The Tropical Rainforest

IB SL

Location

Introduction...• They are the world's most productive ecosystems

in terms of NPP and biomass. • They are complex ecosystems with variations in

climate, temperatures, and vegetation, within individual forests.

• Temperatures are often thought to be permanently high, but they are highest on the forest edge where vegetation is more limited.

• The climate changes on a daily basis within the forest, and the idea of the forest being difficult to penetrate is only true at the edges where the sunlight allows rapid growth of vegetation.

Development

Their development relies on...

Insolation And Temperatures

High temps. Allow All Year Growth Of Vegetation.

Moisture

Varies throughout the year, and true TRFs are said to have rainfall in excess of 2000mm and a dry season of no longer than 2 months.

NutrientsScarce, but are rapidly recycled and transferred. Phosphorus and nitrogen are the nutrients needed most.

StructureLayer: Characteristics:

Top (Euphatic)Most productive (NPP, animal life and biomass). Tress over 25m. 25% of available energy absorbed.

Middle (Oligotrophic) Trees are 10 - 25m.

Bottom Smaller trees and some young saplings between 5 and 10m in height.

Shrub Smaller seedlings and some pygmy trees of 5 to 10m.

Herb Tree seedlings, and ferns in existence.

Top Root Roots that penetrate to a depth of 5cm (majority).

Middle root Fewer roots to a depth of 5 - 50cm.

Bottom root Minimal numbers of roots in this layer, below 50cm.

Structure

Climate• Small annual temperature range (2 - 4 degrees). • Regular insolation, result of location near equator. • Daily temperature range in excess of annual range

(8 - 10 degrees), with daytime temperatures up to 32 degrees.

• High levels of convectional rainfall, often with a minimum in July/August/September.

• Extremely high humidity levels. • Light winds. • Quick evapotranspiration. • Year long growing season (but not all plants in the

forest grow all year).

Vegetation

• Decay of leaf litter is rapid, and nutrient recycling. • Photosynthesis occurs all year. • Extremely large variety of vegetation, trees appear

to be evergreen but are deciduous. • Vegetation adapts to the climate. For example,

buttress roots to support tall trees, drip tips to help remove excess moisture.

• Tallest trees can be over 50m high and are known as emergence.

• Where forests are near the coast Mangrove swamps may be found.

Soils• May appear to be fertile but the tropical latosols

are not. • The humus layer is extremely thin, as is the

amount of litter. • Leaching occurs as a result of the high

precipitation and is increased greatly by deforestation.

• Minerals such as Calcium and magnesium are lost.

• Bedrock is weathered quickly. • The characteristic red colour of the soil is due to

iron and aluminium accumulating.

Carbon Cycle

Nutrient Cycle

Activity

Using Chapter 3 of AS Level Geography P102-103, answer the following questions...

1.Where in the world are Tropical Rainforests mainly located?

2.What are the main vegetation types and how have they adapted to the environment?

3.How does the nutrient cycle work?4.What impacts do humans have on these

areas?