Ecosystems-Tropical Rainforests Flashcards
Tell me about the characteristics
- located in the tropics and 5° either side of the equator
- temps=high and constant 27° C. Average
- annual rainfall= 2000 mm
- rapid decay of leaf litter
Tell me about the impacts of deforestation
- disrupt the food chain- extinction
- vegetation protects soils from heavy rain. When trees are removed, the topsoil is open to erosion and leeching of nutrients and minerals- run off causes sediment to block river channels and increase flooding
- burning leads to local pollution. Forest ability to absorb CO2 as reduced
- can have economic benefits from mining and farming
- culture of indigenous people destroyed as many forced to move
Tell me about the statistics of deforestation in the rainforest
- between 2000 and 2005, Brazil last more than 132,000 km squared of forest
- Brazilian deforestation is correlated to the economic wealth of the country and the decline in deforestation from 1988 to 1991 matched the economic slowdown during the same period
Tell me about indigenous people
- about 50 million indigenous people living in tropical rainforests
- slash and burn techniques practised by these groups is blamed for the destruction of large areas
Tell me about economic development
- mining, forestry, oil exploitation and agriculture all bring economic benefits in the form of local employment
Tell me about agricultural change
- population pressure increases demand for land and food
- poor farmers use slash and burn
- This releases minerals locked up in the vegetation and produces a layer of nutrient-rich material above the poor soil
- cleard area is planted and supports growth
- after the nutrient stock is depleted, large amounts of fertiliser is required to maintain production
- This gets washed into rivers
- land then abandoned as soil Is deprived of nutrients and fertiliser can’t restore it anymore?
- retreats to scrub
- cattle ranches may settle here
- the land is now barely productive
Reasons forest clearance-Soy
- soy farms caused forest clearing directly. Occupy already cleared land and push ranches and subsistence farmers even deeper into the forest
Tell me about shifted cultivations
• These are small scale farmers squeezed out of traditional farmlands
• Have little understanding of the ecological workings of tropical rainforest
• practise unsustainable forms of exploitation
• satellite surveys indicate that the account for 2/3 of deforestation
Tell me about vegetation adaptation- Drip tips
- plants have thick waxy leaves with pointed tips. These drip tips channel the water to a point so it runs off so it doesn’t damage to plant
- no standing water for fungi and bacteria to grow in
Tell me about vegetation adaptation- smooth bark
- many trees have smooth, thin bark as there is no need to protect the trunk from cold temps
- smooth services allow water to run off efficiently to the soil so trees can absorb water
Tell me about vegetation adaptation- buttress roots
- most trees have buttress root to support them as trees compete for sunlight
- the roots grow wide not deep as nutrients exist in the top lay of soil
What is biomass
Total mass of living organisms, mainly plant tissue
Tell me about the soil in tropical rainforests
- mainly thin and poor
- often red in colour as they are rich in iron
- nutrient levels in the soil are low due to the leeching by the heavy rain
Tell me about the nutrient cycle in tropical rainforest
- majority of nutrients are stored in the biomass
- nutrients are rapidly recycled
- warm moist climate provides ideal conditions for decomposers to break down organic material in the litter layer very quickly
What is the litter layer?
All dead organic material
