Chapter 4

Vineyard Site Selection

Global Warming

Overall, wine grapes are a climatically sensitive crop, whereby quality production is achieved across a fairly narrow geographic and climatic range. In addition, wine grapes are grown largely in mid-latitude regions that are prone to both short-term climate variability and long-term climate change. Climatic changes, which influence both variability and average conditions, therefore have the potential to bring about changes in wine styles. While the observed warming over the last fifty years appears to have mostly benefited the quality of wine grown worldwide, projections of future warming at the global, continent, and wine region scale will likely have both beneficial and detrimental impacts.

Historical Observations of Wine Region Climates

In Europe, records show vineyards were planted as far north as the coastal zones of the Baltic Sea and southern England during the medieval “Little Optimum” period (roughly 900 to 1300 AD) when temperatures were up to 1.8 degrees F (1°C) warmer (Gladstones, 1992). However, during the 14th century dramatic temperature declines lead to the “Little Ice Age” (extending into the late 19th century), which resulted in most of the northern vineyards dying out and growing seasons so short that harvesting grapes in much of the rest of Europe was difficult.

Implications

The observed warming over the last 70 years appears to have been largely beneficial for viticulture in many regions through longer and warmer growing seasons with less risk of frost. However, the benefits have been mostly due to latitudinal shifts in viable viticulture zones with increasing area on the pole ward fringe in the Northern Hemisphere (NH) and decreasing area in the Southern Hemisphere (SH) due to the lack of land mass. Within regions, spatial shifts are projected to be toward the coast, up in elevation, and to the north (NH) or south (SH). Some of the viticulture zones that have benefited from global warming include Southern England, Tasmania in Australia, New Zealand’s South Island, and Canada’s Okanagan Valley in British Columbia.

Climate Change Adaptation Strategies

The previous section shows a wide range of potential impacts of climate change at the vine, vineyard and winery levels. In this section we note some options for adaptation to these changes.

Canopy Management

Canopy management practices should be designed to achieve the desirable level of bunch exposure to influence fruit compositional characters as well as disease management, and protection/shading from the sun. The simplest way for wine grape producers to protect bunches from exposure is through canopy management.

Irrigation Efficiency

The irrigation system should be checked to ensure that pressures and flow variations are within acceptable limits, and maintained to prevent losses during delivery to and use within the vineyard. With above ground drip irrigation watering at night can reduce evaporation loses by about 10 percent. Optimize vineyard irrigation requirement using irrigation scheduling plans based on soil type, crop factors, and evaporation timing and volume of irrigation.

Mid-row Management

The mid-row of a vineyard is an important source of reflected heat, even more so than the under-vine strip due to its greater area. Consider growing a mid-row cover crop throughout the season.

Rootstocks

Managing vineyard site variability by matching grapevine varieties and rootstocks with soil types and their water holding capacity and micro climates will be a key area in future vineyard development.

Variety Choice

Grape varieties differ in their drought and heat tolerance. As the climate becomes warmer and drier, there will be an increasing need to grow those varieties that are more tolerant and it is therefore important that we know which characters to look for in both existing and new varieties.

Vineyard Design

Vineyard design, too, is key in managing the effects of climate change. One of the most important parts of design is row orientation. Vineyards with rows running North-South intercept more light than to East-West rows.

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