Luca Fibbi

Free Air CO2 Enrichment (FACE) of grapevine (Vitis vinifera L.) : II. Growth and quality of grape and wine in response to elevated CO2 concentrations

Abstract A FACE (Free Air CO2 Enrichment) experiment was carried out on Grapevine (Vitis vinifera L.) in 1996 and 1997 in an existing vineyard in Italy. Four FACE arrays were used to fumigate adults plants, while two arrays were used as control. Three CO2 exposure levels were used in these arrays (ambient, 550 and 700 μmol mol−1). Dynamics of vegetative and reproductive biomass and grape quality compounds (sugar and acid concentrations) were monitored during the two growing seasons. Chemical analyses of the main wine quality compounds were made after fermentations. Elevated atmospheric CO2 levels had a significant effect on biomass components (total and fruit dry weight) with increases that ranged from 40 to 45% in the 550 μmol mol−1 treatment and from 45 to 50% in 700 μmol mol−1 treatment. Acid and sugar contents were also stimulated by rising CO2 levels up to a maximum increase in the middle of the ripening season (8–14%); however, as the grapes reached the maturity stage the CO2 effect on both quality parameters almost completely disappeared. Wine quality was not significantly affected by elevated CO2. Furthermore, no significant differences were detectable among the plants grown in the two enriched treatments (550 and 700 μmol mol−1), and the effects of elevated CO2 concentration were similar in the two growing seasons. The absence of any further stimulation of the highest CO2 treatment (700 μmol mol−1) on grapevine growth and yield quality (i.e. grapes and wine) may be explained as a result of transport and/or sink limitations. We can conclude that the expected rise in CO2 concentrations may strongly stimulate grapevine production without causing negative repercussions on quality of grapes and wine.

Chlorophyll concentration of potatoes grown under elevated carbon dioxide and/or ozone concentrations

Abstract Potato cv. Bintje was grown in open-top-chambers and free-air-CO2-enrichment systems at 7 sites across Europe for 2 years (1998–99). The effect of different treatments (CO2 enrichment and O3 fumigation) on the chlorophyll content of fully expanded upper and lower canopy leaves was investigated collecting Minolta SPAD-502 meter readings. In both CO2 treated and O3 fumigated plants, leaves had lower chlorophyll content than those in ambient air controls; season-long chlorophyll averages were 9.3% lower in the ‘CO2’ treatments, 9.1% lower in ‘O3’ treatments and 12.3% lower in ‘CO2+O3’ treatments. The analysis of chlorophyll content in three different growth phases (Emergence–Tuber Initiation; Tuber Initiation–Maximum Leaf Area; Maximum Leaf Area–Harvest) showed that in the early growth period, i.e. before tuber initiation there was a slight indication for an higher chlorophyll content at elevated CO2 (+3.8%) or O3 (+1.7%). However, from tuber initiation onwards the leaves of plants grown under elevated CO2 or O3 showed a progressively lower chlorophyll content (−4.8% for CO2 treatments and −2.6% for O3 treatments) indicating a faster senescence of leaves that increased during the late growth period (−12.8% for CO2 treatments and −12.7% for O3 treatments) and that was enhanced by CO2–O3 interaction (−17.8%).

Calibration and application of FOREST-BGC in a Mediterranean area by the use of conventional and remote sensing data

The current work deals with the use in a Mediterranean environment of a simulation model of forest ecosystem processes which was originally created for temperate areas (FOREST-BGC). The model was calibrated and applied on two deciduous forest stands in Tuscany (Central Italy) by using conventional and remote sensing data as inputs. First, information on the two stands needed to initialise the model was derived from different sources, while meteorological data were extrapolated from a nearby station by an existing procedure (MT-Clim). Temporal profiles of leaf area index (LAI) were then derived both from direct ground measurement and from the processing of NOAA-AVHRR NDVI data. The model was calibrated using stand transpiration values obtained for 1997 by a sap flow method. Next, its performances were tested against the same transpiration values measured in 1998. The results obtained indicate that FOREST-BGC is capable of simulating water fluxes of Mediterranean forests when suitable LAI profiles are considered. Moreover, the derivation of these profiles from NDVI data can improve the model performance probably due to an enhanced consideration of the effects of the typical Mediterranean summer water stress. These results support the final objective of the work, which is the development of a procedure capable of integrating conventional and remote sensing data to operationally simulate water and carbon fluxes on a regional scale.

Free Air CO2 Enrichment (FACE) of grapevine (Vitis vinifera L.): I. Development and testing of the system for CO2 enrichment

Abstract The control of CO 2 levels is reported for a Free-Air Carbon dioxide Enrichment (FACE) facility employed in a vineyard at Rapolano, Italy in 1996 and 1997. This control is required for evaluating the validity of a biological experiment conducted on grapevine in CO 2 enriched and control experimental plots. Six rectangular emission arrays enclosing seven plants each were installed in the vineyard imposing three CO 2 exposure levels (ambient, 550 and 700 μmol mol −1 ) and monitoring CO 2 levels at the centre of each experimental plot. In the 2 years, average seasonal (May–September) CO 2 levels during treatment hours (05:00–19:00 h) varied from 697 to 698 μmol mol −1 for 700 μmol mol −1 target treatment and from 549 to 550 for 550 μmol mol −1 target treatment. The averaged 1 min measurements of CO 2 concentration were within 20% of the target concentrations for more the 80% of the time. The FACE facility also provided a good spatial control of CO 2 concentration for an experimental sampling volume of 15.7 m 3 (8 m×1.4 m×1.4 m), including five plants per plot.

Integration of remote sensing and ecosystem modelling techniques to estimate forest net carbon uptake

Estimates of forest gross primary production (GPP) can be obtained using a parametric model (C‐Fix) that combines ground and remotely sensed data. A methodology is presented to convert these GPP estimates into values of net ecosystem exchange (NEE). The methodology is based on the use of a process model (BIOME‐BGC) that, after proper calibration, simulates all main functions of forest ecosystems at the climax condition. The estimated photosynthesis and respirations are transformed into net carbon fluxes of actual forests by using a simplified approach that relies on the difference between actual and potential stand biomass. The methodology was applied to eight forest sites in Italy where flux measurements were available and GPP estimates had been previously produced. The comparison of the obtained NEE estimates to the ground data indicates the potential of the approach and the prospects for future investigation.

Simulation of Mediterranean forest carbon pools under expected environmental scenarios

Simulating the effects of possible environmental changes on the forest carbon budget requires the use of calibrated and tested models of ecosystem processes. A recently proposed simulation approach...

Estimating daily forest carbon fluxes using a combination of ground and remotely sensed data

Several studies have demonstrated that Monteiths approach can efficiently predict forest gross primary production (GPP), while the modeling of net ecosystem production (NEP) is more critical, requiring the additional simulation of forest respirations. The NEP of different forest ecosystems in Italy was currently simulated by the use of a remote sensing driven parametric model (modified C-Fix) and a biogeochemical model (BIOME-BGC). The outputs of the two models, which simulate forests in quasi-equilibrium conditions, are combined to estimate the carbon fluxes of actual conditions using information regarding the existing woody biomass. The estimates derived from the methodology have been tested against daily reference GPP and NEP data collected through the eddy correlation technique at five study sites in Italy. The first test concerned the theoretical validity of the simulation approach at both annual and daily time scales and was performed using optimal model drivers (i.e., collected or calibrated over the site measurements). Next, the test was repeated to assess the operational applicability of the methodology, which was driven by spatially extended data sets (i.e., data derived from existing wall-to-wall digital maps). A good estimation accuracy was generally obtained for GPP and NEP when using optimal model drivers. The use of spatially extended data sets worsens the accuracy to a varying degree, which is properly characterized. The model drivers with the most influence on the flux modeling strategy are, in increasing order of importance, forest type, soil features, meteorology, and forest woody biomass (growing stock volume).

Estimation of wheat production by the integration of MODIS and ground data

This paper presents a methodology capable of combining Moderate Resolution Imaging Spectroradiometer (MODIS) Normalized Difference Vegetation Index (NDVI) imagery and ancillary data to estimate durum wheat production in Tuscany (Central Italy). First, the phenological stages of winter wheat are simulated by the use of an agro-meteorological model (Syrius 4.1). Next, MODIS NDVI images at 250 m spatial resolution are utilized to identify fields likely grown with winter wheat. The multitemporal NDVI profiles of these fields are then integrated with Syrius 4.1 outputs through a previously developed procedure in order to simulate wheat above-ground biomass and harvest index. This allows the computation of wheat yield, which, combined with relevant cropped area, provides provincial wheat production estimates. The methodology is tested using ground and MODIS data taken over four Tuscany provinces where winter wheat is widely cultivated. The accuracy of all estimated variables (wheat cropped area, yield and production) is finally evaluated against provincial statistical data. The results of this experiment indicate that the accuracy of wheat cropped area estimation and yield simulation is variable, but interannual production variations are reproduced well for all provinces.

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.

Improved simulation of soil water content by the combination of ground and remote sensing data

Abstract The simulation of site water balance requires the assessment of actual evapotranspiration (ETA), which is highly variable both in space and in time depending on several factors (climate, soil, vegetation). In a recent work we proposed a new method based on remotely sensed NDVI data which can estimate daily ETA operationally over large areas. The current paper utilizes these ETA estimates to drive two crop coefficient models, WinEtro and FAO56, in the prediction of soil water content (SWC). The outputs of the simulations are evaluated versus daily measurements of SWC taken in a Tuscany forest site (Barbialla) during four years. The results obtained indicate the efficiency of the proposed data combination, which improves the SWC simulations of both models examined. Recommendations are finally expressed for the possible extension and enhancement of the method described.