Street Tree Management Research Articles

Inventorying and proposing solutions for street tree management in Thu Duc city, Ho Chi Minh City

Tree inventory plays an essential role in the urban landscape master plan. It serves as the foundation for data acquisition that supports the planning strategy and decisions relating to the community’s interests, particularly in recently established cities like Thu Duc city. This research was carried out from October 2021 to December 2022 in this city and aimed to inventory to gather qualified information for managing the city’s street trees. The study used an inventory form of street trees including criteria such as name, family, diameter at breast height (DBH), total height, and indicators of vitality and distance from trees to infrastructure. By this form, 287 streets were surveyed. The total number of investigated trees was 31.023 trees belonging to 65 species and 24 flora families, of which the species with a high percentage (from 10% or more) were Dipterocarpus alatus, Hopea odorata, Peltophorum pterocarpum, and Lagerstroemia speciosa. The most numerous plant family was Fabaceae. These trees typically had a height of less than 10 m, with a DBH of less than 20 cm. Many streets did not guarantee the distance between trees and infrastructure, particularly the distance to the electrical systems. The survey also showed that the majority of trees were healthy and grow healthily. From the current situation of Thu Duc city street trees, three solutions must be prioritized in order to improve street trees in this city.

Street Tree Management Strategies for Different Special-Purpose Areas: Using Citizen Science Data

Background and objective: This study investigated the occurrence characteristics of street tree management factors based on different special-purpose areas with emphasis on citizen participation in data collection.Methods: We collected growth and management data of street tree sections and individual trees within sections using a monitoring form developed for street trees in four special-purpose areas in the urban area of Chuncheon. We used a binary logistic regression model to analyze the probability of occurrence for each management factor (pruning traces, sign blocking, disease and pest, felled trees, piled objects, and broken branches).Results: The probability of occurrence of management factors varied by special-purpose area, which was related to the characteristics of each area.Conclusion: This study suggests the need to develop efficient street tree management strategies by prioritizing management factors in consideration of differences in special-purpose areas

Improving the ecological benefits evaluation on urban street trees: Development of a living vegetation volume quantifying framework with multi-source data

The rate of urbanization is increasing, and solutions to the pollution issue are desperately needed. Urban street trees are an essential factor in improving the environmental quality of cities. Quantifying precise ecological benefits of individual trees is important for monitoring urban ecology. However, since street tree surveys are time-consuming and expensive, it is challenging to assess the ecological benefits of street trees. Besides, there is still a need for more investigation into the advantages of multi-source data for ecological benefits estimates. Effective living vegetation volume (eLVV) as an urban green space indicator is beneficial for providing the vertical structure of street trees and offering a possibility for estimating the ecological benefits. The objective of this study is to evaluate the accurate ecological benefits of street trees by calculating eLVV. We developed and validated a framework for evaluating the ecological benefits of urban vegetation using point cloud and image processing techniques. Terrestrial laser scanning and unmanned aerial vehicle data were used to predict indicators at the single tree scale and road scale. Models based on game theory were applied to score all the indicators and assess the ecological benefits. The results showed that: (1) The proposed framework demonstrated that multi-source data allowed for the exact indicators of ecological benefits. (2) The eLVV of the street trees on two roads was less on the north side than on the south side, reflecting the difference in the ecology of the street trees in terms of orientation. This paper explores the advantages of multi-source data in measuring detailed ecological benefits, which support the digital management of street trees and the sustainability of regional ecology.

Distribution Pattern of Urban Street Trees in Rome (Italy): A Multifactorial Evaluation of Selection Criteria

Street trees play a significant ecological role in modern urban ecosystems, but usually the selection criteria follow pragmatic reasons rather than bio-ecological suitability. Understanding the influence of such factors can be relevant, especially in cities having a certain complexity and area. This paper aims to analyze the variation in the distribution of street tree species within the city’s municipia of Rome to determine the influence of some factors in the selection process. Here, we have described the species of street trees in fourteen municipia of Rome, and we created five clusters of factors (bio-ecological, aesthetic, historical–cultural, health, and economic) that could constitute selection criteria for street trees. From our data analysis, the municipia of Rome were grouped into four main groups and the choice of trees was based on multiple selection criteria. Foliage type, longevity, fruit type, autochthony, and economic value were the primary criteria. In 90–100% of municipia, deciduous species dominate, with 50–150 years longevity, dry fruits, exotic species, and prices of <€500 per tree. Additionally, the flower type, allergenicity, size class, and cultural value were the secondary criteria. The biological and ecological characteristics of trees are key factors to consider in order to reduce the management of street trees and relative costs.

A Study on Street Tree Maintenance: Focusing on Suseong-gu, Daegu in South Korea

Purpose: In urban society, street trees are closely related to our lives. However, many people do not recognize the existence and necessity of street trees on ordinary days. This study investigated the changes in the growth of street trees exposed to environmental damage and artificial management due to street maintenance. This paper aims to provide necessary data for street tree management by analyzing changes in the growth of street trees according to the road size in terms of temporal change and management of street trees.
 Method: Field surveys were conducted from June to September 2021 to identify the direction of maintenance for street trees by road size. The researchers collected and analyzed data on street tree roads and basic plan data on street trees in Suseong-gu in 1997. This paper conducted One-way ANOVA by six items(tree height, root-collar diameter, crown width, diameter at breast height, degree of tree health, and degree of environmental damage). Microsoft Office Excel 2007 program and Spss Statistics 21 statistical program were used for statistical analysis.
 Results: As a result of analyzing the current state of street trees in 2021 and the change amount by road size in 1997 data, on average, the tree height increased by 5.4m, the root-collar diameter increased by 22.3cm, the crown width increased by 2.1m, and the diameter at breast height increased by 12.8cm. The degree of tree health decreased by 0.2 points, and the degree of environmental damage decreased by 1.1 points.
 Conclusion: The tree form of street trees did not have a natural tree shape due to artificial management, and street trees were damaged due to lack of management and damage from surrounding shops. The analysis results show that the appearance of street trees has grown, but street trees' growth aspects(tree health, environmental damage) have regressed due to incorrect pruning work with tall trees according to laws and ordinances. This paper suggests that street trees' species selection and improvement supplement work should be done through continuous research in the future, and systematic and efficient management should be continuously carried out for satisfaction with street trees and pedestrians.

Evaluating the quality of street trees in Washington, D.C.: Implications for environmental justice

Urban street trees are part of the bundle of environmental amenities that support healthy social, economic, and environmental functions. In this study, we systematically evaluate the quality of 196,825 street trees at the US. Census tract level in Washington D.C., as well as related impacts from socioeconomic, landscape patterns and environmental factors using Ordinary least-squares (OLS) regression, geographically weighted regression (GWR) and structural equation modeling (SEM). Our results reveal that environmental and socioeconomic factors can explain most of the spatial variation of street tree quality in Washington, D.C. There is a substantial statistical negative relationship between median household income and the percent of street trees under stress, which provided the evidence of the inequities of street tree quality in Washington D.C. Higher-income neighborhoods exhibited a lower proportion of street trees under stress. In addition, the extreme summer temperature is positively associated with the proportion of street trees under stress. The quality of street trees is directly impacted by environmental and landscape pattern factors. There is also an indirect impact from socioeconomic factor toward quality of street trees. Our findings suggest that multiple variables, related to income, age, education, landscape pattern, and environment contribute to the quality of street trees in D.C. Based upon our findings, we identify strategies and insights for urban street tree management in DC to not only address environmental inequity and injustice, but also promote a more inclusive and resilient urban greenery system.

Understanding Urban Residents’ Perceptions of Street Trees to Develop Sustainable Maintenance Guidelines in the Seoul Metropolitan Area, Korea

Street trees play a crucial role in improving urban environments, and their management depends on the perceptions and preferences of urban residents. This study surveyed 884 urban residents’ preferences and perceptions towards street trees in a metropolitan area in Korea and proposed guidelines for their sustainable management. Urban residents were aware of the presence of street trees based on visual changes and were generally satisfied with their shape, size, and growth. They preferred trees that provide environmental and ecological services, such as offering shade, purifying the air, and preserving the ecosystem, while viewing the generation of debris from street trees as the most significant problem. Urban residents’ perspectives on street tree preference and issues varied based on age, income, and housing type. Although urban residents acknowledged the need for the maintenance and management of street trees, they believed that this was the responsibility of central and local governments, not local residents. Collectively, the residents had a positive view of urban street trees and believed that maintenance and management are necessary to address problems caused by their presence. Our research findings provide valuable information to help city and landscaping experts select street tree species and establish maintenance and management strategies.

가로수 현황 및 담당자 인식조사를 통한 개선 방안

This study investigates the status of street tree plantation and management in 17 metropolitan cities and provinces of local governments from the time the management of street trees, which are beloved by citizens, was transferred to the Korea Forest Service until now, 20 years later. It also surveys the consciousness of public officials in charge of street tree management in order to find a more efficient management method. First, this study reviewed the definition, history, function and effect of street trees through theoretical considerations, and also looked into the departments responsible for street tree work, relevant laws and policies, and so on. In addition, previous studies such as street tree selection, function, current status and analysis, growth environment, and maintenance were reviewed. In order to investigate the current status and condition of street tree management, the Forest Service statistical data such as the Forestry Statistical Yearbook and the performance report of the street tree creation and management were used to investigate the new street tree status (by tree type, city/province), the cumulative status of street trees (by tree type, city/province), street tree management status (per each category, city/province), street tree civil complaints, city/province street tree project cost, and street tree education status under the jurisdiction of the Korea Forest Service. The awareness survey of public officials in charge of street tree service consisted of「Identification of the subjects of the survey and matters related to work/organization」and「Matters related to the creation and management of street trees」, and surveyed public officials in charge of street tree service in 17 metropolitan cities and provinces of local governments.

도시 가로수 관리 품셈 개선에 관한 연구†

This study aims to provide basic data for high-quality street tree management by setting reasonable management items and appropriate unit prices by reviewing the adequacy of current street tree management. Currently, street tree management items, except for street tree pruning, use general landscape tree quantity per unit for the street tree management quantity per unit. KEPCO (Korea Electric Power Corporation) applied pruning items from standard electric production infrastructure and carried out the activities at an average unit price of 51% lower for heavy pruning and 39% lower for light pruning than the standard estimate. This was judged to be a level that could not maintain or increase the quality of street tree management. It was determined that an appropriate standard unit price for street tree management was necessary. To improve the quantity per unit for the proper management of street trees, it was necessary to review costs in the field. However, due to the absence of data on actual construction costs in the domestic landscape field, detailed items of the US RSMeans Building Construction Cost Data (RSMeans) were reviewed, and the actual construction costs were calculated by applying personal domestic expenses. As a result, the standard of the estimated unit showed a good ratio of 107% for heavy pruning of street tree pruning compared to the actual construction cost, but light pruning was underestimated with a 59% ratio. Shrub pruning was 82%, weeding was 92%, tree fertilization was 87%, and windbreak wall installation was 91% under-engineered. In addition, it was also confirmed that the watering by sprinkler trucks and chemical spraying were over-designed compared to the actual construction cost at the rates of 118% and 124%, respectively. Due to the specificity of the street trees, the increase in personal expenses and the input cost of equipment, such as road safety controls, were judged to be the main cause of the underestimation of items. Therefore, it is necessary to add items related to street trees and general landscape trees to the landscape maintenance items of the standard of the estimated unit.

Estimating Carbon Budget from Growth and Management of Urban Street Trees in South Korea

Although street trees take up carbon by vegetation growth, they emit carbon directly or indirectly into the atmosphere due to the need for regular management, such as pruning and, irrigation, etc. This study estimates the annual carbon budget from the growth and management of urban street trees in South Korea and suggests management strategies to minimize the degree of management and annual carbon emissions. Annual carbon emissions from management practices such as pruning, irrigation, pesticide and fungicide application, and fertilization were estimated based on maintenance data, interviews with managers, and actual measurements. Annual carbon emissions from the management of urban street trees were calculated to be 2.4 kg/tree/year. From this total, pruning was the largest contributor at 91%. The average net carbon uptake for each street tree was 5.5 kg/tree/year. The street trees included in this study played an important role in carbon uptake, which was equivalent to 90–550% of the annual carbon emissions from street tree management. Based on these results, suggested management strategies include pruning, irrigation, pesticide and fungicide application, and fertilization. These study results will be useful for designing practical low-carbon landscapes with minimal management and carbon emissions.

Classification of Street Tree Species Using UAV Tilt Photogrammetry

As an important component of the urban ecosystem, street trees have made an outstanding contribution to alleviating urban environmental pollution. Accurately extracting tree characteristics and species information can facilitate the monitoring and management of street trees, as well as aiding landscaping and studies of urban ecology. In this study, we selected the suburban areas of Beijing and Zhangjiakou and investigated six representative street tree species using unmanned aerial vehicle (UAV) tilt photogrammetry. We extracted five tree attributes and four combined attribute parameters and used four types of commonly-used machine learning classification algorithms as classifiers for tree species classification. The results show that random forest (RF), support vector machine (SVM), and back propagation (BP) neural network provide better classification results when using combined parameters for tree species classification, compared with those using individual tree attributes alone; however, the K-nearest neighbor (KNN) algorithm produced the opposite results. The best combination for classification is the BP neural network using combined attributes, with a classification precision of 89.1% and F-measure of 0.872, and we conclude that this approach best meets the requirements of street tree surveys. The results also demonstrate that optical UAV tilt photogrammetry combined with a machine learning classification algorithm is a low-cost, high-efficiency, and high-precision method for tree species classification.

The state of a street tree management plan and a citizen participation system in local Japanese government

In this study, we will understand the actual situation of street trees maintenance management systems in local governments in Japan and the development status of street trees maintenance management plans and management guidelines. Next, this study was to understand the current state of the street trees maintenance management system and its impact, and to investigate the problems of citizen’s participation in street trees maintenance management. As a result, street trees maintenance work is mainly done in the civil engineering road sector. In large local governments, staff specializes in landscaping, while in small local governments, it’s mainly civil engineering. In addition, most street trees management methods are outsourced by contractors, with less than half direct management by staff. The policy to maintain street trees is positioned in many local government green master plans. Since 2015, local governments have developed conservation plans for street trees and are working on sound conservation. Since the 2000s, local governments have been working on maintenance management systems with the participation of residents. Most of them are road beautification activities based on adaptive systems. In the future, the challenge will be to further expand the system and raise citizen’s interest and value perception.

Street tree management and its recent movements in abroad

Street tree management and its recent movements in abroad

Street Tree Diversity in Massachusetts, USA

Pests, disease, and climate change pose major challenges to street tree survival, and diversity in tree species and genera is widely considered to promote the sustainability of municipal street tree populations. Conversely, the lack of sufficient diversity in street tree population was judged a contributing factor in the death and removal of thousands of street trees in Worcester, Massachusetts, that state’s second most populous city, due to an infestation of the Asian longhorned beetle (ALB, Anoplophora glabripennis). Therefore, reducing the dominance of prevalent street tree species and genera and increasing tree species and genera diversity are considered vital to sustainable street tree management and to the preservation of the ecosystem services and social benefits that street trees provide. This paper assesses street tree diversity in Massachusetts by analyzing a nonrandom sample of collated municipal street tree inventory data stratified by plant hardiness zones. Consistent with results previously found for Connecticut, New Jersey, New York, and Pennsylvania, results in Massachusetts indicate that a relatively small number of species and genera dominate the composition of most municipal street tree populations, including in particular Acer spp. (maple), one of the ALB’s favorite host genera. There is accordingly a need for greater species and genus diversity in municipal street tree populations statewide. While there may be a trend towards increased street tree diversity and reduction in the dominance of Acer spp., considerable work remains to be done.

Importance of urban street tree policies: A Comparison of neighbouring Southern California cities

Research points to numerous benefits provided by urban street trees including qualitative and quantitative public health, economic, and environmental advantages for a city and its residents. As with other key aspects of city management that help develop municipal success, urban forestry requires foresight, commitment and planning that lead to effective policies and strategies. Good street tree management based on effective policies can maximise street tree benefits. Poorly conceived policies or the absence of effective policies can lead to the opposite result. A case study of the neighbouring cities of Loma Linda and Redlands, California illustrates this difference. The urban tree care and protection policies in these two cities have evolved differently. The differences may be attributable to contrasting municipal commitments to preservation and to best-practice management principles. Based on a comparative analysis of street tree policies of the two cities, it can be concluded that a local culture favouring tree protection and reflective guidelines and policies can result in proactive and successful management of an urban forest. Such policies also include provision for gathering data essential for strategic tree planting, care and removal.

Street Tree Diversity in Three Northeastern U.S. States

Street tree diversity is widely viewed as a key component in the resilience of street tree populations to pests, diseases, and climate change. Assessment of street tree diversity is considered integral to sustainable street tree management and preservation of the ecosystem services and social benefits that street trees provide. This paper assesses street tree diversity in three northeastern U.S. states—New Jersey, New York, and Pennsylvania— by analyzing municipal street tree inventory data stratified by the 2012 USDA Plant Hardiness Zones. Despite the lesson learned from the historical devastation of overplanted American elms (Ulmus americana) by Dutch elm disease, and awareness of the contemporary threats posed to ashes (Fraxinus spp.) by the emerald ash borer (Agrilus planipennis) and to maples (Acer spp.), and other tree genera by the Asian longhorned beetle (Anoplophora glabripennis), results presented here indicate a current concentration of street trees among a relatively small number of species and genera, and in particular the dominance of maples as street trees. Results also show a positive relationship between street tree diversity and warmer average minimum winter temperatures. Consequently, there is a clear need in all three states for greater species and genus diversity in statewide and municipal street tree populations. However, meaningful impediments exist to increasing street tree diversity, especially in the short term.

Developing the volume models for 5 major species of street trees in Gwangju metropolitan city of Korea

Street trees are one of the most important parts of an urban forest system because they have various functions including environmental conservation, harmony of scenery, traffic safety, and prevention. Moreover, of the analysis factors considered for street trees, volume is mainly used not only for further research on health assessment, environment analysis, carbon storage estimation, and economic analysis, but also for local government management of street trees. For this reason, this study was performed to develop volume models for the 5 major species of street tree of Gwangju metropolitan city in Korea. After selecting the 5 major species – Ginkgo biloba, Zelkova serrata, Metasequoia glytroboides, Prunus serrulata, and Platanus occidentalis – one hundred sample trees of each species were randomly chosen considering diameter at the breast height (DBH), and then diameter at every 2m height, height, and crown radius were measured. Volume was calculated using the Huber equation. Regression analysis, variance analysis, and descriptive statistical analysis were conducted using the 4 regression equations, and the best volume model was chosen by comparing precision, accuracy, credibility, and normality. From the results, all species showed the same patterns according to model type. That is, models that included diameter and height out-performed models with crown basal area had the highest precision, while model type IV using crown basal area (CBA) as a parameter showed the lowest goodness of fit because CBA can be influenced by volume, planting distance and space, or pollarding. Thus, using DBH and H together should be suitable for designing the volume models for urban-grown trees. However, properly trained experts are very important in order to avoid measurement error. Moreover, a large amount of data on Platanus ocidentalis is required to avoid large error in volume due to pollarding treatment. To sum up, model type III was chosen as the best fit models for all species with lowest MSE and highest R2, and that models can be used to forecast the volume of and making ordinances for street trees in Gwangju metropolitan city, Korea.

商店街商業者の意識に基づく商店街の活性化に資する街路樹のマネジメントに関する研究

The purpose of this study is to clarify factors of efforts concerning street trees contribute to the activation of the shopping districts and to consider the direction of the future management of street trees. In this study, first, we carried out a questionnaire survey. The subjects of investigation were shopping districts with street trees in Hokkaido. The contents of the questionnaire survey were “Current Status of efforts for the activation of the shopping districts”, “Effect of shopping districts expect to street trees” and “Satisfaction for the efforts concerning street trees of shopping districts”. Then, we conducted the aggregate and analysis of data obtained as a result of the questionnaire survey. The results are as follows: 1) There is a difference in the efforts for the activation of the shopping districts. 2) There is a recognition for shopping districts merchants that Street trees is a regional resources. 3) Satisfaction with the efforts concerning street trees is 3.5 point (5-point scale). 4) Shopping districts merchants have the expectation and satisfaction with changing properties of people who come to the shopping districts by management of street trees. 5) Shopping districts merchants have begun to expect for the economic effects of their shop.

A cloud-based spatial-temporal inventory for sustainable urban soil management

Spatial and temporal databases that integrate urban tree inventories and soil quality information are needed for modern-day sustainable urban forest management. The objective of this study was to demonstrate the usefulness of low-cost and widely-available technology, such as global positioning system (GPS)–enabled cameras to photo-document sites and cloud-based products and services (Google Picasa and Fusion Tables), to aid in developing sustainable street tree management programs. Google Fusion Tables provide a cloud platform to store, share and map urban tree and soil data over time using internet connected computers, tablets or mobile devices. Although indicators of urban soil quality and best methods to assess it are not yet standardized, we demonstrate here promising indicators that are both useful and easy to incorporate into spatial and temporal databases of trees managed in urban environments. By utilizing technology, we demonstrate that site-specific urban soil quality indicators can be used together with readily-available soil rating systems specific to different plant types as a means to better evaluate and manage conditions for optimal street tree growth and health.

Simple Street Tree Sampling

Information on street trees is critical for management of this important resource. Sampling of street tree populations provides an efficient means to obtain street tree population information. Long-term repeat measures of street tree samples supply additional information on street tree changes and can be used to report damages from catastrophic events. Analyses of several street tree populations reveal that a 2%–3% sample of block segments with known length within a city will likely produce estimates on the total number of trees with a standard error around 10% of the total population estimate (relative standard error of 10%). Ratio estimates of number trees per length of street sampled reduced the number of block segments needed to attain a 10% relative standard error. Communities with a small tree population, or analyses of specific subsets of the population (e.g., individual species information), will likely need a higher proportion of block segments sampled to attain the same relative precision. This paper presents a simple means to sample street tree populations to aid in street tree management and presents information on how many block segments need to be sampled to achieve a desired sampling precision. Results can be used to develop simple, cost-efficient, and accurate means to sample street tree populations.