Study of the carbon budget of a vineyard in Northern Italy: Partitioning and interannual variability

The environmental sustainability of viticulture can be enhanced with the application of proper management practices (e.g. grassed inter-row), which can lead to an increase of soil carbon sequestration. However, studies on vineyard carbon budget and its partitioning are still very scarce. In Northern Italy vineyard alleys are often grassed, playing then an important role in the ecosystem carbon budget. In this context, the partitioning of vineyard net ecosystem CO2 exchange into soil and vine components deserves special attention. We monitored vineyard CO2 flux applying the Eddy Covariance method for three years from 2014 to 2016. Additionally, in 2015, soil CO2 flux measurements have been carried out using soil chambers (transparent and dark). In our conditions, the vineyard was shown to be a moderate sink of carbon on an annual basis (-80 g C m ‒ 2 y ‒ 1), however the largest part of carbon assimilation was due to the grassed soil compartment (-60 g C m ‒ 2 y ‒ 1). The interannual variability of seasonal carbon budget was shown 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, the net uptake reached its maximum value of about -250 g C m ‒ 2. Our results showed that the vineyard can act as a carbon sink, giving an additional value of sustainability toviticulture, however extreme climatic conditions have a large impact on ecosystem performance.