Phenology- and light-based parameterization of stomatal conductance model for urban woody species in northern China.

Surface ozone (O3) poses a significant threat to urban vegetation health, and assessing the O3 risk across woody species is of vital importance for maintaining the health of urban infrastructure. In the present study, Jarvis-type stomatal conductance model was parameterized for ten urban species in northern China. Incorporating the effects of time of day and diurnal O3 concentration significantly enhanced the model performance. For different plant functional types (greening trees, greening shrubs, and orchard-grown trees), three parameterizations were established to estimate stomatal O3 uptake (POD1, phytotoxic O3 dose over an hourly threshold of 1 nmol m-2 s-1). The differences in POD1 between greening trees and shrubs were primarily due to the difference in their stomatal sensitivity to light. Orchard-grown trees displayed the lowest O3 removal capacity (lowest value of POD1) because of their shorter growing season despite of high stomatal conductance. These results indicated that plant phenology and light responsiveness determined stomatal O3 uptake, and the three parameterizations developed here could be applicable to various urban species in northern regions. Among climatic factors for O3 risk assessment, O3 concentration was the most important factor determining annual variation of POD1, which was primarily driven by air temperature. However, when O3 pollution decreased, O3 concentration exhibited less dependence on temperature and more dependence on light. These findings provide crucial insights for urban policy-makers and environmental scientists aiming to mitigate O3 pollution effects and enhance urban vegetation health.

Local climate, air quality and leaf litter cover shape foliar fungal communities on an urban tree.

Foliar fungi on urban trees are important for tree health, biodiversity and ecosystem functioning. Yet, we lack insights into how urbanization influences foliar fungal communities. We created detailed maps of Stockholm region's climate and air quality and characterized foliar fungi from mature oaks (Quercus robur) across climatic, air quality and local habitat gradients. Fungal richness was higher in locations with high growing season relative humidity, and fungal community composition was structured by growing season maximum temperature, NO2 concentration and leaf litter cover. The relative abundance of mycoparasites and endophytes increased with temperature. The relative abundance of pathogens was lowest with high concentrations of NO2 and particulate matter (PM2.5), while saprotrophs increased with leaf litter cover. Our findings show that urbanization influences foliar fungi, providing insights for developing management guidelines to promote tree health, prevent disease outbreaks and maintain biodiversity within urban landscapes.

Contrasting effects of urban trees on air quality: From the aerodynamic effects in streets to impacts of biogenic emissions in cities.

Urban trees are often not considered in air-quality models although they can significantly impact the concentrations of pollutants. Gas and particles can deposit on leaf surfaces, lowering their concentrations, but the tree crown aerodynamic effect is antagonist, limiting the dispersion of pollutants in streets. Furthermore, trees emit Biogenic Volatile Organic Compounds (BVOCs) that react with other compounds to form ozone and secondary organic aerosols. This study aims to quantify the impacts of these three tree effects (dry deposition, aerodynamic effect and BVOC emissions) on air quality from the regional to the street scale over Paris city. Each tree effect is added in the model chain CHIMERE/MUNICH/SSH-aerosol. The tree location and characteristics are determined using the Paris tree inventory, combined with allometric equations. The air-quality simulations are performed over June and July 2022. The results show that the aerodynamic tree effect increases the concentrations of gas and particles emitted in streets, such as NOx (+4.6 % on average in streets with trees and up to +37 % for NO2). This effect increases with the tree Leaf Area Index and it is more important in streets with high traffic, suggesting to limit the planting of trees with large crowns on high-traffic streets. The effect of dry deposition of gas and particles on leaves is very limited, reducing the concentrations of O3 concentrations by -0.6 % on average and at most -2.5 %. Tree biogenic emissions largely increase the isoprene and monoterpene concentrations, bringing the simulated concentrations closer to observations. Over the two-week sensitivity analysis, biogenic emissions induce an increase of O3, organic particles and PM2.5 street concentrations by respectively +1.1, +2.4 and + 0.5 % on average over all streets. This concentration increase may reach locally +3.5, +12.3 and + 2.9 % respectively for O3, organic particles and PM2.5, suggesting to prefer the plantation of low-emitting VOC species in cities.

The effect of local habitat and spatial connectivity on urban seed predation.

PREMISE: During the last centuries, the area covered by urban landscapes is increasing all over the world. Urbanization can change local habitats and decrease connectivity among these habitats, with important consequences for species interactions. While several studies have found a major imprint of urbanization on plant-insect interactions, the effects of urbanization on seed predation remain largely unexplored. METHODS: We investigated the relative impact of sunlight exposure, leaf litter, and spatial connectivity on predation by moth and weevil larvae on acorns of the pedunculate oak across an urban landscape during 2018 and 2020. We also examined whether infestations by moths and weevils were independent of each other. RESULTS: While seed predation varied strongly among trees, seed predation was not related to differences in sunlight exposure, leaf litter, or spatial connectivity. Seed predation by moths and weevils was negatively correlated at the level of individual acorns in 2018, but positively correlated at the acorn and the tree level in 2020. CONCLUSIONS: Our study sets the baseline expectation that urban seed predators are unaffected by differences in sunlight exposure, leaf litter, and spatial connectivity. Overall, our findings suggest that the impact of local and spatial factors on insects within an urban context may depend on the species guild. Understanding the impact of local and spatial factors on biodiversity, food web structure, and ecosystem functioning can provide valuable insights for urban planning and management strategies aimed at promoting urban insect diversity.

The European trees phyllosphere characteristics and its potential in air bioremediation.

The air pollution remediation is naturally carried out by plants. Their overground parts called phyllosphere are a type of a natural filter on which pollutants can be adsorb. Moreover, microbial communities living in phyllosphere perform a variety of biochemical processes removing also chemical pollutants. As their pollution is nowadays a burning issue especially for highly developed countries, the development of effective and ecological technologies for air treatment are of the utmost importance. The use of phyllosphere bacteria in the process of air bioremediation is a promising technology. This article reviews the role of phyllospheric bacteria in air bioremediation processes especially linked with the moderate climate plants. Research results published so far indicate that phyllosphere bacteria are able to metabolize the air pollutants but their potential is strictly determined by plant-phyllospheric bacteria interaction. The European tree species most commonly used for this purpose are also presented. The collected information filled the gap in the practical use of tree species in air bioremediation in the moderate climate zone.

Mapping pollen allergenicity from urban trees in Valencia: A tool for green infrastructure planning.

Urban trees provide many benefits to citizens but also have associated disservices such as pollen allergenicity. Pollen allergies affect 40% of the European population, a problem that will be exacerbated with climate change by lengthening the pollen season. The allergenic characteristics of the urban trees and urban parks of the city of Valencia (Spain) have been studied. The Value of Potential Allergenicity (VPA) was calculated for all species. The most abundant allergenic trees with a very high VPA were the cypresses, followed by Platanus x hispanica and species of genera Morus, Acer and Fraxinus, with a high VPA. On the contrary, Citrus x aurantium, Melia azedarach, Washingtonia spp., Brachychiton spp. and Jacaranda mimosifolia were among the most abundant low allergenic trees. VPA was mapped for the city and a hot spot analysis was applied to identify areas of clustering of high and low VPA values. This geostatistical analysis provides a comprehensive representation of the VPA patterns which is very useful for urban green infrastructure planning. The Index of Urban Green Zone Allergenicity (IUGZA) was calculated for the main parks of the city. The subtropical and tropical flora component included many entomophilous species and the lowest share of high and very high allergenic trees in comparison with the Mediterranean and Temperate components. Overall, a diversification of tree species avoiding clusters of high VPA trees, and the prioritization of species with low VPA are good strategies to minimize allergy-related impacts of urban trees on human health.

Where the not-so-wild things are in cities? The influence of social-ecological factors in urban trees at multiple scales.

Green infrastructure plays an essential role in cities due to the ecosystem services it provides. However, these elements are shaped by social and ecological factors that influence their distribution and diversity, affecting ecological functions and human well-being. Here, we analyzed neighborhood tree distribution - trees in pocket parks, squares and along streets - in Lisbon (Portugal) and modelled tree abundance and taxonomic and functional diversity, at the parish and local scales, considering a comprehensive list of social and ecological factors. For the functional analyses, we included functional traits linked to dispersal, resilience to important perturbations in coastal Mediterranean cities, and ecosystem services delivery. Our results show not only that trees are unevenly distributed across the city, but that there is a strong influence of social factors on all biological indices considered. At the parish and local scales, abundance and diversity responded to different factors, with abundance being linked to both social and ecological variables. Although the influence of social factors on urban trees can be expected, by modelling their influence we can quantify how much humans modify urban landscapes at a structural and functional level. These associations can underlie potential biodiversity filters and should be analyzed over time to inform decisions that support long-term ecological resilience, maximize trait functional expression, and increase equity in ecosystem services delivery.

Diversity and negative effect of PM0.3-10.0 adsorbed by needles of urban trees in Irkutsk, Russia.

The study was performed in natural forests preserved within the Boreal zone city, Irkutsk, Russia. Test sites were selected in the forests in different districts of the city, where samples of Scots pine (Pinus sylvestris L.) and Siberian larch (Larix sibirica Ledeb.) needles were taken to study the adsorption on their surface of aerosol particles of different sizes, in microns: PM0.3, PM0.5, PM1, PM2.5, PM5, PM10. Scanning electron microscopy was used to obtain high-resolution photographs (magnification 800- × 2000, × 16,000) and aerosol particles (particulate matter-PM) were shown to be intensively adsorbed by the surface of needles, with both size and shape of the particles characterized by a wide variety. Pine needles can be covered with particles of solid aerosol by 50-75%, stomata are often completely blocked. Larch needles often show areas, which are completely covered with aerosol particles, there are often found stomata deformed by the penetration of PMx. X-ray spectral microanalysis showed differences in the chemical composition of adsorbed PMx, the particles can be metallic if metals predominate in their composition, carbonaceous-in case of carbon predominance-or polyelemental if the composition is complex and includes significant quantities of other elements besides metals and carbon (calcium, magnesium, potassium, sodium, sulfur, chlorine, fluorine). Since the particles contain a large proportion of technogenic pollutants, accumulation by the needles of some widespread pollutants was investigated. A direct correlation of a highly significant level between the concentration of PMx in the air and the accumulation of many heavy metals in pine and larch needles, as well as sulfur, fluorine, and chlorine, has been revealed, which indicates a high cleaning capacity of urban forests. At the same time, the negative impact of PMx particles on the vital status of trees is great, which shows in intense disturbance of the parameters of photosynthesis and transpiration, leading to a significant decrease in the growth characteristics of trees and reduction in the photosynthetic volume of the crowns. We consider that the results obtained are instrumental in developing an approach to improvement of urban forests status and creating a comfortable urban environment for the population.

Citizens and urban greening: Do Bobo Dioulasso dwellers participate in greenhouse gas mitigation through urban forestry and greening?

Urban trees and forests play a vital role in maintaining the balance of urban ecosystems and mitigating global warming. However, due to the lack of data and information on the potential of urban forests, their importance remains largely unknown. This study aims to describe citizens' perceptions of trees and assess the forest community's density, diversity, and carbon stock in the residential area of Bobo-Dioulasso, the second-largest city in Burkina Faso. To carry out the study, tree inventories, and interviews were conducted on 240 selected dwellinghouses using a two-stage stratified sampling approach. The sample was allocated proportionally to three strata based on their population size: the center town (20 %), pericenter (20 %), and periphery (60 %). Trees were found in 86 % ± 0.5 % of dwellings, with an average of four trees per dwellinghouse (4 ± 1). About 63 % of households reported planting trees in their homes, including along roadsides. The main motivations for planting trees were for fruits, shading, and ornamental purposes. However, factors such as discomfort, property ownership, and management costs discouraged some residents from planting more trees. A total of 934 trees belonging to 69 species and 30 botanic families were counted in the study sample. The most abundant species families were Anacardiaceae, Moraceae, and Moringaceae. Mangifera indica (41 %), Ficus polita (12 %), and Moringa oleifera (8 %) had the highest relative densities of all species found in dwellings. Using existing allometric equations, the study estimated that the residential area trees stored about 210,000 tons of carbon dioxide equivalent. Based on these findings, it is recommended that city governments implement an action plan to promote urban forestry to strengthen and protect urban forest cover.

Influence of urban forests on residential property values: A systematic review of remote sensing-based studies.

Urban forests provide direct and indirect benefits to human well-being that are increasingly captured in residential property values. Remote Sensing (RS) can be used to measure a wide range of forest and vegetation parameters that allows for a more detailed and better understanding of their specific influences on housing prices. Herein, through a systematic literature review approach, we reviewed 89 papers (from 2010 to 2022) from 21 different countries that used RS data to quantify vegetation indices, forest and tree parameters of urban forests and estimated their influence on residential property values. The main aim of this study was to understand and provide insights into how urban forests influence residential property values based on RS studies. Although more studies were conducted in developed (n = 55, 61.7%) than developing countries (n = 34, 38.3%), the results indicated for the most part that increasing tree canopy cover on property and neighborhood level, forest size, type, greenness, and proximity to urban forests increased housing prices. RS studies benefited from spatially explicit repetitive data that offer superior efficiency to quantify vegetation, forest, and tree parameters of urban forests over large areas and longer periods compared to studies that used field inventory data. Through this work, we identify and underscore that urban forest benefits outweigh management costs and have a mostly positive influence on housing prices. Thus, we encourage further discussions about prioritizing reforestation and conservation of urban forests during the urban planning of cities and suburbs, which could support UN Sustainable Development Goals (SDGs) and urban policy reforms.

A probabilistic approach to stormwater runoff control through permeable pavements beneath urban trees.

One of the most current and urgent challenges is making cities sustainable and resilient to climate change. From this perspective, Nature-Based Solutions (NBSs) are well-recognized strategies for stormwater control and water cycle restoration. Urban trees are an example of NBS. However, the high degree of soil sealing typically found in urban environments limits natural processes such as infiltration and hinders the water and nutrient supply for proper root development, which weakens tree stability. Permeable pavements at the base of urban trees, on the one hand, facilitate infiltration, which helps runoff control, and on the other hand, improve stormwater retention and soil humidity, which enhance root feeding. This paper proposes an analytical-probabilistic approach to estimate the contribution of permeable pavements to stormwater management. The equations developed in this study relate the runoff probability to the storage volume, the infiltration rate into the underlying soil, and the average values of the hydrological variables in the input. The model allows us to select different runoff thresholds and considers the possibility that residual volume from previous rainfall events prefills the storage capacity. An application to a case study in Sao Paulo (Brazil) has been presented. It investigates the influence of the different parameters used in the model on the results. The comparison of the outcomes obtained using the developed equations with those obtained from the continuous simulation of measured data confirmed the effectiveness of the proposed analytical-probabilistic approach and the suitability of using permeable pavements at the base of urban trees for improving stormwater retention.

Sources of variation in nutrient loads collected through street sweeping in the Minneapolis-St. Paul Metropolitan Area, Minnesota, USA.

Excess non-point nutrient loading continues to impair urban surface waters. Because of the potential contribution of tree litterfall to nutrient pollution in stormwater, street sweeping is a promising management tool for reducing eutrophication in urban and suburban regions. However, nutrient concentrations and loads of material removed through street sweeping have not been well characterized, impeding the development of pollution reduction credits and improvement of models for stormwater management. We evaluated the role of canopy cover over streets, street sweeper type, season, and sweeping frequency in contributing to variation in concentrations and loads of nitrogen (N), phosphorus (P), and solids recovered in street sweepings, using analyses of samples collected during regular street sweeping operations in five cities in the Minneapolis-St. Paul Metropolitan Area, Minnesota, USA. We expected that nutrient concentrations and loads would be highest in seasons and places of higher tree litterfall. We also expected that regenerative-air sweepers would recover higher loads compared to mechanical broom sweepers. Total N and P concentrations in sweepings increased most strongly with canopy cover in June, October, and November. Total N and P recovered in street sweepings similarly increased with canopy cover in June, October, and November, and peaked in early summer and autumn, times of high litterfall. In contrast, total dry mass in sweepings was greatest in early spring, following winter snowmelt. However, nutrient loads and concentrations did not differ between sweeper types. Our results add to growing evidence of the importance of street trees in contributing nutrient pollution to urban surface waters. Street sweeping focused on high-canopy streets during early summer and autumn is likely an effective management tool for stormwater nutrient pollution.

Decoupling between stomatal conductance and photosynthesis occurs under extreme heat in broadleaf tree species regardless of water access.

High air temperatures increase atmospheric vapor pressure deficit (VPD) and the severity of drought, threatening forests worldwide. Plants regulate stomata to maximize carbon gain and minimize water loss, resulting in a close coupling between net photosynthesis (Anet ) and stomatal conductance (gs ). However, evidence for decoupling of gs from Anet under extreme heat has been found. Such a response both enhances survival of leaves during heat events but also quickly depletes available water. To understand the prevalence and significance of this decoupling, we measured leaf gas exchange in 26 tree and shrub species growing in the glasshouse or at an urban site in Sydney, Australia on hot days (maximum Tair > 40°C). We hypothesized that on hot days plants with ample water access would exhibit reduced Anet and use transpirational cooling leading to stomatal decoupling, whereas plants with limited water access would rely on other mechanisms to avoid lethal temperatures. Instead, evidence for stomatal decoupling was found regardless of plant water access. Transpiration of well-watered plants was 23% higher than model predictions during heatwaves, which effectively cooled leaves below air temperature. For hotter, droughted plants, the increase in transpiration during heatwaves was even more pronounced-gs was 77% higher than model predictions. Stomatal decoupling was found for most broadleaf evergreen and broadleaf deciduous species at the urban site, including some wilted trees with limited water access. Decoupling may simply be a passive consequence of the physical effects of high temperature on plant leaves through increased cuticular conductance of water vapor, or stomatal decoupling may be an adaptive response that is actively regulated by stomatal opening under high temperatures. This temperature response is not yet included in any land surface model, suggesting that model predictions of evapotranspiration may be underpredicted at high temperature and high VPD.

Irrigated urban trees exhibit greater functional trait plasticity compared to natural stands.

Urbanization creates novel ecosystems comprised of species assemblages and environments with no natural analogue. Moreover, irrigation can alter plant function compared to non-irrigated systems. However, the capacity of irrigation to alter functional trait patterns across multiple species is unknown but may be important for the dynamics of urban ecosystems. We evaluated the hypothesis that urban irrigation influences plasticity in functional traits by measuring carbon-gain and water-use traits of 30 tree species planted in Southern California, USA spanning a coastal-to-desert gradient. Tree species respond to irrigation through increasing the carbon-gain trait relationship of leaf nitrogen per specific leaf area compared to their native habitat. Moreover, most species shift to a water-use strategy of greater water loss through stomata when planted in irrigated desert-like environments compared to coastal environments, implying that irrigated species capitalize on increased water availability to cool their leaves in extreme heat and high evaporative demand conditions. Therefore, irrigated urban environments increase the plasticity of trait responses compared to native ecosystems, allowing for novel response to climatic variation. Our results indicate that trees grown in water-resource-rich urban ecosystems can alter their functional traits plasticity beyond those measured in native ecosystems, which can lead to plant trait dynamics with no natural analogue.

Response of tropical trees to elevated Ozone: a Free Air Ozone Enrichment study.

Tropospheric ozone (O3) has become one of the main urban air pollutants. In the present study, we assessed impact of ambient and future ground-level O3 on nine commonly growing urban tree species under Free Air Ozone Enrichment (FAOE) condition. During the study period, mean ambient and elevated ozone (EO3) concentrations were 48.59 and 69.62 ppb, respectively. Under EO3 treatment, stomatal density (SD) significantly decreased and guard cell length (GCL) increased in Azadirachta indica, Bougainvillea spectabilis, Plumeria rubra, Saraca asoca and Tabernaemontana divaricata, while SD increased and GCL decreased in Ficus benghalensis and Terminalia arjuna. Proline levels increased in all the nine plant species under EO3 condition. EO3 significantly reduced photosynthetic rate, stomatal conductance (gs), and transpiration rates (E). Only A. indica and N. indicum showed higher gs and E under EO3 treatment. Water use efficiency (WUE) significantly increased in F. benghalensis and decreased in A. indica and T. divaricata. Air Pollution Tolerance Index (APTI) significantly increased in Ficus religiosa and S. asoca whereas it decreased in B. spectabilis and A. indica. Of all the plant species B. spectabilis and A. indica were the most sensitive to EO3 (high gs and less ascorbic acid content) while S. asoca and F. religiosa were the most tolerant (lowgs and more ascorbic acid content). The sensitivity of urban tree species to EO3 is a cause of concern and should be considered for future urban forestry programmes. Our study should guide more such studies to identify tolerant trees for urban air pollution abatement.

Responses of tree growth, leaf area and physiology to pavement in Ginkgo biloba and Platanus orientalis.

Trees growing on paved lands endure many environmental stresses in the urban environment. However, the morphological and physiological mechanisms underlying tree adaptation to pavement in the field are less known. In this study, we investigated 40 sites where Ginkgo biloba and Platanus orientalis grow on adjacent pairs of paved and vegetated plots in parks and roadsides in Beijing, China. Relative to the vegetated land, the mean increments in the diameter at breast height and height in the paved land were significantly decreased by 44.5% and 31.9% for G. biloba and 31.7% and 60.1% for P. orientalis, respectively. These decreases are related to both the decrease in assimilation products due to the reductions in leaf area, leaf total nitrogen content, and chlorophyll content and the increase in energy cost due to the synthesis of more soluble sugar and proline for mitigating stress. The increase in leaf soluble sugar content, proline content, and δ13C indicated that trees could adapt to the paved land through the regulation of osmotic balance and the enhancement of water-use efficiency. Piecewise structural equation models showed that trees growing on the paved land are stressed by compounding impacts of the leaf morphological and physiological changes. Therefore, it is critical to explore the complex response of plant morphological and physiological traits to the pavement-induced stress for improving tree health in urban greening.

Macro-Morphological Traits of Leaves for Urban Tree Selection for Air Pollution Biomonitoring: A Review.

Urban trees provide different ecosystem benefits, such as improving air quality due to the retention of atmospheric particulate matter (PM) on their leaves. The main objective of this paper was to study, through a systematic literature review, the leaf macro-morphological traits (LMTs) most used for the selection of urban trees as air pollution biomonitors. A citation frequency index was used in scientific databases, where the importance associated with each variable was organized by quartiles (Q). The results suggest that the most biomonitored air pollutants by the LMTs of urban trees were PM between 1-100 µm (Q1 = 0.760), followed by O3 (Q2 = 0.586), PM2.5 (Q2 = 0.504), and PM10 (Q3 = 0.423). PM was probably the most effective air pollutant for studying and evaluating urban air quality in the context of tree LMTs. PM2.5 was the fraction most used in these studies. The LMTs most used for PM monitoring were leaf area (Q1) and specific leaf area (Q4). These LMTs were frequently used for their easy measurement and quantification. In urban areas, it was suggested that leaf area was directly related to the amount of PM retained on tree leaves. The PM retained on tree leaves was also used to study other f associated urban air pollutants associated (e.g., heavy metals and hydrocarbons).

Phyllosphere bacterial communities in urban green areas throughout Europe relate to urban intensity.

The phyllosphere harbours a diverse and specific bacterial community, which influences plant health and ecosystem functioning. In this study, we investigated the impact of urban green areas connectivity and size on the composition and diversity of phyllosphere bacterial communities. Hereto, we evaluated the diversity and composition of phyllosphere bacterial communities of 233 Platanus x acerifolia and Acer pseudoplatanus trees in 77 urban green areas throughout 6 European cities. The community composition and diversity significantly differed between cities but only to a limited extent between tree species. We could show that urban intensity correlated significantly with the community composition of phyllosphere bacteria. In particular, a significant correlation was found between the relative abundances for 29 out of the 50 most abundant families and the urban intensity: the abundances of classic phyllosphere families, such as Acetobacteraceae, Planctomycetes, and Beijerinkiaceae, decreased with urban intensity (i.e. more abundant in areas with more green, lower air pollution, and lower temperature), while those related to human activities, such as Enterobacteriaceae and Bacillaceae, increased with urban intensity. The results of this study suggest that phyllosphere bacterial communities in European cities are associated with urban intensity and that effect is mediated by several combined stress factors.

Mapping Tree Canopy in Urban Environments Using Point Clouds from Airborne Laser Scanning and Street Level Imagery.

Resilient cities incorporate a social, ecological, and technological systems perspective through their trees, both in urban and peri-urban forests and linear street trees, and help promote and understand the concept of ecosystem resilience. Urban tree inventories usually involve the collection of field data on the location, genus, species, crown shape and volume, diameter, height, and health status of these trees. In this work, we have developed a multi-stage methodology to update urban tree inventories in a fully automatic way, and we have applied it in the city of Pamplona (Spain). We have compared and combined two of the most common data sources for updating urban tree inventories: Airborne Laser Scanning (ALS) point clouds combined with aerial orthophotographs, and street-level imagery from Google Street View (GSV). Depending on the data source, different methodologies were used to identify the trees. In the first stage, the use of individual tree detection techniques in ALS point clouds was compared with the detection of objects (trees) on street level images using computer vision (CV) techniques. In both cases, a high success rate or recall (number of true positive with respect to all detectable trees) was obtained, where between 85.07% and 86.42% of the trees were well-identified, although many false positives (FPs) or trees that did not exist or that had been confused with other objects were always identified. In order to reduce these errors or FPs, a second stage was designed, where FP debugging was performed through two methodologies: (a) based on the automatic checking of all possible trees with street level images, and (b) through a machine learning binary classification model trained with spectral data from orthophotographs. After this second stage, the recall decreased to about 75% (between 71.43 and 78.18 depending on the procedure used) but most of the false positives were eliminated. The results obtained with both data sources were robust and accurate. We can conclude that the results obtained with the different methodologies are very similar, where the main difference resides in the access to the starting information. While the use of street-level images only allows for the detection of trees growing in trafficable streets and is a source of information that is usually paid for, the use of ALS and aerial orthophotographs allows for the location of trees anywhere in the city, including public and private parks and gardens, and in many countries, these data are freely available.

Termite diversity and damage assessment in urban trees from different parks of Lahore, Punjab, Pakistan.

Termite infestation is one of the fundamental problems associated with the loss of urban trees and ecological services. However, no such study has been performed in Pakistan to investigate the termite occurrence and assess such damages to urban trees caused by termites. For Lahore, research and comparable data on urban tree damages are rare or missing. This study surveyed six different microhabitats, including Bagh-e-Jinnah, canal vegetation, Model Town Park, Jallo Forestry, Race-Course Park, and FC College Vegetation employing the three belt transects (100 × 5 m) method. We geo-referenced termite-infested trees to investigate the termite occurrence on living and dead standing trees, termite diversity, and the assessment of tree damage by termites' attack. We recorded four termite species (Odontotermes obesus Rambur, Coptotermes heimi Wasmann, Heterotermes indicola Wasmann, and Microtermes obesi Holmgren) representing two families (Rhinotermitidae and Termitidae). However, the diversity indices revealed that O. obesus (higher termite) and C. heimi (lower termite) were dominant with 46.60 and 36% of occurrence among observed trees, respectively. Kernel density function indicated that the Lahore Canal and Bagh-e-Jinnah plantation shared all four termites' infestation evenly compared to other study sites. We observed the maximum number of damaged trees by termites in canal vegetation with the most damaged exotic tree species Populus euramericana along the canal green belt. Additionally, we observed significant (P < 0.05) termite-tree interactions with exotic, living, and dead standing tree species and found termite colony size positively (R = 0.985) correlated with the tree trunk diameter up to breast height (DBH). The average population of termites per unit volume of deadwood log was (0.39/cm3) within all plantation sites. In conclusion, this study provides simple, reckless, and inexpensive knowledge about the assessment of termite damage to trees, which may give a better idea in making decisions on tree selection and management in urban ecosystems.