Tropical Rainforest Threats

Tropical Rainforest Threats

1. Direct threats

   • Commercial hardwood logging
     • Furniture/ construction
     • Road building for logging needs tree clearance
   • Subsistence agriculture
     • Farmers grow food to eat
       • 'Slash-and-burn'
         • Trees cut down - undergrowth burned - crops planted
           • Nutrients quickly leached out - weed growth - next plot
             • Growing population - reuse plots straight away - no time to recover nutrients
   • Commercial agriculture
     • Space for cattle grazing, palm oil or soya plantations
   • Local demand for fuel wood
     • Locals - cooking
     • Charcoal - important African cities
   • Demand for biofuels
     • Fuel made from plants - palm oil
       • Cut down trees to grow them
     • Reduce reliance on fossil fuels
   • Mining for mineral resources
     • Gold, copper, ore minerals
     • Dig deep pits/ explosives to clear earth
   • Electricity (Hydroelectric power dams)
     • Flood large area of forest behind dams
   • Causes are linked to poverty, debt, economic development and demand for resources:
     • Poverty
     • Debt
     • Economic development
     • Demand for resources

2. Indirect threats

   • No direct cause between one thing and another. (Don't deliberately cut down trees but still lead to damage to the ecosystem)
   • Climate change
     • Increasing global temperatures - impact equatorial climates of shifting the wet-season’s intertropical convergence zone, northwards - reduces wet season rain reaching rainforests - hotter - drier - droughts.
       • Fires more likely.
         • Soil is peat – when peat dries out and catches fire it can smoulder for months - constantly ignite fires on the surface.
       • Drought - drying of the leaf litter - decomposer organisms die out - threaten nutrient cycle.
         • Leaves in the canopy dying - reduce the food supply and affecting food webs.
           • If drought becomes more common, rainforests suffer permanent damage and die back - could become sources of CO2, not carbon dioxide sinks.
             • Increase climate change
       • Plants and animals evolved to constant temperature conditions - can't tolerate heat spikes (heatwaves).
         • Plants not able to tolerate a long drought: kills some and stresses the survivors.
           • Stressed plants and animals have less resistance to disease - extinction. Conditions drier and hotter - those adapted would spread and out-compete trf species.