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Global warming is causing earlier phenological dates for vines and changes in the quality of wines all around the world. To understand how vines are liable to react to future climate evolution, the climate of viticultural areas needs to be known as accurately as possible. In this article, temporal evolution and spatial variability of temperature in the wine producing area of the Loire Valley were analysed with a multi-scalar approach. First, the regional evolution of temperature and bioclimatic indices were studied over the past 60 years in the wine-producing area of the Loire Valley and showed a general warming at all locations in the regional weather station network (Météo-France). Secondly, temperature data from weather stations located within the vineyards between Angers and Saumur were studied for the year 2010 and underlined spatial variability of temperature between the different plots according to the different topoclimates. Finally, particular attention was paid to the Coteaux du Layon vineyards (sweet wine producing appellation) where 21 temperature data loggers were set up in the vine rows to study climate at local scale. The study showed, in particular, that the spatial variability of temperature and bioclimatic indices in these vineyards was greater than those observed at larger scales. Copyright © 2012 Royal Meteorological Society [ABSTRACT FROM AUTHOR]

To optimise the functioning of the grapevine in a specific environment and to improve grape and wine quality, suitability of climatic parameters for key grapevine physiological processes needs to be assessed at fine scales. This paper presents methodology using hourly weather data in three wine producing regions of South Africa (Coastal Region -- Stellenbosch district; Breede River Valley -- Robertson district; Central Orange River Region -- Upington district) during the pre- (November to December) and post-véraison (January to February) periods. Durations inside and outside an optimum climatic range and of extreme climatic conditions were calculated over a 5-year period (1999/2000 to 2003/2004) to quantify a climatic profile related to grapevine physiological requirements. Climatic requirements for optimum photosynthetic activity were defined as follows: temperature 25°C to 30°C, windspeed <4 m/s, relative humidity 60% to 70%. Unsuitable climatic periods for vine performance were calculated as <20°C and >35°C, >4m/s, <50% and >80%. A coefficient was assigned to each climatic parameter according to an assumed importance level for physiological processes. Optimum temperature requirements for other physiological parameters were also investigated. A diurnal minimum/maximum temperature range of 25°C to 30°C was used for sugar content and organic acid levels and a maximum night/day temperature range of 15°C/25°C for colour and lavour. Light intensity was accepted as being sufficient. Stations were classified according to their potential for meeting the climatic requirements of each physiological parameter. Marked variation in climatic profiles and available time for optimal physiological functioning occurred between regions. All factors considered, the climatic profile of the Coastal Region (Stellenbosch district) seemed to best satisfy the climatic requirements of the physiological parameters studied. [ABSTRACT FROM AUTHOR]

Spatial variability of temperature was studied in relation to the berry basic composition and secondary compounds of the Tannat cultivar at harvest from vineyards located in Canelones and Montevideo, the most important wine region of Uruguay. Monitoring of berries and recording of temperature were performed in 10 commercial vineyards of Tannat situated in the southern coastal wine region of the country for three vintages (2012, 2013, and 2014). Results from a multivariate correlation analysis between berry composition and temperature over the three vintages showed that (1) Tannat responses to spatial variability of temperature were different over the vintages, (2) correlations between secondary metabolites and temperature were higher than those between primary metabolites, and (3) correlation values between berry composition and climate variables increased when ripening occurred under dry conditions (below average rainfall). For a particular studied vintage (2013), temperatures explained 82.5% of the spatial variability of the berry composition. Daily thermal amplitude was found to be the most important spatial mode of variability with lower values recorded at plots nearest to the sea and more exposed to La Plata River. The highest levels in secondary compounds were found in berries issued from plots situated as far as 18.3 km from La Plata River. The increasing knowledge of temperature spatial variability and its impact on grape berry composition contributes to providing possible issues to adapt grapevine to climate change.

The rise of temperatures may enable species to increase their activities during winter periods and to occupy new areas. In winter, resource density is low for most species and an increased number of active consumers during this season may produce heightened competitive pressure. In Western France, the aphid parasitoid species Aphidius avenae Haliday has been known to adopt a winter diapausing strategy adjacent to newly sown cereal crops, until recent reports of active winter populations in cereal crops. We investigate how the addition of this species to the winter guild of parasitoids may change the structure of the aphid-parasitoid food web and the host-exploitation strategies of previously occurring parasitoids. We showed that in winter, Aphidius avenae was mostly associated with two aphid species, Sitobion avenae Fabricius and Metopolophium dirhodum Walker, while the generalist species Aphidius rhopalosiphi was restricted to the aphid species Rhopalosiphum padi L. in the presence of Aphidius avenae. Due to this new competition, winter food webs present a higher degree of compartmentalization and lower proportional similarity index values than spring ones. Parasitoid and aphid abundances responded significantly to changes in daily high temperatures, suggesting that the host-parasitoid community structure can be partly predicted by climate. This study demonstrates how a change in the winter strategy of one species of a guild can modify complex interspecific relationships in host-parasitoid systems.