Elisabetta Salvatori

Urban ecosystem services: tree diversity and stability of tropospheric ozone removal.

Urban forests provide important ecosystem services, such as urban air quality improvement by removing pollutants. While robust evidence exists that plant physiology, abundance, and distribution within cities are basic parameters affecting the magnitude and efficiency of air pollution removal, little is known about effects of plant diversity on the stability of this ecosystem service. Here, by means of a spatial analysis integrating system dynamic modeling and geostatistics, we assessed the effects of tree diversity on the removal of tropospheric ozone (O3) in Rome, Italy, in two years (2003 and 2004) that were very different for climatic conditions and ozone levels. Different tree functional groups showed complementary uptake patterns, related to tree physiology and phenology, maintaining a stable community function across different climatic conditions. Our results, although depending on the city-specific conditions of the studied area, suggest a higher function stability at increasing diversity levels in urban ecosystems. In Rome, such ecosystem services, based on published unitary costs of externalities and of mortality associated with O3, can be prudently valued to roughly US

A multiscale analysis of canopy structure in Fagus sylvatica L. and Quercus cerris L. old‐growth forests in the Cilento and Vallo di Diano National Park

2 and

Early and late adjustments of the photosynthetic traits and stomatal density in Quercus ilex L. grown in an ozone-enriched environment

3 million/year, respectively.

Photosynthetic performance and biochemical adjustments in two co-occurring Mediterranean evergreens, Quercus ilex and Arbutus unedo, differing in salt-exclusion ability

Abstract Broadleaved forest is one of the most severely exploited and threatened ecosystems worldwide such that many authors have highlighted the scarcity of undisturbed old‐growth broadleaved forests, especially in southern Europe. From an ecological perspective, old‐growth forests are considered to be significant for their structural diversity and complex ecological relationships among species. In this paper, we compare ground measurements of leaf area index (LAI) and the remotely sensed normalized difference vegetation index (NDVI) autocorrelation pattern of two old‐growth forest stands in the Cilento National Park (southern Italy) with two nearby managed forests stands of the same type. Results show that old‐growth forests have higher fine‐scale variability in both LAI and NDVI values and longer autocorrelation ranges than the corresponding managed forests. The potential relevance of these findings for the single large or several small (SLOSS) debate is also briefly discussed.

Comparison of Drought Stress Response and Gene Expression between a GM Maize Variety and a Near-Isogenic Non-GM Variety

Quercus ilex L. seedlings were exposed in open-top chambers for one growing season to three levels of ozone (O3 ): charcoal filtered air, non-filtered air supplemented with +30% or +74% ambient air O3 . Key functional parameters related to photosynthetic performance and stomatal density were measured to evaluate the response mechanisms of Q. ilex to chronic O3 exposure, clarifying how ecophysiological traits are modulated during the season in an ozone-enriched environment. Dark respiration showed an early response to O3 exposure, increasing approximately 45% relative to charcoal-filtered air in both O3 enriched treatments. However, at the end of the growing season, maximum rate of assimilation (Amax ) and stomatal conductance (gs ) showed a decline (-13% and -36%, for Amax and gs , respectively) only in plants under higher O3 levels. Photosystem I functionality supported the capacity of Q. ilex to cope with oxidative stress by adjusting the energy flow partitioning inside the photosystems. The response to O3 was also characterised by increased stomatal density in both O3 enriched treatments relative to controls. Our results suggest that in order to improve the reliability of metrics for O3 risk assessment, the seasonal changes in the response of gs and photosynthetic machinery to O3 stress should be considered.

Ecophysiological and phytochemical response to ozone of wine grape cultivars of Vitis vinifera L.

The responses to mild root zone salinity stress were investigated in two co-occurring Mediterranean woody evergreens, Quercus ilex L. and Arbutus unedo L., which differ in morpho-anatomical traits and strategies to cope with water deficit. The aim was to explore their strategies to allocate potentially toxic ions at organism level, and the consequential physiological and biochemical adjustments. Water and ionic relations, gas exchange and PSII performance, the concentration of photosynthetic pigments, and the activity of antioxidant defences, were measured. Q. ilex displayed a greater capacity to exclude Na+ and Cl- from the leaf than A. unedo, in part as a consequence of greater reductions in transpiration rates. Salt-induced reductions in CO2 assimilation resulted in Q. ilex suffering from excess of light to a greater extent than A. unedo. Consistently, in Q. ilex effective mechanisms of nonphotochemical quenching, also sustained by the lutein epoxide-lutein cycle, operated in response to salinity stress. Q. ilex also displayed a superior capacity to detoxify reactive oxygen species (ROS) than A. unedo. Our data suggest that the ability to exclude salt from actively growing shoot organs depends on the metabolic cost of sustaining leaf construction, i.e. species-specific leaf life-span, and the relative strategies to cope with salt-induced water stress. We discuss how contrasting abilities to restrict the entry and transport of salt in sensitive organs relates with species-specific salt tolerance.

Effects of high Zn and Pb concentrations on Phragmites australis (Cav.) Trin. Ex. Steudel: Photosynthetic performance and metal accumulation capacity under controlled conditions

Maize MON810, grown and commercialised worldwide, is the only cultivated GM event in the EU. Maize MON810, variety DKC6575, and the corresponding near-isogenic line Tietar were studied in different growth conditions, to compare their behaviour in response to drought. Main photosynthetic parameters were significantly affected by drought stress in both GM and non-GM varieties to a similar extent. Though DKC6575 (GM) had a greater sensitivity in the early phase of stress response as compared with Tietar (non-GM), after six days of stress they behaved similarly, and both varieties recovered from stress damage. Profiling gene expression in water deficit regimes and in a generalised drought stress condition showed an up-regulation of many stress-responsive genes, but a greater number of differentially expressed genes was observed in Tietar, with genes belonging to transcription factor families and genes encoding heat shock proteins, late embryogenesis abundant proteins and detoxification enzymes. Since induction of these genes have been indicated from the literature as typical of stress responses, their activation in Tietar rather than in DKC6575 may be reminiscent of a more efficient response to drought. DKC6575 was also analysed for the expression of the transgene CryIAb (encoding the delta-endotoxin insecticidal protein) in water deficit conditions. In all the experiments, the CryIAb transcript was not influenced by drought stress, but was expressed at a constant level. This suggests that though possessing a different pattern of sensitivity to stress, the GM variety maintains the same expression level for the transgene.

Urban green and its relation with air pollution: Ecological studies in the metropolitan area of Rome

Abstract Vitis vinifera sensitivity to tropospheric ozone (O3) has been evidenced in several studies. In this work, physiological and metabolic effects of O3 on two wine cultivars of V. vinifera (i.e. Maturano and San Giuseppe) have been studied. Moreover, chlorogenic acid (CGA) production, in consideration of its importance in the biosynthetic pathway of polyphenols and as antioxidant, has been investigated. Maturano cultivar resulted more sensitive to O3, as evidenced by the gas exchange reduction at the early stage of treatment, and by the increase in Ci/Ca and the decoupling of net photosynthesis and the stomatal conductance at the end of the treatment. Unexpectedly, O3 did not activate stilbene production. Ozone induced an early CGA decrease, significantly more consistent in cv. Maturano, and an increase after 8 days, more consistent in cv. S. Giuseppe. These results suggest that CGA could be considered a biochemical marker of O3-induced stress in V. vinifera.

Effects of nitrogen deposition, drought and their interaction, on functional and structural traits of Fraxinus ornus L. and Quercus ilex L.

abstract The response of Phragmites australis (Cav.) Trin. Ex. Steudel to zinc (Zn) and lead (Pb) was studied separately in two hydroponic tests, during a three weeks experiment. The effects on ecophysiology and biomass partitioning were evaluated during the metal treatments and at the recovery, and total metal content and accumulation capacity in different plant organs were assessed. Zn and Pb had different effects on the overall measured parameters, highlighting different mechanism of action. In particular, Zn concentration was higher in roots and, being a micronutrient, it was translocated into leaves, producing a reduction of assimilation rate, stomatal conductance (–71.9 and –81.3% respect to the control plant respectively), and a strong down regulation of photosystems functionality both at PSII and PSI level. Otherwise, Pb was accumulated mainly in the more lignified tissue such as rhizomes, with slightly effect on gas exchange. Chlorophyll a fluorescence highlighted that Pb inhibits the electron transfer process at the PSI donor side, without recovery after the removal of the metal stress. Despite these physiological limitations, P. australis showed a high capacity to accumulate both metals, and only slight reduction of biomass, being therefore a suitable species for phytoremediation interventions.

Ultrastructural alterations induced by tropospheric ozone: comparison between resistant and sensitive clones of Trifolium repens L. CV. Regal

Tropospheric ozone (O3) and Particulate Matter (PM) have become a major concern in most European cities. In particular, in Italy the O3 concentrations exceed the limits established for the protection of both human health and vegetation. More integrative studies are revealing that urban trees could concretely help in improving air quality, not only because of their well known aesthetic and recreational benefit, but also for their capability to reduce air temperature and to remove air pollutants. This reduction takes place both directly, by dry deposition to plant surfaces and uptake through stomata, and indirectly, by mitigation of the urban heat island intensity by canopy transpiration and building shading, that lowers the activity of chemical reactions that led to the formation of photochemical pollutants in air. This is of particular importance especially for those cities located in the Mediterranean Basin, whose urban vegetation is often characterized by VOC-emitting species that can contribute significantly to the O3 formation and destruction dynamics. The aim of this paper is to present a short review of ecological research performed on vegetation of the metropolitan area of Rome, at different spatial and temporal scale, in order to evaluate the functional role of urban green to monitor and improve urban air quality. In the frame of the project HEREPLUS (EU FP7), all of this information, opportunely integrated with climatic and pollutant data, will be implemented in a GIS and, by the use of geo-statistical methods, the ameliorating effect of urban vegetation will be quantified and mapped.