the savanna biome Flashcards
where is the savanna grassland located
between the tropics of cancer and capricorn
5* - 20* N/S of the equator
what are the distinct features of the savanna
-large patches of grassland
-usually found in brazil, africa, australia and india
-periods of drought
-wildfires are common
-mix of tropical forest and desert
-trees, occasional shrubs
- 22-28 degrees celcius
- 20-50 inches of rainfall (1000mm per year)
-rainfall is concentrated in 6-8 months
-fires may occur during drought
what do the fires that occur during a drought result in?
the fires kill enough trees to prevent it becoming a forest
describe the environment during the wet season
leaves on trees
green elephant grass(3-4m tall)
describe the environment during the dry season
no leaves
yellow grass which dies leaving it vulnerable to erosion
properties of the baobab tree
-stores water
-thick bark
-grows over 30m in height and 7m in diameter
- shallow roots
- fire resistant
-fewer leaves
- large barell-like trunk
what do the shallow roots on a baobab tree mean
it can collect water as soon as it rains
what do the fewer leaves on a baobab tree result in
reduces the water lost by transpiration (water droplets not being able to reach the ground as being blocked by the leaves)
how much water does the large barell-like trunk of a baobab tree store
up to 500litres of water
properties of the acacia tree
- wide
- leaves are high up
- provides shade for animals
- grows up to 20m in height
-2m in diameter
-small leaves with waxy skin
-thorns on branches - long tap roots
how big does the baoban tree grow
over 30m in height abd 7m in diameter
what is good about the leaves being high up on the acacia tree
cant be eaten by animals
how big does the acacia tree grow
up to 20m in height and 2m in diameter
what do the small, waxy leaves on the acacia tree reduce
it reduces the amount of water lost through transpiration
what do the thorns on an acacia tree’s branches do
deter animals from eating then
whats a benefit of the acacia trees long tap roots
during the dry season the roots are able to reach water stores underground, keeping the tree alive for longer
what is the soil in the savanna like
-porous, drains rapidly
- thin humus layer
- not many plants to provide nutrients
- high rates of decomposition in the wet season
- humus-decomposed leaf litter has lots of nutrients
what is desertification
degregation of land and vegetation, soil erosion and loss of top soil + fertile land
(turning into a desert)
facts about desertification
every country is affected by soil degration (desertification)
can take 500yrs to create 2.5cm of soil but only a few years to destroy it, caused by human factors
how can farming damage soils
soil is vulnerable, chemical fertilasation weaken the living organisms responsible for
soil fertility. regular plowing dries out and comacts the soil
how much land is lost through desertification
12 million hecter, a third of land threatened and 10 countries affected
what is the impact of desertification
soil exhaustion reduces food production
20 million tonnes of grain lost through desertification
sustainable solutions of desertification
-planting trees to slow down wind erosion
- the great green wall in africa
-vegitation fences to anchor the soil
- farming without plowing
what is agroecology
sustainable farming that works with nature
is desertification a human or natural process
human
how does plowing lead to desertification
compacts and dries up soil
how does monoculture lead to desertification
plants will take all of a certain nutrients
how does taking too much ground water lead to desertifcation
leaves little water for vegitation
how does overgrazing lead to desertification
theres no crops or vegitation if farm animals eat them
how does using fire lead to desertification
releases co2 and destroys vegitation
how does poor irrigation lead to desertification
bad water, too much salt and chemicals
how does over cropping lead to desertification
not enough nutrients for all the plants
what does the great green wall in africa achieve
provides micro nutrients for the soil
provides an income
what is happening to lake chad
is disapearing due to climate change
- poor irrigation methods removing too much water
-intense farming
how can the tranaqua project help lake chad
could transfer 50 billion m^3 of water a year to lake chad through a series of dams
- generate up to 15-25 billion kwh of hydro electricity
