Results and conclusion: Some trees have the most translu- cent shadows most likely due to nictinastic movements and consequently less temperature attenuation. On the other hand, other trees have denser shadows and can generate more substantial thermic attenuations. Regarding temper- ature data, the hour of the day shows the greatest influ- ence on the variability of air temperature and the species shows the greatest influence on the variability of surface temperature. Honey berry (Meliccoca bijugatus) and Malay almond (Terminalia catappa) trees have denser shadows and can generate more substantial thermic attenuations. Tree physiology can play an important role in temperature attenuation in cities as a result of shadow effects and can be applied as a criterion to select urbantrees in tropical cities.
Urban forests provide several ecosystem services such as reducing the effects of the urban heat island by providing shade (Brabant et al. 2019), promoting biodiversity, decreasing air temperature and promoting urban aesthetic values (Aval et al. 2019). In this way, urbantrees improve the quality of urban life and reduce stormwater runoff, decrease air pollution and maintain environmental health (Li et al. 2019). The ecosystem services provided by urbantrees vary with tree type, structure, density and location (Pretzsch et al. 2015). Trees such as Platanus spp., Quercus spp. and Eucalyptus spp. are often selected as urban forest trees because of their height and broad leaves which can suppress noise, provide shade and act as windbreaks (Love et al. 2009). Proper planning, monitoring and use of sustainable management practices such as urban greening are crucial measures for ensuring a balance between the natural environment and human developments through careful use of such long-lived resources, caring for the inheritance of future generations (Dizdaroglu et al. 2009). An effective urban forest management plan requires precise and timely information on the patterns, distribution and conditions of the trees at both spatial and temporal levels, and remote sensing could be an effective tool to accomplish such mapping and assessment (Li et al. 2019).
The services that urbantrees provide to human society and the natural environment are widely recognized, but urbantrees are in jeopardy due to climate change and urban stressors. With drought as a major threat in many areas, it is important for the future of urban forestry to select species composition based upon performance under water stress. Certain leaf functional traits can help horticulturalists more accurately predict water usage of urbantrees. Comprehension through rigorous experimentation is lacking, partly due to the thousands of mostly exotic species. Previous studies suggest that species whose leaves have a denser arrangement of smaller stomata and a higher leaf mass per area (LMA) are better adapted to low water availability. We sampled 70 urban tree species California and analyzed their stomatal length, stomatal density, and LMA. We compared the traits with water use data from the Water Use Classification of Landscape Species to assess possible correlations. All pairwise trait comparisons show significant correlation (P < 0.05), and LMA is significantly higher in low water use species
Urban ecosystems are an important component in the global carbon cycle. In the context of urban sprawl, quantifying the carbon storage for urban areas is very important in terms of getting reliable estimation of carbon sequestration rate and magnitude. But it is a difficult and complex task that requires advanced analysis techniques and data sources to achieve fine- scale estimation. The methods developed here provide an accurate and detailed estimate of how urbantrees in a Canada’s city plays the role as a carbon sink. The presented approach of estimating carbon stocks in urbantrees takes the advantages of the available Canada-wide allometry relationship between biomass and the tree DBH and height, and also the power of the ALS system in providing the estimation of dendrometric parameters. The methodology proposed in the present study does not require destructive sampling or large-scale field works. It is applicable to other urban areas and is beneficial to better understand urban carbon budgets and urban heat island effects. It also provides valuable information on the impact of climate change to city planners.
This method is experimented in an urban environment to test the performance for detecting urbantrees. The classified output of urbantrees is further overlaid with the cadastral parcel layer of study area in order to generate parcel level statistics. These metrics can be meaningful to guide urban planning and land management practices. The urban tree density map of cadastral parcels will have research as well as policy impacts. Further research on ecological abundance, foraging of birds and habitat mapping will be benefited by the density map produced in this research. In term of policy, the output from this research will inform urban planner and cadastral surveyors to bring in their planning of urban suburbia.
Urban vegetation is one of the determining factors in in- creasing the market values of vicinity properties (Lindsey et al. 2004; Saphores 2012), thereby having a considerable commercial importance. Urban green spaces provide employment opportunities and help attract businesses and tourists to an area (Swanwick et al. 2003). The city’s vege- tation effectively plays its role in moderating urban heat island impacts and urban hydrology and air quality and in reducing noise pollution as well as the energy demands (Pauleit and Duhme 2000; Fang 2005; González et al. 2005; Konijnendijk et al. 2005). What is not known is how resilient urban vegetation is and will it change over time. This is particularly relevant in the context of predictions for climate change and changing social and personal values related to open space (Wu 2008). Urbantrees and vegetation have profound effects on biodiversity and also on provision of aesthetic, psychological, and socioeco- nomic ecosystem services to the dwellers (Schoeder and Cannon 1983; Ulrich 1986; Kaplan and Kaplan 1989; Huang et al. 1992; Kaplan 1992; McPherson et al. 1994; Sullivan and Kuo 1996; Wolf 1999; Nowak 2001). There- fore, the study of environmental-related issues and conse- quent impacts due to urbanization has now become an area of prime importance (Chen 2007; Li and Yao 2009; Martínez-Zarzoso and Maruotti 2011).
forests (76 tC/ha; 77 tC/ha per unit of tree cover). A high fraction of those forest-like areas in the city of Leipzig certainly contributed to a high city-wide average of 68 tC/ha per unit of tree cover compared to our Berlin case study of around 24 tC/ha per unit of tree cover (Strohbach and Haase 2012). Therefore including such less urbanized land of high tree coverage in our calculations could have substantially affected and increased the average urban forest carbon density of the city of Berlin. Schreyer et al. (2014) calculated the carbon densities of urbantrees for selected urban Berlin structure types. Those calculations were extrapolated across the total city including those dense woodlands resulting in an average density of 11.53 tC/ha for the city of Berlin. Similar differences were shown for the city of Karlsruhe, Germany, which stated urban forest carbon estimates of 9.5 tC/ha carbon for highly urbanized areas, and an exponential increase to a total average of 32.3 tC/ha, if state and city forests were included as they are part of the administrative boundaries of Karlsruhe (Kändler et al. 2011). Tree density is influenced by various factors in different case studies such as land use, differences between countries and city development. For example, our results of Berlin had an average range of 10–40 trees/ha across densely built areas (excluding parks and forest-like areas), which is close to the average of 30.7 trees/ha in the city of Karlsruhe, Germany (Kändler et al. 2011). Residential areas of Cambridge, UK, showed a range from 33.7 to 55.7 trees/ha (Wilson et al. 2015). Almost 80 % of 167 cities in the state of Gujarat, India, showed values below 30 trees/ha compared to its capital Gandhinagar with an average of 152 trees/ha (Singh 2013). For selected US cities, the average tree density had a large range from below 25 (Casper, Wyoming) up to 280 trees/ha (Atlanta, Georgia) (Nowak et al. 2008). Hence, tree density differences certainly have a large impact on carbon density values, which needs to be considered for comparisons between and within cities. Additionally, carbon density would slightly increase, if we included root biomass. Though, our case study excluded it since little research has been conducted on the carbon storage of urban tree root systems and high uncertainty surrounds the research that has been conducted (Nowak and Crane 2002; Johnson and Gerhold 2003).
The traditional methods for evaluating the forests’ value include the opportunity costs, the estimated maintenance costs and the forest production value. These methods are based on assessing the market value of forest goods, so their use in city forests is limited . The methods used in evaluating the benefits (services) of forests without including the market value are: Contingent Valuation Method (CVM), Hedonic Price Method (HPM) and Travel Cost Method (TCM). Additional methods for evaluating the benefits of city forests include the tree value evaluation and the ecological benefit evaluation [4, 10]. Putting value on urban forest benefits helps the decision makers to make informed decisions about urban forests, ideally based on cost- benefit analysis. This is in line with the concept of usable science, where scientific results can serve as valuable information to the political actors in the process of deliberation . The objective of this research is to determine monetary values of urbantrees in Ribnjak Park using Danish method.
Direct estimation of percent carbon was done by a CHN analyzer. For this, a portion of fresh sample of stem, branch and leaf from selected trees (two trees/species/plot) of individual species (covering all the selected plots) was oven dried at 700C, separately ground to pass through a 0.5mm screen (1.0mm screen for leaves). The carbon content (in %) was finally analyzed for each part of
Plants represent an important link in transport and distribution of radionuclides, heavy metals and other pollutants in the environment and are often used as biomonitors of atmospheric 2004; Djuric and Popović 1994; Aničić little is known regarding bio-monitoring of radionuclides from environment; even less is known about radionuclide contamination and removal by vegetation in khadra and Eissa 2008). As known, higher plants monitors of environmental pollution as et al., 2003; Popović et al., 2008). However, in urban areas where moss and lichen are rarely found, higher plants could alternatively be used for biomonitoring purposes (Smith et al 2004; Popović et al., 2009;). Identification of tree species that can biologically monitor air pollution and can endure air pollution is very much important for a sustainable green belt development around any et al., 2010; 2011; 2012a, b, c; As an environmental stress, large doses of radionuclides due to increase of anthropogenic activities are known to induce adverse effects on organisms (Wi et al., 2005; Reisz et al., 2014). Physiological responses as defensive mechanisms are loped by plants to protect themselves under various stress including radiation. Many studies focused on various aspects of the defense mechanisms in plants, such as the activity of
urban areas the roadside trees are in the close proximity to the source of vehicular emissions. They serve as an important component in reducing such emissions. In this city the urban tree cover provides benefits such as carbon storage and sequestration along with the reduction in the air pollutant. Keeping in mind the above relevant facts the need for evaluating and assessing the roadside tree cover in an urban ecosystem becomes imperative. This green cover in the form of urban forest has a significant potential in carbon sequestration (Nowak et.al. 1994). Nowak, 2002 has brought out that Carbon sequestration is not only related to the increased tree cover but also very much related to the increased proportion of large and healthy trees in population. In the present study this point is very clearly brought out as certain roads of Vadodara city with similar number of species exhibited variation in the values of the carbon sequestered (Table 1). The amount of carbon sequestered by these road side trees has amounted to 73.59 tons (Table 1) of carbon dioxide per year. The source of carbon sequestered by these trees can be attributed to the different categories of vehicles passing by these trees.
roughness and consequently the evolution of the mixing-layer height. These changes in local meteorology can alter pollution concentrations in urban areas b . Although trees usually contribute to cooler summer air temperatures, their presence can increase air temperatures in some instances c . In areas with scattered tree canopies, radiation can reach and heat ground surfaces; at the same time, the canopy may reduce atmospheric mixing such that cooler air is prevented from reaching the area. In this case, tree shade and transpiration may not compensate for the increased air temperatures due to reduced mixing d . Maximum mid-day air temperature reductions due to trees are in the range of 0.04 o C to 0.2 o C per percent canopy cover increase e . Below individual and small groups of trees over grass, mid-day air temperatures at 1.5 m above ground are 0.7 o C to 1.3 o C cooler than in an open area f . Reduced air temperature due to trees can improve air quality because the emission of many pollutants and/or ozone-forming chemicals are temperature dependent. Decreased air temperature can also reduce ozone formation.
From our review, we argue that decision making frameworks need to be locally tailored and embedded into bottom-up decision making processes. This enables communities to articulate what matters to them about urbantrees, and not just have technical scientific mean- ings used to justify ecological interventions (e.g. Tadaki et al. ). Urban greening initiatives should be pur- sued through a process where the multiple meanings of urbantrees (cultural as well as scientific) can be articu- lated and deliberated together. A universal list of poten- tial societal benefits provided by urbantrees (such as those listed by Roy, et al. ) can provide a starting point for conversation with affected stakeholders about how urbantrees might become meaningful to the future of a particular community, but scientific lists and frame- works should not be used instead of meaningful engage- ment from diverse community voices and perspectives. Frameworks such as the ‘Right Tree Right Place’ check- list for urbantrees in London  can provide sensitiz- ing questions that draw on accumulated scientific knowledge, while also requiring and supporting context- ually specific and locally justified responses.
Impervious surface cover can benefit pests by increasing the local temperature and by causing tree stress (Raupp et al. 2012; Meineke et al. 2013; Dale & Frank 2017). Thus, as the area of impervious surface around a tree increases, pest abundance and damage often increase too (Speight et al. 1998; Sperry et al. 2001; Dale et al. 2016; Just et al. 2018). For example, impervious surface predicted nearly 50% of the variation in abundance of the invasive Asian citrus psyllid in urban landscapes, five times more than any other environmental variables (Thomas et al. 2017). Likewise, infestations of horse chestnut scale, mimosa webworm, and honey locust spider mite become more severe as the amount of impervious surface around trees increases (Speight et al. 1998; Sperry et al. 2001). Mechanisms underlying these patterns include higher development rate, population growth, fecundity, and winter survival (Hart et al. 1986; Raupp et al. 2012; Dale & Frank 2014b). The relationship between pest density and impervious surface is typically evaluated on established trees that already have pest infestations (e.g., Sperry et al. 2001; Dale et al. 2016). Thus, little is known about the progression of pest density on trees from the time of tree planting to maturity. Pest density may gradually increase over time in relation to variables such as impervious surface, or pest populations may erupt at particular periods in tree development. Understanding the progression of pest density on urbantrees will identify times when scouting or other IPM tactics will be most effective to identify or prevent infestations.
under particularage group was compared (Table 3), it was found that a 40 years Ashoka tree (Polyalthia longifolia) has a potential 54 times higher than a 5 year old Ashoka tree. Similarly, Raintree (Samanea saman) with a age above 50 years, sequestered carbon 21 times more than a tree of 15 years of old tree. It may be noted that Ashoka tree (Polyalthia longifolia), Desi badam (Terminalia catappa) and Saptparni (Alstonia scholaris) are the most commonly preferred trees during any tree plantation drive, as these are fast growing and occupy comparatively lesser canopy area. Some researchers also estimated as low as 1.0 Kg (0-7 cm DBH) to as high as 92.7 Kgs (77+cm DBH) of C sequestration/tree/year for urbantrees(Nowak, 1994 b).Also it may be noted that different tree species of similar age exhibited different potential for carbon sequestration. Ashoka (Polyalthia sp.) of age 5 years sequestered only 5.63 Kgs C/yr, half the amount as compared to Saptparni (Alstonia sp.) and Desi badam (Terminalia sp.) (Table 3). Moreover, a 15 year old Saptparni (Alstonia sp.) sequestered 78.2 Kgs C/year and it was almost double than the amount sequestered by Raintree of similar age (35.24 Kgs C/year). The data reflected that Desi badam (Terminalia catappa) appears to be one of the best candidate for tree plantation in the urban space, as this plant besides growing fast also displayed higher carbon sequestration potential compared to other trees in the study area (Table 3). The ability of Desi badam (Terminalia catappa) to sequester more carbon than the other trees from the study site may be attributed to the larger leaf area (leaf size) of the plant (Villers et al., 2014). Stocks of organic carbon in soil vary with land use systems. The share of soil organic carbon in the total carbon stock may vary from 50% to 84% in forests to 97% in grasslands.
The morphological and anatomical traits in leaves can serve as a bioindicator of plant response to altered environmental conditions, specifically air [15,24] and soil [2,25, 26] pollution. Trees exposed to auto-exhaust pollution exhibited leaf structural changes (e.g., increased stomatal density, trichome length, collapsed epidermal cell), yet no differences in leaf phenology . Leaf size and stomate density were reduced in London plane trees in a highly urbanized environment compared to a rural area; however, area of palisade parenchyma cells and spongy parenchyma cells were unchanged with urbanization . In many disturbed ecosystems and experimental studies, reports of dryer or wetter soils [2,27], soil contaminant enrichment , and altered soil biogeochemistry  seem to result in contrasting plant response traits [11,19,20,24,30,31]. Tree species that display morpho-anatomical responses and physiological acclimation to abiotic stressors in contrasting environmental impacts can provide more insights into multiple cumulative impacts on urbantrees. In urban environments, red maple trees exhibit enhanced productivity  and increased concentration of secondary metabolites , which suggests red maple trees physiologically acclimate to urban conditions, yet little is known about red maple morphological and anatomical responses to urbanization.
Cities profoundly alter biological communities, favoring some species over others, though the mechanisms that govern these changes are largely unknown. Herbivorous arthropod pests are often more abundant in urban than in rural areas, and urban outbreaks have been attributed to reduced control by predators and parasitoids and to increased susceptibility of stressed urban plants. These hypotheses, however, leave many outbreaks unexplained and fail to predict variation in pest abundance within cities. Here we show that the abundance of a common insect pest is positively related to temperature even when controlling for other habitat characteristics. The scale insect Parthenolecanium quercifex was 13 times more abundant on willow oak trees in the hottest parts of Raleigh, NC, in the southeastern United States, than in cooler areas, though parasitism rates were similar. We further separated the effects of heat from those of natural enemies and plant quality in a greenhouse reciprocal transplant experiment. P. quercifex collected from hot urbantrees became more abundant in hot greenhouses than in cool greenhouses, whereas the abundance of P. quercifex collected from cooler urbantrees remained low in hot and cool greenhouses. Parthenolecanium quercifex living in urban hot spots succeed with warming, and they do so because some demes have either acclimatized or adapted to high temperatures. Our results provide the first evidence that heat can be a key driver of insect pest outbreaks on urbantrees. Since urban warming is similar in magnitude to global warming predicted in the next 50 years, pest abundance on city trees may foreshadow widespread outbreaks as natural forests also grow warmer.