Vineyards in the Azores have been traditionally settled on lava field terroirs but the practical limitations of mechanization and high demand on man labor imposed by the typical micro parcel structure of these vineyards contradict the sustainability of these areas for wine production, except under government policies of heavy financial support. Besides the traditional vineyards there are significant areas in some of the islands whose soils, climate and physiographic characteristics suggest a potential for wine production that deserves to be the object of an assessment, with a view to the development of new vineyard areas offering conditions for better management and sustainability.
The landscape zoning approach for the present study was based in a geographic information system (GIS) analysis incorporating factors related to climate, topography and soils. Three thermal intervals referred to climate maturity groups were defined and combined with a single slope interval of 0–15 % to exclude the landscape units above this limit. Over this resulting composite grid, the soils were then selectively cartographed through the exclusion of the soil units not fulfilling the suitability criteria.
The results show that the thermal interval of warmer conditions, well represented in the traditional terroir of Pico island, has practically no expression in the other islands. However, for the intermediate and the cooler classes, we could map areas of 5611 and 18 115 ha respectively, fulfilling the defined soils and slope criteria, indicating thus the existence of some landscapes in the studied islands revealing adequate potential for future development of viticulture, although certainly demanding a good judgment on the better grape varieties to be adapted to those climatic conditions.
Winkler scale distribution for S. Miguel, Terceira, Faial and Graciosa islands of the Azores.
Under the holistic concept of terroir, which deals with the influence of environmental factors on vine behavior and grape ripening, climate is recognized as the factor that exerts one of the most significant effects on the ability of a region to produce quality grapes (Jones, 2006).
It is also well accepted that geology and the particular soil conditions are of great importance in defining the characteristics and qualities of the wine as the final product (Mackenzie and Christy, 2005), in spite of the recognized difficulty of establishing and interpreting this relationship clearly.
Moreover, although it is known that the vine is adaptable to a wide
diversity of soil types, it appears also that many of the world's most
famous vineyards are installed in poor, shallow or rocky terrain (Van Leeuwen and Seguin, 2006)
where no other crop would be grown in favorable
conditions. Such is the case, which is almost extreme, of the vines planted in the
lands of
Due to the financial support measures implemented by the regional government of the Azores, the maintenance and recovery of abandoned areas of traditional vineyards within the limits of the classified area have recently gained a renewed interest by the land owners and wine producers. However, outside of these limits, there are vast areas with similar conditions where the ancient vineyards have been abandoned for a long time without any perspective of recovery, being presently colonized by invasive trees and shrubs species, predominantly the Pittosporum undulatum Vent. In fact, the practical limitations of mechanization and high demand on man labor imposed by the micro parcel structure of the vineyards aggravated by the absence of financial subsidies outside of the classified area make it impossible to admit the recovery of these areas for the wine production in present times.
Besides Pico island, where the costal landscape is dominated by lava fields of abandoned vineyards with the exception of the classified area, a few small spots also exist in some of the other islands of the archipelago, where in most cases the production has been partially abandoned as well.
Apart from this traditional Azorean model of terroir of recognized cultural value and where a few interesting wines have been produced, there are significant areas in some of the islands whose soils, climate and physiographic characteristics suggest a potential for wine production that deserves to be the object of an assessment, with a view to the development of new vineyard areas offering conditions for a better management and sustainability. We refer specifically to landscape units of the lower area of some islands, in many cases presently devoted to pasture where productivity tends to be marginal because it is strongly affected by water stress during the summer. Such areas, presenting gentle to moderate slopes and providing conditions to the mechanization of farming operations, comprise some well drained soils of the Andisol order (Soil Survey Staff, 2014).
In this preliminary study climatic, pedological and topographical characteristics of the landscape are considered based on GIS tools in order to define the distribution of the most representative landscape units with the greatest apparent potential for wine production in some islands of the Azores. It is not our objective to produce a detailed cartographic definition of vineyard suitability classes but rather to establish some basic criteria for prediction and identification of new areas from which representative sites can be depicted for experimental studies in a subsequent phase.
Normal climate and a typical sequential water balance at the littoral of the Azores Islands.
The landscape zoning approach for the present study is that of the so-called “natural terroir units” (Laville, 1993; Priori et al., 2014) and was based on a Geographic Information System (GIS) analysis incorporating factors of climate and topography which was then combined with the soil mapping units fulfilling the suitable criteria concerning the soil properties taken as the most relevant for viticulture (Van Leeuwen et al., 2004; Deloire et al., 2005; Jones et al., 2004; Dutt et al., 1985).
In this work, the spatial climatic differentiation for viticulture is based
on climate and/or maturity classes defined from the sum of the daily average
temperatures that exceeds a base temperature of 10
A first cartographic approach has been attempted (Fig. 1) using the full
Winkler scale (Amerine and Winkler, 1944; Winkler et al., 1974) for the
traditional April–October Period, allowing for comparisons with other wine
regions of the northern hemisphere. However, those results when compared
with the cartography of the geographical distribution of the traditional
vineyards of the Azores Islands (Madruga et al., 2011), denoted an evident lack
of resolution. The temperature of 278
From this evidence, we implemented an alternative GDD criteria based in
only three thermal classes, being the temperature of the maturity
groupings narrowed to 200
For the establishment of these three classes, the thermal conditions found in the traditional vineyards mainly of Pico and Terceira islands, were taken as the baseline reference and from those the accumulating growing degree-days were defined in the following intervals: I: 1600–1800; II: 1800–2000; III: 2000–2200. These temperature intervals for the classes being narrower than those defined in the Winkler criteria, allow for a better discrimination of the thermal variability within short distances as it occurs in the Azores islands where cloudiness and humidity degree can show significant differences in relatively short distances affecting local energy balance; the altitude is the factor which mostly defines its differentiation.
The three thermal intervals referred to climate maturity groupings were combined with a single slope interval of 0–15 % to exclude the landscape units above this limit. The resulting composite grid for each island was finally combined with the respective digitized soil map to select and incorporate the cartographic units of Hapludands, Udivitrands and Eutrudepts, whose average parameters of drainage, water holding capacity, depth to bedrock and pH, fall within the adequacy limits for grapevine growth and production, as depicted from the soil survey database and reports.
The Azores Archipelago, located in the middle of the Atlantic Ocean basin, north of the predominant influence of the trade winds and on the influence of the subtropical high-pressure belt, sits in an area of transition and confrontation between air masses from the tropics and colder air masses coming from the North. Sufficiently far apart from the continental coasts, the air masses that hit the Azores islands reveal a strong increment in properties associated with their maritime route. In this geographic context, the climate of the Azores islands depends, quite evidently, on their geographical setting and relationship with the surrounding sea. Normal climatology and sequential water balance for the lower altitudes (< 100 m) of the Azores islands is presented in Fig. 2.
A strong climatic differentiation can be observed in altitude, as well as significant climatic asymmetries inland of each island. The spatial expression of the climatic elements is related in each island with its dimension and orography, the topographical orientation, the superficial geologic structure, the top soils and the vegetation. In some cases the climate of one island is affected by the shadow effect from its neighboring islands (Azevedo, 1996).
Locally, important subscale characteristics and mechanisms have a prominent role in the climatic spatial differentiation. Advective transport of air and the consequent adiabatic cooling due to the orographic obstacle is determinant in the configuration of the temperature and humidity fields. The same mechanism is in the origin of the orographic clouds generation that, besides the direct role as water source by the reinforcement of precipitation, have an indirect but important interference on the local water balance since they act like a filter to direct solar radiation and as a source of long-wave radiation affecting the local balance of energy. Also, the saturation (or near saturation) conditions that they provide constitute a barrier to water vapor diffusion in the mechanisms of evapotranspiration (Azevedo et al., 1998).
The annual average air temperature on the coast of Pico Island (the one that
presents the greatest climatic diversity of the whole archipelago) is
around 18.0
Particular aspects of the climate of the islands can also be explained locally by its singular geology as is the case of the unevolved lava fields in many cases traditionally occupied by vineyards. In these situations, the mild climate felt on the littoral of the islands is now a result of the conjugated effect of the ocean's proximity and the high thermal accumulation capacity of the black basalt lava flows, a situation that also inversely affects the relative humidity of the air (Azevedo, 2014).
The wind is a constant of the Azorean climate. Throughout the year the wind
blows regularly, more moderately in the summer months, and more vigorously
in the winter. The wind speed increases from islands of the Oriental Group
to the ones on the Occidental Group. Generally, in winter, the syncopated
evolution of the low pressure systems north of the Archipelago leads to the
winds circumventing the islands by north and from the west to the east.
During the summer, with the rise in latitude of the high pressure systems,
the islands are besieged by winds from the southwest. The wind speed
increases with altitude and as the atmospheric circulation releases itself
gradually from the friction of the planetary boundary layer, all the while
assuming greater regularity on its orientation. On the coast of the islands
the annual average wind speed is around 17 km h
According to the Köppen–Geiger climate classification (Essenwanger,
2001; Peel et al., 2007), the littoral climate of the Azores archipelago is
included in the temperate climates category (group C), characterized by
having a summer and a winter and an average temperature of the colder month
below 18
Major soil categories represented in potential new areas for viticulture in S. Miguel, Terceira, Faial and Graciosa islands of the Azores.
In this work the CIELO model (
The model consists of two main sub-models. One, relative to the advective component simulation, assumes the Foehn effect to reproduce the dynamic and thermodynamic processes. This makes it possible to simulate the fields of the air temperature, air humidity, cloudiness and precipitation as influenced by the orography along its trajectory. The second concerns the radiative component as affected by the clouds of orographic origin and by the shadow produced by the relief.
The CIELO model has been successfully applied for modeling species distributions (e.g. Hortal et al., 2010; Jiménez-Valverde et al., 2009; Aranda et al., 2011; Boieiro et al., 2013; Florencio et al., 2013; Guerreiro et al., 2014) and patterns of species richness (e.g. Borges et al., 2006) in the Macaronesian islands.
The topography influences grapevine growth and quality through elevation, slope, exposure and morphology of the proximate landscape which may also define the occurrence of microclimatic zones (Van Leeuwen and Seguin, 2006).
In this work the topography was analyzed based on the tridimensional models of the islands in GIS. Instead of various slope classes we considered only one global interval in the 0–15 % range as the suitability limit to include the best slopes for the mechanization of the vineyard cultural operations (Jones et al., 2004).
Soils of the Azores archipelago originate from modern volcanic materials that have evolved under the humid and moderate Atlantic climate. In general they accomplish the criteria to be classified in the Andisol Order (Soil Survey Staff, 2014).
The typical parent material of Andisols is tephra, a general term for all airborne volcanic ejecta, regardless of morphology, size and composition, being often quite porous with a large active specific surface. It is also difficult to determine the mineralogy of tephra because of microcrystallinity and/or non-crystalline nature of the materials (Dahlgren et al., 1993).
Andisols present unique soil properties resulting from the weathering of volcanic materials and in particular of their tephra glassy products which show a very low resistance to chemical weathering, suffering a rapid evolution to the formation of large amounts of non-crystalline products, usually referred in literature as short range-order materials (SROM). The noncrystalline materials consist primarily of allophane, imogolite and ferryhidrite (Parfitt and Kimble, 1989). In the Azores, at the lower altitudes where climatic conditions can be marked by a dry spell in the summer, the Andisols show an evolutionary tendency to other soil categories mainly of the Inceptisol Order, especially in the more stable and older geological areas of the islands (Pinheiro, 1990). Andisols may have AC, ABC, or multisequa of these horizon sequences, as the soil environment is characterized by deposition of parent materials, gradually or repeatedly being buried under new fresh vitric materials. Vitrands formed from thick pumice or scoria tephras show the AC profile while intermittent tephra deposition and subsequent soil formation result in the development of other Andisols with a multisequum profile (Shoji et al., 1993).
Soils of the Azores Archipelago have been studied in detail, and their characteristics and classification have been discussed in several papers (Auxtero et al., 2004; Pinheiro et al., 2001, 2004; Madeira, 1980; Madeira et al., 2002, 2003; Pinheiro, 1990, 1999; Madruga, 1995; Medina and Grilo, 1981; Ricardo et al., 1977).
For the present study soils were analyzed based on data and soil map units as defined in the soil surveys of the Azores archipelago (ongoing project by the soils group of the University of the Azores). As presented in the maps in Fig. 3, Hapludands and Udivitrands great groups of the Andisol as well as Eutrudepts (Inceptisols) (Soil Survey Staff, 2014) where the andic character is only weakly expressed, were selected as the taxonomic soil categories mostly represented in the lower surfaces of the islands and where grapevine growth can be admitted. Table 1 shows some analytical data of representative pedons of the major cartographed soil units, mostly selected as significant soil properties for viticulture.
Pedological properties of three soils representative of the potential new areas for viticulture in the Azores.
The soil conditions of the delineated new areas are hardly comparable to the
traditional vineyards of the Azores since these ones have been settled over
cracked lava fields where even the hydric and nutrient plant nourishment
processes are frequently difficult to access and to explain. Additionally to
the stony condition of the terrain, the micro parcel structure of the
vineyards drastically limits the workability and trafficability of the
traditional vineyards, making them highly costly and dependent on man labor
for almost every management practices. Figure 4 shows the distribution of the
existing traditional vineyard areas and DOC (
Distribution of the existing traditional vineyard areas and DOC limits in the Azores Islands.
The soil properties taken as the most relevant for the analysis and definition of the potential vineyard areas were drainage, water holding capacity, depth to bed-rock and pH. From these parameters, soil suitability classes were defined (Table 2) based on the concept and criteria as adapted from Bucelli and Costantini (2009). Table 3 show the areas of the soil suitability classes for each island, based on the soil parameters as established in Table 2.
Functional soil parameters and suitability classes of the potential new areas for viticulture in the Azores.
Areas (ha) of the suitability classes for viticulture in the Azores islands.
Soil drainage, being dependent on various soil characteristics such as texture, structure depth and slope, affects crop health and management conditions. Soil depth, not only defines the soil volume for root development and mineral nutrition as it defines and limits the available soil water capacity. Soil pH, being a regulator of chemical and biological processes, gives an indication of the potential for nutrient availability. The neutral to slightly acid reaction is the best pH condition for nutrient fertility and balance in the soil. However, it is well recognized that the nutritive fertility for grapevines should be only moderate, as a high nutritional condition leads to excessive vegetative growth and induces an overall lowering of the quality parameters in the wine.
Different water levels in the soil affect grape quality and reflects in wine quality (Conradie et al., 2002). Andisols can retain a large amount of water primarily due to their large volume of mesopores and micropores produced within the stable soil aggregates.
Formation of these aggregates is greatly enhanced by noncrystalline materials and soil organic matter (Maeda et al., 1977).
High water permeability is a distinctive physical property of volcanic ash soils under both saturated and unsaturated conditions. Under unsaturated conditions, Andisols have greater hydraulic conductivity than other mineral soils such as clayed alluvial soils (Nanzio et al., 1993). Both Hapludands and Udivitrands of the considered areas generally present average to good drainage conditions without impeding layers. Even the finer textured Hapludands, found in the older geological areas of the islands Terceira (Pinheiro, 1999) and Graciosa (Medina and Grilo, 1981) showing an eutric character, have no drainage constraints.
Composite landscape units with potential for viticulture in each island with distribution depicted by climate maturity groups.
In these soils the available water-holding capacity (AWC) is relatively
high, varying between 0.20 and 0.25 cm
In volcanic landscapes the profile characteristics concerning horizon sequence and thickness can be quite variable even within short distances. Depth to bed rock of the Hapludands in the selected areas averages 60 cm with no less than 40 cm and the Udivitrands are in general more than 1 m deep.
The soil reaction found in the considered altitudes for both soil categories is in general slightly acid to neutral, being the pH range of 5.6 to 6.5. From a soil standpoint, high-quality wines are made from grapes grown in many different types of soils with no single type considered ideal (Wilson, 1998). Grapevines will tolerate a wide range of soils, but yield and variation in vine vigor commonly match changes in local soil properties, which in turn can influence grape characteristics (Bramley, 2001, 2005; Reynolds et al., 2007). In spite of the relative variability in both physical and chemical parameters as generally described above, the soils considered here reflect an overall suitability for the viticulture expansion in the Azores.
Along the last half-century the agricultural activity in the Azores has been progressively concentrated to the milk industry. Presently, the wine production represents a very small part of the economy, around 0.3 % of the agricultural product as referred to in the new program of rural development of the Azores – Prorural 2014–2020. However, the ongoing abolishment of milk quotas in the EU and the increased risk on milk price volatility is expected to negatively affect the economical behavior of the dairy industry in the Azores.
This research provides a definition of the environmental characteristics of potential new areas of higher yielding vineyards under technically adequate mechanization conditions, allowing an efficient management of the crop and improvement of the wine industry in the Azores, contributing thus to the diversification and development of the agricultural sector as a whole.
Here, we attempt to define and map landscape areas with apparent potential for grapevine growing in the Azores islands of S. Miguel, Terceira, Faial and Graciosa, as an alternative to the traditional terroir. The lava field terroir was not included in the potential areas here defined because the management costs imposed by the peculiarities of these vineyards, established over a micro parcel and stony structure, deny their economical sustainability and maintenance in the Azores, except under significant government funding as it is the case of the UNESCO protected vineyard area in Pico island.
Cool Night Index (September average minimum temperature).
Growing season accumulated precipitation in millimeters (April–October).
Under the specificity of the Azorean environmental conditions, white wines produced from several adapted winegrape varieties (e.g.,Verdelho, Arinto and Terrantês), which started to be introduced in the Archipelago since the 15th century in the advent of the colonization of the islands and probably originated from Cyprus and the Madeira islands (Duarte Jr., 2001), have been more successful than red wines most probably due to the generally lower heat demand for maturation of the white grape varieties. The more recognized and typical white wines of the Azores have been produced in the lava field terroirs of Pico, both table and dessert wines. Biscoitos, a small village of stony volcanic cover in Terceira island, is also recognized by its white wines in spite of the reduced overall production. There are very few studies of chemical characterization of wines from the Azores. Ribeiro de Lima et al. (2004) found that the concentrations of iron, copper manganese and zinc in Azorean wines correspond with the mean values observed for other regions in Europe. Batista et al. (2001) presented a comparison study of polyphenols and aroma in red wines from the Portuguese mainland versus the Azores islands.
The spatial potential for viticulture of each island is presented in the maps in Fig. 5, with the area distribution depicted by climate maturity groups. The cartographic representation of these landscape areas resulted from a GIS supported spatial analysis of climate, soils and topography based on the combination of the selected criteria for each of these three factors. Three thermal classes defined as climate/maturity groupings were established from a baseline reference (vineyards area of Pico island), and then combined with the soils fulfilling the most advantageous characteristics of moderate to good drainage, adequate soil depth, fair to good water-holding capacity and near neutral pH, and being distributed within a slope interval of 0 to 15 % taken as the most adequate to the vineyard cultural operations.
The calculated surfaces (ha) of the cartographic areas with potential for grapevine production, as defined for each island and thermal class are presented in Table 4. The warmer conditions of thermal class III, well represented in the traditional terroir of Pico island, has practically no expression in the other islands. However, for the intermediate class II and the cooler class I, we could map significant areas – 5611 and 18 115 ha respectively – fulfilling the defined soils and slope criteria. These results indicate that landscape units exist across the climate maturity classes II and I of the studied islands revealing adequate potential for future development of viticulture, although certainly demanding a good judgment on the better grape varieties to be adapted to those climatic conditions.
Areas (ha) with potential for grapevine production for each island and climate maturity class.
The defined thermal classes, based in the degree-day concept for a base
temperature of 10
The present study, through the use of overlay GIS spatial analysis based on climate, soils and slope, conducted at an intermediate scale level, provides an overall perspective and understanding of the potential for expansion of viticulture in the Azores. Additionally, the results presented should serve as a decision support tool in the site selection process for new vineyards establishment. However, there are limitations and further issues to be addressed before developing any individual site. In fact, the resolution limits of the landscape analysis, related to elevation and slope data as well as to soils variability, request a detailed site specific assessment to be conducted prior to any final decision on a new vineyard establishment. The expansion of the viticulture onto new soil types will also affect resulting grape and wine characteristics and will imply an additional effort of experimental study and research on the adaptation of traditional and new varietals to the alternative environmental conditions here defined. Furthermore, future research activities on viticultural and oenological results are needed to check the wine suitability of the delineated new areas of potential natural terroir units.
E. B. Azevedo developed the climatic analysis and with F. Reis and F. Fernandes they adapted the GIS model. J. Madruga and J. Sampaio selected the background soils data and analysis. J. Pinheiro participated in soil analysis and prepared the manuscript with contributions from all co-authors.
The climatic CIELO model simulations for this work were done under the framework of the project ESTRAMAR (FEDER – MAC/3/C177) from the Program MAC 2007–2013, Transnational Cooperation. The CITA_A and the CCMMG are partially supported by the Autonomous Government of the Azores, through the Regional Fund for Science. Edited by: E. Costantini