earth's life support system 3 (APRA (are placing areas in the…
earth's life support system 3
global distributions of rainforests
20 degrees north + 20 degrees south
found between 10 degrees north + south of the equator
annual patterns of temperatures
wetter season because the cloud band remains at the equator near Manaus. 'drier' seasons are in the Summer, because the rain band shifts further north, leaving Manaus uncovered by the rain band
temperature is consistent all year. fluctuates between 26-27.7 meaning the range is 1.7 degrees. it is warm all year around, small seasonal variation occurs. cloud cover due to higher rainfall in these months = blocks incoming solar radiation
characteristics of the rainforest vegetation
tropical rainforests only cover 6% of the surface. but due to favorable climatic conditions they contain more than half of its plants and animal species
because the density of the vegetation is so high, tropical rainforests continuously recycle carbon dioxide into oxygen.
the high temperatures and high quantity of rainfall means that fast-growing trees form a dense canopy. this canopy prevents sunlight from reaching the floor which leads to a densely vegetated but clearly layer structure
characteristics of rainforest soil
they may appear to be fertile but the tropical latosols are not. leaching occurs as a result of the high precipitation and is increased greatly by deforestation.
however, the top 15-20cm of the soil is the nutrient rich leaf litter, composed of decaying leaves, wood and other organic matter.
rainforest soils are very deep due to rapid chemical weathering of the bedrock which as accumulated over millions of years to form deep soils
50% of precipitation is evaporated out
30% reaches the sea ( rain )
48% that has evaporated is going to fall as rain again
stores of carbon
vegetation = large store as there is a vastness of vegetation covering the forest. trees typically store carbon in their roots 40% + above ground (60%)
soils also store carbon. atmosphere = respiration occurs due to the vegetation and also there is a loss because absorption is greater than respiration rates
shifting cultivation is a traditional, sustainable method of agriculture which has been practiced by indigenous tribes for thousands of years.
a small area is cleared the vegetation is burned and provides nutrition. this area is left for a few years so the soil remains sufficiently fertile to grow crops
these areas are planted on + then left without being touched to restore fertility. these areas receive nutrient seeds from surrounding vegetation. the farmers will then move onto another area
effect of shifting cultivation on the water cycle
lowered number of vegetation means that less interception takes place due to the removal of vegetation
infiltration rates increase causing through-flow levels to increase. due to higher surface area infiltration and percolation will therefore increase
evaporation will decrease because there are less vegetation. bedrock will erode faster due to the increased rates of percolation.
cattle ranching has been cited as causing 80% of current rates of deforestation. it is responsible for 0.34 GT of carbon into the atmosphere
large areas of forest are cleared to make way for the cattle ranges. the government ordered forest clearing to become a major milk producing and meat producing area.
managing deforestation in the amazon
protection through legislation of large expanses of primary forest so far unaffected by commercial developments
projects to reforest areas degraded or destroyed by subsistence farming, cattle ranching, logging and mining.
improving agricultural techniques to make permanent cultivation possible
are placing areas in the rainforest under strict protection
they are going to achieve this by: reversing deforestation, increasing number of hectares in protected areas and balancing the demand for natural resources
this is funded by: german department bank, world bank and the global environmental facility
this will affect the carbon cycle: via photosynthesis trees take in carbon dioxide thus reducing global warming. if deforestation occurs more carbon dioxide would be released