Abiotic Factors

Front 1

Humid tropical environments

Back 1

• Found worldwide around the equator

• Extremely high levels of rainfall

• Poor nutrient content in solid down to high rainfall

• Three main climatic zones;

1. The equatorial through zone

2. The monsoon areas

3. The trade-wind zones cli

Front 2

Climate

Back 2

Much of the suns energy is absorbed in the tropics- acts as a source of head transfer to energy- deficit regions

Front 3

Equatorial Trough Zone

Back 3

• Temperatures are uniformly high, with a greater diurnal than annual variation

• Precipitation occurs throughout the year, though most areas have drier season

Front 4

Huge plant diversity

Back 4

• Large trees have shallow root systems evolved to be able to quickly absorb nutrients as soon as they become available and before the rains wash them away

• Very dense plant growth and very high level of productivity

Front 5

Geomorphology

Back 5

• Humid tropics are associated with deep weathering caused by the higher activity rates of chemical processes at warmer temperatures when moisture is available

• In steeper areas mass movement is the main process operating on the landscape

Front 6

Soils

Back 6

• Tropical soils are the products of rapid weathering and strong leaching

• They are dominated by Kaolinitic clays

• Organic matter is rapidly decomposed under tropical conditions

• Maintaining organic matter at all levels suitable for agriculture is a major problem

Front 7

Mediterranean environments

Back 7

• Found in Arid regions with Mediterranean climate

E.g. European and African areas bordering the Mediterranean Sea; Southern California, Southern tip of Africa, Southwestern tip of Australia

• Winters are rainy and mild, Summer days are long, hot and very dry

• The stresses imposed by the heat and aridity of the summer months have striking influences on Mediterranean ecosystems -Vegetation, souls and wildlife

Front 8

Seasonality

Back 8

• Physical and ecological processes are active in the winter months, when winter precipitation provides the moisture necessary for:

1. Landscape processes, e.g. weathering, erosion of soils and hill slopes, river action

2. Soil processes, e.g. humification, leaching, clay translocation and clay mineral formation in soils; and the net primary productivity

• By contrast, the summer is a season of desiccation, drought and relative inactivity in landscape processes

Front 9

Impact of human activities

Back 9

• Has has a major impact on regions with Mediterranean environments

• Long history of human modification of the natural landscape, stretching back into prehistoric times

• However, impacts from agriculture and non-agricultural industries have continued to increase

Front 10

Natural?

Back 10

• Fires are caused by natural means, by deliberate land management, by accident or by arson

• Aforestation of Mediterranean lands has greatly increased the fire risk, owing to the widespread planting of pine and eucalyptus

Front 11

Deserts (1)

Back 11

• The subtropical anticyclone belt is the main area of the dry lands

• Where the high pressure are stable in position we find the main desert areas of the world

• On their margins areas of seasonal rainfall occur, with annual rainfall totals gradually increasing away from the desert cores

Front 12

Subtropical anticyclone belt

Back 12

• At higher levels, dry, subsiding are and stable atmosphere prevent precipitation forming

• Cold oceanic currents can increase the aridity along some coastal areas

• Dry land environments may also be found in continental interiors, far removed from sources of moist, rising air

Front 13

What is a desert?

Back 13

Approximately 1/3 of the earths land surface is desert, arid land with meager rainfall that support only sparse vegetation and a limited population of people and animals

Front 14

Deserts (2)

Back 14

• Most deserts and semi-deserts support widespread but relatively sparse vegetation

• Many species have evolved methods of coping with lack of water and extreme heat

• Desert soils are typically little weathered and lacking in humus

• Saline accumulation may be a problem in some areas

Front 15

Water demand

Back 15

Increasing most parts of the world;

• Increasing populations

• Greater demand of increased hygiene

• Greater prosperity

Water use per head and total volume are both factors

In some parts of the world the problem had been compounded by decreases in precipitation

Front 16

Characteristics of polar and alpine biomes

Back 16

Periglacial environments

Regions

- N. Hemisphere

- Polar regions

Short summer, harsh winter

Vegetation- sparse, low

Ground exposed, frozen