Tropical Rainforest - Amazon Rainforest, Brazil

overview

spans 5.5.million km²

one of largest and most biodiverse ecosystems

water cycle: precipitation

receives high rainfall (2,000-3,000 annually)

water cycle: evapotranspiration

trees release water vapour into atmosphere, contributing to cloud formation

accounts for large portion of precipitation, self-sustaining cycle

water cycle: runoff and infiltration

rainwater that falls on forest floor either infiltrates soil or flows into river systems

carbon cycle: carbon sequestration

acts as a carbon sink

carbon cycle: decomposition

dead organic matter decomposes and releases carbon back into atmospshere

heavily influenced by deforestation and fires rates

carbon cycle: soil carbon storage

organic carbon stored for longer periods

soil fertility and microbial activity crucial for storage and release of carbon

environmental change: mining

mercury used to separate metal from surrounding soil, leaching into rivers

generates sediment runoff, clogging rivers and streams

hydraulic mining erodes soils

clears large areas of forest

roads built for it disrupt habitats, fragmentation

environmental change: deforestation

for agriculture (soy production, cattle ranching)

transpiration decreases - drier conditions

less carbon sequestration

forest fires used to clear land

loss of biodiversity

deforestation on water cycle

reduced EVT - drier conditions, reduced rainfall, vulnerable to droughts

reduced vegetation - less water absorbed by soil, more runoff, flooding

amazon river depends on consistent rainfall, disruptions can reduce water table

deforestation on carbon sequestration

carbon stored in biomass released, could become carbon source

regrowth is slow, especially as soil quality degrades

positive feedback loop as it releases carbon, contributing to climate change and further disrupting forest health

human response and mitigation: NGO and government action

efforts into reducing deforestation through conservation programmes, establishing protected areas

sustainable land management practices - agroforestry, certified sustainable logging

human response and mitigation: international pressure and agreements

paris agreement, urged amazonian countries to protect rainforests as part of global climate change mitigation efforts

human response and mitigation: reforestation and afforestation efforts

replant parts of forest and regenerate degraded areas

rewilding initiatives bring back lost species, stabilising ecological processses