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GrapeLinks Viticultural Knowledge
Management
Geo-climatic zoning of vineyards in the Macedon Ranges
Erika Winter* and Hew Richards+ *GrapeLinks, Melbourne, ([email protected]), +Macedon Ranges Vignerons Association, Kyneton, VIC, Australia.
Introduction The Macedon Ranges vineyards are amongst the highest in Victoria at altitudes between 400 and 800 m. They produce high quality cool climate wines. The aims of this project are to: 1. Describe each of the 28 vineyards with
respect to their temperature signatures to enable site adapted vineyard management practices.
2. Determine geo-climatic zones in order to demonstrate the diversity and potential of the region therewith enabling to market the very special sub-regional attributes and to point to potentially promising new vineyard sites.
3. Observe the effect of a changing climate on day and night temperature profiles from budburst to harvest over several vintages to be able to mitigate climate change.
Fig. 1: Data logger (yellow) embedded in the bunch zone.
Material and Methods Vineyards (mainly white varieties) received electronic data loggers (Tinytag Gemini, Hastings, Port Macquarie) of which one was attached to the cordons or posts within the vine canopy at the height of the bunch zone1 (Fig. 1) in November. Temperatures were recorded hourly and investigated from 15. December to veraison and veraison harvest. To eliminate the effect of various canopy structures and enable early logging a second logger was placed in most vineyards in July into a wooden box nailed to a post, south facing at 1.40m above ground (Fig. 2). Data from 1. August to 15. December, and on to harvest were recorded. Cumulative degree hours from a base of 0°C were calculated for all periods as well as average degree hours in order to enable comparison of vineyards with different days of hangtime. A report, which also contained all diurnal temperature graphs, was supplied to each participant with information on their code number.
Fig. 2: Data logger in a South facing side and bottom open wooden box close to the bunch zone logger.
Results and Discussion The climatic conditions of these cool climate vineyards, which have a predominance of cold nights, were in all seasons particularly well characterised through their average degree hours below 15°C and above 35°C before (Fig. 3) and after veraison (Fig. 4). This information enabled vineyard managers to – if so desired – decrease bunch zone heat loads with under-vine vegetation or to increase grape warmth with dark soil or mulches2.
Fig. 3: Average degree hours below 15°C (blue) and above 35°C (red) pre-veraison, 3 seasons. The Macedon Ranges vineyards could be grouped into 5 zones according to their hot and cold signatures (Fig. 3) and from their average degree hours (degree hours base 0°C / days of observation) (Fig. 4). Loggers in boxes eliminated annual variations in bunch zone canopy density and logger exposures. Vineyards in the Northern part of the GI were warmest, the vineyards South of Mt Macedon were colder pre-veraison and warmer pre-harvest, Western vineyards (sheltered by the Dividing Range from the cold SW wind) were warmer before veraison than later in the season, and vineyard temperature signatures in the Central area very much depended on airflow from mountain ridges. Finally, vineyards at High altitudes of 650-800 m were coldest all year. These climatic zones largely determine the portfolio of wines in the subregions and point to promising sites for new vineyard developments for high value cool climate wine styles.
Fig. 4: Average degree hours base 0°C veraison to harvest in 5 geo-climatic zones over 3 seasons. Note the effect of the 2016 El Niño summer with very short hangtimes in cooler sites (except 6, late picked Riesling). The effect of climate variability was very obvious in the cooler vineyards of the West and High altitudes in the warm El Niño summer in 2016. Due to extremely short hangtimes, average degree hours post veraison were higher than normal. Comparing with other regions, vineyards in all subzones had, even in 2016, very cool night temperatures. These data from a large number of vineyards characterized sites, zones and the region better than MJT or phenological dates. The temperature signatures can be used to create a coloured geo-climatic winery map as an important tool to tell the story of this region’s diversity and to improve the public’s knowledge of the region’s wine styles. Acknowledgements This research was funded by the Macedon Ranges Vignerons Association. Initial studies were supported by Landcare3. References 1. Winter, E. and Lowe, S. (2011) Canopy management
offers solutions to variable climate. The Australian & New Zealand Grapegrower & Winemaker 573, 38-41.
2. Winter, E. and Lowe, S. (2011) Undervine management research reveals fruitzone temperature controls. The Australian & New Zealand Grapegrower & Winemaker 574, 37-42.
3. Ellender, G., Richards, H. and Winter, E. (2010) Bunchzone and berry temperature measurement for optimum Chardonnay cluster exposure. ICCS Seattle.
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