Island and coastal vineyards in the context of climate change

Aim: The notion of “terroir” enables the attribution of distinctive characteristics to wines from the same region. Climate change raises issues about viticulture, especially the growth of the vines and even more importantly the economic situation of actual wine-growing regions (Schultz and Jones 2010; Quénol 2014). Several studies have addressed the impacts of climate change on viticulture in many wine-growing regions of the world, but only a few have focused on the potential of island and coastal vineyards. However, in the context of climate change, ultramarine and coastal vineyards could become increasingly coveted according to their specific climatic conditions. In regions subject to significant warming, thermal regulation and oceanic influence can limit extremes temperatures, which could be a major advantage for grapevine production. This contribution, first step of a spatial optimization approach to define suitable agro-climatic patterns, will present a typology of these vineyards, to understand their specificities and their adaptability.

Methods and Results: An in-depth bibliographical search has been conducted to provide a global inventory and to highlight relevant variables to describe and categorize the world’s island wine-growing regions. From this approach, three main themes have been defined as variables: climate characteristics, vineyards characteristics and cultivars and associated management systems.

Climate plays a very important role in terroir, and especially temperatures, which determine the regional characteristics of viticulture (van Leeuwen et al., 2004; Hall and Blackman, 2019). In this study we consider the following climatic data: seasonal^[1] average temperatures, annual and seasonal¹ mean daily amplitude, completed by the average annual sunshine duration, average annual precipitation, winds and sea sprays.

Concerning vineyard characteristics, topological aspects like altitude or distance to ocean can limit diurnal and extremes temperatures (Bonnardot et al., 2001; Koufos et al., 2013; Fourment et al., 2017; Heras-Roger et al., 2018). Vineyards soils and especially soils’ composition, depth and water holding capacity are also completed. Vineyards’ characteristics were supplemented by economic data like surface area (ha), production (hl), market target and appellations. 

Due to their specific climatic conditions and/or because their relative isolation from other continents, many islands harbour autochthonous and rare varieties (Scherrer et al., 2009). In connection with vine variety, rootstock and diseases variables are integrated in the typology. Moreover, several coastal and island vineyards integrate traditional practices to manage the hydric stress without irrigation (i.e. mitigate wind effects on plants) (Drumonde-Neves et al., 2017; Heras-Roger et al., 2018). These practices were highlighted with management systems variables (implementation and management system, space between vines and rows, vine density, mechanization and irrigation system).

When applied to vineyards of Lanzarote, this approach describes structural elements of ultramarine vineyards. In 2009, Canarian viticulture represented 36% of total cultivated area of the archipelago, and 2.9% of total Spanish viticulture. In Lanzarote’s island, the climate is defined as subtropical with low precipitation (average of 150 mm/year), warm temperatures throughout the year and a high average annual sunshine duration (3000 h/year). 

Lanzarote’s island has a low relief and vineyards are planted on volcanic soils. Poured thick layers of volcanic ashes called “picóns” are added at the base of the vine stock. These porous volcanic granules have a great thermal inertia. Indeed, during the day picóns store heat and give it back to the plant at night. Picóns also have good water retention capacity (Troll et al., 2017; González Morales et al., 2015). Lanzarote’s vineyards under the appellation “Denominación de Origen Protegida de Lanzarote” were about 1850 ha in 2016-2017, for a production above 4330 hl and 1800 winegrowers (DO Lanzarote, 2020). The target market is local in scope. Mainly due to the isolation of the archipelago from the mainland, phylloxera is not present in the vineyards of Lanzarote. Vines are not grafted and Malvasia represents ¾ of the vine stock of the island. Vine varieties such as Listàn blanco, Moscatel de Alejandria, Verdello and Gual are often planted to produce dry and sweet white wines. Listàn negro and Negramoll varieties are preferred to produce red wine (DO Lanzarote, 2020). Low-growing vines are planted in drilled holes, and low walls of volcanic rocks are built to protect them from drought and hot drying winds. Due to their specific implementation, vines are widely spaced (400-500 m between them), yields are low and mechanization is not possible. 

This information has been documented and summarised for each wine-growing region. Thanks to this approach, key elements of insular vineyards can be described with generic indicators.  The resulting typology enables comparisons between different wine-growing regions with a generic framework.

Conclusions:

This first step of characterization of vineyard variables highlights the specificities of insular and coastal vineyards. Then, discriminant characteristics will be exploited in a process of spatial optimization in order to identify suitable agroclimatic patterns for different climate change scenarios. The main objective is to implement an approach under multiple constraints (climatic, agronomic, spatial, etc.). The results expected will be compromises between these several constraints.