tropical rainforest Flashcards
general facts
20-28 degrees
2000 mm
convectional rainfall
covers only 5% but supports over 50% of biotic species
soil moisture budget
balance between inputs and outputs is high because precipitation is higher than potential evaporation
latosol
high in metal oxides like aluminum
nutrient poor
quick decomposition - ideal microclimate for bacteria
all year growing season - nutrients continuously recycled and reabsorbed
– leaching by heavy rainfall
layers of the rainforest
emergent
main canopy
under canopy
shrub layer
emergent layer
buttress routes - withstand strong winds
30-35m high
example: mahogany
main canopy
continuous layer of trees
most productive layer
dense leaves create shade – prevent sunlight reaching lower layers increases competition
under canopy
younger trees that aren’t fully grown
only survive if there are breaks in the canopy
only recieve about 10% of sunlight
example: lianas - form green corridors
shrubs layer
little sunlight
have large leaves to absorb as much sunlight as possible
drip tips - adaptations
waxy leaves with pointed tips that channel water so it runs off
ensure it does not break off or grow mold
abscission - adaptations
leaves fall yearly to allow the trees and plants to grow all year long
epiphytes - adapatations
lianas that climb up trees to reach the sunlight - also form bridges across the canopy which allow animals to move around
orchids - hold water in the canopy and prevent further soil leaching
sloths - adaptations
slow moving saves energy
algae grown on fur - helps with camouflage
long claws which help them to hang from tall trees and lianas
anteaters - adaptations
under the canopy - low light conditions - adapted a good sense of smell
characteristics of the rainforest
low latitudes within the tropics
low diurnal range at 5 degrees
no seasons - wet and hot all year round
88% humidity
high biodiversity 50%
nutrient cycling
continual yearly growing season
fast recycling of nutrients
– loose leaves all year round
– rapid decomposition due to optimal bacterial conditions
– plants grow quickly when light breaks through the main canopy so nutrient uptake is rapid
leads to large biomass
small litter and soil
npp in rainforests
very high
humus
organic component of soil that helps retain moisture and nutrients
composed mostly of organic plant matter
how does climate impacts the soil
parent rock type can remain the same but different climatic conditions create different soils
high temperatures - determines the rate of chemical and biological decay and influences humification (the formation of humus)
results in a deep profile with many well developed horizons
aerated soils
soils with pore spaces has a rich brown colour
soil texture
determines permeability
smaller mineral particles = decreased permeability
clay - compact and lacks pore space
soils with ample pore space will allow roots to develop and support vegitation growth
soil moisture budget
high - precipitation exceeds potential evapotranspiration
short time lapse between rainfall peaks - never reaches a deficit
water surplus all year round
soil importance
important factor in the development of vegitation that has driven ecological change and succession
completely reliant on the rainforest to remain fertile - deforested: nutrient leaches and humus is no longer being replaced
mining of minerals - human impact
large scale deforestation strips the soil of nutrients and exposes it to erosion
water clogged with silt leads to downstream flooding
eg: carajas, brazil
agricultural practices - human impacts
slash and burn creates pasture for grazing
single cash crops like soy create a monocultural environment - decreases biodiversity and increases vulnerability to ecological change
Tilling - human impact
Tilling causes the breaking up of topsoil which releases carbon into the atmosphere, and it’s predicted by within the next 60 years the entirety of the world’s topsoil will be gone
Since the 1970s, one third of the global topsoil has been decertified: the process of soil turning to desert.
The rate at which we till influences the rate of global desertification.
Depleting our soils and releasing sequestered carbon from the pedosphere is accelerating the rate at which carbon is being released into the atmosphere
greatly impacting the global carbon budget through a positive feedback loop which is moving the carbon budget away from equilibrium.
animal husbandry
breeding maintenance and slaughtering of livestock
consuming 70% of agricultural land
80% deforested areas in brazil are used for grazing of livestock
agroforestry and crop diversity
Peru - working towards replenishing soils
the project itself is comprised of having a multitude of crops being planted to enable the microorganisms within the soil to have access to a variety of root types and allow the micronutrients to be replenished in a way that is sustainable and will restore the optimum microclimate so that autotrophs can photosynthesize, absorbing more carbon from the atmosphere than is being released into it.
road construction - human impact
highways connect parts of the rainforest that were previously inaccessible encouraging human development
eg: transamazonian highway extends 6000km into the rainforest
global impacts of human development
forests store up to 100x more carbon that fields - loosing an essential carbon store
75% of brazils emissions come from deforestation
1.5 billion tons are released due to deforestation
disrupts the global carbon budget - out of equilibrium - more imput of carbon that outputs (loosing trees that sequester carbon)
leads to a surplus of carbon emissions and a deficit of carbon storage
economic impacts
income needed to pay of debts and improve development in the country – eg brazil: short term jolt to the economy - new resources lure development and investment
Agri-commodities are the biggest export of brazil
local employment has risen - employed by tncs - but little income actually reaches them and instead either returns to the tnc home country or invested into the government - however they do gain an element of education
social impacts
dilution of native culture due to increasing presence and interaction with foreign tncs - less ecosystem services
240 tribes left in the amazon and an estimated 80% of tribes have disappeared since arrival of Europeans in the 1500s
environmental impacts
loss of habitat and biodiversity - less interception and roots to bind soil - more leaching of nutrients and less recycled in the nutrient cycle so less available for plant growth - evapotranspiration reduced which can drastically alter the climate as the soils and vegitation are increasingly dependent on each other to support and sustain life in the rainforest (ecological change)
economic development - threats to the rianforest
increases populations wealth and access to resources which drives an increase in consumption and demand for new products which further increases deforestation (positive feedback)
investment in infrastructure has lead to road developments opening up previously inaccessible areas
human population change - threats to the rainforest
manaus brazil: 100,000 to 2 million by 2015
increased population pressure means the demand for resources and land space increases - places pressure on forest clearance and agri-commodities to accommodate the increase in demand
monoculture cash crops have lead to mass land degradation and infertility causing more land to be cleared
agricultural practices - threats to the rainforest
80% of land deforested in brazil is due to cattle ranching
slash and burn could be a sustainable technique however not enough time is left between periods of burning to allow the forest to recover - land is farmed again before fertility and nutrient stores are able to recover causing degradation
fragmentation of the rainforest decreases species genetic diversity and can lead to species extinction
local rainforest management schemes
ecotourism - gives economic value to the forest and wildlife
education: recieve education about the rainforest and subsistence farmers are given training and certification in sustainable agriculture
international rainforest management schemes
tropical forest alliance 2020 - aims to reduce deforestation globally
debt-for-nature swaps - reduce debts in a country in exchange for conservation of parts of the rainforest
negatives of sustainable management schemes
sustainable forestry supports less local jobs than conventional forestry
bring conflict over land ownership
