Vineyards as alternative ‘carbon sinks’ in peri-urban areas

Abstract

Land use and land cover may deeply influence the environmental quality and agriculture, in particular, can represent an important ‘carbon sink’ systems, alternative to forestry. The agro-ecosystems may reduce carbon dioxide in the atmosphere by storing carbon both into the rizosphere and directly in the above-ground and below-ground biomass. This function of the cropping systems acquires a high value in sensitive areas like the rural-urban fringe ones, where land degradation owing to land misuse, climate change and urban sprawl is more relevant. Many peri-urban areas all over in Europe are still intensively cultivated and responsible for economically important grape and wine productions and the structure and functions of these spaces are studied also for the ecosystem services that can provide. The aim of the study was to evaluate the carbon sink function of the vineyards in an highly urbanized area by measuring the carbon partitioning throughout the season among vines organs and soil, and by calculating the sequestration of CO₂ equivalents for quantifying the environmental function of viticulture. The analysis was carried out in the DOC area  ‘Castelli Romani’ (southern peri-urban area of Rome) where viticulture represent more than 40% of the UAA  and the vineyards are integrated into the urban tissue owing to the urban sprawl. The carbon storage in vineyard-ecosystem (cv Merlot, mature vines) was evaluated by the Net Primary Production (NPP) methodology that consider the amount of dry matter produced in the above-ground and below-ground biomass (fine-roots turnover). Carbon balance has taken into account also soil total organic carbon (TOC), soil respiration (R)  and  microbial biomass (BM).

The carbon sink function of the vineyard agro-ecosystem under the tested environmental and technical conditions has been calculated in  6,6 t C ∙year^-1∙ha^-1, equal to 24 t CO₂eq.∙year^-1∙ha^-1 in  the  year 2011. The carbon storage was significantly attributable to the fine-root turnover, that accounted for 1/4 of the total carbon stored. Moreover important was the assessment of the fraction of microbial biomass. The results point out the role of viticulture in sequestering CO₂, therefore preserving in peri-urban areas the environmental quality, containing the urban pollution and improving the quality of atmosphere, like urban forest does. These important ecosystem functions, by underlining the multifunctional character of viticulture, may contribute to counteract soil loss and land degradation, that are today’s environmental emergencies.