Vegetation In Urban Environment Research Articles

Effect of exotic species management on the recovery of relict forests through citizen participation

AbstractIn the cities, remnants of the vegetation that originally occupied these areas can be found. Exotic species have established in these relicts, and therefore these spaces require management aimed at recovering native vegetation. In this study, we evaluated the impact of the removing exotic species on the floristic composition of the remnants of an oak forest. We compared the abundance/cover and composition of exotic plants in a forest that has been managed through citizen participation with that of reference forests (both with remnants, but the former without protection and the latter with protection). We established 48 sampling sites to characterize the vegetation in three strata (upper, middle, and low) and monitored changes in composition in managed forest sites for a period of 3 years. The results indicate that the managed forest hosts different species than those found in the reference forests, with lower abundance and cover of exotic plants in the upper and lower strata. Regarding temporal changes, we observed shifts in floristic composition before and after management activities, and a reduction in the cover of exotic species before and after management, with consistently low cover three years later. This underscores the effectiveness of citizen-led management activities, offering a viable alternative for restoring native vegetation in urban environments.

High-Resolution Remote Sensing Images Can Better Estimate Changes in Carbon Assimilation of an Urban Forest

Urban forests have the potential to sink atmospheric CO2. With the improvement of coverage of vegetation in urban environments, more attention has been paid to the carbon sequestration potential of the urban forest. However, the high fragmentation of urban forests makes it difficult to evaluate their carbon budget on a regional scale. In this study, the GPP-NIRv relationship model was employed to estimate GPP in Suzhou by MODIS, Landsat-8 and Sentinel-2 remote sensing data, and to further explore what kind of remote images can figure out the spatial-temporal pattern of GPP in urban forests. We found that the total GPP of the terrestrial ecosystem in Suzhou reached 8.43, 8.48, and 9.30 Tg C yr-1 for MODIS, Landsat-8, and Sentinel-2, respectively. Monthly changes of GPP were able to be derived by MODIS and Sentinel-2, with two peaks in April and July. According to Sentinel-2, urban forests accounted for the majority of total GPP, with an average of about 44.63%, which was larger than the results from GPP products with coarser resolutions. Additionally, it is clear from the high-resolution images that the decline of GPP in May was due to human activities such as the rotation of wheat and rice crops and the pruning of urban forests. Our results improve the understanding of the contribution of the urban forest to the carbon budget and highlight the importance of high-resolution remote sensing images for estimating urban carbon assimilation.

Diversity of Ruderal Communities in Urban Environments—A Case Study from Serbia (SE Europe)

The high diversity of ruderal vegetation in urban environments is well known. Although it has been a subject of numerous studies in Serbia, in recent years it has been slightly overlooked, although, due to the dynamics of ruderal habitats, constant research is required. We investigated ruderal vegetation in 20 cities across Serbia during a period of 5 years. Most of the relevés were collected during the summer months, and within 712 relevés, 422 taxa were recorded. Results of the cluster analyses and identified diagnostic species revealed 26 plant communities, of which nine are dominated or co-dominated by aliens. The relevés can be grouped into six ecologically well-differentiated major vegetation groups. Our study revealed the ruderal communities which are the most widespread in urban environments in Serbia. Additionally, some communities were registered for the first time in the country.

Remotely Sensed Tree Characterization in Urban Areas: A Review

Urban trees and forests provide multiple ecosystem services (ES), including temperature regulation, carbon sequestration, and biodiversity. Interest in ES has increased amongst policymakers, scientists, and citizens given the extent and growth of urbanized areas globally. However, the methods and techniques used to properly assess biodiversity and ES provided by vegetation in urban environments, at large scales, are insufficient. Individual tree identification and characterization are some of the most critical issues used to evaluate urban biodiversity and ES, given the complex spatial distribution of vegetation in urban areas and the scarcity or complete lack of systematized urban tree inventories at large scales, e.g., at the regional or national levels. This often limits our knowledge on their contributions toward shaping biodiversity and ES in urban areas worldwide. This paper provides an analysis of the state-of-the-art studies and was carried out based on a systematic review of 48 scientific papers published during the last five years (2016–2020), related to urban tree and greenery characterization, remote sensing techniques for tree identification, processing methods, and data analysis to classify and segment trees. In particular, we focused on urban tree and forest characterization using remotely sensed data and identified frontiers in scientific knowledge that may be expanded with new developments in the near future. We found advantages and limitations associated with both data sources and processing methods, from which we drew recommendations for further development of tree inventory and characterization in urban forestry science. Finally, a critical discussion on the current state of the methods, as well as on the challenges and directions for future research, is presented.

An automated workflow for informing urban greening based on photosynthetic radiation modelling

The deliberate introduction of vegetation in urban environments, referred to as urban greening, is known to improve outdoor thermal comfort and mitigate the effects of Urban Heat Island in cities. Urban greening can be applied on ground level or elevated parks, roof tops, and building facades. The main parameters that affect plant growth are space, light, water, humidity, oxygen, carbon dioxide, mineral elements, and temperature. Of these parameters, light and temperature are the ones more unlikely to be supplemented in a non-controlled urban setting. This research presents the development of an automated workflow that facilitates design decisions on vegetation growth potential and vegetation species selection within their climatic and geometrical context. This novel scripting-based prototype uses hourly radiation results to extract location specifications, such as photoperiod, hardiness zone, and hourly annual Daily Light Integral values on a user-defined grid. It then seamlessly compares the data against seasonal light and soil temperature requirements of listed cultivars to evaluate their suitability within the constraints of the analysis area. A basic plant dataset is created that is open to expansion based on plants growth data availability. This automated workflow can be employed by agriculturalists, urban planners, and landscape designers to perform vegetation selection for applications such as urban greening in dense contexts or vertical farms.

Urban spontaneous vegetation helps create unique landsenses

ABSTRACT Non-cultivated, spontaneous vegetation in urban environments plays a key role in supporting urban and rural disturbed ecosystems because of the advantages of low input and low energy consumption. There is a contradiction between such plants and conventional cultivated species in terms of sensory characteristics that could affect people’s acceptance of such vegetated landscapes. Taking the most developed city of China Mainland, Shanghai, as a case study, this work aims to better understand how the public perceive these spontaneous plants in terms of physical and psychological senses based on the recently developed framework of landsenses ecology. Overall, these species activate people with positive senses, such as naturalism and nostalgia. Most people support the importance of their visual aspect, such as colourful fruits/flowers are more important for prompting such species. Our study indirectly supports the idea that the public seem not concern whether plants have soft or hard, smooth or rough tactility in parks. Similarly, people do not make high demands on the plants’ olfactory output. These results may provide a wide range of space for design and management strategies since there are abundant choices. The key influencing factor in our study was ‘childhood living environment’ whereas the commonly related factor ‘level of education’ showed no connection. Based on the framework of landsenses ecology that specifically emphasizes incorporating sensory experience into places, this study may help practitioners connect people’s multi-senses to non-cultivated vegetation and help accommodate a wider range of specific ecological attributes, constraints, priorities and people’s concerns in a more human-centric way.

The impacts of urbanization and climate change on urban vegetation dynamics in China

Climate change and urbanization are the two major drivers that can alter vegetation growth processes in the urban environment. However, the effects of these two drivers on the continuous vegetation dynamics in the urban environments are not well understood, especially at a high spatial resolution. This study identified the urban fringe zones and explored the spatiotemporal variations of vegetation dynamics (Normalized Difference Vegetation Index) and the mechanisms underlying these variations in the urban core areas and urban fringe zones of China during 2000–2013. The results suggested that from 2000 to 2013, rapid urbanization regions in Yangtze River Delta experienced a high probability of vegetation degradation. However, some rapid urbanization areas in other parts of China did not undergo such sharp vegetation degradation. We demonstrated that about 63 % of the vegetated areas in urban environments showed increasing trends, and the greening trend in the urban core areas was higher than that of urban fringe regions. Furthermore, the relative contributions of climate change, urbanization, and other factors to vegetation variation in the urban area were 33 %, 24 %, and 43 %, respectively. The contribution of urbanization was higher in urban fringe zones than in urban core areas, while the climate change and residual factors were both higher in urban core areas. Our results verified that the urbanization process would not necessarily result in large-scale vegetation degradation. The vegetation in urban environments was mainly determined by climatic variables rather than urbanization. Based on these findings, we propose that the development of fringe areas outside the urban core areas should be avoided as much as possible to effectively mitigate vegetation degradation and the positive influences of urbanization on vegetation growth through effective urban landscape planning should be encouraged.

Recreation in the City-A Part of Cultural Ecosystem Services

Abstract Cultural ecosystem services (CES) are mainly intangible benefits, obtained by aesthetical and other experiences, recreation, learning and spiritual enrichment, or by the ability to distinguish values. In other words, what makes a service ‘cultural’ is its ‘non-economical’ character. CES are ecosystem services with direct impact on the quality of life in urban systems, and they are directly appreciated by inhabitants and visitors of these urban systems (Plieningeret al., 2013; Zulian et al., 2018). In order to satisfy the needs and expectations of the wider urban community, a ‘broader portfolio of areas’ is needed, which can meet the expectations of different users, from children to older adults. The new methodological approach tested on three model areas in the city of Nitra in the housing estate Chrenová was used to establish the level of benefits provided by existing vegetation areas in urban environment in terms of recreation as a CES. Following data were collected: the quality of vegetation, spatial design, management of vegetation elements, selected environmental aspects, available amenities and architectural elements needed for recreation. In our article, we present the assessment of vegetation in relation to the provision of recreation as a CES. Our results show that the assessed areas can be classified in the category of average to low provision of benefits related to recreation. Vegetation on area P1 is in good condition, mainly the quality of trees and shrubs was assessed as very good (4). Other areas (P2 and P3) assessed provide only low levels of benefits derived from recreation as one of the CES. This was caused by some vegetation deficiencies (mainly related to horticultural and compositional aspects). Methodological approach can be used for different vegetation areas in urban environment and after suitable modifications (e.g. adding other components for assessment) also for different cultural ecosystems services. The results can be used in landscape planning documents or in other types of documents dealing with the quality of vegetation in urban environment.

Assessment of the potential for urban facade greening in Xinjiekou District, Nanjing, China.

Green facade is an important strategy to improve the urban eco-environment and reduce the negative effects of human activities in central districts of cities which are land-scarce and lack green spaces. We first summarized the limiting factors for the construction of green facades locally and internationally. Then, we used the Xinjiekou District of Nanjing City in China as a case study area, and selected the wind environment, solar environment, and physical build environment that might impact the potential development of green facades as key factors to quantitatively analyze singlely by geographic information systems (GIS) and computational fluid dynamics (CFD). Finally, the potential area to develop green facades was assessed through a multi-factor overlay analysis. The results showed that 17726 m2 of wall spaces in the Xinjiekou District had a high potential for facade greening, accounting for 30.8% of all exterior wall space under a height of 12 m and 17.3% of the entire study area. Sunlight was a key limiting factor in determining whether a green facade should be developed. Irrigation was identified as another important factor that might strongly affect the growth of vertical vegetation in urban environment. The spatial distribution of walls suitable for facade greening was uneven, with an "inner-high and south-high" spatial pattern. Our results would help to guide the design and development of green facades in Xinjiekou, and also provide a reference for planning and utilizing green wall space projects in other built and dense urban areas.

Urban Green Space Management As a Support for the Climatic Function of Vegetation in Urban Environment (Case Study – Nitra)

Urban Green Space Management As a Support for the Climatic Function of Vegetation in Urban Environment (Case Study – Nitra)

Effects of settlement size, urban heat island and habitat type on urban plant biodiversity

Urbanized areas with high habitat heterogeneity and intense human impact form unique environment which is surprisingly rich in plant species. We explore the effect of the settlement size on plant species richness, composition and temperature requirements of plant communities.We studied three habitats with different disturbance regime in 45 Central European settlements of three different sizes. We sampled 1-ha plots in each habitat by recording all spontaneously occurring vascular plant species. We divided recorded species into groups according to their origin and residence time and according to their temperature requirements based on Ellenberg indicator values. We used ordination methods and ANOVA to detect that species communities in urban areas are generally more species rich in larger settlements than in small ones. These differences are mostly pronounced in residential areas. Increasing settlement size is significantly reflected by neophytes that are dependent on constant input of propagules caused by human activities and by native species that survive in remnants of semi-natural vegetation in urban environment. In contrast archaeophytes as a homogeneous group of species with similar traits are widespread equally through settlements of all sizes. We did not confirm the effect of urban heat island on species composition, indicating that species composition is significantly more affected by local habitat conditions than by urban size. Our results highlight the importance of urban size as important factor shaping biodiversity of native and alien plant communities in individual urban habitats and the important role of habitat mosaic for maintaining high species richness in city floras.

The impact of vegetation on urban microclimate to counterbalance built density in a subtropical changing climate

The purpose of this research is to assess the microscale cooling effects of vegetation in urban environment, especially during daytime, to counterbalance urban warming effects resulting from an increase in built density in a subtropical climate. Considering that Brazil’s climate will be warmer in the coming decades, the paper presents a brief review of planning with high-density and urban greening, having in mind that even low-density land use can contribute to urban heating, depending on the urban occupation pattern. In high-density cities, the most important vegetation effect is to prevent heating in urban canyons, decreasing solar radiation absorption by shading and evapotranspiration. Parametric studies exploring different scenarios of high-density urban blocks and greening have been carried out to investigate different distributions of dense trees to ameliorate urban microclimate using ENVI-met V4 Preview I, previously calibrated with field measurements of local climate and vegetation data. Aiming to benefit urban activities, air, surface and mean radiant temperatures at the pedestrian level are compared among different greening strategies and built densities’ scenarios. Based on the results, two outdoor comfort indexes TEP –Temperature of Equivalent Perception and PET – Physiological Equivalent Temperature were applied to verify the contribution of vegetation to better comfort conditions.

AVALIAÇÃO QUALI-QUANTITATIVA DA ARBORIZAÇÃO URBANA NA BACIA HIDROGRÁFICA CÓRREGO DO SAPATEIRO, SÃO PAULO – SP

This vegetation in urban environments can cause numerous ecological, economic and social contributions. This research aimed to valuate qualitative and quantitatively urban forest in a watershed Corrego do Sapateiro the city of Sao Paulo (SP). Thus, were surveyed every shrub and tree individuals and were collected physical, biological and plant health. We found 532 individual trees, over 54 species belonging to 22 families. There was a predominance of native species and most of the trees have a favorable conservation status (67%). Was also evaluated the need for some actions to improve the quality of urban trees, some examples pruning of construction magnification, fertilizer, removal of interfering vegetation, among others.

Comparative microclimate and dewfall measurements at an urban green roof versus bitumen roof

Urban green roofs are discussed as a local climate adaptation measure to limit surface warming and increase evaporative cooling by vegetation in urban environments. A five month measurement campaign was conducted to observe surface and air temperatures as well as dewfall dynamics and amounts on an urban green and co-located bitumen roof. Measurements were performed in the period from August to December 2012.Surface temperatures indicated differences of up to 17.4 K, which lead to measurable air temperature differences (ΔTA) at a height of 0.5 m above roof level. During August afternoons (3 pm) the green roof air temperature (TA) drops below TA of the bitumen roof by up to 0.7 K on average. By using a linear regression based approach differences in sensible turbulent heat flux densities (QH) between green and bitumen roof of 200 W m−2 on a hot day with 30 °C and wind velocities of 2 m s−1 were estimated.During the measurement campaign a total of 60 and 52 dew events were observed on the bitumen roof and the green roof, respectively. At both urban sites the number of dewfall events was distinctly smaller compared to the rural site (94 events). Roof dewfall turned out to be a negligible source in the green roof water balance compared to precipitation amounts. Inhibited dewfall on roofs could be one important factor for the phenomenon of urban moisture excess since roofs represent a high fraction of urban surfaces.

Urban environment and vegetation: comfort and urban heat island mitigation

This paper analyses the outcomes of an experimental simulation on the microclimatic effects and on thermal comfort of vegetation in urban environment, conducted by means of a three-dimensional microclimate model, ENVI- met 3.1. The simulation considers a wide range of hypothetical cases of typical city areas with different characteristics related to: building density, building height, vegetation type and density. The results of the study show how different combinations of amount and type of vegetation, density and height of buildings affect the urban heat island phenomenon in Mediterranean climate.

Evaluation of Microclimatic Data on Localities with Different Ratio of Vegetation in Urban Environment

AbstractMany authors (Akbari, Taha, 1992; Čaboun, 2008; Klein, 2013; Keresztesová, 2013) proved the influence of vegetation on microclimate as well as on the decrease of heat islands. We were interested in how different ratio of vegetation and open spaces influences microclimatic factors. From April to July 2012 microclimatic factors of two different localities with respect to various ratios of vegetation and open spaces were observed in Nitra, Slovakia. More specifically we observed the air temperature, relative air humidity and surface temperatures of four selected points in both localities. We have found out that in the park, i.e. in the locality with a higher portion of vegetation than open space was the course of temperatures more balanced, thanks to the attribute of vegetation to keep a stable microclimate. We have not observed any major Differences between the monitored points variously located in the vegetation in one locality, but on the other hand, we have observed remarkable differences between the two monitored localities. We may allege that the ratio of vegetation and open spaces makes significant contribution to microclimatic conditions of urban environment.

Grassland communities of urban open spaces in Bloemfontein, Free State, South Africa

Natural vegetation in urban environments is greatly impacted by human activities and it is in constant threat of degradation and destruction as a result of urbanisation. This vegetation, although fragmented, serves an important ecological function and needs to be properly managed and conserved. Studies on urban vegetation are lacking in South Africa, with only a handful having been carried out since the end of the last century. This study was initiated to identify, classify and describe the grassland communities of the urban open spaces in Bloemfontein. Relevés were compiled in 61 sample plots, where species present and habitat information were recorded. Care was taken to restrict sample plots to vegetation in pristine condition, wherever possible, and severely degraded stands were avoided. A two-way indicator species analysis (TWINSPAN) classification, refined by Braun-Blanquet procedures, revealed two distinct major communities, seven communities and four sub-communities. Both detrended and canonical correspondence analyses indicated the vegetation units to be associated with soil texture and pH, although biotic factors such as overgrazing, burning and mowing also influence the composition of the vegetation. The proper management and conservation of urban open spaces requires in-depth knowledge of the spatial distribution, floristic, structural and functional compositions within the major vegetation types in this environment. The present study further contributed towards formulating ways for the proper management, utilisation and functioning of the open spaces within the Bloemfontein area.Conservation implications: The Grassland Biome of South Africa is poorly conserved, mainly because of its status as an agricultural hub of the country. The preservation of natural and semi-natural forms of urban vegetation is important because such vegetation, although often disturbed and degraded, could form dispersal corridors between peri-urban and rural vegetation.

Object-Based Point Cloud Analysis of Full-Waveform Airborne Laser Scanning Data for Urban Vegetation Classification.

Airborne laser scanning (ALS) is a remote sensing technique well-suited for 3D vegetation mapping and structure characterization because the emitted laser pulses are able to penetrate small gaps in the vegetation canopy. The backscattered echoes from the foliage, woody vegetation, the terrain, and other objects are detected, leading to a cloud of points. Higher echo densities (>20 echoes/m2) and additional classification variables from full-waveform (FWF) ALS data, namely echo amplitude, echo width and information on multiple echoes from one shot, offer new possibilities in classifying the ALS point cloud. Currently FWF sensor information is hardly used for classification purposes. This contribution presents an object-based point cloud analysis (OBPA) approach, combining segmentation and classification of the 3D FWF ALS points designed to detect tall vegetation in urban environments. The definition tall vegetation includes trees and shrubs, but excludes grassland and herbage. In the applied procedure FWF ALS echoes are segmented by a seeded region growing procedure. All echoes sorted descending by their surface roughness are used as seed points. Segments are grown based on echo width homogeneity. Next, segment statistics (mean, standard deviation, and coefficient of variation) are calculated by aggregating echo features such as amplitude and surface roughness. For classification a rule base is derived automatically from a training area using a statistical classification tree. To demonstrate our method we present data of three sites with around 500,000 echoes each. The accuracy of the classified vegetation segments is evaluated for two independent validation sites. In a point-wise error assessment, where the classification is compared with manually classified 3D points, completeness and correctness better than 90% are reached for the validation sites. In comparison to many other algorithms the proposed 3D point classification works on the original measurements directly, i.e. the acquired points. Gridding of the data is not necessary, a process which is inherently coupled to loss of data and precision. The 3D properties provide especially a good separability of buildings and terrain points respectively, if they are occluded by vegetation.

Concentrations of Pb, Zn, and Cu in Taraxacum spp. in relation to urban pollution

The combustion of petroleum fuel and exhaust emissions are major sources of atmospheric pollution in cities which result in the deposition of toxic substances, particularly heavy metals, in the surface layers of soils. Lead in particular enters the environment from the use of tetraethyl lead as an antiknock agent for petrol engines constituting 21% of fine particles emitted from cars burning leaded petrol. Antiwear protectants incorporated in lubricants often contain Cd, Cr, Cu, Hg, Ni, Pb and/or Zn which are also released into the environment by inefficient engines and irresponsible dumping of engine oils. Zn from tyre wear and Cu from diesel engines also add considerably to the environmental metal burden. Lowering of the permitted lead content of petrol and the growing use of unleaded fuel are expected to lead to reductions in the environmental lead burden, however, until unleaded fuel becomes universally accepted lead contamination, particularly of roadside soils and vegetation is a major cause for concern. A direct relationship between car exhaust, the Pb content of needles of Abies alba and reduced growth has been observed and can extend hundreds of metres from major highways. Lead tolerance has been observed in higher plants growing mine waste soils andmore » to a lesser extent on lead-contaminated roadside soils. Automobiles which are responsible for line sources of pollution emissions in rural and suburban areas have a more far-reaching impact on roadside vegetation, already under considerable stress, in urban areas. Information on heavy metal effects on vegetation in urban environments however, are scarce. Modeling and multivariate analysis of a few of the factors involved have provided only limited data related to plant performance in these complex environments. Therefore in this study, the extent of heavy metal pollution by Pb, Zn, Cu and Cd in soils and in dandelion plants in the city of Thessaloniki has been examined. 20 refs., 2 figs., 3 tabs.« less