Ozone affects plant, insect, and soil microbial communities. A threat to terrestrial ecosystems and biodiversity

Elevated tropospheric ozone concentrations induce adverse effects in plants. We reviewed how ozone affects (i) the composition and diversity of plant communities by affecting key physiological traits; (ii) foliar chemistry and the emission of volatiles, thereby affecting plant-plant competition, plant-insect interactions, and the composition of insect communities; and (iii) plant-soil-microbe interactions and the composition of soil communities by disrupting plant litterfall and altering root exudation, soil enzymatic activities, decomposition, and nutrient cycling. The community composition of soil microbes is consequently changed, and alpha diversity is often reduced. The effects depend on the environment and vary across space and time. We suggest that Atlantic islands in the Northern Hemisphere, the Mediterranean Basin, equatorial Africa, Ethiopia, the Indian coastline, the Himalayan region, southern Asia, and Japan have high endemic richness at high ozone risk by 2100

Strategic roadmap to assess forest vulnerability under air pollution and climate change

Although it is an integral part of global change, most of the research addressing the effects of climate change on forests have overlooked the role of environmental pollution. Similarly, most studies investigating the effects of air pollutants on forests have generally neglected the impacts of climate change. We review the current knowledge on combined air pollution and climate change effects on global forest ecosystems and identify several key research priorities as a roadmap for the future. Specifically, we recommend (1) the establishment of much denser array of monitoring sites, particularly in the South Hemisphere; (2) further integration of ground and satellite monitoring; (3) generation of flux-based standards and critical levels taking into account the sensitivity of dominant forest tree species; (4) long-term monitoring of N, S, P cycles and base cations deposition together at global scale; (5) intensification of experimental studies, addressing the combined effects of different abiotic factors on forests by assuring a better representation of taxonomic and functional diversity across the similar to 73,000 tree species on Earth; (6) more experimental focus on phenomics and genomics; (7) improved knowledge on key processes regulating the dynamics of radionuclides in forest systems; and (8) development of models integrating air pollution and climate change data from long-term monitoring programs.</p

Biomonitoring of concentrations of platinum group elements and their correlations to other metals

Biomonitoring of Pt, Pd, Pb, Mn, Cu, Fe and Zn was conducted using leaves (two and six months old) of laurel (Lauras nobilis L.) ornamental shrubs grown in 14 sampling sites located on the central green belts of six avenues and streets of Athens. In this biomonitoring we determined, for the first time in Greece, the concentrations of the new urban &apos;pollutants&apos; Pt and Pd, and we estimated the correlations among the concentrations of all the above-mentioned metals as well as among the metal concentrations and the traffic load. Cluster analysis and principal component analysis (PCA) of the data revealed three distinct groups of metals and two groups of sites (one with high and the other with relatively low levels of pollution). Using varimax-rotated PCA for the metals, four factors were extracted explaining 92.3% of the total shared variance, which are further discussed. The importance of seasonal timing of sampling is revealed by the data and discussed in connection with the meteorological conditions

Photochemical air pollutant levels and ozone phytotoxicity in the region of Mesogia-Attica, Greece

The levels of photochemical air pollutants: O-3, NO and NO2, were monitored in Athens and in the neighbouring region of the Mesogia plain (Spata, Artemis and Markopoulo) from 1 May-31 August 2000. Phytodetection of ozone was also conducted using bioindicator plants of Bel-W3 and Zichnomirodata (KK6/5) tobacco varieties. The average maximum daily O-3 concentration was 60-75 ppb, while the 24 hour average ranged from 40-65 ppb. The AOT40 (ppb hours) index was very high in Athens (16 679 over 121 days), Spata (16325 over 110 days), Artemis (8093 over 22 days) and Markopoulo (18 646 over 113 days), suggesting potentially phytotoxic ozone levels. The ozone bioindicator plants of Bel-W3 and KK6/5 tobacco varieties were highly injured in all regions confirming the phytotoxicity of those ozone levels. The levels of NO and NO2 recorded at the three stations, in the Mesogia plain, were considerably lower than those occurring in Athens. The data presented here provide important background information concerning pollution levels in the Mesogia plain shortly before the operation of the new international airport 'Eleftherios Venizelos' in this region (March 2001)

Ozone Effects on Vegetation: A Walk from Cells to Ecosystems

We summarize effects of ground-level ozone (O3) on plants beginning at the atmosphere–leaf interface, and then following with responses at the cellular level and the resulting foliar injury leading to impacts on plant growth. Impacts on crop yield are discussed with the potential for improving O3 tolerance through plant breeding. Impacts of O3 on trees are analyzed with reference to ecosystem functioning and trophic interactions. Facilities to investigate O3 effects on vegetation, O3 phytotoxicity metrics, and O3-protectant chemicals are described

Effects of different isosmotic salt solutions on leaf gas exchange of hydroponically-grown Valerianella locusta

Nowadays there is an increasing interest in hydroponic floating system cultivation of several leafy greens. Floating could also be used to apply moderate salinity stress in order to increase the nutritional quality of fresh-cut leafy greens. In this study, we aimed to assess the effect of different types and rates of salinity on the leaf gas exchange of corn salad (Valerianella locusta). Five nutrient solutions were used: a basic nutrient solution used as control (Std), and four saline nutrient solutions that were prepared by adding to the basic nutrient solution, NaCl or CaCl2 at two concentrations (low and high). At each salinity level, the salt concentrations were iso-osmotic. Hence, the two concentrations for NaCl were 20 mM and 40 mM, LNa and HNa and for CaCl2 were 13.3 mM and 26.5 mM, LCa and HCa (low and high, respectively). For the light response curves of the photosynthetic rate (A), transpiration rate (E), stomatal conductance (gs) and intercellular CO2 concentration (Ci), youngest fully expanded leaves were placed inside the chamber of LCpro T (ADC) and irradiated with 0, 43, 87, 174, 261, 435, 696, 870, and 1044 μmol m-2 s-1. From 435 μmol m-2 s-1 and on, Std maintained the highest A. From 0 to 696 μmol m-2 s-1 HCa had the lowest E, while the LNa treatment had the highest. For gs, differences appeared after the 87 μmol m-2 s-1 point. Std had the highest gs while HCa had the lowest values. Moreover, Ci values were higher in the HNa and lower in the LCa. Finally, the Water Use Efficiency (WUE) was calculated as the A/E ratio and appeared greater in the HCa and lowest in the LNa. The obtained results indicate that even though the dominant factor for the impact of salinity on corn salad is the osmotic potential level, the source salinity should also be considered accordingly