tropical rainforests - P Flashcards
1
Q
how much rain do rainforests receive per year
A
around 33 feet
2
Q
how much of the earths surface area is made up of rainforests
A
6%
3
Q
what does the green vegetation of the rainforest help do
A
regulate global temperatures - by absorbing radiation from the sun and CO2
4
Q
why are rainforests being destroyed
A
through deforestation for human uses
5
Q
where are tropical rainforests usually located
A
in the tropical climate region
6
Q
why do tropical rainforests have a humid climate
A
they are hot and wet all year round
7
Q
what is the annual rainfall like in the tropical rainforest
A
high - as it rains almost every day
8
Q
what are the temperatures like in the tropical rainforest
A
they are constant all year round usually with a range if a few degrees - there are no distinct seasons
9
Q
what are the two main kinds of rainfall in the tropical rainforest
A
- convectional rainfall
- relief rainfall (orographic)
10
Q
what is convection rainfall
A
occurs when the ground is heated by the sun, causing evaporation of moisture - this condenses into the air creating clouds which the rain
11
Q
what is relief rainfall
A
occurs when air carrying moisture is forced to rise over mountains - this causes the air to condense forming clouds which rain over high ground areas
12
Q
how large is the amazon rainforest
A
6.7million km**2
13
Q
what are the three distinct features of the climate in tropical rainforests
A
- small seasonal variation in temperature
- higher average temperatures 20-30 degrees C due to intense insolation
- high average precipitation >2000mm with no dry season
14
Q
what is the temperature range throughout the year in tropical rainforests
A
25-28 degrees C
15
Q
what does a 25-28 degree C lead to in tropical rainforests
A
- high rates of evapotranspiration
- rapid rates of decomposition and low levels of soil carbon
- facilitate high levels of plant growth and biosphere sequestration
- enhance biological and chemical weathering rates
16
Q
what are the effects of convection in tropical rainforests
A
- high atmospheric humidity, the development of thunderstorm clouds (cumulonimbus) and intense precipitation
- water cycled continually between land, vegetation and atmosphere
17
Q
how much precipitation is recycled in the Amazonia
A
50-60%
18
Q
what does high humidity result in in the tropical rainforest
A
- high levels of soil saturation
- high ppt and soil moisture - rapid decomposition rates and nutrient leaching so low soil carbon storage
19
Q
what pattern does decomposition in tropical rainforests follow
A
rates of precipitation - Feb-May are the highest, Jun-Aug are the lowest
20
Q
what does precipitation result in in the tropical rainforest
A
- high annual ppt >2000mm
- strong convection - high atmospheric humidity - development of thunderstorm clouds (cumulonimbus) and intense ppt
- rapid runoff and overland flow is experienced due to intense rainfall
21
Q
how much precipitation is intercepted by the forest canopy in tropical rainforests
A
10%
22
Q
how many trees are there in the Amazon rainforest
A
400 billion trees
23
Q
how much carbon is stored in the Amazon rainforest
A
60 billion tonnes of carbon
24
Q
what are the effects of vegetation in tropical rainforests
A
- dense vegetation enhances biological weathering
- dead plants provide material for decomposition
- roots absorb water from soil which reduces soil organic content and carbon store.
25
what is the dense canopy layer made up of in the tropical rainforest
emergent trees
26
what height can emergent trees grow to in the tropical rainforests
40m in height
27
how much carbon do emergent trees store above and below ground
180 tonnes C/ha - above ground
40 tonnes C/ha - below ground in roots
28
what type of roots do large trees have in tropical rainforests
shallow buttress roots - they don't tap into groundwater supplies
29
what is the average net primary productivity of the Amazon rainforest per year
2000 g/m***2/yr
30
what does rock type affect in a tropical rainforest
- the underlying geology of the Amazon is impermeable, ancient igneous and metamorphic rocks
- these have minimal storage capacity - rapid run off
31
how does relief affect the tropical rainforest
- most of Amazon is lowlands with lots of overland flow, throughflow
- in the West the Andes create steep catchments with rapid run-off
- in the South widespread flooding across floodplains stores water for months slowing movement into rivers
- the rapid runoff rates and enhanced nutrient leaching results in rapid and sustained transport of C in the Amazon
32
where is the Madeira Basin
in Southern Brazil - Madeira river is the largest tributary in the Amazon
33
how many km**2 of the rainforest were deforested
11,088 km**2
34
how much did deforestation increase from the previous year (rainforest)
9.5%
35
why could deforestation of the rainforest have increased by 9.5%
Jair Bolsonaro (the president) encouraged agriculture and mining activities
36
how many species live in the Amazon
around 3 million species
37
how many indigenous people live in the amazon
around 1 million people
38
what was the goal of slowing the pace of deforestation by 2020
cutting deforestation to 3,9000km**2 annually by 2020 - however Bolsonaro cut funding to federal agencies with power to fine and arrest those breaking environmental law
39
what are the main reasons for deforestation in the Amazon
cleared for: cattle grazing, soya cultivation and mining
40
what did Bolsonaro describe the Amazon as
a periodic table
41
at the time how large of an area was cleared every minute
an area the size of a football pitch
42
what does MAAP stand for
the Monitoring of the Andrean Amazon Project
43
what did MAAP find
that 1.9 million hectares of the Amazon were lost last year
44
when did the Amazon lose a lot of Primary Forest
2021
45
where is most of the deforestation happening
Brazil and Bolivia
46
where does MAAP show most deforestation is happening
along major roads in states that are hotspots for legal & illegal cattle ranching
47
what does the biomass of the Rainforest represent of all CO2 in the atmosphere
60%
48
what is the above ground carbon biomass
180 tonnes/ha - most C is in the soil and roots & dead organic matter
49
what does burning produce more of
3x more CO2 than the forest absorbs
50
how much more CO2 has the Amazon absorbed than released in the past decade
20%
51
what is happening to the efficiency of rainforests at trapping carbon
they are becoming less efficient
52
how much land of previously intact forests are now submerged in the Madeira River Dam
78% - this decays and decomposes releasing CO2 and methane
53
how does Agriculture affect the tropical rainforest
- biomass of grasslands in former rainforest is 16.2 tonnes/ha and soya cultivation is 2.7 tonnes/ha
- deforestation removes organic matter - so soils are depleted of C and support fewer organisms - reducing flow from soil to atmosphere
- thinner soils are less able to store water heightening flood risk
- drier soils are more susceptible to being eroded by the wind which transfers C stored in soil to the atmosphere
54
how are carbon levels measured
by flux towers - located in rainforests as they are important C stores which help maintain the C balance
55
why is photosynthesis important for trees
it provides them with energy to grow and fix themselves
56
what are the 4 layers of the tropical rainforest (with heights)
shrub layer - ground - 10m
lower tree canopy - ground - 20m
main canopy - 20 - 40m
emergents - over 50m
57
which two layers are part of the understory
shrub layer and lower tree canopy
58
how much light reaches the shrub layer
less than 3%
59
what is gross primary productivity (GPP)
the amount of carbon removed from the atmosphere by plant photosynthesis
60
how much carbon do trees use to make new tissue
40%
61
what is net primary productivity (NPP)
the difference between the amount of carbon taken up through photosynthesis and the amount that's lost through respiration - measured in grams of C per square meter
62
how much of the CO2 we release is fixed by tropical rainforests
around a quarter of all CO2 released
63
how much carbon is stored in the tropical rainforest above and underground
250 tonnes in one hectare above ground
50 tonnes per hectare underground
30 tonnes per hectare in deadwood
64
how often are flux measurements taken in tropical rainforests
every week - so we can tell if it is a sink or source of carbon and water vapour
65
is the tropical rainforest a sink or source in the day and night
day - sink
night - source
this is because trees only photosynthesise with light but they constantly respire
66
how much carbon can primary tropical rainforests store
300 tonnes of C per hectare
66
what do research teams use to see how much carbon is allocated to plant growth in the tropical rainforest
leaf traps, growth bands and CO2 collars
67
how much can selective logging reduce the carbon stored by
around 50%
68
what happens to trees and stumps left from logging in tropical rainforests
decomposers or detritovores break down the organic matter and produce CO2
69
after logging what happens in tropical rainforests
there is more light for photosynthesis so trees grow rapidly and become carbon sinks again however this takes time
70
what is a common for logged areas to become in tropical rainforests
they become palm oil plantations which only store 30 tonnes per hectare of C in comparison to 200
71
how often do oil palms have to be replaced
every 20 - 30 years so the carbon they fix is not a long term biomass
72
how much more land will be converted into palm plantations by 2025
9 million hectares
73
for every hectare converted from primary rainforest what happens
more than 100 tonnes of C is released and for each year plantations remain another 13 tonnes are released instead of stored
74
how much rain does a tropical rainforest get each year
at least 2000mm but most get 3000-4000mm
75
how are plants in the tropical rainforest adapted to not rot
they have leaf drips and smooth bark which means water runs off them so they don't rot - the water landing on the ground allows for decomposition of materials
76
what is a positive feedback loop to do with the tropical rainforest and palm oil plantations
plantations reduce evapotranspiration and cloud formation preventing rain which then repeats the loop.
77
what does the volume of rain means happens in the soil of the tropical rainforest
the volume of rain dissolves and leaches nutrients from the soil leaving behind insolubles like iron, and aluminium oxides giving the soils a reddish colour
