Climate Zones & Biomes Study Guide

Astronomic Climate Zones

• Tropic of Cancer: $23.5°N$
• Tropic of Capricorn: $23.5°S$
• Arctic Circle: $66.5°$

Thermal Zones

• Defined by annual temperature.
• Examples include Polar/Subpolar, Mid-Latitude, and Subtropical zones.

Determining Factors

• Determined by stars: Tropics.
• Determined by the sun: Polar/Subpolar zones.
• Determined by temperature: Thermal zones.

Climate and Vegetation Zones: Maps

• Didaktische Klimakarte nach Siegmund/Frankenberg 1991
  • Elements:
    • Jahresdurchschnittstemperatur (Annual average temperature).
    • Anzahl der humiden Monate (Number of humid months).
    • Jahresamplitude der monatlichen Durchschnittstemperatur (Annual amplitude of monthly average temperature).
• Klimazonen (Climate Zones)
  • Polare Zone (Polar Zone)
    • Jahresmittel der Temperatur unter $-10°C$ (Annual average temperature below $-10°C$).
  • Subpolare Zone (Subpolar Zone)
    • Jahresmittel der Temperatur zwischen $-10°C$ und $0°C$ (Annual average temperature between $-10°C$ and $0°C$).
  • Mittelbreiten (Mid-Latitudes)
    • Jahresmittel der Temperatur zwischen $0°C$ und $12°C$ (Annual average temperature between $0°C$ and $12°C$).
  • Subtropen (Subtropics)
    • Jahresmittel der Temperatur zwischen $12°C$ und $24°C$ (Annual average temperature between $12°C$ and $24°C$).
  • Trockenklimate (Arid Climates)
    • Jahressumme des Niederschlags unter $250 mm$ (Annual precipitation below $250 mm$).
  • Tropen (Tropics)
    • Jahresmittel der Temperatur über $24°C$ (Annual average temperature above $24°C$).
• Land Use Considerations:
  • Polar/Subpolar: Zu kalt für intensive landwirtschaftliche Nutzung (Too cold for intensive agricultural use).
  • Trockenklimate: Zu trocken für intensive landwirtschaftliche Nutzung (Too dry for intensive agricultural use).
• Climate map showing different climate zones based on temperature and humidity.
  • Examples include cool-continental, temperate, subtropical, tropical-semi-arid, tropical humid, and mountain climates.

Climate and Vegetation Zones: Maps

• Pol (Pole)
  • Tundra
• Boreale Zone (Boreal Zone)
  • Mixed forests, coniferous, Boreal
  • Deutschland (Germany)
• Feuchte Mittelbreiten (Humid Mid-Latitudes)
  • Mediterranean
• Trockene Mittelbreiten (Dry Mid-Latitudes)
  • Desert
• Immerfeuchte Subtropen (Ever-Humid Subtropics)
• Winterfeuchte Subtropen (Winter-Humid Subtropics)
• Trockene Subtropen und Tropen (Dry Subtropics and Tropics)
  • Savannahs
  • Zentralafrika (Central Africa)
• Immerfeuchte Tropen (Ever-Humid Tropics)
  • Rainforest
  • Äquator (Equator)
• Wechselfeuchte Tropen (Seasonally Humid Tropics)
• Map illustrating climate and vegetation zones, including polar, boreal, humid mid-latitudes, dry mid-latitudes, and various tropical zones.

Climate and Vegetation Zones: Maps

• Natural Vegetation
  • Map clip depicting forest landscapes and open landscapes.
  • Each ecozone experiences some human impact, but less than in cultivated land.
  • Land use class comprises cropland, meadows, and intensive pastures.
• Polar desert
  • Too cold for vegetation, e.g., Central Greenland.
• Tundra
  • Sparse vegetation.
• Boreal forest
  • Coniferous trees like spruce and pine; moss, lichen, shrubs.
  • Scandinavia
• Temperate deciduous and mixed forest
  • e.g., oak, beech, fir; coniferous mountain forest included.
  • Alps
• Mediterranean vegetation of winter rain region
  • Cypress, stone pine, macchia shrubland.
• Desert and semi-desert
  • Very sparse vegetation, cactuses.
  • Grand Erg
  • Libyan Desert
  • Kazakh Steppe
  • Caucasus
  • Iranian Highlands
  • Tien Shan
  • Hindu Kush
  • Tharr Desert
  • Rub al Khali
  • Ethiopian Highlands
  • Not Equatorial Highlands
  • Namib Desert
  • Kalahari Desert
  • Drakensberg
• Thornbush savanna (bush savanna)
  • Knee-high grass, shrubs, sparse trees.
• Dry savanna
  • Breast-high grass, trees like umbrella acacia or baobab (monkey bread tree).
• Moist savanna
  • Very tall grass, forests.
• Tropical rain forest
  • Climbing plants; over 4,000 evergreen tree species, including precious wood like teak or mahogany.
  • Equator
• Vegetation profile included.

Biomes and Ecosystems

• Biome: Large regions on different continents with similar plants, animals, and climate.
  • Global.
• Ecosystem: Local.
• Biomes are made of many similar ecosystems.

Distribution of Biomes

• Desert Distribution
  • Around the Tropic of Cancer and Capricorn.
  • Subtropical high-pressure belt (see circulation of tropics).
  • Inside of continents: rain shadow of mountain ranges.
  • Examples: Australia, Egypt, Mali
• Tropical (Rain)forest Distribution
  • Near the equator.
  • Tropical low-pressure belt (see circulation of tropics).
  • Examples: Brazil, India, Thailand.

Tropical Circulation

• Sequence of Events
  1. The equator region heats up most.
  2. Heated air becomes lighter and rises.
  3. As this air rises, it cools down.
  4. Cooler air can keep less moisture.
  5. Huge thunderclouds are formed, reaching up to 14km.
  6. In the upper atmosphere, the air moves polewards and sinks around 30° North and South.
  7. As this air sinks, it gets warmer and drier.
  8. The results are high-pressure areas on the surface.
  9. From this high pressure, wind flows to the Equator.
  10. This wind is deflected by the Earth's rotation and becomes the North East and South East trade winds.
• This circulation pattern explains why deserts are found around the tropics.

Temperature, Moisture, and Vegetation

• High temperature leads to high evaporation, resulting in drier, more arid conditions and sparse vegetation, leading to deserts.
• Dry conditions: plants reduce transpiration.
• Hot and wet conditions lead to high humidity and high plant growth/bio-productivity.
• Cold conditions: short vegetation growth period.
• Examples of biomes include Spain, Germany, and Italy.

Tasks from Diercke Activity Book

• Tropical Soils
• Vegetation
  • Bottom (floor):
    • Light: low
    • Temperature: 20-25°C and stable
    • Water: low evaporation, humid, less rainfall
    • Type of plants: shrubs, ferns, broad leaves
    • Litter: decomposing plant material, max. 30cm high layers
  • >25m (top):
    • Light: direct light
    • Temperature: 35-40°C
    • Water: heavy or persistent rain
    • Type of plants: tall giant trees
• High Productivity and Biodiversity
  • Due to:
    • Constant high temperature (all year)
    • High precipitation (more than 1500mm)
    • Humid
• Nutrient Cycle
  • Nutrients stored in organic material (dead leaves-litter-roots, tree).
• Role of Mycorrhizae (Wurzelpilze)
  • Absorb nutrients and nurture the roots/tree= root fungus

Nährstoffkreislauf des tropischen Regenwaldes (Nutrient Cycle of the Tropical Rainforest)

• M1: Fertility of Tropical Soils
  • Initial belief in incredible fertility was disproven during the colonization of the Amazon.
  • Most tropical soils are infertile due to nutrient leaching, except for some fertile floodplains and limestone soils already in agricultural use.
  • Tropical rainforests obtain nutrients through a closed nutrient cycle (nutrient recycling).
• M2: Vegetation in the Rainforest
  • Leaves are kept for 3-5 years due to the lack of seasons, robust to withstand rainfall, radiation and insects.
  • Leaves are leathery, thick, and shiny to allow water to run off faster.
  • Decomposition is slowed despite high temperatures, fungi, and soil insects.
  • Trees shed all leaves of a branch or the entire crown, followed by rapid new growth.
• M3: Nährstoffrecycling (Nutrient Recycling)
  • Deadwood, leaf litter, animal cadavers, and excrement are quickly decomposed in the tropical rainforest.
  • Termites mainly process wood.
  • Insects, worms, fungi, and bacteria process other components.
  • Moisture is readily available, and high temperatures accelerate chemical processes, so the litter layer is thin. This explains why rainforests regenerate poorly when felled, as the thin, biologically active layer disappears.
  • Mycorrhiza, a symbiosis between plant roots and fungi, provides roots with nutrients and receives carbohydrates in return. This is crucial for rainforest tree afforestation.
  • Trees can be interconnected through roots, exchanging nutrients, aided by mycorrhiza.

Deforestation

• Nutrient transport through the trunk to branches and leaves.
• Layer of organic material (decomposed plant/animal remains, rapid conversion into nutrients).
• Leaves, dead branches, dead animals, feces, etc. end up on the ground

Tropical Soils

• Characteristics:
  • High precipitation leads to depletion of nutrients.
  • Humus is washed away (erosion).
  • Soil cannot store minerals (low CEC).
  • Higher temperature results in less water in the soil.
  • Monoculture, deforestation, and overgrazing are man-made factors.
• Agroforestry: Agriculture with trees (Kationen-Austausch-Kapazität).
  • Trees provide extensive shade, protecting from hard rain/evaporation.
  • Prevents leaching and soil erosion.
• How to Avoid Drops in Yields:
  • Avoid monocultures.
  • Use animal waste.
  • Increase the humus layer as a nutrient store.
• Cocoa Tree Growth Conditions:
  • Temperature: 16-35°C (best: 25°C).
  • Precipitation: 1,250-2,000mm per year.
• Soil: Wet, deep, rich in organic matter, deep.
• Most productive age: 10-12 years.
• No direct sunlight.

Consequences of Deforestation

• Fragile ecosystems rely on continuous nutrient recycling.
• Hot, wet conditions weather the surface rocks intensively, leading to deep soils that are not fertile.
• Heavy rainfall leaches nutrients from the soil.
• Without a constant input of leaf litter, nutrients are quickly removed, causing infertile soils that erode easily.
• No leaf litter to form humus layer
• Loss of nutrients for plants
• Less protection and loss of biodiversity
• Less CO2 storage
• Less evaporation and rainfall, leading to droughts

Effects on the Water Cycle

• High evapotranspiration results in cool, wet conditions.
• Strong sensible heat flux results in warm, dry conditions.

Agroforestry

• Soil protection and conservation.
• Plants at different layers.
  • Upper layer: tall trees
  • Middle layer: mango, avocado
  • Bottom layer: vegetables
• Main goals: Working with and for nature, learning with nature.

Savannas

• Savannas are between deserts and rainforests.
• Savanna = Tropical grasslands.
• Examples: Thorn bush, grasses treeless knee-high.
• Climate:
  • Seasonal shift of the Trade Winds and the sun position causes alternating wet and dry seasons.
  • The further away from the Equator, the shorter the wet season.
• Vegetation:
  • The dryer the climate, the shorter and sparser the vegetation/trees.
• Savanna Types:
  • Bush savanna
  • Dry savanna
  • Wet savanna
  • Isolated Trees
• Adaptation of Plants:
  • Can store water.
  • Small feathered shaped leaves reducing evaporation.
  • Surface needles and thorns to keep water inside.
  • Deep roots
• Global Distribution:
  • Sub-tropics (semi-arid edge of desert).
  • SE USA/Brazil/Madagascar

Savannas in Africa

• Rainfall Patterns:
  • The area where the Sun is at its zenith shifts due to the Earth's tilted axis, affecting rainfall patterns.
  • The Intertropical Convergence Zone (ITCZ), with the highest precipitation, shifts parallel to the zenith of the Sun.
• Savanna Types:
  • Bush savanna: Only rainfall during some months (rainy season < 4 months).
  • Dry savanna: Rainy season 4-6 months.
  • Wet savanna: Rainy season 6-10 months.

Agriculture in the Savannas

• Most people in Africa live in the savanna regions and depend on agriculture.
• Low soil fertility and long periods without rainfall make food production difficult.
• Traditional land-use is slash-and-burn farming (shifting cultivation).
• Farmers clear vegetation, let it dry, and burn it.
• Crops like yams, rice, millet, and vegetables are grown in the fertile ashes.
• After a few years, farmers move on to another piece of land and leave the former fields fallow.
• Cash crops are produced for the market or export.
• Subsistence farming focuses on growing enough food to feed themselves and their families.

Causes of Desertification

• Population growth in the western Sahel and northern Nigeria.
• Less rainfall and increased drought.
• Vegetation dies, increasing overgrazing.
• Vegetation cover is removed by deforestation.
• Soil is exposed to wind and rain erosion.
• Vegetation cannot re-establish itself.