Gaetano Zipoli

Use of NOAA-AVHRR NDVI images for the estimation of dynamic fire risk in Mediterranean areas

Abstract Wildfires are a major cause of land degradation in the Mediterranean region due to their frequent recurrence in the same areas. The evaluation of fire risk is therefore of high practical importance, particularly during the summer arid season, when fires are most frequent and harmful. Recent studies have demonstrated that the evaluation of dynamic fire risk can be carried out by the use of remotely sensed images, and specifically of NOAA-AVHRR Normalized Difference Vegetation Index (NDVI) data. This use relies on the sensitivity of the index to vegetation dryness, which is a major predisposing factor for fire occurrence. Several problems, however, remain linked to the spatial variability of the risk in environmentally heterogeneous areas, which requires the application of suitable processing techniques to the low-resolution imagery. The current work reports on the development and testing of different methodologies for estimating dynamic fire risk by the use of NOAA-AVHRR data. The investigation was conducted in Tuscany (Central Italy) using a large archive of fires that occurred in the region and NOAA-AVHRR NDVI data of 16 years (1985–2000). Relying on previous methodological achievements of our group and other research groups, several procedures were tested to extract information related to fire risk from the remotely sensed images. These trials led to define an optimum method which is based on the identification of pixels where the accordance between interyear variations in fire probabilities and NDVI values is maximum. The accuracy of the risk estimates from this optimum method was finally evaluated by a leave-one-out cross-validation strategy. In this way, the performance of the methodology was assessed, together with its potential for operational fire risk monitoring and forecasting in Mediterranean areas.

Analysis of the relationships between climate variability and grapevine phenology in the Nobile di Montepulciano wine production area.

Climate represents one of the main inputs necessary for plants to complete their vegetative–productive cycle, having a direct effect on the onset and duration of phenological stages and development of crops. Equally important are its indirect effects, affecting field operations such as the application of fertilizer, pruning and crop protection, finally determining the yield. In the present study, phenological stages of the Sangiovese grapevine for the production of Nobile di Montepulciano wine were analysed and related to historical series of meteorological information (since 1970 in Tuscany, Italy). Weather conditions were described through large-scale meteorological information; in particular geopotential height at the 500 hPa level (500 hPa GPH) and North Atlantic Oscillation (NAO) index were considered. All data were provided by the National Oceanic and Atmospheric Administration-Cooperative Institute for Research in Environmental Sciences (NOAA-CIRES) Climate Diagnostics Center, Boulder, Colorado, USA, available from the NOAA-CIRES website ( http://www.cdc.noaa.gov/ ) and processed by the National Center for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR) Reanalysis Project. Conventional meteorological data, such as air temperature and cumulated rainfall, from ground weather stations were also used. The effects of meteorological parameters on crop phenology (bud-break, flowering and harvest time) were investigated by means of regression analysis, while teleconnections between phenological data and large-scale meteo-climatological data were analysed through correlation maps created using the interactive plotting and analysis link from the NOAA-CIRES website ( http://www.cdc.noaa.gov ). All correlations were calculated on a monthly to a multi-monthly basis, and also in relation to the different physiological stages of the crop, from 1970 to 2006. The climate change and variability impact on the crop was investigated by trend analysis of meteorological information and its effect on the onset of grapevine phenological stages. The results demonstrated that large-scale meteorological information has a significant effect on the onset of the phenological stages of grapevine. In particular, winter NAO was negatively correlated with bud-break and flowering dates, while GPH of February–March, March–May and May–September were negatively correlated with bud-break, flowering and harvest dates, respectively. The trend analysis demonstrated that the change and variability of climate, due to global warming, directly affects the development of grapevine leading to an anticipation of all considered phenophases.

Laboratory and outdoor assessment of UV protection offered by flax and hemp fabrics dyed with natural dyes.

The safest protection from UV radiation (UVR) exposure is offered by clothing and its protectiveness depends on fabric composition (natural, artificial or synthetic fibers), fabric parameters (porosity, weight and thickness) and dyeing (natural or synthetic dyes, dye concentration, UV absorbing properties, etc.). In this study the UV protection properties of two fabrics made of natural fibers (flax and hemp) dyed with some of the most common natural dyes were investigated. UVR transmittance of fabrics was measured by two methods: one based on the utilization of a spectrophotometer equipped with an integrating sphere (in vitro test), and the other based on outdoor measurements taken by a spectroradiometer. Transmittance measurements were used to calculate the ultraviolet protection factor (UPF). Experimental results revealed that natural dyes could confer good UV protection, depending mainly on their different UVR‐absorbing properties, provided that the fabric construction already guaranteed good cover. An increase in cover factor caused by the dyeing process was also detected. Weld‐dyed fabrics gave the highest protection level. The comparison between the two methods applied to measure fabric transmittance pointed out that the UPFs calculated by in vitro measurements were generally lower than those based on outdoor data, indicating an underestimation of the actual protection level of tested fabrics assessed by the in vitro test.

Assessing the response of plant flavonoids to UV radiation: an overview of appropriate techniques

Abstract Flavonoids are a large group of plant secondary metabolites that are present in most plants, and are vital for plant growth, development and protection. Among the many functions of these compounds is their contribution to stress amelioration. The accurate identification and quantification of total or individual flavonoids in plants exposed to stressful conditions (e.g. ultraviolet radiation) is challenging due to their structural diversity. The present review provides the up to date knowledge and highlights trends in plant flavonoid analysis. The review covers all steps from the field to the laboratory, focussing on UV-B effects on flavonoids, and identifying critical issues concerning sample collection, pre-treatment, extraction techniques and quantitative or qualitative analysis. A well-planned sampling and sample prehandling strategy is vital when capturing organ, tissue and developmental-stage dependent changes in flavonoids, as well as the dynamic changes due to time of UV-exposure and diurnal or seasonal parameters. A range of advanced extraction and purification techniques can facilitate the quantitative transfer of flavonoids to solvents. The advantages and disadvantages of analytical methods, including chromogenic assays, liquid and thin-layer chromatography, mass spectrometry, nuclear magnetic resonance detection, and non-destructive in situ fluorescent analysis need to be consciously evaluated in the context of the specific biological question posed. Thus, no one method can be applied to every single study of flavonoid. The message of this review is that researchers will need to carefully consider the biological process that they intend to study, and select an analytical method that optimally matches their specific objectives.

Oak (Quercus robur L.) seedling responses to a realistic increase in UV-B radiation under open space conditions

Plants show different levels of sensitivity to ultraviolet-B (UV-B) radiation and acclimation to high UV-B irradiances had been developed in many species. A field experiment was performed during 1995 to study the adaptative responses of oak plants (Quercus robur L.) to artificial UV-B supplementation The most important effect of UV treatment was the increase in leaf thickness and the accumulation of phenolic compounds in the secondary wall of the adaxial epidennis of leaves in UV treated plants; the secondary wall of cells in the abaxial epidermis, that is not directly exposed to supplemental UV-B. did not present any alterations. No effects were observed on photosynthesis while plant morphology was sensible to UV treatment.

The Use of Commercially Available Personal UV-meters Does Cause Less Safe Tanning Habits: A Randomized-controlled Trial

UV Index information is currently recommended as a vehicle to raise public awareness about the risk of sun‐exposure. It remains unknown to what extent this information can change personal sun‐protective behavior. The aim of the study was to analyze the effects of UV‐Index (UV‐I) information provided by low cost, commercially available UV‐I sensors on major indicators of sun‐tanning behavior. A randomized‐controlled trial was carried out on 94 healthy volunteers aged 21–23 years. After the exclusion of subjects with photosensitive disorders (n = 3), 91 subjects were randomized in two arms after stratification based on phototype and sex. Both arms received a diary to be filled every day with a log of intentional sun‐exposure during summer. Subjects in the intervention group also received a commercially available UV‐I sensor. The UV‐I sensors were switched on and the UV‐value was recorded in 77% of days with sun‐exposure. During days of sun‐exposure, subjects randomized to the intervention group had longer average time of sun‐exposure (227.7 vs 208.7 min per day, P = 0.003), also between noon and 4 pm (P < 0.001), and less frequently adopted sun protective measures than controls (hat [6.4%vs 10.2%, P = 0.007], sunglasses [23.9%vs 30.8%, P = 0.003], sunscreen [41.4%vs 47.2%, P = 0.02]) and they experienced more frequent sunburns (27.8%vs 21.5%, P = 0.004). The odd ratio of sunburns was 1.60 for subjects in the intervention group compared with controls (after adjustment for sex, sunscreen use and skin type). The mean UV‐I value recorded by volunteers was lower (5.6 [SD ± 0.9]) than that (7.3 [SD ± 0.46]) recorded by a professional instrument in the same period at the same latitude. Poststudy laboratory tests showed that the sensor was able to detect only about 60% of the solar diffuse radiation. The use of UV‐I sensors changed the sun protective behavior of sunbathers in the direction of less use of sun protective measures. One possible explanation is that the low cost UV‐meters may have functioned incorrectly and under‐reported UV exposure. This may have led to an underestimation of UV‐I values, erroneously reassuring subjects and causing a less protective sunbathing behavior. Another hypothesis relies on a cognitive pitfall in the subjects’ dealing with intermediate UV‐I values, as they may have been discouraged in the use of sunscreen as they did not feel that they had yet been exposed to very harmful UV radiation.

Might outdoor heat stress be considered a proxy for the unperceivable effect of the ultraviolet-induced risk of erythema in Florence?

Erythema is the most familiar short-term symptom of human skin associated with overexposure to unperceivable ultraviolet radiation (UV). However, people are able to perceive the warm infrared component of the solar radiation by means of thermal (dis)comfort. This study investigated the potentiality of perceived outdoor heat stress as a valuable proxy for the unperceivable effect of UV-induced risk of erythema in a Mediterranean city. Meteorological data and UVB (280-320nm) measurements were obtained for the 2004-2012 period by a weather station located in the municipality of Florence. Continuous measurements of erythemally effective UV (UVEry) were performed by means of a broadband temperature-corrected radiometer with the spectral response close to the erythemal action spectrum. Hourly UVEry doses were expressed as Standard Erythemal Doses (SEDs). The newly developed Universal Thermal Climate Index (UTCI), that represents the state-of-the-art of outdoor thermal (dis)comfort evaluation, was also assessed. Descriptive analyses of the hourly distribution per month of the frequencies of days with heat stress and UVEry exceeding 2.0, 3.0, 4.5 and 6.0 SEDs were carried out based on the general skin-type characteristics. The association between UVEry and UTCI was analyzed by a two-way contingency table approach. The probability of UVEry exceeding specific SED thresholds when heat stress occurs was often significantly higher than the same probability when no heat stress is perceived. Furthermore, increased magnitudes of the ratios, ranging from the very sensitive to the minimally sensitive skin types, were also found. However, during several months, too many days occur without any signs of heat discomfort, even when people may be exposed to relevant doses of harmful UVEry for the skin of various phototypes. These findings underlie the need for public health authorities to provide differentiated advice per month in relation to potential UV skin damage in the city of Florence.

Environmental plasticity of Pinot noir grapevine leaves: A trans-European study of morphological and biochemical changes along a 1,500-km latitudinal climatic gradient

A 2-year study explored metabolic and phenotypic plasticity of sun-acclimated Vitis vinifera cv. Pinot noir leaves collected from 12 locations across a 36.69-49.98°N latitudinal gradient. Leaf morphological and biochemical parameters were analysed in the context of meteorological parameters and the latitudinal gradient. We found that leaf fresh weight and area were negatively correlated with both global and ultraviolet (UV) radiation, cumulated global radiation being a stronger correlator. Cumulative UV radiation (sumUVR) was the strongest correlator with most leaf metabolites and pigments. Leaf UV-absorbing pigments, total antioxidant capacities, and phenolic compounds increased with increasing sumUVR, whereas total carotenoids and xanthophylls decreased. Despite of this reallocation of metabolic resources from carotenoids to phenolics, an increase in xanthophyll-cycle pigments (the sum of the amounts of three xanthophylls: violaxanthin, antheraxanthin, and zeaxanthin) with increasing sumUVR indicates active, dynamic protection for the photosynthetic apparatus. In addition, increased amounts of flavonoids (quercetin glycosides) and constitutive β-carotene and α-tocopherol pools provide antioxidant protection against reactive oxygen species. However, rather than a continuum of plant acclimation responses, principal component analysis indicates clusters of metabolic states across the explored 1,500-km-long latitudinal gradient. This study emphasizes the physiological component of plant responses to latitudinal gradients and reveals the physiological plasticity that may act to complement genetic adaptations.

UV hazard on Italian Apennines under different shading and ground cover conditions during peak tourist seasons of the year

Abstract In solar UV irradiance monitoring and forecasting services UV information is generally expressed in terms of its effect on erythema and referred to horizontal surface. In this work we define the UV radiative regime, in terms of biologically effective UV irradiance (UVBE) for skin and eye, under full sun and shaded conditions, over a mountainous tourist area of central Italy by means of two all-day measurements (summer and early spring) with different ground albedo (grass and snow cover respectively). UV irradiance was monitored on tilted surfaces (the most frequent for people standing and walking). Results show the significant contribution of ground albedo and sun position in determining the incident UVBE irradiance. On early spring days the UVBE irradiance measured on horizontal surface was much lower than on tilted ones; the opposite condition was observed in summer. The highest UVBE irradiance values, in particular conditions of sun elevation and ground cover, were reached in periods different from the summer both in full sun and shaded condition.

Development and application of a forecasting system to avoid spring frost damage in chiana valley

Late frost is one of the more serious adversity for Italian agriculture. Several methods have been developed to protect cultivations, but their application results particularly effective (also from an economic point of view) only if supported by forecasting systems during the more susceptible period of the year. On these basis a forecasting system of late frost in Val di Chiana (an area in central Italy mainly cultivated with cereals and high quality fruits) was developed. The system consists in an empirical model, based on a preventive agroclimatic analysis of the area to identify night cooling dynamics (for several meteorological conditions) in the spring. A network of 10 thermohygrometric stations was installed in the area integrating the information obtained by a local agrometeorological station network. The final product was a forecasting bulletin emitted every three hours beginning from the 13:00 p.m. A validation of the system was performed for 2006 to verify the forecast skill.