Factors limiting development of TRFs

1. Factors limiting development of TRFs

2. Tropical rainforest Vegetation

3. Tropical rainforest Vegetation • Forest floor- little light reaches the ground so there is little plant growth except near rivers and in clearings. There is a thick covering of dead and rotting plant matter, this is called HUMUS. This is quickly absorbed by the forest with little remaining in the soil. This means the soil is INFERTILE. • Forest Scrub layer- theis is a layer of scrubs and ferns growing to about 10 metres. There leaves form a dense canopy intercepting (blocking) THE LIGHT FROM REACHING THE GROUND. • Forest Canopy- these trees are 10-25 metres in height. The branches and leaves in competition for the light form an umberella which reduces the amount of light and rain reaching the forest floor. • Forest Emergents- these are the very tallest trees, which can reach up to 45 metres in height. They have large buttresses to strengthen their roots, and are more spaced out to allow their crowns to receive as much sunlight as possible.

4. Tropical rainforest Vegetation • The trees do not grow in single species strands. Instead more than a hundred different species of trees can be found in a single hectare of land. This can cause problems for logging.

5. Shifting cultivation Task- Complete the flow diagram to show how shifting cultivation operates.

6. Deforestation pressures on the Tropical rainforest

7. Problems with shifting Cultivation • The reduction in the area of tropical rainforest available has greatly increased pressure on the remaining area of rainforest. This pressure has impacted on the landscape and on the people who live there. Impact on the landscape • Population densities have increased • Tribal people are forced to reduce fallow periods, and revisit sites more often. • The soil has had insufficient time to regenerate, and soil productivity declines, infertility increases and the soils are more prone to erosion. • Large areas of cleared land are now open to the heavy rains. • Deforestation breaks the humus cycle. Nutrients are rapidly leached out of the soil, leaving it infertile. • Soil erosion leads to silting up of rivers, resulting in flooding. • The loss of wildlife habitats reduces biodiversity.

8. Problems with shifting Cultivation • The decline in the fallow period is usually accompanied by the emergence of semi-permanent settlement. The land immediately surrounding the settlement is intensively farmed and most seriously degraded with more distant land cultivated in rotation. This is called ROTATIONAL BUSH FALLOWING.

9. Impact on People • Impact on the way of life • With enough land and a low enough population density, shifting cultivation is a sustainable type of farming, However, the reduction in land available and the increased population density in Amazonia have had a huge impact on the traditional shifting cultivation way of life. • with less land available, the shifting cultivators return to the same area of land more frequently↓fallow times are shorter ↓there is a reduction in crop yields↓trees do not get the time needed to regenerate properly and the soil does not recover its fertility↓the traditional way of life can become unsustainable

10. Impact on People • There has been a huge reduction in the number of native Amerindians in Amazonia, both by killings and by the introduction of 'Western' diseases. Tribal lands have been taken over and this has forced tribes, like the Kayapo, deeper into the more inaccessible forest. The alternatives for the Amerindians are to live on reservations or move to shanty towns in large urban areas. • The overall population density has, however, increased as people have moved into the rainforest for farming and other related jobs.

11. Possible consequences of deforestation in tropical rainforests