steppe zone is in areas where the predominant species of protective plantations are Crimean pine or Scots pine. According to the adapted classification of fireplaces, the forest stands affected by ground fires are evaluated as heavily damaged. Despite an increase in the area of light, the projective cover of herbaceous vegetation reaches 80–100% only in the 4th-5th year after the fire. Natural regeneration of protective plantations occurs at the expense of invasive species of woody vegetation, such as maple ash, small-leaved elm, and green ash. In order to study the rate and extent of natural regeneration of the stand after ground fires, an assessment of plantations in the Shakhtinsky forest area of the Rostov region that were affected by ground fires in 2018–2022 was carried out.

Fluctuating asymmetry of the Acer negundo L. leaf: an indicator of its state and the quality of the urban environment

The purpose of this study was to analyze the protective function of Acer negundo L. by assessing the indicators of developmental stability by fluctuating leave asymmetry depending on the value of the influence of anthropogenic factors. The materials were obtained from 25 test sites on areas that differed in the degree of road transport impact in 2018–2021 in Irkutsk. The values of the indicators of the developmental stability of each test site were determined as the average of the coefficients of fluctuating asymmetry, considering the eight characteristics of the leaves collected from them. These values indicate that A. negundo is sufficiently resistant to anthropogenic impacts, particularly the effects of emissions from road transport, compared with other types of phanerophytes involved in the landscaping of urbanized areas. The coefficient of weighted average of this indicator between sites in recreational areas and along highways was 1.33. The correlation coefficient between the values of development stability and the distance of growth of A. negundo from highways was r = –0.64±0.18, which confirms the average connection between these characteristics. Analysis of variance was used to assess the stability of tree development in four classes of traffic intensity (high, medium, low, and absent), determined through a correlation ratio, the level of which n = 0.70 demonstrates a high level of connection. To limit the implementation of A. negundo in the local flora, it is recommended that measures be gradually implemented to remove it from parks, squares, gardens, and adjacent territories, with the replacement of woody vegetation species that are well adapted to grow in these habitats.

Формирование надземной фитомассы лиственных древесных пород на постагрогенных землях

The withdrawal of lands from active agricultural use and their overgrowth with woody vegetation have a steady trend in Russia, especially in the boreal zone. Studying the plantations developed on fallow lands of agricultural territories enables estimation of their resource potential for further use. The aboveground phytomass of vegetation is the most reliable indicator of habitat productivity. It is possible to determine the volume of carbon storage by assessing the phytomass of tree and shrub vegetation, which is relevant in the context of global climate change. The study object was a field out of active agricultural use in the Gatchina district of the Leningrad region. A trial area was laid out on the test site, where a complete enumeration of native hardwoods (birch, aspen, tree and shrub willows) with the determination of the basic inventory indicators was carried out. In order to find out the volume of phytomass, from 6 to 8 model trees of each species were cut down. Allometric equations for calculating the fractional composition of phytomass with a high determination coefficient were derived based on the data obtained on the values of individual fractions of the trunk ground part. The accuracy of the derived equations is reduced due to the high variability of crown characteristics in dense deciduous young growth. The highest phytomass is in the trunk part, and the lowest in the assimilation apparatus for all species of woody vegetation. Calculation of aboveground phytomass on the test site according to the obtained equations showed that the highest value per 1 ha at this successional stage is typical for downy birch. Currently, the participation of woody vegetation growing on post-agrogenic lands in carbon sequestration has no reliable full assessment for the study region. Wood that was grown on lands out of active agricultural use can serve as a biofuel source and be harvested in the form of technological chips.

Biomass and mortmass of woody vegetation in metal-contaminated areas (Southern Urals, Russia).

BackgroundSince the mid-2000s, long-term monitoring of various components of natural ecosystems under conditions of industrial pollution has been carried out in the Southern Urals. As a part of these monitoring programmes, the data on various components of biota in different biotopes, collected with different methods and in different time intervals, continue to be gathered. In addition, data collected through these monitoring programmes can also be used to study the local biodiversity of non-polluted areas.In 2012, in the vicinity of the Karabash Copper Smelter, a study of communities of small mammals was carried out, considering the heterogeneity of their habitats. Within the framework of this project, we presented a detailed description of the state of woody vegetation in the study area.New informationThe dataset (available from the GBIF network at https://www.gbif.org/dataset/61384edd-2d0a-437b-8cf0-ff4d2dfcc0da) includes the results of an assessment of the woody vegetation biomass at seven habitats (pine, birch and floodplain forests, reed swamp, sparse birch stand, marshy meadow and dump of household waste) of areas with different levels of industrial pollution in the vicinities of the Karabash, the Southern Urals. Karabash Copper Smelter (KCS) is one of Russia’s most significant point polluters; the main components of its emissions are heavy metals, dust and sulphur dioxide. Parameters of woody vegetation (diameter at breast height, diameter at root collar level and biomass) were estimated for seven forest elements (forest stand, subcanopy (undergrowth and underwood), half-dead tree of a forest stand and four types of coarse woody debris (downed bole, fragment of downed bole, standing dead tree and stump)) at 41 sampling plots (20 at unpolluted and 21 at polluted areas) and 165 subplots (81 and 84, respectively). The dataset includes 411 sampling events (estimation events of the forest elements at sampling plots and subplots), corresponding to 5786 occurrences (estimations of the woody vegetation components) observed during July 2012. For most woody vegetation components (72%), an estimate of the above-ground phytomass is given. For each sampling event, information on the presence or absence of woody vegetation species at the considered habitats is provided (a total of 1479 occurrences with status "absent"). The dataset can be used for environmental monitoring, sustainable forest management, modelling forest productivity considering global changes, studying the structure and biodiversity of forest cover and assessing forests’ carbon-sequestration capacity. In addition, the dataset provides information about different forest ecosystems under the influence of strong industrial pollution.

Quantifying the influence of individual trees on slope stability at landscape scale

Silvopastoralism in New Zealand's highly erodible hill country is an important form of erosion and sediment control. Yet, there has been little quantitative work to establish the effectiveness of space-planted trees in reducing shallow landslide erosion. We propose a method to provide high-resolution spatially explicit individual tree influence models at landscape scale for the dominant species in pastoral hill country. The combined hydrological and mechanical influence of trees on slopes is inferred through the spatial relationship between trees and landslide erosion. First, we delineate individual tree crowns and classify these into four dominant species classes found in New Zealand's pastoral hill country. This is the first species classification of individual trees at landscape scale in New Zealand using freely accessible data, achieving an overall accuracy of 92.6%. Second, we develop tree influence models for each species class by means of inductive inference. The inferred empirical tree influence models largely agree with the shape and distribution of existing physical root reinforcement models. Of exotic species that were planted for erosion and sediment control, poplars (Populus spp.) and willows (Salix spp.) make up 51% (109,000 trees) in pastoral hill country at a mean density of 3.2 trees/ha. In line with previous studies, poplars and willows have the greatest contribution to slope stability with an average maximum effective distance of 20 m. Yet, native kānuka (Kunzea spp.) is the most abundant woody vegetation species in pastoral hill country within the study area, with an average of 24.1 stems per ha (sph), providing an important soil conservation function. A large proportion (56% or 212.5 km2) of pastoral hill-country in the study area remains untreated. The tree influence models presented in this study can be integrated into landslide susceptibility modelling in silvopastoral landscapes to both quantify the reduction in landslide susceptibility achieved and support targeted erosion and sediment mitigation plans.

Woody plants structure and composition in Burkina Faso Sahel: Case study in Kékénéné village

Understanding woody vegetation composition and structure is important for leading management decisions in the Sahelian vulnerable zones. The objective of the study was to better knowledge woody vegetation structure and richness in natural vegetation and cropland. The study area is Kekenene village located in Soum province, surroundings Djibo in northern Burkina Faso. In total 54 sample plots were surveyed by means of a botanical inventory of woody vegetation species. All trees ≥ 10 cm dbh were measured. The vegetation structure pattern analyzed were diameter at breast height (dbh), basal area, relative dominance, and relative density, Importance Value Index (IVI) and Family Importance Value (FIV). In total 658 trees recorded was belonging to 21 species, 9 families in natural vegetation and 11 species, 5 families in cropland. Tree density was 15.7 stems/ha and 3.7/ha respectively in natural vegetation and cropland. Tree basal area was 0.54 m² ha -1 for cropland and 0.35 m² ha -1 in natural vegetation with a mean dbh of 3.5 cm for the two occupation types. The most importance family according to FIV was Balanitaceae in cropland and Combretaceae in natural vegetation. The Sorensen’ similarity coefficient of family in the two landscapes is lowest than 0.5 which means that the similarities in species family are low between the two occupation types. In natural vegetation, Anogeisus leiocarpus and Balanites aegyptiaca were the most important species in relation to IVI, while in cropland Balanites aegyptiaca, Acacia senegal and Acacia seyal were the most important species. Results reveal an abundance of Balanites aegyptiaca in both cropland and natural vegetation in the study site. Given its high socio-economic value in this region, this tree deserves to be more valued in a perspective of management and sustainable use in Kekenene village. Keywords : Composition and structure, woody species, management, Sahel ecosystems, Burkina Faso.

Species-Level Vegetation Mapping in a Himalayan Treeline Ecotone Using Unmanned Aerial System (UAS) Imagery

Understanding ecological patterns and response to climate change requires unbiased data on species distribution. This can be challenging, especially in biodiverse but extreme environments like the Himalaya. This study presents the results of the first ever application of Unmanned Aerial Systems (UAS) imagery for species-level mapping of vegetation in the Himalaya following a hierarchical Geographic Object Based Image Analysis (GEOBIA) method. The first level of classification separated green vegetated objects from the rest with overall accuracy of 95%. At the second level, seven cover types were identified (including four woody vegetation species). For this, the suitability of various spectral, shape and textural features were tested for classifying them using an ensemble decision tree algorithm. Spectral features alone yielded ~70% accuracy (kappa 0.66) whereas adding textural and shape features marginally improved the accuracy (73%) but at the cost of a substantial increase in processing time. Contrast in plant morphological traits was the key to distinguishing nearby stands as different species. Hence, broad-leaved versus fine needle leaved vegetation were mapped more accurately than structurally similar classes such as Rhododendron anthopogon versus non-photosynthetic vegetation. Results highlight the potential and limitations of the suggested UAS-GEOBIA approach for detailed mapping of plant communities and suggests future research directions.

Land degradation continues despite greening in the Nigeria-Niger border region

Recent satellite observations of the West African Sahel have shown an increase in vegetation greenness. However, many of these studies have little or no field validation to ascertain the actual environmental conditions on the ground. Here, we assess the condition of woody vegetation species in relation to land degradation processes and examine the conditions and patterns of their changes in the Nigeria-Niger border region in West Africa. Indigenous knowledge, a botanical survey, field observations and trend analyses were used to evaluate ecological changes in the area. A survey of 70 respondents which were selected using purposive sampling is presented i.e. 10 respondents each from seven villages, and focus group interviews were conducted to ascertain the condition of woody vegetation changes. The results show that despite the overall increase of vegetation greeness observed from remote sensing, the diversity and density of indigenous woody vegetation species is declining throughout the area. Nearly 80% of all the indigenous plant species of the region such as Borassus aethiopum, Ficus thonningii and Ficus thonningii have either completely disappeared or migrated southward where climatic conditions are more favourable. Therefore, the evidence suggests that land degradation is ongoing in the region and that local knowledge should be integrated in ecological resource management, especially at the local level, where locals rely on woody trees for food, income and fuelwood, so that plant species at risk of extinction can be preserved and where possible regenerated for conservation and sustainable use of the woody plant species in the region.

Optimizing the Timing of Unmanned Aerial Vehicle Image Acquisition for Applied Mapping of Woody Vegetation Species Using Feature Selection

Most recent studies relating to the classification of vegetation species on the individual level use cutting-edge sensors and follow a data-driven approach, aimed at maximizing classification accuracy within a relatively small allocated area of optimal conditions. However, this approach does not incorporate cost-benefit considerations or the ability of applying the chosen methodology for applied mapping over larger areas with higher natural heterogeneity. In this study, we present a phenology-based cost-effective approach for optimizing the number and timing of unmanned aerial vehicle (UAV) imagery acquisition, based on a priori near-surface observations. A ground-placed camera was used in order to generate annual time series of nine spectral indices and three color conversions (red, green and blue to hue, saturation and value) in four different East Mediterranean sites that represent different environmental conditions. After outliers’ removal, the time series dataset represented 1852 individuals of 12 common vegetation species and annual herbaceous patches. A feature selection process was used for identifying the optimal dates for species classification in every site. The feature selection can be designed for various objectives, e.g., optimization of overall classification, discrimination between two species, or discrimination of one species from all others. In order to evaluate the a priori findings, a UAV was flown for acquiring five overhead multiband orthomosaics (five bands in the visible-near infrared range based on the five optimal dates identified in the feature selection of the near-surface time series of the previous year. An object-based classification methodology was used for the discrimination of 976 individuals of nine species and annual herbaceous patches in the UAV imagery, and resulted in an average overall accuracy of 85% and an average Kappa coefficient of 0.82. This cost-effective approach has high potential for detailed vegetation mapping, regarding the accessibility of UAV-produced time series, compared to hyper-spectral imagery with high spatial resolution which is more expensive and involves great difficulties in implementation over large areas.

The Effect of Small Scale Topographic Gradient on the Distribution and Community Utilization of Indigenous Woody Species in a Lowland Dryland Environment, Lokapel Area, Turkana, Kenya

The landscape of Lokapel is characterized by a distinctive dryland vegetation, whose distribution is influenced by altitudinal change and the use of woody species by the local community along 100 m altitudinal gradient from River Turkwel (662 m) to Lokapel Hill (764 m). The paper undertakes the following: (a) to establish the influence of elevation on woody vegetation species distribution in different landscapes in the area and (b) to assess the consumptive and non-consumptive uses of woody vegetation in the area by the local community and determine the utility patterns along the altitudinal gradient. A total of forty three species of woody plants were identified with the top five species in terms of widespread distribution being; Indigofera cliffordearia (10 percent), Acacia tortilis (9.8 percent), A. nubica (8.8 percent), Balanites rotundifolia (6.3 percent), and Acacia reficiens (5.4 percent). The local people used the indigenous woody species to address a total of 18 demands including provision of livestock fodder, household construction, bio-energy, and herbal medicines. The variation in woody species and their uses showed the total number of woody species distribution has the highest peak around 680 m but altitude accounted only for 51 percent of the variation in woody species.

Structure and composition of Spirostachys africana woodland stands in Gonarezhou National Park, southeast Zimbabwe

We investigated the structure and composition of Spirostachys africana woodlands in Gonarezhou National Park (GNP), southeast Zimbabwe. We divided the GNP into three strata, namely northern, central and southern GNP, based on physical feature such as major perennial rivers. The main objective was to determine whether the structure and composition of S. africana woodlands varied across the GNP. In addition, we evaluated whether herbivory and fires played important roles in influencing the structure and composition of S. africana woodland stands. A stratified random sampling design was used and data were collected from a total of 60 sample plots. The following variables were recorded in each study plot: woody plant height, species name, plant status (alive or dead), fire or browse evidence and number of stems per plant. A total of 2,588 woody plants comprising of 73 woody species were recorded from the sampled S. africana woodlands in the GNP. Our results showed that woody species diversity, woody plant heights, shrub density, density of dead plants, sapling density, density of fire damaged plants, and number of stems per plant were significantly different across the S. africana woodlands in GNP. In contrast, only densities of trees and browsed plants did not differ significantly across the GNP. Most plots in the southern GNP had higher tree and sapling densities and taller trees whereas those in the northern GNP had higher densities of fire damaged plants. In addition, plots from central GNP were characterised with higher shrub densities of S. africana woodlands. Overall, our results suggest that there are both structural and compositional differences of S. africana woodland stands across the GNP. Evidence of herbivory did not differ significantly across the GNP suggesting that plants were uniformly affected by herbivores. However, fire evidence seemed to vary across the GNP, with areas having frequent fires being more degraded and having to some extent more woody vegetation species diversity.

Vegetation impoverishment despite greening: A case study from central Senegal

Recent remote sensing studies have documented a greening trend in the semi-arid Sahel and Sudan zones of West Africa since the early 1980s, which challenges the mainstream paradigm of irreversible land degradation in this region. What the greening trend means on the ground, however, has not yet been explored. This research focuses on a region in central Senegal to examine changes in woody vegetation abundance and composition in selected sites by means of a botanical inventory of woody vegetation species, repeat photography, and perceptions of local land users. Despite the greening, an impoverishment of the woody vegetation cover was observed in the studied sites, indicated by an overall reduction in woody species richness, a loss of large trees, an increasing dominance of shrubs, and a shift towards more arid-tolerant, Sahelian species since 1983. Thus, interpretation of the satellite-derived greening trend as an improvement or recovery is not always justified. The case of central Senegal represents only one of several possible pathways of greening throughout the region, all of which result in similar satellite-derived greening signals.

Spatial analysis of fine root distribution on a recently constructed ecosystem in a water-limited environment

Aims: (1) to investigate the spatial distribution of fine roots and its correlation with selected soil properties on an artificial ecosystem dominated by woody vegetation species, and (2) to compare the root distribution to that predicted using a global model for natural ecosystems.

Stand biomass estimation method by canopy coverage for application to remote sensing in an arid area of Western Australia

To estimate forest biomass in a large area, it is necessary to clarify the relationship between attributes of stand structure obtained by remote sensing and woodland biomass. We examined stand structure and estimated woodland biomass in an arid region of Western Australia. The research site was near Leonora located 600 km from Perth in Western Australia. The annual rainfall is approximately 200 mm. The dominant woody vegetation species is Acacia aneura. The spatial characteristics of the woodland in this region are that woodland canopies are not closed and the tree crown silhouette is relatively clear-cut. We established 35 plots (main size, 50 m × 50 m) and the diameters at 1.3 and 0.3 m heights, tree height and canopy silhouette area of all trees in the plots were determined. Each tree biomass was calculated by allometric equations using a destructive sampling method. Results of regression analysis indicated that the appropriate stand structural attributes for estimation of woodland biomass were stand basal area (SBA), canopy coverage (CC) and leaf area index (LAI). SBA had the highest estimation accuracy of woodland biomass but SBA was not suitable for estimation by satellite imagery. The woodland biomass estimation accuracy by CC ( R 2 > 0.94, P < 0.0001) or LAI ( R 2 > 0.92, P < 0.0001) was lower than that by SBA ( R 2 > 0.99, P < 0.0001) but CC and LAI are considered to be powerful indicators for woodland biomass estimation by satellite imagery, where open forest is distributed. Particularly, in the case of arid land, the correlation between CC and woodland biomass was reported in the Salhel region of Africa and in Queensland, Australia; therefore, the forest biomass estimation method by CC is considered to be applicable to other arid- and semiarid-area open forests and woodlands.

The relationship of the soil seed bank and understory vegetation in old-growth northern hardwood–hemlock treefall gaps

In mature northern hardwood forests, small treefall gaps constitute an important mode of compositional and structural change within the long return time of larger catastrophic disturbances. The soil seed bank and patterns in vegetation layers are described in this disturbance regime context. In these small treefall gaps, herbaceous and woody vegetation species present are similar to those of forest understory plots, differing primarily in abundance. Seed bank communities are compositionally more similar among gaps than forest understory plots, but vegetation similarity is equal among forest plots and among gaps. Seed bank-vegetation similarity is greater among forest plots than in gaps. Seed bank strategies differ among the plant species characteristic of the differing forest layers. Dominant canopy tree species (Acer saccharum, Tsuga canadensis, Betula alleghaniensis) are not an important component of the seed bank. Bird-dispersed shrub and herbaceous species and ant-dispersed herbs are important in the seed bank, especially in gaps. In particular, based on gap seed bank response, it appears that understory shrub abundance and pattern within the forest change with the time since large-scale disturbance, in accordance with species adaptations to the size and increase in number of small treefalls in the mature forest. These species patterns may relate to the patchy nature of resource availability that develops, especially that of nitrogen, which is controlled by the canopy species–gap mosaic. Key words: treefall gaps, soil seed bank, disturbance, northern hardwoods, old growth, succession, shrubs.