1,721,018 research outputs found
Effetto combinato di stress abiotici in specie della macchia medieterranea mediante studi di campo e in condizioni semi-controllate
No full textGli ecosistemi a macchia nel Bacino del Mediterraneo, costituiscono la vegetazione preferenziale di aree in cui sono presenti condizioni limitanti determinate sia da dinamiche storico-colturali (pascolo, incendi), sia ecologiche (scarse precipitazioni, suoli poveri di nutrienti). Le specie presenti in tali ecosistemi sviluppano adattamenti fisiologici e strutturali tali da resistere a periodi di stress a cui tali ambienti sono soggetti (stress idrico, alte temperature ed irradianze). Si tratta di ecosistemi che sono distribuiti in aree dove si riscontra la maggiore densità di popolazione e che sono sottoposti anche da stress di origine antropica. Nei prossimi decenni soprattutto le aree costiere saranno al centro d’importanti variazioni nella disponibilità e qualità delle risorse: la diminuzione delle precipitazioni, l’incremento del livello medio del mare, l’avanzamento del cuneo salino, l’intensificarsi degli eventi estremi con conseguente aumento delle deposizioni di spray marino sulla vegetazione e sul suolo, sono tra questi. La popolazione nelle aree costiere è destinata ad aumentare e con essa anche il livello di esposizione della vegetazione ad inquinanti. L’azione fitotossica di quest’ultimi, potrebbe destabilizzare o diminuire l’efficienza con cui le specie presenti fanno fronte agli stress naturali a cui sono adattate. La combinazione di questi scenari fa emergere che per salvaguardare la funzionalità, il naturale accrescimento e mantenimento degli ecosistemi mediterranei a macchia nelle fasce costiere, bisogna comprendere l’effetto che i fattori di stress prospettati, interagendo, possano avere. La regolazione del funzionamento dell’apparato fotosintetico, della fase luminosa e del bilancio tra processi anabolici e catabolici è alla base di molti adattamenti fisiologici e, avendo questi inevitabili conseguenze sulla produttività, anche di adattamenti strutturali. Una questione ancora aperta è quella di determinare se i meccanismi che conferiscono tolleranza alle specie mediterranee costituiscono la base per la resistenza in una condizione di multistress, o se la resilienza che i tratti funzionali tipici di questa tipologia di vegetazione conferisce, possa determinare invece un’incapacità di far fronte al mutamento delle condizioni esterne. Tali riflessioni hanno costituito il background di questa tesi di dottorato nella quale un elemento essenziale per sviluppare gli obiettivi sperimentali è stato quello di adottare un approccio integrato che affiancasse esperimenti in condizioni controllate, in cui testare singole ipotesi sperimentali, ad un lavoro in condizioni naturali, in cui approfondire quanto la variabilità ambientale influisce sui processi funzionali. Gli obiettivi generali di questa tesi di dottorato riguardano lo studio di come le specie sempreverdi mediterranee rispondono all’interazione tra stress di natura ossidativa, ponendo attenzione al ruolo che il funzionamento dell’apparato fotosintetico ha nel modulare i meccanismi di risposta e come il bilancio tra processi anabolici e catabolici cambia in funzione dei diversi stress ossidativi
Effects of nitrogen deposition, drought and their interaction, on functional and structural traits of fraxinus ornus L. and quercus ilex L.
No full textA controlled experiment was conducted in order to understand how functional and structural traits of species with different leaf habits (Fraxinus ornus and Quercus ilex) shift as a consequence of nitrogen (N) addition (30 Kg ha yr-1), and to explore the effect that nitrogen has on the water stress response. The experiment was divided in two stages: stage I, nitrogen addition under well water condition; stage II, nitrogen addition under drought. Functionality of the photosynthetic machinery, growth and biomass partitioning were assessed. The N content at leaf level increases in F. ornus only, that invests resources on photosynthetic machinery, whereas Q. ilex tends to store N in non-photosynthetic biomass, increasing relative growth rate and biomass, resulting in different allometric ratio. This effect may had a role in water stress response. Stomatal conductance of Q. ilex treated with N and subjected to water stress is lower relative to drought treatment. On the contrary, F. ornus takes advantage of N addition that has ameliorative effects on its functionality when drought was imposed. The obtained results, highlighting response mechanisms to multiple stress factors, should help to better understand and assess the performance of forest ecosystem under the foreseen environmental changes
Chlorophyll fluorescence for phenotyping drought-stressed trees in a mixed deciduous forest
Full text linkAmong the environmental constraints affecting growth, productivity and health of crops and forests ecosystems, drought is known to be a key factor particularly in the Mediterranean area, where the typical dry and hot summer conditions may be exacerbated as a consequence of the foreseen Global Climatic Changes. Despite the drought stress response of forest trees has been intensively investigated, phenotyping for functional traits associated to drought adaptation in the field still remains particularly challenging, due to the intrinsic difficulties in screening tall trees in forest environment. In this work, we have applied a high-throughput phenotyping approach to investigate the drought response of two coexisting deciduous tree species (Quercus cerris L. and Fraxinus ornus L.) in a natural mixed forest (Circeo National Park, Central Italy). Our results have shown that the measurement of Chlorophyll fluorescence with the JIP-test application is particularly suitable for phenotyping the drought stress response of adult trees in the field. In particular, among the phenotypic traits investigated, the Total Photosynthetic Performance Index (PITOT) has proven to be the most suitable non-invasive marker of plant response to drought, which is able to provide reliable, fast and synthetic information on plant ecophysiological status
Servizi ecosistemici e qualità dell’aria nelle città: biodiversità vegetale e rimozione di inquinanti atmosferici nella città di Roma
No full textA THREE YEARS PILOT STUDY TO EVALUATE FLUORESCENCE ANALYSIS IN OZONE BIOMONITORING WITH BEAN CLONES NEAR ROME, ITALY
No full textAn ozone (O3) biomonitoring experiment was conducted during the years 2008, 2009 and
2010 in a natural area inside the Castelporziano Presidential Estate (Rome, Italy),
characterized by a typical Mediterranean climate (Manes et al., 1997). Following the UNECE
ICP Vegetation protocols (UNECE, 2008-2010), the O3-sensitive (S156) and ozone-resistant
(R123) genotypes of Phaseolus vulgaris L. were used. 10 to 12 replicates plants per clones,
fully irrigated, were exposed to ambient air for approximately 60 days from mid July 2008
mid June 2009 and end of June, 2010. O3 concentrations and climatic parameters were
continuously monitored in the experimental site, leaf visible injury was evaluated weekly
every year and, at the end of each experiments, pods were harvested and yield evaluated.
Moreover, during the years 2009 and 2010, gas exchanges and direct chlorophyll “a”
fluorescence were measured on fully developed leaves, during selected phenological phases,
and in particular close to the onset of flowering. AOT40 during the experimental periods
(from day 0 to harvest) was 3588, 9273, and 3324 ppb in 2008, 2009 and 2010, respectively.
A clear distinction in the extent of visible leaf injury symptoms between the S and R biotypes
was apparent (UNECE- ICP Vegetation, 2009), although during 2010 also the R variety
showed injury symptoms. However, differently from what reported in previous studies
(Flowers et al., 2007) no clear relationship between the extent of leaf injury, pod yield and
ozone levels were evident across years: production of developed pods was in fact higher in the
R clone only in 2008 (S156/R123 = 0.86), and higher in the S clone during the years 2009 and
2010 (S156/R123 = 3.46 and 1.12 in 2009 and 2010, respectively). Stomatal conductance and
net photosynthesis in the 2009 assessment were slightly lower in the S than in the R clone,
while in the 2010 assessment the S clone had slightly higher gas exchange values, both before
and after flowering. The chlorophyll fluorescence measurements and the application of the
JIP-test (Strasser et al., 2010) give important insight for early evaluation of differences in
photosynthetic efficiency between genotypes. The fluorescence transients analysis highlights
a similar behaviour of both clones, and the OJIP fluorescence parameters did not show the
typical ozone-induced stress response. Both clones appear instead affected by the summer
climatic conditions, and particularly by high temperatures and irradiance values. Moreover,
this response seems to vary with plant developmental stages (Elagöz and Manning, 2005).
Further studies are therefore needed to better investigate the applicability of this
biomonitoring system under environmental conditions typical of the Mediterranean area
Regulating ecosystem services and green infrastructure. Assessment of urban heat island effect mitigation in the municipality of Rome, Italy
No full textThe Urban Heat Island (UHI) effect is one of the main environmental impacts of urbanization, affecting directly human health and well-being of the city dwellers, and also contributing to worsen environmental quality. As a key strategy to address sustainable urban development, the EU has advocated the development of Nature-Based solutions, such as the implementation of Green Infrastructure (GI), which can deliver a wide range of Regulating Ecosystem Services (ES). In this article, the ES of climate regulation provided by GI has been analyzed in the Municipality of Rome, Italy, characterized by a complex territory and by a Mediterranean climate. The methodological approach allowed to characterize the UHI and to analyze its features in a spatially explicit way and on a seasonal basis, through the Land Surface Temperature (LST) derived from Landsat-8 data. The cooling capacity of different GI elements (peri-urban forest, urban forest, street trees), as well as the effect of vegetation cover and tree diversity on the provision of this regulating ES were assessed. The results show that GI significantly mitigates the hot urban climate during summer, with an effect that is dependent on the GI element and the environmental constrains to which it is exposed. NDVI and tree cover resulted the main indicators of the provision of the ES of climate regulation, highlighting that GI elements such as urban and peri-urban forests have the highest potential to provide this ES in a Mediterranean city. In the context of the Mapping and Assessment of Ecosystems and their Services (MAES) process, our results lend support to claims that GI is important for an ecosystem-based climate adaptation strategy in urban environments, contributing to the definition of knowledge based criteria and indicators, relevant for decision-making in Mediterranean cities
Foreste urbane e servizi ecosistemici: abbattimento del particolato aerodisperso (PM10) e tipologia di vegetazione, in contesto urbano e periurbano nell’area metropolitana di Roma
No full textPhotosynthetic traits as indicators for phenotyping urban and peri-urban forests. A case study in the metropolitan city of Rome
No full textPhenotyping for functional traits associated with photosynthetic machinery could be a promising approach for studying the performance of green infrastructures in metropolitan areas. Trait-based indicators hold important information about ecosystem processes and how environmental constrains may influence the provisioning of services. This work aims to apply a high-throughput phenotyping approach to an urban and a peri-urban forest, in order to evaluate the functionality of vegetation through direct measures of photosynthetic traits such as spectroscopy indices, chlorophyll a fluorescence (ChlF) and leaf chemistry (nitrogen and carbon content). Quercus ilex L. was chosen as the target species for its wide distribution in natural and urban greening, sampled at two distances from a high traffic road (urban forest) and in a natural preserved area (peri-urban forest). The reflectance index most related to the general functionality of photosynthetic machinery was the Fluorescence Ratio Indices FRI 740/800 , whereas the highest informative indicator traits to differentiate the functionality of Q. ilex in different periods of the year in the urban and peri-urban forest were Normalized Difference Vegetation Index (NDVI), Structure-Insensitive Pigment Index (SIPI) and Normalized Difference Nitrogen Index (NDNI). Interestingly, Photochemical Reflectance Index (PRI) was not only correlated to functional parameters connected to PSII light absorption side, but also with ChlF parameters related to carbon assimilation such as regeneration capacity of the end acceptors. ChlF parameters are effective indicators for highlighting differences between sites, pointing out that the urban forest sites have lower functionality compared to peri-urban one
Effects of the antiozonant ethylenediurea (EDU) on Fraxinus ornus L.. The role of drought
Full text linkEthylenediurea (EDU) is a synthetic chemical known to protect plants from the phytotoxic effects of tropospheric ozone (O3). Although many studies have proposed the use of EDU for studying the O3 effects under field conditions, its mechanism of action is not fully understood, and it is unclear whether it exerts a specific antiozonant action, or if it may also interact with other oxidative stresses. The aim of this work was to evaluate the effect of EDU on forest species in a Mediterranean environment where, during summer, vegetation is exposed to multiple oxidative stresses, such as O3 and drought. The experiment was conducted on Fraxinus ornus L. (Manna ash) plants growing in six mesocosms, three maintained under full irrigation, while the other three were subjected to drought for 84 days. In each mesocosm, three plants were sprayed every 15 days with 450 ppm EDU. Gas exchange and chlorophyll "a" fluorescence measurements carried out through the experimental period highlighted that EDU did not affect stomatal conductance and had an ameliorative effect on the functionality of drought-stressed plants, thus suggesting that it may act as a generic antioxidant. The implications of these findings for the applicability of EDU in field studies are discussed
Combination effect of sea spray and ozone on gas exchange parameters and fluorescence O-J-I-P transients in mediterranean maquis species
No full textCOMBINATION EFFECT OF SEA SPRAY AND OZONE ON GAS EXCHANGE PARAMETERS AND FLUORESCENCE O-J-I-P TRANSIENTS IN MEDITERRANEAN MAQUIS SPECIE
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