water/carbon cycle in contrasting locations

Created by

olivia thorley

Cards (50)

2 case studies for water and carbon cycles
amazon rainforest
arctic tundra
climatic features of amazon
high annual temperatures between 25 and 30
small seasonal variation in temperatures
high average rainfall - 2000mm+ with no rainy season
evapotranspiration in amazon 
50-60% of precipitation is recycled by evapotranspiration
characteristics of precipitation in the amazon (water cycle)
high average rainfall
rainfall fairly evenly distributed through year
high intensity, convection rainfall
high interception by forest trees
intercepted rainfall = 20-25% of all evaporation
characteristics of evapotranspiration in the amazon (water cycle)
high rates due to high temperatures, abundant moisture and dense vegetation.
strong evapotranspiration-precipitation feedback loops sustain high rainfall
most evaporation is from intercepted moisture from leaf surfaces
characteristics of run-off in the amazon (water cycle)
rapid run-off related to high rainfall, intense rain events and well-drained soils.
river discharge peaks in 1/2 months per year
characteristics of the atmosphere in the amazon (water cycle)
high temperatures allow atmosphere to store large amounts of moisture
high absolute and relative humidity
characteristics of soil/groundwater in the amazon (water cyle)
significant water storage in soils and aquifers due to abundant rainfall
characteristics of vegetation in the amazon (water cycle) 
rainforest trees store and absorb water from soil and release it by transpiration
net primary productivity in amazon
high - average of 2500 grams/m2/year
amazon as carbon store
stores around 2.4billion tonnes/year
effect of geology on water cycle in the amazon 
impermeable catchments have minimal water storage capacity = rapid run-off
permeable and porous rocks e.g., limestone store rainwater and slow run-off
effect of relief on water cycle in the amazon
majority of amazon is lowlands
gentle relief = water moves via overland flow or through flow to streams and rivers
in the west, the Andes create steep catchments with rapid run-off
effect of temperature on water cycle in the amazon
high annual temperatures generate high rates of evapotranspiration
convection is strong, leading to high atmospheric humidity, development of thunderstorm clouds and intense precipitation
physical factors affecting stores and flows in carbon cycle - forest trees
forest trees dominate biomass of amazon and store around 100 billion tonnes in total
absorb 2.4 billion tonnes a year and release 1.7 billion tonnes via decomposition
60% of rainforest carbon is stored in above ground biomass
geology and the carbon cycle in the amazon
carbonates largely absent in amazon basin
in western areas of basin, outcrops of limestone occur which are large regional carbon stores in slow carbon cycle
deforestation rates 1970 - 2013
17,500km squared/year
deforestation since 1970 
almost 1/5th of primary forest destroyed/degraded
flooding of madeira river 2014 
main driver was deforestation in bolivia and peru
river reached 20m above normal in places
60 died
68,000 people evacuated
outbreaks of cholera
effect of human activity in upper madeira basin
deforestation reduced water storage in trees, soils, permeable rocks and atmosphere
less trees = less evapotranspiration and less precipitation
total run off and run off speeds have increased = higher flood risk
deforestation in bolivia 2000-2012
30,000km2 of bolivian rainforest removed for subsistence farming and cattle ranching
majority of this occurred on steep slopes of andes = massive reduction in water storage and accelerated run off
converting rainforest to grassland and impact on run-off
increases run off by factor of 27
half of all rain falling on grassland goes directly into rivers
future predictions of effects of deforestation in amazon
20% decline in regional rainfall
human factors affecting carbon and nutrient flows and stores
croplands and pasture contain only small amounts of carbon
deforestation reduces inputs of organic matter into soil. soils depleted of carbon support fewer decomposer organisms, reducing flow of carbon from soil to atmosphere
deforestation destroys main nutrient store and removes majority of nutrients from ecosystem
nutrients no longer taken up by roots are leached away
brazil commitment 2030 
restore 120,000km squared of rainforest by 2023
3 categories of managing the amazon rainforest
protection via legislation of primary forest
projects to reforest ares degraded/destroyed
improving agricultural techniques
protected areas in the amazon by 2015
44% of brazilian amazon comprised of national parks, wildlife reserves and indigenous reserves
Amazon regional protected areas cover area 20x size of belgium
parica project in western amazon
sustainable forestry scheme aiming to develop 1000km squared commercial timber plantation on government owned land
? monoculture and so cant replicate biodiversity of primary forest
! sustainable and sequesters carbon in trees and soil; reduces co2 emissions, re-establishes water and carbon cycles; reduces run-off and leaching
UN's REDD scheme 
provides payment to Surui tribe for protecting rainforest and abandoning logging.
grants credits to tribe which can then be bought by international companies that have exceeded carbon quotas
improved agricultural techniques  
diversification - soil fertility maintained by rotational cropping and combining livestock and arable operations
human engineered soils - soils made of inputs of charcoal, waste and human manure. attract micro-organisms and allow soils to retain fertility long term = allow intensive permanent cultivation ? still in production
climatic conditions in tundra
temps below freezing for 8/9 months
temps below -40 in winter
mean annual precipitation is low
key features of water cycle in arctic tundra
low annual precipitation (50-250mm) with majority falling as snow
small stores of moisture in atmosphere due to low temperatures
limited transpiration
low rates of evaporation
limited groundwater and soil moisture soils - permafrost barrier
sharp increase in river flow in spring/summer due to melting of active layer
temporary storage of water in summer due to permafrost barrier
carbon cycle in tundra
vast carbon sink - 1600GT globally
low carbon accumulation due to low temperatures slowing decomposition
amount of carbon in tundra soils = 5x greater than above soil biomass
NPP in tundra 
less than 200grams/m2/year
decomposition in tundra 
snow cover can insulate microbial organisms and allow some decomposition
effect of temperature on water cycle in tundra
temperatures below freezing for most of year so water stored as ground ice in permafrost.
temperature increase in summer means top 1 metre thaws
meltwater forms pools and lakes
drainage is poor due to permafrost
winter - sub-zero temperatures mean no evapotranspiration
summer - some evapotranspiration occurs from standing water, saturated soils and vegetation
effect of permeability on water cycle in tundra
low due to permafrost and crystalline rocks dominating geology
effect of rock permeability on water cycle in tundra
rock surface underlying tundra reduced to gently sloping plain by erosion and weathering = impede drainage and contribute to waterlogging in summer
effect of temperature on carbon cycle in tundra
limited plant growth (also due to unavailability of liquid water and little nutrients) = total carbon biomass store is low and low NPP
short growing season (3 months) in summer
carbon mainly stored as partly decomposed plant remains frozen in permafrost - locked away for 500,000 years
low temperatures and waterlogging = slow decomposition and respiration
effect of permeability on carbon cycle in tundra
little influence due to impermeability of permafrost