Francisco J. Rebollo

Climatic spatial variability in Extremadura (Spain) based on viticultural bioclimatic indices.

The evaluation of general suitability for viticulture in wine regions requires a knowledge of the spatial variation in temperature, which is also used to assess different grapevine cultivars and to delimit appropriate zones for winegrape production. However, usually temperature data and methods applied to properly delineate homogeneous areas are not adequate to generate accurate maps. With the aim of providing an analysis using four temperature-based indices, quantifying their spatial variability, and representing the spatial pattern of each index throughout Extremadura, one of the most important Spanish wine regions, temperature data from 117 meteorological stations, considering the 1980–2011 period, were utilized. The statistical properties of each index were assessed and, later, they were mapped by means of an integrated geographic information system (GIS) and a multivariate geostatistics (regression-kriging) approach. Results show that heat-sum temperature indices were highly related to the more simple growing season temperature; however, temperature regime differences varied upon which index was employed. The spatial variability of climate within Extremaduran natural regions (NR) is significant; although the warmer conditions predominate, some NR have part of their territory by up to eight climate classes. This information enables a better understanding of the viticulture suitability within each NR and delineating homogeneous zones. The use of consistent bioclimatic indices and an advanced geostatistical algorithm have made it possible to delimit and compare within-region climates and also enabled comparisons of Extremaduran NR with others worlwide, which should be taken into account to select varieties and assess the possibilities of producing new wines.

Application of climatic indices to analyse viticultural suitability in Extremadura, south-western Spain

Although climate is recognised as one of the main drivers of viticulture success, its main features have not been sufficiently described in many viticultural regions, including Extremadura, which contains one of the largest grapevine-growing areas in Europe. Using climatic data from 80 weather stations located throughout Extremadura, seven bioclimatic indices were calculated to estimate heat accumulation and potential water balance during the growing season and the thermal regime during the ripening of grapes. Differences in some climatic indices were found, and after a multivariate geographic analysis, four groups were delimited containing weather stations with similar climatic features, with variability between groups explained by heat accumulation and tempearture and thermal amplitude during the ripening season. Suitability for cultivation of grapevines without thermal restriction and temperate nights during the ripening period are the main characteristics of the weather stations studied, but spatial variability found in climatic potential denotes the importance of differentiating locations to properly relate the viticultural climate to grape quality factors and the style of wines produced. The climatic features of the four groups are very similar to those described in other viticultural regions, including those in close proximity to Extremadura and others worldwide, but few studies have used broad and updated temporal climate data for computing bioclimatic indices as in this case study. Finally, trends in climate indices were analysed. Results revealed that all groups have experienced warmer growing seasons, driven mainly by changes in minimum temperatures. This fact has numerous potential impacts, including changes in grapevine phenological timing, disruption of balanced composition in grapes (ultimately affecting wine characteristics), alterations in varieties grown and spatial changes in viable winegrape-growing zones.

Spatial analysis of the annual and seasonal aridity trends in Extremadura, southwestern Spain

The knowledge of drought (or wetness) conditions is necessary not only for a rational use of water resources but also for explaining landscape and ecology characteristics. An increase in aridity in many areas of the world is expected because of climate change (global warming). With the aim of analysing annual and seasonal aridity trends in Extremadura, southwestern Spain, climate data from 81 locations within the 1951–2010 period were used. After computing the De Martonne aridity index at each location, a geographic information system (GIS) and multivariate geostatistics (regression kriging) were utilised to map this index throughout the region. Later, temporal trends were analysed using the Mann-Kendall test, and the Sen’s estimator was utilised to estimate the magnitude of trends. Maps of aridity trends were generated by ordinary kriging algorithm, providing a visualisation of detected annual and seasonal tendencies. An increase in aridity, as the De Martonne aridity index decreased, was apparent during the study period, mainly in the more humid locations of the north of the region. An increase of the seasonal De Martonne aridity index was also found, but it was only statistically significant in some locations in spring and summer, with the highest decreasing rate in the north of Extremadura. Change year detection was achieved using cumulative sum graphs, obtaining that firstly the change point occurred in spring, in the mid-1970s, later in the annual period in the late 1970s and finally in summer at the end of the 1980s.

Integration of climatic indices in an objective probabilistic model for establishing and mapping viticultural climatic zones in a region

Different climatic indices have been proposed to determine the wine suitability in a region. Some of them are related to the air temperature, but the hydric component of climate should also be considered which, in turn, is influenced by the precipitation during the different stages of the grapevine growing and ripening periods. In this study, we propose using the information obtained from ten climatic indices [heliothermal index (HI), cool night index (CI), dryness index (DI), growing season temperature (GST), the Winkler index (WI), September mean thermal amplitude (MTA), annual precipitation (AP), precipitation during flowering (PDF), precipitation before flowering (PBF), and summer precipitation (SP)] as inputs in an objective and probabilistic model, the Rasch model, with the aim of integrating the individual effects of them, obtaining the climate data that summarize all main climatic indices, which could influence on wine suitability from a climate viewpoint, and utilizing the Rasch measures to generate homogeneous climatic zones. The use of the Rasch model to estimate viticultural climatic suitability constitutes a new application of great practical importance, enabling to rationally determine locations in a region where high viticultural potential exists and establishing a ranking of the climatic indices which exerts an important influence on wine suitability in a region. Furthermore, from the measures of viticultural climatic suitability at some locations, estimates can be computed using a geostatistical algorithm, and these estimates can be utilized to map viticultural climatic zones in a region. To illustrate the process, an application to Extremadura, southwestern Spain, is shown.

Using an objective model to estimate overall ozone levels at different urban locations

Ground-level tropospheric ozone is one of the air pollutants of most concern. Ozone levels become particularly high in regions close to high ozone precursor emissions and during summer, when high insolation and high temperatures are common. Ozone levels continue to exceed both target values and the long-term objectives established in EU legislation to protect human health and prevent damage to ecosystems, agricultural crops and materials. Researchers or decision-makers frequently need information about atmospheric pollution patterns in urbanized areas. The preparation of this type of information is a complex task, due to the influence of several factors and their variability over time. In this work, some results of urban ozone distribution patterns in the city of Badajoz, which is the largest (140,000 inhabitants) and most industrialized city in Extremadura region (southwest Spain) are shown. Twelve sampling campaigns, one per month, were carried out to measure ambient air ozone concentrations, during periods that were selected according to favourable conditions to ozone production, using an automatic portable analyzer. Later, to evaluate the overall ozone level at each sampling location during the time interval considered, the measured ozone data were analysed using a new methodology based on the formulation of the Rasch model. As a result, a classification of all locations according to the ozone level, which was the value of the Rasch measure, was obtained. Moreover, information about unexpected behaviours of ozone patterns was generated. Finally, overall ozone level at locations where no measurements were available was estimated which can be used to generate hazard assessment maps.

Spanish vineyard classification according to bioclimatic indexes: Spanish vineyard bioclimatic classification

Background and Aims Spain has more than one million hectares of vineyards, being the first country in the world, and the third in production of wine. Local zoning studies have been carried out using bioclimatic indexes to show the influence of climate; however, no detailed study has been undertaken at national level that included the current area of vineyards. The aim of this study was to prepare a thermal characterisation and zoning of winegrowing areas in Spain through four bioclimatic indexes. Methods and Results From data of the European Climate Assessment & Dataset (1980–2010), four bioclimatic indexes adapted to viticulture were calculated and integrated into a geographic information system, which allowed the graphical visualisation of their patterns by means of geostatistical interpolation techniques (kriging). The results show that there is a significant spatial variability of the climate from a winegrowing perspective, and each index defines the differences between the climatic classes suitable for viticulture. Conclusions In order to define and assess the climatic differences in wine production and the suitability of the Spanish mainland territory, it is necessary to combine several indexes. Significance of the Study For the first time, the climatic variability of Spain has been described and the peculiarities that differentiate its vineyards have been highlighted. High‐resolution kriged maps have made this study possible.

Characterization of soil fertility using the Rasch model

A quantification of the overall soil fertililty potential should integrate the main soil physical and chemical properties, with different units. The formulation of the Rasch model is proposed as an instrument to measure soil fertility potential, integrating 11 soil properties (clay, silt and sand content, organic matter -OM-, pH, total nitrogen -TN-, available phosphorus -APand potassium -AK-, cation exchange capacity -CEC-, and deep -ECdand shallow -ECssoil apparent electrical conductivity, 0-90 and 0-30 cm depth respectively) measured at 70 locations in a field. In the case study, the considered soil variables fit the model reasonably, having an important influence on soil fertility, except pH, probably due to its homogeneity in the field. Moreover, a ranking of all soil samples according to their fertility potential and the influence of each variable on soil fertility are provided, being ECd, ECs, and the textural fractions of soil the most influential properties on soil fertility and, on the other hand, AP and AK the less influential properties. Results are in accordance with a previous work in the same field considering only five soil properties, both ECd and ECs and texture, denoting the importance of these variables to estimate soil fertility potential. Rasch model resulted to be useful to rationally determine locations in a field where high soil fertility potential exists and establishing those soil samples or properties with anomalies. This information can be necessary to conduct site-specific treatments, leading to a more cost-effective and sustainable field management.

Proximal sensing for monitoring the productivity of a permanent Mediterranean pasture: influence of rainfall patterns

Proximal sensing for monitoring the productivity of a permanent Mediterranean pasture: influence of rainfall patterns J Serrano, S Shahidian, J Marques da Silva, F Moral and F Rebollo Departamento de Engenharia Rural, Instituto de Ciências Agrárias e Ambientais Mediterrânicas (ICAAM), Escola de Ciências e Tecnologia, Universidade de Évora, Apartado 94, 7002-554 Évora, Portugal, Departamento de Expresión Gráfica, Universidad de Extremadura, Badajoz, Spain jmrs@uevora.pt