Enhanced Cooling Efficiency of Urban Trees on Hotter Summer Days in 70 Cities of China

Increasing the urban tree cover percentage(TCP) is widely recognized as an efficient way to mitigate the urban heat island effect. The cooling efficiency of urban trees can be either enhanced or attenuated on hotter days, depending on the physiological response of urban trees to rising ambient temperature. However, the response of urban trees' cooling efficiency to rising urban temperature remains poorly quantified for China's cities. In this study, we quantify the response of urban trees' cooling efficiency to rising urban temperature at noontime [~1330 LT(local time), LT=UTC+8] in 17summers(June, July, and August) from 2003–19 in 70 economically developed cities of China based on satellite observations. The results show that urban trees have stronger cooling efficiency with increasing temperature, suggesting additional cooling benefits provided by urban trees on hotter days. The enhanced cooling efficiency values of urban trees range from 0.002 to 0.055℃ %-1 per 1℃ increase in temperature across the selected cities, with larger values for the lowTCP-level cities. The response is also regulated by background temperature and precipitation, as the additional cooling benefit tends to be larger in warmer and wetter cities at the same TCP level. The positive response of urban trees' cooling efficiency to rising urban temperature is explained mainly by the stronger evapotranspiration of urban trees on hotter days.These results have important implications for alleviating urban heat risk by utilizing urban trees, particularly considering that extreme hot days are becoming more frequent in cities under global warming.

Insights from i-Tree Eco-efficiency Assessment Management of Urban Trees in Oxford,UK

In the era of stock development following the acceleration of urbanization,the revitalization of urban green space has assumed an increasingly significant role.Consequently,the management of urban trees has emerged as a critical focus of urban governance,contributing to the enhancement of livability in human settlements.This study offers a comprehensive analysis of the urban tree management system in Oxford,UK,identifying that its primary objective is to optimize and maintain a harmonious balance between human activities and the natural environment through the implementation of high-quality planting practices.The system emphasizes enhanced management practices and establishes a robust framework for the development of targeted policies and management regulations,utilizing i-Tree eco-efficiency assessment and real-time feedback mechanisms.China’s urban tree management is in its nascent stages,and there is an urgent need for the development of urban green space.By adopting the refined management assessment methodologies employed for urban trees in Oxford,UK,it is possible to enhance the ecological value of urban trees,which represent a significant green resource within cities,and contribute to the creation of more livable urban spaces.

Analysis of socio-environmental impacts of the loss of urban trees and vegetation in Lahore,Pakistan:a review of public perception

Introduction:This paper focused on the process of urbanization in Lahore and its correlation with the loss of urban vegetation and perceived environmental impacts based on local population’s perception through administration of a questionnaire survey.Lahore is known as a city of gardens and green spaces in Pakistan and always possessed rich green character in its long history.For the past few decades due to rapid urbanization,the city has lost its aesthetically important urban vegetation,tress,and greenery.The field studies and remote sensing data revealed that the loss of vegetation has been experienced at an astonishing rate in many union councils of the city.Methods:This study was conceived to probe importance and value of the urban tress and vegetation of Lahore in an environmental context and its general importance for the residents of the city.The objectives were to analyze the role of vegetation in the life of citizens;the specific objective was to reveal the attitudes and responses of city dwellers about loss of urban trees/vegetation and its role in the overall environment,process of urbanization,and maintenance strategies.In the present paper,perception of local people(n=2080)regarding the socio-environmental impacts due to the ongoing process of urbanization and detriments of vegetation loss has been probed through administration of a household questionnaire.The collected data has been tested with respondent’s age,gender,marital status,education,monthly income,and occupation.Results:This study was an attempt to document and explore the change in historical transformation in vegetation and perception of the sample population of Lahore.This perception survey has revealed that urbanization is the major cause of loss of vegetation and has caused a number of perceived environmental problems in the city.Conclusions:The study underlined an analysis of people’s perceptions regarding the loss of trees and vegetation.The perceived socio-environmental findings revealed that the urbanization and population growth are the fundamental reasons for trees/vegetation loss in the city.

Study on the Effect of Reducing Haze by Urban Greening Trees

Although small in size, PM25 can do great harm to the environment, and city greening trees can reduce PM2.5 pollution to a certain extent. This paper reviewed the mechanism of city greening trees to reduce PM2.5 pollution, screening and classification of green land allocation model of PM2.5 reducing greening trees, and made prospect on how to construct the evaluation index system of PM2.5 re- ducing greening trees and urban green land allocation.

Damaging Agents and Tree’s Health Condition in an Urban Forest

Urban trees are subjected to different damaging agents throughout their lifetime. The aims of this study were to identify tree damaging agents, and to obtain a Damage Severity Index (DSI) in order to categorize tree health condition at San Juan de Aragon Park. Each tree was identified at species level in 28 randomly established plots in ten sections of the study area. Up to two types of damage were recorded per tree, based on the FIA (Forest Inventory an Analysis Program) protocol, and a DSI was obtained for each damaged tree considering location of damage, nature of the damaging agent and severity. A total of 753 trees were assessed and 12 species and 27 damaging agents were identified. Cankers, galls, the pepper tree psyllid and the red gum lerp psyllid were the most frequent damaging agents. Australian pine, red gum, Mediterranean cypress, Mexican white cedar, and California pepper were the most affected species. The DSI ranged from 3 to 17 and the average was 7.9. Sections J and H and the species California pepper, Australian pine, and Mexican white cedar presented the highest DSI. The tree population had a moderate health condition, while the aforementioned sections and tree species showed the poorest.

Effects of the urban heat island and climate change on the growth of Khaya senegalensis in Hanoi,Vietnam

Background: Recent projections expect that Vietnam will be affected most severely by climate change with higher temperatures, more precipitation and rising sea levels. Especially increased temperatures will worsen the situations in cities, amplifying the urban heat island effect. Green infrastructures, i.e. urban trees are a common rtool to improve the urban micro-climate for humans. Vital and well growing trees provide greatest benefits such as evaporative cooling, shading, air filtering and carbon storage. However, urban tree growth is often negatively affected by urban growing conditions such as high soil sealing with compacted tree pits providing small growing spaces with limited water, nutrient and oxygen supply, further warm temperatures and high pollution emissions. This study analyzed the growth of urban and rural African mahogany(Khaya senegalensis(Desr.) A. Juss.) trees in the city of Hanoi, Vietnam and the effects of the surrounding climate conditions on tree growth.Results: The results showed that rural African mahogany trees grew better than trees situated in the city center, which is contrary to other results on tree growth of temperate and subtropical cities worldwide. Moreover tree growth was similar regardless of the time of growth. Other results regarding stem growth of African mahogany located in different areas of Hanoi(east, west, north, city center) revealed a better growth in the northern and western outskirts of the city compared to the growth of trees in the city center.Conclusion: African mahogany trees in the urban centers of Hanoi showed a decreased growth compared to rural trees,which was likely induced by a low ground-water level and high pollution rates. In view of climate change and global warming, the decreased tree growth in the city center may also affect tree service provision such as shading and cooling. Those climate mitigation solutions are strongly needed in areas severely affected by climate change and global warming such as Vietnam.

Floristic and Structural Analysis of Urban Tree Canopy: From Its Ecology to Its Social Issues

Currently, urban areas are the largest segment of the world’s population, and they can reach up to 80% of it in some countries. Understanding green areas is of paramount importance to also understand the population’s mental health and well-being, as well as to achieve ecological understanding and its impact on urban infrastructure. Thus, the aim of the present study is to carry out a survey on both urban afforestation structure and on its social impact on a Brazilian municipality. It also sought to understand the damages caused by these species to urban infrastructure in comparison to data collected in 2009, to assess forest coverage in this municipality and tree planting underutilized capacity. Accordingly, all the streets in this municipality’s urban area, the botanical data of each tree and its damage to the city’s infrastructure and phytosanitary conditions were surveyed (from 1 to 5). Data were compared to those from the 2009 census, and social issues were analyzed. In total, 5044 individuals belonging to 189 species were recorded. The most often found species were Lagerstroemia indica and Murraya paniculata. Out of the total number of trees, 458 trees scored at least one score “5” in one of the criteria, and this number represents 8.9% of the total of the trees. L. indica was the species accounting for the highest rates of phytosanitary and infrastructure issues. Data comparison evidenced that urban tree canopy lost 25% of its vegetation between the two measurements taken herein, but the number of species has increased. When it comes to damages, many trees started showing phytosanitary issues or damage to urban infrastructure.

i-Tree Eco Analysis of Landscape Vegetation on Remediated Areas of Oak Ridge National Laboratory

The Oak Ridge National Laboratory (ORNL) is the largest and most diverse energy, research, and development institution within the Department of Energy (DOE) system in the United States. As such, the site endures constant land development that creates rigorous growing conditions for urban vegetation. Natural resource managers at ORNL recognize that trees are an integral component of the landscape and are interested in characterizing the urban forest and their associated ecosystem services benefits. We evaluated the urban forest structure, quantified ecosystem services and benefits, and estimated economic value of resources using i-Tree Eco at ORNL. While this assessment captured over 1100 landscape trees, the ORNL Natural Resources Management for landscape vegetation can be expanded to include unmanaged landscapes, e.g. riparian areas, greenspace, and other vegetative attributes to increase ecosystem services benefits. Assigning a monetary value to urban forest benefits help to inform decisions about urban forest management, ideally on cost-benefit analysis.

Biogenic Emissions of Volatile Organic Compounds by Urban Forests

All plants emit a wide range of volatile compounds, the so-called biogenic volatile organic compounds(BVOC). BVOC emissions have received increased scientific attention in the last two decades because theymay profoundly influence the chemical and physical properties of the atmosphere, and may modulate planttolerance to heat, pollutants, oxidative stress and abiotic stresses, and affect plant-plant and plant-insectinteractions. Urban forestry may have a high impact on atmospheric composition, air quality, environment,and quality of life in urban areas. However, few studies have been carried out where the emission of BVOCcould have important consequence for the quality of air and contribute to pollution episodes. A screening ofBVOC emission by the mixed stand constituting urban forests is therefore required if emissions are to bereliably predicted. Monitoring the emission rates simultaneously with measurements of air quality, plantphysiology and micrometeorology on selected urban forests, will allow detailed quantitative information onthe inventory of BVOC emissions by urban vegetation to be compiled. This information will make itpossible to propose an innovative management of urban vegetation in cities characterised by heavy emissionsof anthropogenic pollutants, aiming at the abatement of BVOC emissions through the introduction or selectionof non-BVOC emitting species in urban areas subjected to pollution episodes and in the new afforestationareas covering peri-urban parks, green belts and green corridors between peri-urban rural areas and theconurbations.

Urban Forestry Research in Europe-An Overview

A comprehensive European overview of recent and ongoing research in Europe has been carried out within the framework of COST Action E12 'Urban Forests and Trees', a pan-European research network. This paper presents some of the main findings of a comparative analysis of 20 individual country reports. The analysis shows that research on urban forests and urban trees in Europe has a wide scope and is rather fragmented and uncoordinated. Universities and state research institutes, mostly with a forestry or...

A field experimental study on the impact of Acer platanoides,an urban tree invader,on forest ecosystem processes in North America

Background:Invasive species affect community dynamics and ecosystem functions,but the mechanisms of their impacts are poorly understood.Hypotheses on invasion impact range from Superior Competitor to Novel Function,from Enemy Escape to Microbial Mediation.In this study,we examined the effects of an urban tree invader,Acer platanoides(Norway maple,NM),on a mesic deciduous forest in contrast to its native congener Acer rubrum(red maple,RM)with a split-plot design experiment.A total of 720 maple seedlings were transplanted to 72 plots under 24 trees of three canopy types.The three experimental treatments were removal of resource competition at above-and belowground and removal of leaf-litter effect.Soil moisture and nitrogen-related microbial activities were followed for each plot.Results:We found that partial canopy removal increased canopy openness and light transmission to the forest floor,but to a greater extent under NM than under RM trees.NM seedlings were more shade tolerant than RM seedlings in height growth.During the reciprocal transplantation in the mixed forest,biomass accumulation of NM seedlings under RM trees were twice as much as under NM,while that of RM seedlings under NM trees was 23.5%less than under RM.Soil net nitrification and relative nitrification were significantly higher,but mineralization rate was much lower under NM than under RM trees,which would lead to faster N leaching and lower N availability in the soil.Plots with litter removal had significantly higher seedling mortality due to herbivory by the end of 2 years,especially for NM seedlings under NM trees.Trenching enhanced soil water availability but there was no difference among canopy types.Conclusions:Our results demonstrated that invasion of NM not only altered forest canopy structure but also changed herbivory rate for seedlings and N dynamics in the soils.NM seedlings were more shade tolerant under NM canopies than RM seedlings and were more protected by NM litter under NM canopies than under RM canopies.These altered biotic and abiotic environments will likely facilitate further invasion of NM in the forests,hence positive feedbacks,and make it an increasingly serious tree invader in North America.

GREEN FURNITURE:AN ASSESSMENT OF FURNITURE SOCIETY MEMBER WORK

The Furniture Society is a member-based nonprofit organization founded in 1996.Its mission is to advance the art of furniture making by inspiring creativity,promoting excellence and fostering an understanding of this art and its place in society.By sponsoring a variety of programs that contribute to the education and enrichment of members and the public,the Furniture Society champions excel-lence,refinement,responsibility,and craftsmanship in furniture.It seems that when it comes to woodworking and working with our hands,we are inherently more connected to nature than many other occupations.I attend the Furniture Society’s annual conference every year in June.In almost every furniture maker presentation that I’ve listened to,the artist has mentioned nature as a source of inspiration.And in most encounters with fellow makers,I find that the lot genuinely tries to do good by our planet and its limited resources.Of course,the level of awareness varies among each maker,but consciousness of how we’re using resources seems to exist on at least some level.What is green furniture?There are many elements to consider when identify-ing green furniture,and I’ve listed only some of the ingredients below that respon-sible furniture makers are taking into account as they design and build.There are other elements to consider,and within the list below,one can continue to dissect each depending on the degree of responsibility a person chooses to pursue.Materials-How are materials sourced and used,and is there waste?Are they renewable,recyclable,reused or repurposed?Are they safe?Do they off-gas?Manufacturing Practices-Is the object designed well,and is it easy/efficient to manufacture?Are alternative sources of energy used during its manufacture?Use-Keep it out of the landfill!Is the object durable,useable,and/or multi-functional?What happens at the object’s end of life?Is it easily recycled or repurposed?Fair Labor-Are the folks involved in the manufacture of the object treated and paid fairly?Maybe this doesn’t apply to a one-person woodshop,but what about the laborers who made or processed the materials the furniture maker is using?Transportation-Is the object going to a local client?How are materials trans-ported to the woodshop or place of manufacture?How does the final product reach the client?Is the maker able to walk or ride a bike to work?Rather than try to place my own judgments about what’s green enough,I opted to highlight the green practices that Furniture Society members are endeav-oring.There’s always room for improvement just like there’s always more to learn.It’s my hope that this peek into what different makers,educators,and businesses are doing will inspire even better things to come.