1,104 research outputs found
Study of vegetation-atmosphere interactions over vineyards: CO2 fluxes and turbulent transport mechanics
No full textThe study of vegetation‒atmosphere exchanges is today of great interest in order to understand and model plant responses to environmental conditions and their potential influence on global climate change. A special attention is usually given to carbon dioxide (CO2) fluxes and, in general, natural ecosystems such as forests received more attention. In the present work we investigated vegetation‒atmosphere interactions over vineyards, focusing on the annual carbon budget and turbulent transport processes driving exchanges of mass and energy.
Vineyard is a complex ecosystem with distributed sources/sinks of scalars (water vapour, carbon dioxide, heat), where vines and soil surface combine to give the overall flux of the canopy. In Northern Italy vineyard inter-row is often grassed, playing then an important role in the whole carbon budget. In this context, the partitioning of net ecosystem CO2 exchange (NEE) into soil and vine components deserves a special attention. We monitored vineyard NEE applying the eddy covariance (EC) method for three years, while soil CO2 flux measurements have been carried on using soil chambers (transparent and dark). In 2015, the annual carbon budget of the vineyard was about ‒ 80 g C m‒2 y‒1, however the largest part of carbon assimilation was due to grassed soil compartment (‒ 60 g C m‒2 y‒1). The interannual variability of seasonal carbon budget showed to be high and significantly affected by heat waves and drought spells in summer. During the growing season of 2014, characterized by plenty of rainfall, NEE reached its maximum value of about ‒ 250 g C m‒2.
The organization in rows of the vineyard determines a peculiar turbulent transport dynamics within the canopy. However, the morphological structure of the vineyard is greatly variable over the year, shifting from an empty canopy during vine dormancy to dense foliage in summer. We investigated the influence of foliage development on turbulence statistics deploying a vertical array of sonic anemometers. Turbulent flow showed to be greatly influenced by canopy structure. Without leaves, turbulent regime is typical of a rough‒wall boundary layer flow, whereas at full foliage development it assumes the features of a mixing‒layer flow, even if the inflection point at canopy top is weak, due to sparseness of the vineyard. Coherent structures involved in momentum transport and their temporal scales have been also investigated, showing the increasing importance of sweeps throughout the growing season. The average duration of dominating coherent structures was in the order of 6 ‒ 10 s and no clear influence by canopy structure evolution was detected.
The research demonstrated the importance of long‒term monitoring of vegetation‒atmosphere exchanges, and also the complexity of turbulent transport dynamics in the canopy space. However, only a thorough comprehension of this mechanics could lead to a solid interpretation of the role of vegetation in fundamental biogeochemical cycles
Emerging technologies in solid drug delivery: An interview with Nadia Passerini
No full textNadia Passerini is interviewed by Hannah Makin, Commission Editor. Nadia Passerini is Associate Professor of Pharmaceutical Technology at the University of Bologna (Bologna, Italy). She obtained the degree in Pharmaceutical Chemistry and Technology at the University of Bologna in 1992 and the PhD in Pharmaceutical Science in 1997. Her research focuses on the study of drug delivery systems, developing new technologies and new apparatus for the production of solid dosage forms (microparticles, granules and tablets), which can optimize the bioavailability of drugs according to the specific needs of the therapy. Furthermore, she is interested in the solid-state characterization of the produced delivery systems in order to correlate their physicochemical properties to the in vitro release of the drugs. Currently, her research focuses in particular on the production and characterization of microparticles produced by the spray congealing technology. She is author of over 50 international peer-reviewed publications and over 50 contributions (poster and oral presentations) to national and international conferences
Disentangling the carbon budget of a vineyard: The role of soil management
No full textThe environmental sustainability of viticulture can be enhanced with the application of conservative management practices (e.g. resident vegetation or cover crop on the inter-row), which can lead to an increase of soil carbon (C) sequestration. However, studies disentangling the vineyard C budget are still very scarce. In this context, comparing vineyard net ecosystem CO2 exchange (NEE) with soil fluxes is especially useful. From January 2015 to August 2016, we continuously monitored vineyard NEE with the eddy covariance method and ground CO2 fluxes with an automated chamber system in a commercial vineyard in North Eastern Italy. At the site, inter-rows are covered with resident herbaceous vegetation, however, due to low soil permeability, soil cultivation (ripping or tillage) was performed on alternate alleys in autumn and, sometimes, spring in order to improve water infiltration. Measured annual soil respiration was comparable, but lower, to values estimated by previous studies in vineyards and the net uptake of the grass cover laid in the middle of yearly C budget range reported in the literature for grasslands. At the end of the measurement period, the vineyard ecosystem showed to be a net sink of CO2, absorbing around −233 gC m−2. However, the C sequestration could have been much greater if no soil cultivation had been applied. Indeed, the ground compartment was a source of CO2, but without inter-row cultivation it could have been a net sink, with an overall vineyard C budget of about −421 gC m−2. This confirms that grass cover of the inter-rows can play an important role in the C budget of woody crops. Additionally, the pattern of C fluxes reveals that the activity of herbaceous vegetation in summer decreased well before vines, thus reducing water competition during dry periods. These results provide important information for the tuning of management practices aimed at improving the environmental sustainability of viticulture
Effects of evolving canopy structure on turbulence statistics in and above a hedgerow vineyard
No full textComparison of CO2 fluxes from eddy covariance and soil chambers measurements in a vineyard
No full textComparison of sensible heat fluxes by large aperture scintillometry and eddy covariance over two contrasting−climate vineyards
No full textMeasurements of turbulent energy fluxes between land-surface and the atmosphere are commonly carried out applying the eddy covariance (EC) method. Nevertheless, in some cases (e.g. surface heterogeneity, remote sensing or model validation), the use of a Large Aperture Scintillometer (LAS) is more appropriate. We compared LAS and EC measurements of sensible heat flux (H) over two contrasting vineyards of Southern (MIN site) and Northern (LIS site) Italy, mainly differentiating for climate (i.e. dry and humid), water management (i.e. irrigated and rainfed), and LAS setup. The relationship between H by LAS (HLAS) and by EC (HEC) was good at both sites, but with slightly higher HLAS. At MIN, where multiple EC stations were deployed, the best agreement was found with the station in the center of LAS path. Surface heterogeneity due to irrigation had different impact on HLAS depending on location of the source area. The canopy growth at LIS during the study period caused the approaching of LAS beam to the roughness sublayer, resulting in a reduction of HLAS compared to HEC. The closure of energy balance was higher (79%) at MIN and lower (64%) at LIS, but the agreement between HLAS and HEC was similar at both sites, suggesting that particular attention should be given to latent heat flux measurements by EC in order to better understand the energy balance closure issue
Evolution of turbulent flow characteristics in a hedgerow vineyard during the growing season
No full textThe characteristics of turbulent flow at the land-atmosphere interface and within plant canopies are strongly modified by the interactions with vegetation elements. However, only few experimental studies were conducted so far on the effect of changing leaf area on within-canopy turbulence statistics. This aspect is important for deciduous forests and perennial woody crops (orchards and vineyards), where the variation of leaf area is recurrent and substantial during the growing season. Increasing the understanding on canopy turbulence is fundamental to improve the parameterization of multi-layer models to predict vegetation-atmosphere exchanges. In this context, we conducted an experimental campaign in a hedgerow vineyard in North-East Italy carrying out measurements with a vertical array of 3D sonic anemometers, together with canopy structure characterization, in order to analyze the evolution of turbulent flow characteristics from a leafless canopy to full development. Additionally, the effects of wind direction with respect to rows and of atmospheric stability were analyzed. We found that the aerodynamic properties of the vineyard were not only influenced by canopy height and total leaf area, but also by the vertical distribution of leaf density, with the thickness of the mid-upper layer playing a major role in determining the canopy roughness and the mean level of momentum absorption. The characteristics of within-canopy turbulent flow became more similar to a well-defined mixing-layer type flow as foliage developed, but only for diagonal and across-row wind. In contrast, with wind parallel to rows the effect of increasing leaf density was lower and the vineyard was more similar to an open canopy. The influence of atmospheric stability was less important compared to wind direction or leaf density, except for the free convection class. Nevertheless, a variation of canopy aerodynamic parameters with stability was observed and this should be taken into account in atmospheric models
Study of the Carbon Budget of a Temperate-Climate Vineyard: Inter-Annual Variability of CO2 Fluxes
No full textAgriculture can play a positive role in the global carbon budget through reduction of emissions and increase of soil carbon sequestration. Woody crops, like vineyards, present biological, structural and management peculiarities (e.g. perennial structure, abundant pruning debris, inter-row cover cropping), which allow to potentially sequester a significant amount of CO2. However, only few studies have been conducted over this kind of ecosystems. In this paper, we present results from a long-term study running in North Eastern Italy on the carbon budget of a vineyard (cv Sauvignon Blanc, Guyot pruned, VSP trellised, with grass-covered alleys). We used the eddy covariance technique to continuously monitor the net ecosystem CO2 exchange (NEE), and here we analyze the first three years of measurements (May 2014 to April 2017). The vineyard showed to act as a moderate carbon sink, with an average annual net carbon uptake of 134 gC/m2. However, the inter-annual variability of NEE was considerably high and environmental conditions during vine growing season showed to have a strong impact. The summer of 2014 was characterized by plenty of rainfall and the annual carbon uptake was the highest (207 gC/m2). On the contrary, in 2015, several heat waves reached the area and the annual carbon uptake decreased to 69 gC/m2. Elevated air temperature and low soil moisture in summer significantly reduced net carbon flux in the period of the year when the activity of the vineyard is at its maximum. Nevertheless, we showed that the vineyard can behave as carbon sink on the medium-long term, and we suggest this should be taken into account in agricultural and environmental policies, complementing standard Life Cycle Assessment of the wine production chain
- …
