Andrea Pitacco

Canopy Architecture and Turbulence Structure in a Coniferous Forest

Synchronous sonic anemometric measurements at five heightswithin a mixed coniferous forest were used to test two different parameterisations ofcanopy architecture in the application of a second-order turbulence closure model. Inthe computation of the leaf drag area, the aerodynamic sheltering was replaced with anarchitectural sheltering, assumed to be analogous to the clumping index defined in radiativetransfer theory. Consequently, the ratio of leaf area density and sheltering factor was approximatedby the effective leaf area or the mean contact number, both obtained from the inversion of non-destructive optical measurements. The first parameter represents the equivalentrandomly dispersed leaf area in terms of shading, the second is the average number of leavesthat a straight line intercepts penetrating the canopy with a certain zenith angle. Theselection of this direction was determined by the analysis of the mean angle of the wind vectorduring sweep events. The drag coefficient values obtained from the inversion of themomentum flux equation, using the two proposed parameterisations, are in good agreement withvalues found in the literature. The predicted profiles of turbulence statistics reasonablymatch actual measurements, especially in the case of the mean contact numberparameterisation. The vertical profile of leaf drag area, obtained by forcing the turbulence modelto match the observed standard deviation of vertical velocity (σw), is intermediatebetween the two empirical ones. Finally, the proposed canopy parameterisations were appliedto a Lagrangian transport model to predict vertical profiles of air temperature, H2O andCO2 concentration.

Comprehensive transcript profiling of two grapevine rootstock genotypes contrasting in drought susceptibility links the phenylpropanoid pathway to enhanced tolerance

Highlights Drought tolerance in the M4 grapevine rootstock genotype could be associated with a higher capability to counteract oxidative stresses by enhancing the accumulation of resveratrol in roots.

Solar radiation directly affects larval performance of a forest insect

Solar radiation can affect the performance of insect herbivores directly by increasing body temperature, or indirectly through alteration of either host plant quality or natural enemy activity. To test for the direct effect of solar radiation on larval performance, young Pinus sylvestris trees growing on the island of Gotland (Sweden) were assigned to one of four shading treatments for the whole duration of the first larval instar of the northern pine processionary moth Thaumetopoea pinivora. There was a strong, linear relationship between shading and the temperature of the first‐instar colonies of T. pinivora, resulting in higher growth of the larvae exposed to full sunlight, but there were no effects on developmental rate or larval mortality. Putative negative effects of UV radiation on the larvae are not consistent with higher growth in full sunlight, but it is possible that UV effects might have modulated the response. Thaumetopoea pinivora has a strong preference for light and open pine stands, i.e. habitats with frequent intense incoming solar radiation. The data in the present study suggest that the opportunity for young larvae to bask in the sun during cold spring weather is an important determinant of the spatial distribution of T. pinivora.

Micrometeorological test of microsprinklers for frost protection of fruit orchards in Northern Italy

Microclimate modification induced by intermittent water sprinkling at ground level has proven to be suitable to enhance protection against spring hoarfrosts in orchards. This research investigates about the efficiency of different sprinkler types and water volumes in enhancing air temperature in the canopy layer and to optimise the amount and the cycling of the water applied. Tests have been done over three consecutive years in purpose-built boxes delimited by polyethylene film where different sprinklers and sprayers tested were positioned along two pipes. Microsprinklers and microsprayers with different characteristics and outflow capacity were compared to evaluate whether the size of the drops can induce modification of energy balance at the surface. The impact of below-tree water sprinkling on the temperature profile appeared to be evident independently on the irrigation device and of the outflow tested. While no substantial differences between sprinklers and sprayers did not arise when the temperatures kept above 3 C, when temperatures fell below 3 C (even down to 7/)8 C), a better performance of the microsprinklers with respect to microsprayers was observed. Differences tend to fade out with height. In the same temperature conditions, a better performance of the microsprinklers with higher outflow (65 l/h) with respect to the same model characterised by a lower outflow (45 l/h) clearly emerged.

Carbon, water and energy fluxes of terrestrial ecosystems in Italy

In this chapter the Eddy Covariance network of Italy is presented, with a short introduction to each of the 29 sites that were active during the CarboItaly project. These sites provided a unique dataset for a better study and understanding of the carbon cycle of terrestrial ecosystems and the links between carbon sink capacity and the main environmental factors. After a number of examples of Eddy Covariance time series where it is possible to see the effect of interannual climate variability and disturbances and managements practices, an analysis of the role of the Carbon Uptake Period in the total Net Ecosystem Exchange (NEE) definition and a study of the effect of temperature and precipitation on the interannual variability of NEE are presented in order to show the way these data can contribute to a better understanding of the role and response of ecosystems to climate change.

Study of the Carbon Budget of a Temperate-Climate Vineyard: Inter-Annual Variability of CO2 Fluxes

Agriculture can improve the global carbon budget by reducing emissions and increasing soil carbon sequestration. Woody crops like vineyards present biological, structural, and management peculiarities, such as perennial structure, abundant pruning debris, and interrow cover cropping, which could potentially sequester a significant amount of CO2. However, such ecosystems are still poorly understood. Here, we present results from a long-term study from northeastern Italy on the carbon budget of a vineyard (cv. Sauvignon blanc, Guyot pruned, vertical shoot-positioned trellised, with grass-covered alleys). We used the eddy covariance technique to continuously monitor the net ecosystem CO2 exchange (NEE), and here we present the first three years of data (May 2014 to April 2017). The vineyard acted as a moderate carbon sink, with an average annual net carbon uptake of 134 g C/ m2. However, the inter-annual variability of NEE was high, and environmental conditions during the growing season had a strong impact. The annual carbon uptake was greatest in 2014 (207 g C/m2), when there was abundant rain in summer. In contrast, in 2015, several heat waves decreased the annual carbon uptake to 69 g C/m2. Elevated air temperature and low soil moisture in summer significantly reduced net carbon flux during times when the vineyard activity was at maximum. Nevertheless, we show that a vineyard can behave as a carbon sink in the medium-to-long term, which should be factored into agricultural and environmental policies, complementing the standard life cycle assessment of the wine production chain.