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Drought occurs naturally all over the world. Global warming has led an increase in the areas affected by this phenomenon. The study of drought involves the analysis of indicators and indices used to assess changes in the hydrological cycle of a region. A large number of indices developed for drought monitoring are based on meteorological and hydrological variables. This research has applied the Ombroxeric Index for the first time in California. It is based on the concept of ombroxericity: a condition of the territory characterised from an ombrothermic point of view, which can develop in relatively humid areas/zones, depending on the time scale of the study (i.e. monthly, seasonal or annual basis). Temperatures and precipitation from 180 meteorological stations have been considered for a period of observation from 1980 to 2016. In order to know the evolution of this index, a modified trend analysis based on the Mann-Kendall test and a modified Sen slope analysis were used. Empirical Bayesian Kriging was applied as an interpolation technique. Results are presented in both surface and contour maps. California showed a wide range of ombroxeric levels that went from upper strong dry in northern zones, to lower weak arid. Trend results showed an increase in bioclimatic drought throughout the whole State. In addition, summer showed the highest levels on the Ombroxeric Index. An increase in drought trends was observed at the seasonal level, being more pronounced in summer and spring. In both cases are increases in the central (+5 and +3.6 units year−1 respectively) and the southern (+4 and +4.5 units year−1 respectively) areas of the State. Increasing frequency and severity of droughts could have implications for the management of water resources and the survival of Californian vegetation types, such as conifers.

The microscopic morphology of the leaves of six varieties of Vitis vinifera taken in the León Denomination of Origin is studied: the varieties Albarín Blanco, Malvasía, Mencía, Prieto Picudo, Tempranillo and Verdejo Blanco. The morphology is studied in two leaf fragments (basal and distal) related to the midvein, and parameters such as the thickness of the mesophyll and the stomatal density are measured. There are no works on the microscopic characteristics of the Prieto Picudo variety. All the varieties have the structural characteristics typical of V. vinifera varieties used for commercial purposes. The leaf blades are dorsiventral and hypostomatic with anomocytic stomata. There are two types of trichomes in the abaxial epidermis: some prostrate with a woolly appearance and others upright on which the previous trichomes rest. There are no significant differences between the values for the basal and distal samples of the leaf blade. The Prieto Picudo variety has the thinnest leaf blade and with the lowest stomatal density. It is assumed that the thicker the spongy parennchyma – which implies more intercellular spaces – and the higher the stomatal density, the greater the vulnerability of these varieties to infection by Plasmopara viticola. There are no scientific studies on this subject in the DO León, and very few with the Prieto Picudo variety. One of these studies reports the Prieto Picudo variety as being highly susceptible to the fungus, in which case the starting hypothesis could be rejected and the opposite hypothesis proposed: the thinner the spongy parenchyma and the lower the stomatal density (which are the peculiarities of the Prieto Picudo variety), the greater the vulnerability to P. viticola. However, there are inconsistencies in the works on mildew in the bibliography, possibly because not all the possible variables involved on vulnerability to the fungus are considered.

The aim of this research is to enlarge knowledge of space-time evolution of precipitation in California over the last decade on a monthly, seasonal and annual time-scale. This study also analyses the relationship between precipitation and teleconnection patterns with most influence on Californian climate. The homogeneity of the data from the selected stations was verified and finally 165 meteorological stations were used with an obser- vation period that ranged from 1980 to 2019. In order to evaluate trends and statistical significance, both the non-parametric Mann-Kendall test and modified Sen’s slope method were used. Correlation analysis using the partial non-parametric Spearman Test (95% confidence level) was performed to find out relationships between precipitation and nine teleconnection patterns in the State of California. Spatial analysis was achieved using Empirical Bayesian Kriging (EBK). Finally, this research, as a novelty, shows regionalisation of California State as a function of significance in the correlation of precipitation with teleconnection patterns. To achieve this, Principal Component Analysis (PCA) and Agglomerative Hierarchical Cluster analysis (HCA) was performed. Results show a positive precipitation trend in winter and negative precipitation trend in late summer and autumn. The teleconnection patterns more correlated with precipitation are El Ni ̃no along Southern Oscillation (ENSO), Antarctic Oscillation (AAO) and North Atlantic Oscillation (NAO). Four areas were discerned outlining the Mojave Climate Region (Area 4) by having ENSO as the teleconnection pattern that best account precipitation.

Global change is expected to impact on the distribution and abundance of forests. Spain represents the south-western limit of distribution for several types of deciduous forests and, as part of the Mediterranean Basin, it has all the characteristics to be affected by climate change. This study analyses the effects of climate change on habitat suitability and vulnerability in four categories of deciduous forests: Fagus sylvatica L., Quercus petraea (Matt.) Leibl., Quercus robur L. and Betula celtiberica Rothm. and Vasc. The approach combines an ensemble platform for species distribution models (SDMs) using three algorithms applied to four global circulation models (GCMs) driven by two representative concentration pathways (RCPs). Bioclimatic, biogeographic, soil and topographic variables were taken into consideration as predictors to build 320 single distribution models. Ensemble-forecasting models were then produced for each forest category and RCPs by computing a consensus of single-model projections. The adapted proposal of the Intergovernmental Panel on Climate Change (IPCC) was also applied to deal with the uncertainty and notify the likelihood of the outcomes. The results revealed generalized losses in habitat suitability compared to current conditions for all the forest categories, which were more drastic for the RCP 8.5 emission pathway. Exceptions worth noting are forests of Fagus sylvatica (likelihood 25%-50%) and Quercus robur (likelihood 75%-100%) in the Orocantabrian biogeo-graphic subprovince, and Quercus petraea formations in the Cantabrian Atlantic subprovince (likelihood 25%- 50%). Betula celtiberica would suffer the largest losses of habitat suitability under the climate change scenarios analysed. The vulnerability analysis confirmed that the deciduous formations least affected by climate change in future will be the Orocantabrian forests, while the Pyrenean and Oroiberian communities are the most vulnerable. The models developed in this study provi

[EN] The microscopic morphology of the leaves of six varieties of Vitis vinifera taken in the León Denomination of Origin is studied: the varieties Albarín Blanco, Malvasía, Mencía, Prieto Picudo, Tempranillo and Verdejo Blanco. The morphology is studied in two leaf fragments (basal and distal) related to the midvein, and parameters such as the thickness of the mesophyll and the stomatal density are measured. There are no works on the microscopic characteristics of the Prieto Picudo variety. All the varieties have the structural characteristics typical of V. vinifera varieties used for commercial purposes. The leaf blades are dorsiventral and hypostomatic with anomocytic stomata. There are two types of trichomes in the abaxial epidermis: some prostrate with a woolly appearance and others upright on which the previous trichomes rest. There are no significant differences between the values for the basal and distal samples of the leaf blade. The Prieto Picudo variety has the thinnest leaf blade and with the lowest stomatal density. It is assumed that the thicker the spongy parennchyma – which implies more intercellular spaces – and the higher the stomatal density, the greater the vulnerability of these varieties to infection by Plasmopara viticola. There are no scientific studies on this subject in the DO León, and very few with the Prieto Picudo variety. One of these studies reports the Prieto Picudo variety as being highly susceptible to the fungus, in which case the starting hypothesis could be rejected and the opposite hypothesis proposed: the thinner the spongy parenchyma and the lower the stomatal density (which are the peculiarities of the Prieto Picudo variety), the greater the vulnerability to P. viticola. However, there are inconsistencies in the works on mildew in the bibliography, possibly because not all the possible variables involved on vulnerability to the fungus are considered

[EN] Global change is expected to impact on the distribution and abundance of forests. Spain represents the southwestern limit of distribution for several types of deciduous forests and, as part of the Mediterranean Basin, it has all the characteristics to be affected by climate change. This study analyses the effects of climate change on habitat suitability and vulnerability in four categories of deciduous forests: Fagus sylvatica L., Quercus petraea (Matt.) Leibl., Quercus robur L. and Betula celtiberica Rothm. and Vasc. The approach combines an ensemble platform for species distribution models (SDMs) using three algorithms applied to four global circulation models (GCMs) driven by two representative concentration pathways (RCPs). Bioclimatic, biogeographic, soil and topographic variables were taken into consideration as predictors to build 320 single distribution models. Ensemble-forecasting models were then produced for each forest category and RCPs by computing a consensus of single-model projections. The adapted proposal of the Intergovernmental Panel on Climate Change (IPCC) was also applied to deal with the uncertainty and notify the likelihood of the outcomes. The results revealed generalized losses in habitat suitability compared to current conditions for all the forest categories, which were more drastic for the RCP 8.5 emission pathway. Exceptions worth noting are forests of Fagus sylvatica (likelihood 25%-50%) and Quercus robur (likelihood 75%-100%) in the Orocantabrian biogeographic subprovince, and Quercus petraea formations in the Cantabrian Atlantic subprovince (likelihood 25%-50%). Betula celtiberica would suffer the largest losses of habitat suitability under the climate change scenarios analysed. The vulnerability analysis confirmed that the deciduous formations least affected by climate change in future will be the Orocantabrian forests, while the Pyrenean and Oroiberian communities are the most vulnerable. The models developed in this study pro

[EN] Drought occurs naturally all over the world. Global warming has led an increase in the areas affected by this phenomenon. The study of drought involves the analysis of indicators and indices used to assess changes in the hydrological cycle of a region. A large number of indices developed for drought monitoring are based on meteorological and hydrological variables. This research has applied the Ombroxeric Index for the first time in California. It is based on the concept of ombroxericity: a condition of the territory characterised from an ombrothermic point of view, which can develop in relatively humid areas/zones, depending on the time scale of the study (i.e. monthly, seasonal or annual basis). Temperatures and precipitation from 180 meteorological stations have been considered for a period of observation from 1980 to 2016. In order to know the evolution of this index, a modified trend analysis based on the Mann-Kendall test and a modified Sen slope analysis were used. Empirical Bayesian Kriging was applied as an interpolation technique. Results are presented in both surface and contour maps. California showed a wide range of ombroxeric levels that went from upper strong dry in northern zones, to lower weak arid. Trend results showed an increase in bioclimatic drought throughout the whole State. In addition, summer showed the highest levels on the Ombroxeric Index. An increase in drought trends was observed at the seasonal level, being more pronounced in summer and spring. In both cases are increases in the central (+5 and +3.6 units year−1 respectively) and the southern (+4 and +4.5 units year−1 respectively) areas of the State. Increasing frequency and severity of droughts could have implications for the management of water resources and the survival of Californian vegetation types, such as conifers.

[EN] In 2018, Spain was the third largest producer and the leading exporter of wine in the world. Viticulture is an important economic activity in the Castilla y León region, and is an element capable of halting the flight from the countryside and favouring demographic settlement in rural areas. A new integrated methodology for characterizing and delimitating areas suitable for vineyard cultivation is proposed here. The approach combines traditional climate indices with others used in bioclimatology and with soil variables, and applies various statistical analyses to select the predictors that best characterize the vineyards. These predictors are then integrated in species distribution models and a geographic information system. The methodology was tested in the Denomination of Origin León (hereafter DO León) in northwest Spain. Ten single models using the maximum entropy modelling algorithm were run for each of the six wine-grape varieties. Single-model projections built as a consensus of the ten models into an ensemble-forecasting approach were later used to generate maps of suitable areas for each variety. The results confirm the delimitation of the DO León as a Denomination of Origin. The bioclimatic variables Compensated Thermicity Index and Continentality Index and the soil variables pH, Clay Content, Soil Retention Capacity and Soil Saturation Humidity are defining for all the varieties studied. Garnacha and Mencía were the most different varieties in relation to their bioclimatic and soil requirements. Suitability maps revealed that the DO could be extended into neighbouring areas up to 30 km around it. The proposed methodology is a useful tool for agronomic and oenological management; it allows a more effective selection of sites for new vineyards, improves vineyard management, and can even be used to protect territories with a historical and cultural heritage of grape cultivation, thus favouring demographic settlement in rural areas and avoiding depopulati