deforestation Flashcards
define deforestation
removal of trees in an unsustainable way
reasons for deforestation
demand for timber as a construction material
wood used for fuel
make paper and cardboard packaging
clear the land for farming
improve transport infrastructure by building new roads
targeting high value trees
what are the three main consequences of deforestation?
global climate change
destruction of habitats
soil erosion
how can deforestation contribute to global climate change?
trees are cut down = less carbon dioxide removed from the atmosphere by photosynthesis
how can felled trees increase the concentration of carbon dioxide in the atmosphere?
combustion of trees releases carbon dioxide from biomass
fossil fuels burnt in transport of logs
logs decompose and decomposers release CO2
what effect will the destruction of habitats due to deforestation have on biodiversity and why is this a particular issue in tropical rainforests?
reduces biodiversity
50% earth’s species live in rainforests –> damaging to global biodiversity
rainforest plants may have undiscovered medical properties
what is soil erosion?
removal of topsoil which contains valuable nutrients
why is there an increase in soil erosion if trees are removed from an area?
no roots to hold soil
soil can easily wash away
what does the removal of trees on higher slopes lead to?
lowland flooding after heavy rainfall
topsoil can be also swept by the rain
why is removal of top soil a particular problem?
top soil ‘fertile’ –> high nutrient concentration
soil below is not suitable for crop growth
what happens to evaporation vs transpiration due to deforestation?
evaporation from soil returns water more slowly to the atmosphere than transpiration does
leading to reduced local rainfall and accelerated desertification
what happens to decreased oxygen in soil due to deforestation?
soil becomes wetter
water fills the soil’s airspaces
oxygen available for roots decreases
what happens to the reduced soil temperature in soil due to deforestation?
takes wet soil longer to warm up than dry soil
meaning these soils are cold
reduces germination and root activity
what happens to the denitrifying bacteria due to deforestation?
cold, damp soil favours the growth of denitrifying bacteria
soils lose inorganic nitrogen compounds
is less ‘fertile’
