humans and the rain forest - eth z · kuda-kuda log hauling method. log raft. industrial...
TRANSCRIPT
Extinctions and humans• Over the last 50,000 years
extinction of large mammals has been relatively common loosing as many as 90 genera (why?)
• The earliest extinction due to humans was 11K years ago (late pleistocene) largely through hunting and fire. Ground sloths and Gomphotheres
• Americas experienced major extinction wave of 70-80% of large mammals, associated with the ‘Clovis hunters’
Holocene extinctions
• African forest seen less extinctions
• Indonesian Island of Java seen loss of many large mammals in last 2600 years
• Oceanic islands have been especially vulnerable to human driven extinctions
Human migration
• As humans moved eastward across the Pacific some 2000 bird species became extinct.
• Wave of extinctions on Madagascar shortly after humans arrived circa 2000 BP
• Driven by introductions, disease and habitat loss and fire
• The dodo Raphus cucullatus
Collapse of the world’s largest herbivores
Ripple et al 2015 Science Advances
60% of large herbivores threatened
Willis et al. 2004. How “virgin” is virgin rainforest. Science 304, 402
Human impacts are not completely irreversible…
… scope for developing strategies for enhancing resilience and resistance to impacts, which would aid in later recovery
Human legacies
• Only the rain forests of Australia seem to have been uninhabited
• human habitation considerable impact on the forest
• Agricultural long history in the wet tropics with selective pressures on plant species
Palaeohuman settlements
• Large scale landscape transformation in the Amazon altered forest composition and soil 6-12 people per Km2
Humans and Fire• Radio carbon dating demonstrate the
expansion of agriculture with peaks.
• This was followed by a period of abandonment
• Subsequent collapse of American indigenous communities (1500 AD) was followed by regeneration of dense forests.
• Many forest areas of the Amazon are better described as human created
European expansion
• Calamitous collapse of indigenous societies
• Changes in forest legislation to suit colonial timber exploitation
• New systems of land management and “scientific” resource use had a lasting legacy on forest management
• Slavery and disregard for indigenous lives
Hevea brasiliensis
Palaquium gutta
Cinchona
Industrial deforestation
• Broadly caused by agricultural expansion
• Patterns, causes and extent differ across the main tropical regions
• Much of Amazon, SE Asia and Africa were intact until the 1970’s, Mesoamerica and South Asia had already experienced widespread fragmentation
Accelerated forest loss
• Since the 1970’s there has been a dramatic increase in rates of deforestation across the tropics.
• Forest conversion and degradation
• 130,000 km2 of the worlds forest lost annually 55,000 km2
of primary tropical forest
Deforestation in Brazil• Reflects much of
central and south America
• 2/3’s of the Amazon and all tropical Atlantic rain forest are in Brazil
• Early colonisation of the Atlantic costal forest
• Later, Operation Amazonia 1964-1967
Deforestation in Asia• Government sponsored
forest development schemes especially in Indonesia and Malaysia
• Transmigration of people from densely populated island; ITP officially resettled approx. 5 million people (10 -15 million others)
Mining
• Gold, silver, copper, aluminium and other precious metals.
• Associated with major road construction.
• Pollution related to processing (mecury and cyanide for gold)
Conclusion
• No Tropical rainforest remain untouched by humans
• Past history demonstrates the resilience of tropical forests
• Humans have had and continue to have significant and irreversible impacts on tropical forests, often involving huge sums of money
• Many of these processes may be synergistic, such as fragmentation, fire and climate change.