The growing environment Flashcards
Natural factors that effect temperature and sunlight
- Latitude
- Altitude
- Slopes and aspect
- Proximity to water
- Winds
- Characteristics of the soil
- Mist, fog and clouds
Latitude
In general grapes for wine production can grow between 30 and 50 latitude on each side of the Equator.
Region at lower latitudes (Medoza, South Africa) nearer the Equator receive more intense solar ration per annum than those nearer the poles (France, Germany)
Nearer the Poles solar radiation must travel through a larger section of atmosphere to reach the Earth’s surface. By contrast, at the Equator the radiation travels through a smaller section of atmosphere and hits the Earth’s surface at a later angel, so that solar radiation here is more powerful.
Overall, it means that temperatures would be warmer and sunlight more intense in regions at lower latitudes than those at higher latitudes. Broadly speaking, this means that grapes grown at lower latitudes can have higher sugar levels, lower acidity levels, riper aroma’s, riper tannins (black varieties) than those at higher latitudes.
The number of hours of solar radiation though different times in the year is also determined by latitude:
Low latitude reigns receive similar daylight hours (sun and heat) throughout the whole year. High latitude regions have longer daylight hours in there summer, this permits longer duration of time in which photosynthesis can take place in the growing season. Given the cooler temperatures in these regions, this can be useful in helping the grapes to successfully ripen.
Altitude
Temp falls by aprox 0.6 over every 100m increase in altitude.
High altitude sites can therefore be favorable in areas of low latitude that would otherwise be too hot. Salta, Argentina 3000m above sea level, where grapes may even struggle to ripen sufficiently.
Vineyards in high altitude sites, such as Burgundy and the Loire Valley, are at relatively low altitudes, as otherwise temperatures would be too low for sufficient ripening.
Sunshine is more intense in high altitudes than low altitudes, because solar radiation travels through less atmosphere before it reaches these sites which promote anthocyanin and tannin synthesis
High altitude sights often have a high diurnal range (difference between day and night temp). The ground absorbs energy from solar radiation during the day and releases energy into the atmosphere during the night. The high diurnal range can be beneficial for the retention of acidity during grape ripening.
Slopes and aspect
Vineyard planted on slopes will face a particular direction, called aspect. South facing (NH) aspects will receive more solar radiation than those facing the opposite direction.
The importance of aspect and the steepness of the slope increases at high latitudes. Because solar radiation hits the Earth at a low angle at high altitudes. The amount of warmth is often a limiting factor in high altitude sites, so a slope can make a marked difference on the ripeness of the grapes. Extra warmth and light during spring and autumn extend the viable growing season for vines grown on slopes that face towards the sun.
Cooler climates –> Burgundy Grand Cru Sites –> South Facing –> Better ripening
Warm climates –> limit amount of sunshine –> Stellenbosch –> South facing –> retain refreshing acidity
Slopes can provide additional benefits:
- Better drainage (poorer, shallower soils)
- Provide shelter from winds and rain
- Protection form frost (air moment down the slope prevents frost from forming)
However, soil erosion and inability to use machinery on stoop slopes can be problematic.
Slopes facing east
- Benefits from morning sun that heat up the atmosphere when air and soil temp are at their lowest. Extends the hours of vine growth and grape ripening, especially in cool climate.
- The canopy, that can be covered with dew in the morning, dries out earlier in east facing vineyards, reducing the spread of fungal disease.
Slopes facing west
Slopes facing west receive afternoon sun and may become too hot, especially in warm climates and risk of sunburnt grapes is increased.
However, in areas with coasts to the west (California, Western Australia), cool afternoon breezes may alleviate this.
Proximity to water
Large bodies of water (lakes/seas), can have a significant impact on nearby vineyards. Water heats up and cools down more slowly than dry land.
During the day, water and air above a body of water remains relatively cool, and lowers the average temperature in the local area. Air above dry land heats up more quickly than that above water, and this warm air rises. Cool air from above the water is drawn to the land replace the warm air as it rise, resulting in cool, humid afternoon breezes.
The opposite happens at night. The water retains the warmth gained during the day, whereas, the land loses heat relatively quickly. The warmth of the body of the water keeps the local area warmer.
Example:
Finger Lages in New York –> reduces severity of winter freeze –> protection against spring frost (movement of air)
Carneros California –> San Pablo Bay –> Cooling sea breezes –> Possible to ripen early ripening varieties (Chardonnay/Pinot Noir)
The effect of ocean currents on grape ripening in Willamette Valley vs Margaux
Pinot Noir from Willamette Valley in Oregon vs Cab Sauv from Margaux in Bordeaux
- Both at 45 latitude
- Early ripening Pinot Noir
- Late ripening Cab Sauv
- Gulf Stream –> Warmer climate in Bordeaux –> avg 17 in growing season
- California Current –> Cools down North America, including Oregon –> avg 15.9 in growing season
El Nino-Southern Oscillation (ENSO)
A climatic cycle in the Pacific Ocean that has a significant effect on weather patterns. It has two opposite phases:
El Nino en La Nina
El Nino - Effect on different wine regions
Typically occurs every 3-7 years, extreme events being rarer, although these extreme events are becoming more frequent as a part of climate change
El Nino starts when warm water in the western Pacific Ocean moves eastward along the Equator towards the Caribbean.
–> Eastern Pacific Ocean becomes warmer than average and tends to cause high levels of rainfall and risk of hurricanes in South America and California. Rainfall can disrupt pollination and fruit set and lead to excessive water availability (increases vegetative growth and hinder ripening)
–> El Nino brings warmer than avg temp and drier conditions in the Pacific Northwest (Washington and Oregon)
–> On the western side of the Pacific Ocean in Australia El Nino trends to cause warmer temp and drought conditions, which can cause extreme water stress and vine damage.
La Nina
Is caused when the eastern Pacific Ocean is cooler than average. It tends to result in cooler, wetter conditions in the Pacific Northwest and warmer, drier conditions in California and South America. And causes wetter and cooler conditions in Australia.
The effect of winds in a wine region
Winds/breezes can have warming or cooling influences in many wine regions.
Areas near a body of water may experience cool breezes during the day, and moderating the diurnal range of such regions (Bordeaux)
Valley that face the coast or other areas of low land (Petaluma Gap, California) can mean that winds are even felt relatively far inland. Valleys can leas to stronger winds as the moving air is funnelled.
Winds that have travelled over hot land masses can bring warm air that heats the vineyard area (Zonda, Mendoza).
As well as influencing temp, winds and breezes reduce the occurrence of humid, stagnant air in the vine canopy that encourage the development of fungal diseases.
Strong winds can cause damage to vines and vineyard trellising, resulting in lower yields and higher equipment and labour costs (fences)
Characteristics of the soil
The drainage of the soil, structure and colour all influence the warmth of the soil and the air above the soil.
Free draining soils (sand/stony soils) warm up more quickly in the spring than damp soils –> encouraging budburst and shoot growth –> desirable in cool climates
Warm soils also encourage root growth –> vine can absorb more water and nutrients
Light colored soils, rich in clay (Sancerre) –> reflect energy from solar rediation –> beneficial to increase photosynthesis and grape ripening in cool and cloudy climates
Dark colored soils (Volcanic, Etna) absorbs more energy and re-radiate most of it when temperatures are cooler, for example at night. Useful in cool climates or for late-ripening grapes, allowing the development of cooer and degradation of acid to continue during the night
Stoney soils, especially if the underlying soil is slightly damp are also very effective at absorbing heat and releasing it at night, because stony and water are good conductors (geleiders) compared to air
Nutrients
Acquired from the soil
Important for healthy vine growth and can influence yield and grape composition
Low levels are needed. However, if nutrients in the soil are depleted by viticulture its important to monitor nutrient levels for deficiencies
Most important nutrients are:
- Nitrogen
- Potassium
- Phosphorus
- Calcium
- Magnesium
Nitrogen
Essential for vine growth and effects the vines vigor and grape quality
It a component of proteins and chlorophyll (required for photosynthesis)
Too much nitrogen will cause excessive vegetative growth, with sugars being transported to the growing shoots and leaves rather than the grapes, which hinders ripening
An excess of shoots and leafs can also shade the fruit and buds which has consequences for the effects of sunlight, and stimulates poor ventilation (disease) if not managed
Too little nitrogen results in reduced vigour and yellowing of the leaves
Overall, wines with a restricted supply of nitrogen tend to produce higher quality grapes
Potassium
Essential for vine growth and helps to regulate the flow of water in the vine
High levels can cause problems in the uptake of magnesium, leading to reduced yields and poor ripening and have a significant effect on wine quality, as high levels of potassium in the grapes are linked to high pH in the wine
Low levels can lead to lower sugar accumulation in the grapes, lower yields and poor vine growth in general
Phosphorus
Important for photosynthesis
Vines only need a small amount, and usually there is enough presented in the soil (naturally)
A deficiency leads to poorly developed root systems (which lowers the ability to take up water and nutrients from the soil), reducing vine growth and lowers yields
Calcium
Important role in the structure of plant cells and photosynthesis
Deficiency is rare, but can have a negative influence on fruit set
Magnesium
Found in chlorophyll and therefore plays a key role in photosynthesis
Deficiency can result in reduced yields and poor ripening
Magnesium
Found in chlorophyll and therefore plays a key role in photosynthesis
Deficiency can result in reduced yields and poor ripening
Natural factors that effect nutrient availability
Nutrients dissolve in water, which is than taken up by the roots. This means that the soil factors that influence water availability also impact nutrient availability
Soil pH also has an influence on nutrient availability. Different nutrients become more or less available at different pH levels. Iron is poorly available in soils with high pH (limestone soils) which can cause chlorosis, a conditions in which leaves turn yellow and photosynthesis stops (negative effect on ripening and yields)
Different soil textures also have different abilities to hold nutrients. Soils with high proportions of clay are good at holding nutrients, whereas sandy soils are poor at holding nutrients
Topography may also impact the soils levels of nutrients. Soils on slopes are often thinner and less fertile than those on plains or valley floors
Mineralisation
Organic nutrient compounds found in and added to soils (manure, compost) are not available in a form that the vine can take up and need to be converted into inorganic compounds
Organisms that live in the soil (bacteria, fungi, worms) are feeding from the organic matter and converting it into available forms (mineralization)
For this reason its thought to be highly beneficial to encourage soil life and ecosystem within the vineyard (biodiversity)
Climate
A regions climate is defines as the annual pattern of temperature, singling, rainfall, humidity and wind averaged out over several years
30 years is the timescale generally agreed on
Climate does not change from one year to the nest, although it can alter over a period of decades
Climate classifications
Most climate classifications have focused on patterns of temperatures and sometimes rainfall
It should be noted that these models only give a broad picture of a climate because they cannot account for all the natural and human factors that may affect a region or a specific vineyard
The climate classifications are:
- Growing Degree Days (GDD)
- The Huglin Index
- Mean Temperature of the Warmest Month (MJT)
- Growing Season Temperature (GST)
- Koppen’s Classification
- WSET
Growing Degree Days (GDD)
Amerine and Winkler (1944) originally intended for the vineyard regions in California
To calculate the GDD:
- Subtract 10 degrees from the average mean temperature of a month in a growing season
- Multiply this by the number of days in this month
- Make the same calculation for each month in the growing season (NH April to October) and add together the totals to get the GDD
The GDD’s are grouped in five ranges;
- Winkler Zone I (lowest) is cool
- Winkler Zone V (highest) is very hot
The Huglin Index
Huglin (1978) uses a similar formula to GDD but differs in that the calculation takes into account both mean and maximum temperatures and the increased day length experienced in higher latitude areas
Index is split into ranges, with the most suitable grape varieties mapped to each range
Widely used in Europe
Mean Temperatures of the Warmest Month (MJT)
Smart and dry (1980) uses the mean temperature of July/January (Mean/July/January/Temperature) as well as measures of continentality, humidity and hour of sunshine
Again, temperatures have been dived into six bands to aid description and communication, ranging from cold to very hot
Growing Season Temperature (GST)
Uses the mean temperatures of the whole growing season, very similar to GDD
Temperatures are grouped into climatic bands raining from cool to very hot
Koppen’s Classification
In broad terms the majority of the worlds wine regions are categories under three headings:
Maritime
Mediterranean
Continental
Based partly on Koppen’s climate classification (1900) and considers both temperature and rainfall patterns which only applies to wine regions in temperature zones
Maritime climate
Experience low annual differences between summer and winter temperatures
Rainfall is also relatively evenly spread throughout the year
Bordeaux
Mediterranean climate
Also experience low annual difference between summer and winter temperatures
Annual rainfall tens to fall in the winter months, giving dry summers
Napa Valley, Coonawarra
Continental climate
More extreme differences between summer and winter temperatures
Often short summers and cold winters with temperatures rapidly changing in the spring and autumn
Burgundy, Alsace
Cool climates
Regions with an average GST of 16.5 or below
Moderate climates
Regions with an average GST between 16.5-18.5
Warm climates
Regions with an average GST between 18.5-21
Hot climates
Regions with an average GST of 21 or higher
Weather
A regions weather is the annual variation that happens relative to the climates average
Some regions experience greater variation in this pattern than others
Example:
The timing and rainfall in Bordeaux an vary quite considerably; 2007 was cool, cloudy and wet during most of August, whereas in 2003 high temperatures and near drought conditions were experienced
The weather in regions like Central Valley in California are much more predictable, with hot dry weather from one season to the other
Weather can impact yields, rainy years bring more fungal disease, reducing yield. Spring frost can also lead to a significant reduction in yield
Vintage variation
Weather can have a significant influence on a wine produced in a single year which is often called vintage variation
In some wine style, vintage variation is expected and welcomed (Bordeaux) in others such as nv sparkling wines and many high-volume, inexpensive wines where consumers expected the wine to taste the same regardless of the year, vintage variation is not desired and some choices in the winemaking process may be made to reduce any vintage variation in the final wine (blending)
In some regions winemakers may adapt to the weather by producing different styles of wines in cooler years, like more sparkling wines and roses than, compared to warmer and drier years
Climate change
Te main measurable effect of climate change is a rise in temperature and has also a consequent effect of greater evapotranspiration and therefore the likelihood of water stress
Other effect include changes in the geographical distribution of water, greater weather variability and a greater frequency of extreme weather events (storms, hurricanes, floods, heatwaves) which can reduce yields and grape quality
Many producers have already started to act, site selection, choice of planting material, different vineyard management techniques etc
The effect of rising temperatures on viticulture
Warmer temperatures speed up the Vince cycle, budburst occurs earlier and each stage becomes quicker, it speeds up the rate of sugar accumulation and the reduction of acidity. However, it does not quicken the ripening of most aromas and tannin compounds
In order to compensate grapes may be picked at higher levels of sugar, causing higher alcohol and lower acidity levels in wine
Some regions may become to warm for certain varieties, and it may preferable to start growing different, later-ripening grapes
Although warmer temperatures may be problematic in certain regions, in others, like cool regions there is the potential for production to increase or improve quality of the grapes and wine
The effect of drier conditions on viticulture
Result from greater evapotranspiration and altered rainfall patterns may benefit some regions that currently experience plentiful of rainfall in the growing season. It reduces de likelihood of fungal disease and promote the condition of mild water stress, which is positive for grape ripening
However, already dry regions the vine may be subjected to extreme water stress, causing photosynthesis to stop and the vines leaves fall off (California, South-Africa)
Its thought that in some of this regions vineyards sites will be abandoned in the next 50-100 years
Mist, fogs and clouds
Formed by tiny drop of water collection in the air just above an area of ground or water
Usually formed when warm air is rapidly cooled, causing water vapor in the air to condense
For example at night when warm air over a body of water meets cooler conditions above the land
Dense mist is called fog
They form in different vineyard regions at different times of the day; Sonoma, Napa, Leyda Valley and Sauternes. Which in the right conditions can have a beneficial effect on the development of noble rot
Clouds usually form higher in the sky
The effects of mist, fogs and clouds
Depending on the density of mist or amount of clouds, sunlight can be limited tot the extent that photosynthesis is reduced, which also means that temperatures can be lower. This can slow down sugar accumulation and acid degradation in the grapes
The later may be beneficial in warmer regions, but not in cooler regions
Because mist is made up of water and occurs at ground level it also increases humidity in the vineyard and therefore also the occurrence of fungal disease, or in dry areas with sunny afternoons, noble rot
Why does a vine need water
A vine needs water to survive, for turgidity (so it does not fall), photosynthesis and to regulate its temperature
Generally 500 mm in cool regions and 750 mm of rain in warmer regions
Water is also a solvent for the uptake of nutrients from the soil
Transpiration
Water vapour diffuses out of the stomata (pores) on the underside of the leaves
Th loss of water from the cells in thereof cause water to be pulled up from the soil, through the roots and the above ground parts of the vine –> Transpiration
Open stomata allows the fee exchange of water four out of the vine, and let carbon dioxide and oxygen diffuse in and out of the leaves. If the vine has sufficient water, the stomata can kept open all day
A lack of water causes the vine to partially close the stomata, to conserve water, but with that reduce or stop photosynthesis due to a lack of carbon dioxide entering the leaves. Extreme cases can lead to vine death
The effects of (excessive) water during spring and early summer
Vegetative growth (shoots and leaves) will be prolonged and promoted into the period of grape ripening and therefore will act as a competitor for the source of vine’s sugars, delaying ripening
Therefore, mild water stress at the version is beneficial as it inhibits further vegetative growth
An excessive amount of green shoots and leaves can also shade the vines canopy and grape bunches unless controlled this can lead to a reduced formation of anthocanins, tannins and aroma compounds (higher levels of methoxypyrazines) and have poor air circulations, which can lead to diseases in rainy or humid climates
The influence of water availability on the growing environment
Damp soils are often cold, especially in the growing season, and can delay budburst, which can shorten the growing season
Warm soils promote budburst and encourage root growth and therefore the ability for the vine to take up water and nutrients
Hail can cause a major damage to the green parts of the vine, leading to lower yields and reduced quality
Rain creates an humid environment in the vine canopy that can lead to fungal diseases such as powdery mildew and botrytis
Low humidity can increase evapotranspiration and therefore potential of water stress as well as increased grape transpiration and hence higher sugar accumulation in the grapes
Natural factors that effect water availability
- Rainfall
- Characteristics of the soil and land
- Evapotranspiration rate
The effect of rainfall on water availability
Natural source of water for the vine, the amount and timing of it each year is an important factor in producing high quality grapes
In areas where there is not sufficient rainfall, irrigation may be used (depending on laws, and the availability of water)
Rain is caused by water vapor condensing and precipitating. Warm temperatures cause moisture from the land to evaporate rise. As the warm moist air rises in the atmosphere, it cools and condenses into Clauds and eventually rain
Topography can have an influence on patterns of rainfall. Mountain ranges can force winds of warm moist air upwards over high altitudes. Causing water vapour to cool, condense and precipitate. Meaning that the regions on one side of the mountain can experience greater rainfall, whereas regions on the other side are sheltered from the rain
Example: Regions of Washington State, the west of the Cascade Mountains the AVA Puget Sound is cooler and wetter than the warmer, drier AVA’s to the east of the mountains, like Columbia Valley
The effect of the character of the soil and land on water availability
The characteristics of the soil can have a significant impact on the availability of water for the vine’s roots
The amount of water available to the vine depends on how easily water drains, the water-holding capacity of the soil and the soils depth
Example:
Hawkes Bay in New Zeeland receives around 800 mm rain annually, however, the extremely free draining gravels soils mean that irritations is sometimes necessary
Jerez in Spain receives 650 mm rain with virtually no rain in the summer months, the main soil type is albariza, a clay soil that has good water retention and which releases water slowly to the vine
Topography also has an influence, there will be greater surface run-off in vineyard slopes meaning less penetration of water in the soil, and therefore less water available to the roots (advantage in regions with high rainfall)
But, surface run-off causes erosion of the soil and leaching of nutrients (factors that need to be considered at vineyard establishment)
The effect of the evapotranspiration rate on water availability
The evapotranspiration rate is the amount of transpiration from the vine, combined with the evaporation of water from the soils surface
Depends on the temperature, humidity and wind, with hot, dry, windy weather (Mendoza) leading to faster rates
A high rate means that more water is needed to satisfy the vine’s needs that at a low rate
Vines in hot, dry, windy conditions need more water than vines in cool and humid conditions
