Life sciences Grade 11

Climate effects on biomes

Subject teacher Siphiwe Mkhwanazi

What is climate ?

Weather conditions dominating an area in general or over a long period.

Climate is also a measure of the average pattern of the variation in temperature, humidity, pressure , wind, precipitation.

Climate is different from weather, weather only describes the short term conditions of these variables in a given region.

E.g cold, hot, windy, rainy, etc .

What are biomes ?A large naturally occurring community of flora and founa occupying a major habit, e.g. forest of tundra.

Climate effect on biomes

What do temperature, wind and rain have

in common?

They are all part of climate, the statistical

summary

of temperature, humidity, atmospheric

pressure, wind, rainfall, other

meteorological measurements in a given

region over long periods. In other words, is it

dry or wet, hot or cold, or humid? And it is

these abiotic factors that help determine the

nature of a biome.

Plants and temperature Plants and Temperature. Tropical plants are most competitive in the tropical zone and warmer parts of the subtropical zones. These plants generally cannot survive winters, and so are restricted to their homelands. Subtropical plants can tolerate some very light frost, but cannot tolerate any kind of "hard" frost. They survive in the subtropical zones, and in some areas in the tropical zone. Plants that can survive hard frosts or freezes are called Hardy Plants. These plants can handle varying levels and durations of freezing, explaining their distributions up into the high latitudes toward the Polar Circles. Where permafrost exists the thin layer of soil that thaws briefly in summer supports the distinct vegetation known as tundra. These are among the toughest plants on earth. They go through their life cycle in just a few weeks of summer and then tolerate extreme cold for the rest of the year. They tend to be short in stature.

Plants and temperature

Cold and hot weather on

plant

Effect of the sun on growing

plant

South African biomes

Forest

Fynbos

Grasslands

Namakaroo

Savannas

Succulent karoo

Forest Forest is the smallest biome in South Africa, covering only about 0.1% of the country (1 062 km2).

Forests are found from sea level to above 2000 metres. They grow in areas with high rainfall and no frost. Forests are moist and seldom burn.

Forests consist of trees that form a closed canopy, with layers of plants beneath the canopy.

The largest and most famous forests in South Africa are the Knysna and Tsitsikamma Forests of the southern Cape.

fynbos

South African fynbos grows in a

100km- to 200km-wide coastal

belt stretching from the West

Coast to the south-east coast. It

makes up 80% of the Cape Floral

Region, a world of finely

branched plants beautifully

adapted to flourish in poor soils

and wildly varying rainfall

Grasslands

Grassland biomes are large, rolling terrains of grasses, flowers and herbs. Latitude, soil and local climates for the most part determine what kinds of plants grow in a particular grassland. A grassland is a region where the average annual precipitation is great enough to support grasses, and in some areas a few trees. The precipitation is so unpredictable that drought and fire prevent large forests from growing. Grasses can survive fires because they grow from the bottom instead of the top. Their stems can grow again after being burned off. The soil of most grasslands is also too thin and dry for trees to survive.

Namakaroo

The Nama Karoo Biome occurs on the central plateau of the western half of South Africa, at altitudes between 500 and 2000m, with most of the biome failing between 1000 and 1400m. It is the second-largest biome in the region.

Savanna Savannas have warm temperature year round. There are actually two very different seasons in a savanna; a very long dry season (winter), and a very wet season (summer). In the dry season only an average of about 4 inches of rain falls. Between December and February no rain will fall at all. Oddly enough, it is actually a little cooler during this dry season. But don't expect sweater weather; it is still around 70° F.

Succulent karoo

The Succulent Karoo, including desert, covers

about 7.5% of the country (approximately 83

000 km2).

This biome covers the arid western parts of

South Africa, including Namaqualand and the

Richtersveld.

The region is extremely dry in summer and

the temperature often rises above 40oC. Rain

falls in winter and varies from 20 to 290 mm

per year

Terrestrial biomes

unit 8

Terrestrial biomes and climate

Climate is the average weather in an area over a long period of

time. Weather refers to the conditions of the atmosphere from day to day.

Climate is generally described in terms of temperature and moisture.

Temperature falls from the equator to the poles. Therefore, major

temperature zones are based on latitude . They include tropical, temperate,

and arctic zones, However, other factors besides latitude may also influence

temperature. For example, land near the ocean may have cooler summers

and warmer winters than land farther inland. This is because water gains and

loses heat more slowly than does land, and the water temperature influences

the temperature on the coast. Temperature also falls from lower to higher

altitudes. That’s why tropical zone mountain tops may be capped with snow.

Terrestrial biomes

Terrestrial biomes

In terms of moisture, climates can be classified as arid (dry), semi-arid, humid (wet), or semi-humid. The amount of moisture depends on both precipitation and evaporation. Precipitation increases moisture. Evaporation decreases moisture.

The global pattern of precipitation is influenced by movements of air masses. For example, there is a global belt of dry air masses and low precipitation at about 30° N and 30° S latitude.

Precipitation is also influenced by temperature. Warm air can hold more moisture than cold air, so tropical areas receive more rainfall than other parts of the world.

Nearness to the ocean and mountain ranges may also influence the amount ofprecipitation an area receives. This is explained in Figure below .

Evaporation of moisture is greatest where it is hot and sunny. Therefore, cold climates with low precipitation may not be as dry as warm climates with the same amount of precipitation.

Moist air from the ocean rises up over the mountain range.

As the air rises, it cools and its water vapor condenses. Precipitation falls on the windward side of the mountain range.

The air is dry when it reaches the leeward side of the mountain range, so there is little precipitation there. This creates a “rain shadow.”

Climate and plant growth

Plants are the major producers in terrestrial biomes. They have five basic

needs: air, warmth, sunlight, water, and nutrients. How well these needs are

met in a given location depends on the growing season and soil quality, both

of which are determined mainly by climate.

The growing season is the period of time each year when it is warm and wet

enough for plants to grow. The growing season may last all year in a hot, wet

climate but just a few months in a cooler or drier climate.

Plants grow best in soil that contains plenty of nutrients and organic matter.

Both are added to soil when plant litter and dead organisms decompose.

Decomposition occurs too slowly in cold climates and too quickly in hot, wet

climates for nutrients and organic matter to accumulate. Temperate

climates usually have the best soil for plant growth.

Climate and biodiversity

Because climate determines plant growth, it also influences the number and

variety of other organisms in a terrestrial biome. Biodiversity generally

increases from the poles to the equator. It is also usually greater in more

humid climates. This is apparent from the desert and rainforest biomes.

The below picture shows how precipitation is affected by the ocean and the mountain.

Climate and biodiversity

Aloe plant stores water at its

large.

Cactus plant stores water in

its stout , barrel shaped

sterms.