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The rapid socio-economic development and urbanization in China have led to a decline in air quality. Therefore, the spatial and temporal distribution patterns of urban air pollution, as well as its formation mechanisms and influencing factors, have become important areas of research in atmospheric environment studies. This paper focuses on nine monitoring sites in Nanjing, where concentration data for six air pollutants and vegetation index data were collected from 2013 to 2021. The objective of this study is to investigate the changes in air pollutants and vegetation index over time and space, as well as their relationship with each other, and to assess the social and environmental impacts of air pollution. The findings reveal a spatial distribution pattern of air pollution in Nanjing that exhibits significant variability, with pollutant concentrations decreasing from the city center towards the surrounding areas. Notably, the main urban area has lower air quality compared to the peripheral regions. The results obtained from best-fit linear regression models and correlation heatmaps demonstrate a strong correlation (coefficient of determination, R2 > 0.5) between the normalized difference vegetation index (NDVI) and pollutants such as SO2, NO2, PM2.5, PM10, and O3 within a radial distance of 2 km from the air pollutant monitoring sites. These findings indicate that NDVI can be an effective indicator for assessing the distribution and concentrations of air pollutants. Negative correlations between NDVI and socio-economic indicators are observed under relatively consistent natural conditions, including climate and terrain. Therefore, the spatiotemporal distribution patterns of NDVI can provide valuable insights not only into socio-economic growth but also into the levels and locations of air pollution concentrations. [ABSTRACT FROM AUTHOR]

Atmospheric pollution caused by fine particulate matter (PM2.5) seriously damages human health. Urban forests have the ecological function of purifying the atmosphere, which can effectively reduce the ambient PM2.5 concentration. This paper analyzed the ability of different forest types to mitigate PM2.5 pollution and explored the effects of forest quality and morphological parameters on PM2.5 concentration on the forest patch level. The results concluded that the PM2.5 concentration of the Landscape and Relaxation Forest (LF) was significantly lower than that of the Roadside Forest (RF) and Affiliated Forest (AF) due to the environmental quality of their location. The effective distance of LF on PM2.5 reduction was 80 m, which was significantly higher than RF and AF. The Normalized Difference Vegetation Index (NDVI), which indicated forest growth status, was the most effective parameter for improving the urban forest PM2.5 mitigation ability. The concentration of PM2.5 decreased linearly with the increase in NDVI. The area and perimeter of the forest patches had a significant nonlinear negative correlation with PM2.5 concentration. In addition, the more irregular the shape of the forest patch, the lower the PM2.5 concentration of the forest. Moreover, the simpler shape of RF and AF helped to alleviate PM2.5 pollution. The round shape of AF more efficiently reduced PM2.5 concentration. Our study demonstrated that the surrounding environment, forest growth status, and patch forms determined the PM2.5 reduction capacity of an urban forest. The corresponding management and adjustment methods should be implemented in future urban forest management. [ABSTRACT FROM AUTHOR]

The structure and function of many forest ecosystems will be modified as a result of air pollution and climate change. Norway spruce (Picea abies L.) forests are among the first terrestrial ecosystems to respond to this change. We analysed how changes in climate and environmental factors will affect vegetation cover in Norway spruce forests and whether it is possible to assemble a list of diagnostically important/sensitive species that would be the first to react to changes in habitats of Norway spruce in Central Balkan. Significant changes in the vegetation cover of Norway spruce forests are mainly influenced by temperature increases (≈4 °C), and precipitation decreases (≈102 mm) by the end of the 21st century. Projections show that vegetation cover changes and future habitat conditions for Norway spruce forests on podzolic brown soils with a low base saturation and soil pH decreases, and temperature growth and precipitation decline, with the worst in the Rodope montane forest ecoregion. In Dinaric Mountain and Balkan mixed forest ecoregions, the range of natural occurrence of Norway spruce forest will shift to higher altitudes, or to the north. One of the cognitions of this paper is that, through available environmental models and their indices, species from the IUCN Red List should be recognised more properly and included in model calculations. [ABSTRACT FROM AUTHOR]

Currently, forest ecosystems are often located in remote areas, far from direct sources of air pollution. Nonetheless, they may be affected by different types of atmospheric deposition, which can compromise their health and inner balance. Epiphytic lichens respond to air pollution and climate change, and they have been widely adopted as ecological indicators, mainly in urban and industrial areas, while forest ecosystems are still underrepresented. However, in recent years, their use has become increasingly widespread, especially in the context of long-term monitoring programs for air pollution in forests. In this review, we provide a critical analysis of the topic from the point of view of the different methodological approaches based on lichen responses adopted in forest ecosystems. Further, we discuss the main challenges posed by the current global change scenario. [ABSTRACT FROM AUTHOR]

Efficiently mitigating the severe air pollution resulting from rapid progress is crucial for the sustainable development of the socio-ecological system. Recently, concerns about nature-based solutions have emerged in the research on the treatment of air pollution. Studies on the purification of PM2.5 using vegetation currently concentrate on the individual scale of tree species or urban vegetation, ignoring the regional scale, which could better assist ecological governance. Therefore, taking the Fenwei Plain of China as the study area, an assessment framework of the air purification service's spatial distribution reflecting regional vegetation was constructed. The dry deposition model and GeoDetector were used to quantify the spatial-temporal pattern and explore natural driving factors on the removal of PM2.5. The results showed that (1) the PM2.5 purification services offered by various types of vegetation exhibit notable variations. The average removal rates of PM2.5 by vegetation were 0.186%, 0.243%, and 0.435% in 2000, 2010, and 2021, respectively. (2) Meanwhile, a wide range of spatial mismatch exists between the PM2.5 concentration and PM2.5 removal. Insufficient supply regions of PM2.5 purification services account for 50% of the Fenwei Plain. (3) PM2.5 removal was strongly influenced by the types of vegetation and the Normalized Vegetation Index (NDVI), followed by the Digital Elevation Model (DEM), and less affected by meteorological factors; a strong joint effect was shown among the factors. The findings in this research provide a new perspective on regional air pollution management at the regional scale. [ABSTRACT FROM AUTHOR]

In this study, to comprehensively investigate the impact of garden plants on air quality, we measured the leaves of 18 common garden plants in three different areas, namely, Suzhou industrial parks (clean air area (CAA)), Xiangcheng district parks (lightly polluted area (LPA)), and Huqiu district parks (highly polluted area (HPA)). We also measured the leaf functional traits of different life-types of plants. To explore the trade-off strategies of the leaf traits of common garden plants in response to air pollution and to assess the adaptive capacity of different life types of plants to air pollution. The results show that plants in the polluted area had higher leaf dry matter content (LDMC) and leaf nitrogen content per unit mass (Nmass), and a lower specific leaf area (SLA), maximum net photosynthetic rate per unit area (Aarea), transpiration rate (Tr), stomatal conductance (Gs), and chlorophyll value (SPAD). Pearson correlation analysis showed that SLA was significantly positively correlated with Nmass, Tr, photosynthetic use efficiency (PNUE), and SPAD, and significantly negatively correlated with LDMC, while Aarea was significantly positively correlated with chlorophyll value. Redundancy analysis revealed that the correlation between each leaf functional trait and atmospheric pollution factors was as follows: LDMC > Nmass > SLA > LA > Aarea > Tr > PNUE > SPAD. The results suggest that different plant types have varying levels of adaptability to environmental conditions. Trees were found to be the most adaptable, followed by shrubs, herbs, and lianas. Additionally, under the stress of air pollution, herbs and lianas exhibited characteristics of "fast investment-return" on the leaf economic spectrum, meaning they were able to quickly allocate resources to maximize their return. However, trees and shrubs displayed traits of "slow investment-return", indicating a more conservative approach to resource allocation. These results provide valuable insights into the leaf trade-off strategies of plants in Suzhou Park under air pollution stress and can guide the selection of suitable plant species in similar environments. [ABSTRACT FROM AUTHOR]

The mountain pine beetle (MPB) destroys millions of coniferous trees annually throughout Western US forests. Coniferous forests are important air pollutant sinks, removing pollutants from the air such as PM2.5 (particulate matter < 2.5 μm in diameter), O3 (ozone), SO2 (sulfur dioxide), NO2 (nitrogen dioxide), and CO (carbon monoxide). In this paper, US Forest Service data on MPB tree mortality in the Western US is combined with a forest air pollution model (i-Tree Eco) and standard health impact functions to assess the human mortality and morbidity impacts of MPB-induced tree mortality. Modeling results suggest considerable spatial and temporal heterogeneity of impacts across the Western US. On average, MPB is associated with 10.0–15.7 additional deaths, 6.5–40.4 additional emergency room (ER) visits, and 2.2–10.5 additional hospital admissions per year over 2005–2011 due to lost PM2.5 sinks. For every 100 trees killed by MPB, the average PM2.5 mortality health costs are $418 (2019$). Impacts on other criteria pollutants are also estimated. Several sensitivity checks are performed on model inputs. These results have important policy implications for MPB management and on our understanding of the complex couplings between forest pests, forest health, and human health. [ABSTRACT FROM AUTHOR]

Silver fir is one of the longest living and tallest trees in Europe, it has major commercial importance and may be found in various communities predominantly connected with lower mountainous locations in Central Europe. One of the northernmost ranges in the region is the Sudetes. Currently, the once numerous fir is greatly dispersed, with just several specimens to be found together at one site on average. This drastic reduction in the number of specimens is mainly attributable to intensive forest management, based on the artificial cultivation of fir, conducted in the 19th and 20th centuries, and high industrial air pollution (mainly in the 20th c.). Because practically no firs have been cultivated for the last 200 years, the remaining sites of the species that are remnants of its bigger populations should be regarded as natural. This paper compares fir locations with areas of potential natural vegetation. The obtained results indicate that firs may grow in various types of habitats, with the preferred one being fertile beech woods and richer variants of oak-hornbeam forests. In our opinion, the presented findings are of great importance for the knowledge of the ecology of the species in question and for providing appropriate forest management. [ABSTRACT FROM AUTHOR]

Urban forests have important functions to alleviate air pollution, adjust the regional climate, and promote visitors' mental health and well-being. Humans' perceptions towards both atmospheric particulate matter (PM) and meteorological factors can be a gauge for assessing the functional services of urban forests. The geographical locations of host cities experiencing urbanization could take part in effects on emotional states of forest visitors. In this study, a total of 6309 facial photos of urban forest visitors were obtained from social networks in 42 cities of mainland China. Happy, sad, and neutral emotions were rated as percent scores in 2020, when the same-day air pollutants, meteorological factors, and socioeconomic indicators were recorded. The positive emotional index (PEI) was calculated as the difference between happy scores and sad scores. The results reveal that severe air pollutants (jointly PM2.5 > 75 μg/m3, PM10 > 150 μg/m3, and AQI > 150) were more frequently found in cities in the northeastern and northern areas of China. The forest visitors in the northeastern cities showed higher happiness scores compared to the visitors in other regions. The Quasi-Poisson regression suggested that high scores of happiness were frequently disclosed in weathers with low PM10. High scores of sadness were regressed on exposure to cities with a low GDP per capita and low total retail sales but with a high GDP at low-longitudinal and high-latitudinal locations with low levels of PM2.5 pollution, relative humidity, and wind velocity and a high temperature. The happiness score and PEI showed high-value aggregations in mega-sized cities (population over 10 million), such as Beijing and Zhengzhou, and in a metro-sized city (population of 5–10 million in Langfang) from climate regions of China. [ABSTRACT FROM AUTHOR]

A study was conducted to evaluate the effects of restoration practices in a forest ecosystem near the Ulsan Industrial Complex in southeastern Korea. The calcium and magnesium contents in the soil, as well as the soil pH, increased after the application of a soil ameliorator but decreased again after 20 years. Meanwhile, the aluminum content presented the opposite trend. After restoration, the species composition and diversity of vegetation tended to differ from that of the non-restored site over time while continuously becoming more similar to that of the reference site. The ratio of exotic plant species was lower than that at the non-restored site but higher than that at the reference site. The frequency distribution for the diameter class of oaks established through restoration presented a reverse J-shaped pattern, and thus, they can be maintained continuously; similar results were obtained for the reference site. In sum, the forest ecosystem near the industrial park—which had been severely degraded due to air pollution and soil acidification—was restored to a forest close to natural conditions through restorative treatments, including the neutralization of acidic soil and the introduction of tolerant species. [ABSTRACT FROM AUTHOR]

Urban areas with trees provide several ecosystem services to citizens. There is a growing interest in ecosystem services for the removal of air pollutants such as particulate matter. The objective of this paper is to show a study on the variation of intercepted particulate matter concentration (IPMC) by tree leaves in the megacity of Bogotá (Colombia). The relationship between IPMC and PM2.5 concentrations observed in air quality stations in two urban zones with different air pollutions was studied. Influences of climate and leaf morphology variables on IPMC were also analyzed. The species under study were Ligustrum-lucidum, Eucalyptus-ficifolia, Tecoma-stans, Callistemon-citrinus, Lafoensia-acuminata, and Quercus-humboldtii. The results showed that leaf IPMC decreased as the PM2.5 concentration increased. Species that best described this trend were Ligustrum-lucidum and Lafoensia-acuminata. These two species also showed the largest IPMC in their leaves. Indeed, species that showed the largest leaf area were those with the highest IPMC. On average, it was observed that for each 5.0 µg/m3 increase in PM2.5 concentration the IPMCs of the species Ligustrum-lucidum and Lafoensia-acuminata decreased by 33.6% and 23.1%, respectively. When wind speed increased, there was also an increase in PM2.5 concentrations and a reduction in the leaf IPMCs. [ABSTRACT FROM AUTHOR]

Tropospheric ozone (O3) is a detrimental air pollutant causing phytotoxic effects. Several O3 indices are used to assess the risk for vegetation, e.g., the exposure-based AOT40 (accumulated ozone exposure over a threshold of 40 ppb) and the stomatal-flux based POD1 (Phytotoxic Ozone Dose above a threshold of 1 nmol m−2 s−1). Leaf Mass per Area (LMA) is recommended as a simple index to explain the plant tolerance capacity to O3. We therefore tested a new species-specific O3 index (Leaf Index Flux—LIF: calculated as stomatal O3 flux/LMA) as a proxy of the avoidance/tolerance capacity against O3 stress according to datasets of visible foliar injury (VFI) in forest monitoring and a manipulative Free-Air Controlled Exposure (FACE) experiment. For the forest monitoring, AOT40, POD1, and LIF were calculated from hourly O3, soil moisture, and meteorological measurements at nine Italian forest sites over the period 2018–2022. The results were tested for correlation with the O3 VFI annually surveyed at the same sites along the forest edge (LESS) or inside the forest (ITP) and expressed as relative frequency of symptomatic species in the LESS (SS_LESS) and Plant Injury Index per tree in the plot (PII_ITP). Based on VFI occurrence at ITP and LESS, Fagus sylvatica was considered the most O3-sensitive species, whereas conifers (Pinus pinea and Picea abies) and other deciduous/evergreen broadleaf (Quercus petraea, Q. cerris, Q. ilex, and Phyllirea latifolia) showed rare and no O3 VFI. Shrub species such as Rubus spp. and Vaccinium myrtillus were O3-sensitive, as they showed VFI along the LESS. AOT40 did not show significant correlations with the VFI parameters, POD1 increased with increasing SS_LESS (p = 0.005, r = 0.37) and PII_ITP (p < 0.001, r = 0.53), and LIF showed an even higher correlation with SS%_LESS (p < 0.001, r = 0.63) and PII_ITP (p < 0.001, r = 0.87). In the FACE experiment, PII was investigated for five deciduous and three evergreen tree species following one growing season of exposure to ambient and above-ambient O3 levels (PII_FACE). Moreover, PII_FACE resulted better correlated with LIF (r = 0.67, p < 0.001) than with POD1 (r = 0.58, p = 0.003) and AOT40 (r = 0.35, p = 0.09). Therefore, LIF is recommended as a promising index for evaluating O3 VFI on forest woody species and stresses high O3 risk potential for forest species with high stomatal conductance and thin leaves. [ABSTRACT FROM AUTHOR]

In the Siberian Arctic, worldwide largest forest mortality was caused by chronical (since the 1940s) influence of SO2 emissions on the larch-dominant communities. We hypothesized that warming might mitigate SO2 influence by increasing trees' vigor and growth. We studied trees (larch, Larix sibirica; spruce, Picea obovate; birch, Betula pendula) and bushes (willow, Salix sp., alder, Duschekia fruticosa) growth dependence on SO2, air temperature, soil temperature and moisture, and precipitation. We sampled woods in severely damaged larch and moderately damaged mixed larch, spruce and birch forests. We generated tree ring chronologies and growth indices (GI). We used Terra/MODIS satellite data for mapping trends of vegetation (NDVI) and productivity (GPP, NPP) indexes. In the larch forest, we found a strong decrease in GI and tree mortality, which lasted until the end of 1990s. In the mixed forest, larch and birch were more resistant to SO2 influence compared to spruce. SO2, air and soil temperatures were mediators of all woody species growth. Winter precipitation stimulated trees growth by mitigating spring water stress. Warming onset in the 2000s led to a pronounced increase of all woody species growth. June–July air and soil temperatures, together with a moderate decrease in SO2 emissions, were the primary drivers of that phenomenon. Increasing trends of GPP, NPP, and NDVI were observed within the large part of earlier damaged forests, which was attributed to trees GI increase together with the expansion of SO2-resistant grasses and bushes. [ABSTRACT FROM AUTHOR]

Previous studies have shown that climatic and anthropogenic factors influence the variations in the stable isotope signature of tree materials in an urban ecosystem. However, the responses of urban trees to various anthropogenic and precipitation interventions are unclear. To fill the research gap, the isotopic composition (δ15N and δ18O) and total nitrogen content of the soil-plant system of urban forests were measured, focusing on typical urban tree species (Populus tomentosa and Ficus virens). The research was done under various land uses in China's Beijing and Shenzhen megacities (with different humidity conditions). The linear mixed-effect model revealed that the δ15N values in the leaves of roadside Ficus virens were significantly higher than those in urban park sites, away from the road (δ15N difference = 7.2‰). In contrast, Populus tomentosa leaves exhibited a non-significant difference (δ15N difference = −1.8‰). Further regression analysis revealed that the variations in δ15N in tree leaves could be attributed to the proximity to highways, suggesting the influence of vehicle exhaust on δ15N values in roadside trees. The linear mixed-effect model also revealed δ18O values significantly higher in Populus tomentosa leaves than in Ficus virens leaves. To assess the influence of humidity conditions on δ18O values in the leaves, the ratio of the atmospheric and intercellular vapor pressures (ea/ei) of tree canopies was estimated. The result revealed that the ea/ei of Ficus virens was significantly higher than for Populus tomentosa, ascribed to the variation in the humidity conditions of the two megacities. These results highlight that urban trees can potentially serve as bioindicators for atmospheric pollution and humidity. Our findings highlight the ecophysiological responses of urban forests related to N and O as they vary according to traffic exhaust and relative humidity. Consequently, they are potentially valuable indicators of urban atmospheric contamination, forming a nature-based solution for citizen welfare improvement. [ABSTRACT FROM AUTHOR]

The auto exhaust and dust derived from increased traffic volumes have led to an increasing level of atmospheric particulates in urban areas, which have become a primary pollutant of ambient air in urban zones. Roadside plants can effectively retain atmospheric particulates and clean the urban air via foliar capture of road dust. Five common roadside plants in Hangzhou were selected to evaluate their capacity for the retention of particulate matter (PM) and the accumulation of metals. The results showed that the PM retention capacity of the different plants varied greatly, as was the case with Loropetalum chinense var. rubrum Yieh, Osmanthus fragrans (Thunb.) Loureiro, Pittosporum tobira (Thunb.) Ait, Photinia × fraseri Dress and Cinnamomum camphora (L.) Presl. In addition, the amounts of particles retained by the plants varied among seasons, with the highest retention in winter (12.19 g·m−2) and the lowest retention in spring (6.89 g·m−2). The solids on the leaf surface were mainly irregular particles, such as mineral fragments, soot aggregates, and fly ash particles. Meanwhile, these plant species can effectively accumulate heavy metals that attached to the particles. The leaves of the five tree species had the highest amounts of copper (Cu) and the lowest amounts of cadmium (Cd). Among species, L. chinense and P. tobira had the strongest comprehensive capacity to adsorb particulate matter and heavy metals. The results shed light on the rational selection of road plants, both as ornaments and to purify air via dust suppression in subtropical zones. [ABSTRACT FROM AUTHOR]

Urban air quality is a major problem for human health and green infrastructure (GI) is one of the potential mitigation measures used. However, the optimum GI design is still unclear. The purpose of this study is to provide some recommendation that could help in the design of the GI (mainly, the selection of locations and characteristics of trees and hedgerows). Aerodynamic and deposition effects of each vegetation element of different GI scenarios are investigated. Computational fluid dynamics (CFD) simulations of a wide set of GI scenarios in an idealized three-dimensional urban environment are performed. In conclusion, it was found that trees in the middle of the avenue (median strip) reduce street ventilation, and traffic-related pollutant concentrations increase, in particular for streets parallel to the wind. Trees in the sidewalks act as a barrier for pollutants emitted outside, specifically for a 45° wind direction. Regarding hedgerows, the most important effect on air quality is deposition and the effects of green walls and green roofs are limited to their proximity to the building surfaces. [ABSTRACT FROM AUTHOR]

Wet, dry, and occult atmospheric deposition may be modified by vegetation canopies. The aim of this study was to verify canopy drip effect studies conducted in 2012, in 2013, and in 2015/2016. For this purpose, 26 moss samples were taken at each of eight monitoring sites of the European Moss Survey 2020/2021 in Germany from a corresponding number of subplots, each representing the site categories "under tree canopy" and adjacent "open land". The sampling, as well as the chemical analyses, of 12 metals (Al, As, Cd, Cr, Cu, Fe, Hg, Pb, Ni, Sb, V, Zn) and nitrogen (N) and the recording of sample- and site-describing metadata were conducted according to the ICP Vegetation experimental protocol. The results demonstrate an overall higher metal and nitrogen accumulation in moss samples of "canopy" sites compared to neighboring "open land sites" (grassland, heath). The ratios between the "canopy" and "open land" sites of 1.18 to 1.69 and significant correlations of r > 0.8 in case of five elements agree well with corresponding values from samplings in 2012, 2013, and 2015/2016. These results should be used for modeling atmospheric deposition aiming at more realistic results. With regard to the question of whether, and to what extent, moss samples should preferably be taken from "open land" or "canopy" sites, the following can be concluded: The recommendations of ICP Vegetation with regard to the minimum distance to be maintained from trees and shrubs should not be interpreted to mean that "open" sites are fundamentally more suitable for moss sampling in Germany than, for example, clearings in forests. The mostly higher variability of the measured values compared to the "canopy" sites rather suggests that in the open country a much higher number of influencing factors could be significant for the element accumulation in mosses in addition to the background pollution through atmospheric deposition. This is also supported by the fact that the metal contents in the moss samples of the "open" sites can clearly exceed those of the neighboring "canopy" sites in individual cases. With regard to "open" land, grassland sites seem to be less suitable for moss sampling than bog and heathland sites. In grassland, moss occurrences are often sparser and/or cut short by meadow mowing, so that the removal of three-year shoots on grassland, as recommended by ICP Vegetation, must be replaced in places by one-year shoots. The comparatively higher state dynamics of grassland sites also make the resampling of moss at previously sampled sites more difficult. [ABSTRACT FROM AUTHOR]

Air quality issues caused by nitrogen dioxide (NO2) have become increasingly serious in Chinese cities in recent years. As important urban green infrastructure, urban forests can mitigate gaseous nitrogen pollution by absorbing NO2 through leaf gas exchange. This study investigated spatiotemporal variations in the NO2 removal capacity of urban forests in Beijing city from 2014–2019, based on the i-Tree Eco deposition model. The results show that the annual removal capacity of administrative districts within Beijing city ranged from 14,910 to 17,747 tons, and the largest capacity (2684 tons) was found in the Fangshan district. The annual removal rate of NO2 by urban forests in administrative districts within Beijing was estimated at between 0.50–1.60 g/m2, reaching the highest (1.47 g/m2) in the Mengtougou district. The annual average absorption of NO2 by urban forests can account for 0.14–2.60% of annual total atmospheric NO2 and potentially reduce the NO2 concentration by 0.10–0.34 µg/m3 on average. The results of a principal component analysis suggest that the distribution of urban forests in Beijing is not optimized to maximize their NO2 removal capacity, being higher in suburban areas and lower in urban areas. This study provides insights into botanical NO2 removal capacity in Beijing city to mitigate atmospheric N pollution, addressing the key role of urban forests in improving human wellbeing. [ABSTRACT FROM AUTHOR]

Global climate change represents a moving target for plant acclimation and/or adaptation, especially in the Mediterranean basin. In this study, the interactions of severe drought (20% of the effective daily evapotranspiration) and O3 fumigation (80 ppb, 5 h day-1, for 28 consecutive days) on (i) photosynthetic performance, (ii) cell membrane stability, (iii) hydric relations, (iv) accumulation of compatible solutes, and (v) lipophilic antioxidant compounds were investigated in young Quercus cerris plants. In addition to the typical drought-induced stomatal closure, imposition of water withholding dramatically influenced the profile of stress-associated metabolites, i.e., abscisic acid (ABA), proline, and lipophilic antioxidants. However, plants were not able to delay or prevent the negative effects of water deficit, the greatest impacting factor in this study. This translated into a steep decline of photosynthetic efficiency, leaf hydration, and membrane fluidity and permeability. When water stress was coupled with O3, plants orchestrated cross-talk among ABA, proline, and sugar in fully-expanded mature leaves, partially leading to a premature senescence. [ABSTRACT FROM AUTHOR]

The aim of this study was to evaluate Scots pine stand degradation caused by the pollutants emitted from Zakłądy Azotowe Puławy, one of the biggest polluters of the environment in Poland for over 25 years (1966–1990). To assess the pollution stress in trees, we chose the dendrochronological analysis We outlined three directions for our research: (i) the spatio-temporal distribution of the growth response of trees to the stress associated with air pollution; (ii) the direct and indirect effects of air pollution which may have influenced the growth response of trees; and (iii) the role of local factors, both environmental and technological, in shaping the growth response of trees. Eight Scots pine stands were selected for study, seven plots located in different damage zones and a reference plot in an undamaged stand. We found that pollutant emission caused disturbances of incremental dynamics and long-term strong reduction of growth. A significant decrease in growth was observed for the majority of investigated trees (75%) from 1966 (start of factory) to the end of the 1990s. The zone of destruction extended primarily in easterly and southern directions, from the pollution source, associated with the prevailing winds of the region. At the end of the 1990s, the decreasing trend stopped and the wider tree-rings could be observed. This situation was related to a radical reduction in ammonia emissions and an improvement in environmental conditions. However, the growth of damaged trees due to the weakened health condition is lower than the growth of Scots pine on the reference plot and trees are more sensitive to stressful climatic conditions, especially to drought. [ABSTRACT FROM AUTHOR]

A survey on pollutants that affect air quality was carried out at 27 points in the city of Santo Domingo, National District. The removal of air pollutants was estimated in relation to the city's forest cover; using the iTree Canopy software. A principal components analysis and a correlation analysis was also performed to identify the association of these variables. The results show that the average percentage of green infrastructure in the sampling points was 26%. Also, positive correlation was identified between the presence of NO2 and SO2 at the sampling points. It was observed that the higher the presence of forest cover, the higher the concentration of CO and the lower the presence of pollutants. Although five hot spots were defined in terms of air pollution levels in the National District, the study does not show conclusive results regarding the relationship between green infrastructure and air quality in Santo Domingo. Results show that urban planning for environmental quality requires inter-institutional coordination, permanent ecological quality monitoring, and coordinated public policies to establish adequate indicators comparable to the World Health Organization standards. [ABSTRACT FROM AUTHOR]

Scree forests with large numbers of protected plants and wildlife are seriously threatened by climate change due to more frequent drought episodes, which cause challenges for very stony, shallow soils. The effect of environmental factors on the radial growth of five tree species—European beech (Fagus sylvatica L.), Norway spruce (Picea abies (L.) Karst.), sycamore maple (Acer pseudoplatanus L.), European ash (Fraxinus excelsior L.), and mountain elm (Ulmus glabra Huds.)—was studied in the mixed stands (105–157 years) in the western Krkonoše Mountains (Czech Republic) concerning climate change. These are communities of maple to fir beechwoods (association Aceri-Fagetum sylvaticae and Luzulo-Abietetum albae) on ranker soils at the altitude 590–700 m a.s.l. Production, structure, and biodiversity were evaluated in seven permanent research plots and the relationships of the radial growth (150 cores) to climatic parameters (precipitation, temperature, and extreme conditions) and air pollution (SO2, NOX, ozone exposure). The stand volume reached 557–814 m3 ha−1 with high production potential of spruce and ash. The radial growth of beech and spruce growing in relatively favorable habitat conditions (deeper soil profile and less skeletal soils) has increased by 16.6%–46.1% in the last 20 years. By contrast, for sycamore and ash growing in more extreme soil conditions, the radial growth decreased by 12.5%–14.6%. However, growth variability increased (12.7%–29.5%) for all tree species, as did the occurrence of negative pointer years (extremely low radial growth) in the last two decades. The most sensitive tree species to climate and air pollution were spruce and beech compared to the resilience of sycamore and ash. Spectral analysis recorded the largest cyclical fluctuations (especially the 12-year solar cycle) in spruce, while ash did not show any significant cycle processes. The limiting factors of growth were droughts with high temperatures in the vegetation period for spruce and late frosts for beech. According to the degree of extreme habitat conditions, individual tree species thus respond appropriately to advancing climate change, especially to an increase in the mean temperature (by 2.1 °C), unevenness in precipitation, and occurrence of extreme climate events in the last 60 years. [ABSTRACT FROM AUTHOR]

The benefits of 'green infrastructure' are multi-faceted and well-documented, but estimating those of individual street-scale planting schemes at planning can be challenging. This is crucial to avoid undervaluing proposed schemes in cost–benefit analyses, and ensure they are resilient to 'value engineering' between planning and implementation. Here, we introduce prototype software enabling urban practitioners to estimate the site-specific air quality impacts of roadside vegetation barriers: highly localised changes in pollutant concentrations due to changes in the dispersion of vehicular emissions close to source. We summarise the recent shift in understanding regarding the impacts of vegetation on urban air pollution towards changes in pollutant dispersion (cf. deposition) and describe our prototype software, offering rapid estimates thereof. First tests of the underlying model's performance are promising, reproducing: annual mean NO2 and PM2.5 concentrations in a street canyon (Marylebone Road, London, UK) to within 10% and 25%, respectively; and changes in pollutant concentrations of the right order of magnitude behind roadside barriers in a wind tunnel simulation of a street canyon and a real open-road environment. However, the model underestimates the benefits of a barrier in a simulated street canyon under perpendicular wind conditions. The prototype software is a first step towards informing practitioners of the site-specific impacts of vegetation barriers, which should always be additional to (i.e., no substitute for) essential emission reductions. The code is open-source to engage further researchers in its continued development. [ABSTRACT FROM AUTHOR]

Research Highlights: This study was carried out to diagnose the forest ecosystem damaged by air pollution and to then develop a restoration plan to be used in the future. The restoration plan was prepared by combining the diagnostic assessment for the damaged forest ecosystem and the reference information obtained from the conservation reserve with an intact forest ecosystem. The restoration plan includes the method for the amelioration of the acidified soil and the plant species to be introduced for restoration of the damaged vegetation depending on the degree of damage. Background and Objectives: The forest ecosystem around the Seokpo smelter was so severely damaged that denuded lands without any vegetation appear, and landslides continue. Therefore, restoration actions are urgently required to prevent more land degradation. This study aims to prepare the restoration plan. Materials and Methods: The diagnostic evaluation was carried out through satellite image analysis and field surveys for vegetation damage and soil acidification. The reference information was obtained from the intact natural forest ecosystem. Results: Vegetation damage was severe near the pollution source and showed a reducing trend as it moved away. The more severe the vegetation damage, the more acidic the soil was, and thereby the exchangeable cation content and vegetation damage were significantly correlated. The restoration plan was prepared by proposing a soil amelioration method and the plants to be introduced. The soil amelioration method focuses on ameliorating acidified soil and supplementing insufficient nutrients. The plants to be introduced for restoring the damaged forest ecosystem were prepared by compiling the reference information, the plants tolerant to the polluted environment, and the early successional species. The restoration plan proposed the Pinus densiflora, Quercus mongolica, and Cornuscontroversa–Juglansmandshurica communities as the reference conditions for the ridge, slope, and valley, respectively, by reflecting the topographic condition. Conclusions: The result of a diagnostic assessment showed that ecological restoration is required urgently as vegetation damage and soil acidification are very severe. The restoration plan was prepared by compiling the results of these diagnostic assessments and reference information collected from intact natural forests. The restoration plan was prepared in the two directions of soil amelioration and vegetation restoration. [ABSTRACT FROM AUTHOR]

This research concerns the impact of air and soil pollution on the health status of selected tree species in parks and urban forests. The analysis was carried out over a decade, which allowed for creating the best models illustrating the impact of selective factors related to air and soil pollution on the health status of small-leaved limes, maples, oaks, and chestnut trees in the city. (1) Background and Objectives: The research aimed to identify the environmental factors that have the greatest impact on the health condition of trees in urban conditions and show which species are the most resistant to pollution in urban areas. The research object was 2441 individuals of four tree species inhabiting 11 parks and urban forests in Poznań. We assessed the trees in terms of dendrometric parameters and health status. Tree-stand soils were tested for P, K, Ca, Mg, and Na content using various analytical methods. Air data were obtained from a generally accessible WIOS website. The above data were statistically analyzed using one-way ANOVA and canonical correlation analysis (CCA). Our research has shown that unfavorable environmental parameters impact the health status of trees growing in urban areas. The most significant negative impact of O3 on the health of three out of four examined tree species was demonstrated. Other pollutants that affect the trees health include Mn (in the soil) and NO, NO2, CO, and C6H6 (in the air). Oak turned out to be the most resistant species to urban pollution. The area where chestnut trees grew turned out to be the most Fe, Mn, Na, and Pb soil-polluted and air-polluted with most of the substances recorded. The permissible concentration levels were exceeded in the case of tropospheric NOx, PM10, PM2.5, and Pb. [ABSTRACT FROM AUTHOR]

This study was carried out to clarify the vegetation decline due to air pollutants emitted in the process of industrial activities and the passive restoration of the vegetation due to socioeconomic changes after economic growth. To achieve this goal, we investigated the spatial distribution of vegetation, differences in species composition and diversity among vegetation types different in damage degree, vegetation dynamics, the age structure and annual ring growth of two dominant plant species, and the landscape change that occurred in this area over the last 50 years. Plant communities tended to be spatially distributed in the order of grassland, shrubland (dominated by Styrax japonicus Siebold and Zucc. community), and forests (dominated by Pinus thunbergii Parl. and Pinus densiflora Siebold and Zucc. communities), with increasing distance from the pollution source. The result of stand ordination based on vegetation data reflected the trend of such a spatial distribution. Species richness evaluated based on the species rank dominance curve was the highest in shrubland and the lowest in grassland; species richness in forests was intermediate. The size class distribution of woody plant species in four plant communities composing three vegetation types showed the possibility of them being replaced by forest in the late successional stage. However, the density of successor trees was relatively low, whereas the density of shrubby plants, which are resilient to air pollution, was very high. The age class distribution of a dominant species forming shrubland and pine forest showed that most of them were recruited after industrialization in this area. The period when young individuals in both vegetation types were recruited corresponded to the period when the annual ring growth of the pine trees that survived air pollution was reduced. An analysis of the landscape change in this area indicated that coniferous forest and agricultural field decreased greatly, whereas industrial area, residential area, mixed forest, and broadleaved forest showed increasing trends since construction of the industrial complex. As a result, the decrease in coniferous forest is usually due to vegetation decline and partially to succession, as the pine trees dominating the forest are not only sensitive to air pollution but are also shade-intolerant. The increase in mixed and broadleaved forests reflects vegetation decline or succession. Vegetation decline progressed for about 30 years after the construction of the industrial complex; it has begun to be restored passively since then, although the change has been slow. These results are in line with the environmental Kuznets curve hypothesis that environmental degradation increases in the early stages of economic growth to a certain point, and, after a turning point, economic development leads to environmental improvements—thus, there is an inverted U-shaped relationship between economic growth and environmental degradation. [ABSTRACT FROM AUTHOR]

This study is among the first to investigate ozone levels in urban forests in China. It establishes that urban forest air quality in Yuanshan Forest Park (Shenzhen) is suitable for recreational activities and identifies spatial, seasonal, and diurnal O3 patterns and relationships with micrometeorological parameters, suggesting the possibility of manipulating relevant forest characteristics to reduce Surface ozone (O3) levels. An understanding of O3 levels of urban forest environments is needed to assess potential effects on human health and recreational activities. Such studies in China are scarce. This study investigated urban forest O3 levels to improve understanding and support residents engaging in forest recreational activities. We monitored O3 levels in 2015–2016 for three urban forests representing common habitats (foothill, valley, and ridge) in Yuanshan Forest Park and for an adjacent square. The overall mean daily and daily maximum 8 h mean (MDA8) O3 concentrations were highest for the ridge forest and lowest for the valley forest. Each forest's O3 concentrations were highest in summer. Diurnally, forest O3 concentrations peaked between 13:00 and 17:00 and reached a minimum between 03:00 and 09:00. The correlation between forest O3 concentrations and air temperature (AT) was strongly positive in summer and autumn but negative in spring. In each season, O3 concentration was negatively correlated with relative humidity (RH). No MDA8 or hourly O3 concentrations in the forests exceeded National Ambient Air Quality Standard Grade I thresholds (100 and 160 μg m−3, respectively). O3 accumulation is present in ridge urban forest in all seasons. Foothill and valley urban forests have better air quality than ridge forestation. Urban forest air quality is better in spring and autumn than in summer and is better from night-time to early morning than from noon to afternoon. [ABSTRACT FROM AUTHOR]

Smoke from forest fires is a growing concern in Korea as forest structures have changed and become more vulnerable to fires associated with climate change. In this study, we developed a Korean forest fire smoke dispersion prediction (KFSDP) system to support smoke management in Korea. The KFSDP system integrates modules from different models, including a Korean forest fire growth prediction model, grid-based geographic information system (GIS) fuel loading and consumption maps generated by national forest fuel inventory data, and the Korean Weather Research and Forecasting Model, into a Gaussian plume model to simulate local- and regional-scale smoke dispersion. The forecast system is operated using grid-based fires and simulates a cumulative smoke dispersion of carbon monoxide (CO) and <2.5 µm and <10 µm particulate matter (PM2.5 and PM10, respectively) ground-level concentration contours at 30-min intervals during the fire in concert with weather forecasts. The simulated smoke dispersions were evaluated and agreed well with observed smoke spreads obtained from real forest fires in Korea, and the performance of the KFSDP system was also analyzed using "what-if" scenarios. This is the first study to develop an integrated model for predicting smoke dispersion from forest fires in Korea. [ABSTRACT FROM AUTHOR]

Changes in annual tree ring width (TRW) and its size depends not only on the changing climate and natural stress factors such as extreme air temperatures, shortages in rainfall and excess rainfall during the growing season, but also on anthropogenic stress, including chemical compounds emitted to the atmosphere or lowering of the groundwater table caused by the operations of plants with high environmental impact. The purpose of this article is to assess the impact of meteorological conditions and anthropogenic factors on the size of annual growth of Scots pine tree-stands in the conditions of the climate of central-eastern Poland. On the basis of five created site chronologies in the vicinity of Zakłady Azotowe Puławy (nitrogen factories in Puławy) and using the moving correlation analysis and multiple regression analysis, a significant influence of temperature and precipitation conditions on the TRW size is proved. A significant, positive influence of air temperature on TRW was proved for the majority of chronologies created in the period of January–March, as well as in June, while it remained negative in May. The wide rings of Scots pines were formed when the precipitation of October and January (prior to the resumption of cambium activity) was lower than the average, and higher in April and in June–August. After including the anthropopressure factors in the regression equations, the description of the variability of the annual tree ring width was corrected. The coefficient of determination ranged from approx. 29% to even above 45% and was higher, on average by 10%, for all studied chronologies of Scots pine compared to the one calculated for constructed equations considering only meteorological conditions. The strength and direction of the impact of the independent variables (SO2, NH3, NOx) analysed on TRW mainly depended on the distance from the plants, as well as on the direction of inflow of industrial pollution to the stands examined. In light of the proven climate changes in central and eastern Poland, the growth conditions of pine stands will most likely deteriorate. [ABSTRACT FROM AUTHOR]