pa3 , another section Flashcards
what is biodiversity
biodiversity is the number of different plants and animal species in an area
why is biodiversity so high in rainforests
- Good climate for all year round growth and reproduction
- Rainforests are ancient and have a stable climate so thousands of different species evolved
- Multiple layers provide numerous different, specialised habitats, plants and animals have evolved to take advantage of these
how sloths are adapted
- huge claws allow to hang upside down from branches
- fur grows away from their feet to help shed rain when upside down
- green algae growing in their fur helps camouflage them from predators
how big cats are adapted
jaguars, tigers, leopards all have camouflaged fur ‘= dark and light
fur blends with sun/shade on the forest flaw
how birds are adapted
- loud : calls to hear mate rather than see them in the dense canopy
- parrots and macaws have powerful banks to open nuts
how primates are adapted
lemurs and monkeys evolved to live in the canopy where most food is
long tails used for balance
strong claws to grip trees and branches
how evergreen hardwood trees are adapted
tall slender trunks with no branches but huge triangular buttress roots to support weight leaving leaves and branches on top where sunlight is
how epiphytes are adapted
these plants live in the tree canopy
evolved to get nutrients from the soil as roots dangle in mid air
how lianas adapted
climbing plants use tree as their trunk - their stems cling to trees and climb up to sunlight in the canopy while getting water and nutrients from the soil below
how drip tip leaves are adapted
most rainforest plants have thick, waxy leaves with drip tips which shed water. quickly to prevent leaves rotting
how soil supports biodiverse forests
via the nutrient cycle
what do all plants need to grow
nutrients
external factors affecting the nutrient cycle?
Nutrients can be added to an ecosystem by precipitation and weathering
they can also be removed by runoff of leaching (when nutrients are washed out of soil by water moving through it)
They are taken up from soil as plants (on biomass) grow
They are returned to it when they die, first as litter (or decaying leaves and twigs) on the soil surface and then back into the soil as litter clays
therefore
nutrients move between biomass, litter and soil in a continuous cycle that keeps both plants and soil healthy
in the TRF , the nutrient cycle is…
RAPID
Most nutrients in the TRF are stored in biomass so if forest is cut down, most nutrients are destroyed…effects?
Without forest to protect it, litter and soil is easily eroded by heavy rains
As rainforest soils contain few nutrients, land cannot be formed for long before having to move on
Taiga location
between 50 degrees and 70 degrees latitude, mostly in the northern hemisphere
Huge areas of Russia and Canada are covered
how have coniferous (evergreen) trees adapted in Taiga
They have adapted to the cold climate - their shape allows snow to fall, instead of weighing on the branches, and their pine needles prevent damage by wind or snow
Taiga weather
short, wet summers of three months when temperatures rise to 20 degrees celsius
Long cold dry winters with several months below freezing, as low as-20 degrees celsius
Low precipitation
Snow on ground for many months
why is biodiversity so low in the taiga
- only reptiles and amphibians are adapted to cold climate and they are quite rare
- Growing season only 4-5 months so little food int he winter
why must animals adapt to cold. winter in taiga
plants stop growing
snow cover makes grazing difficult even for dead plants
Temperatures are bitterly cold
mammal adaptations to taiga
thick, oily fur to help retain heat and provide waterproofing
Because food is hard to find, some hibernate eg bears
Many birds only live in taiga in summer then migrate for winter due to lack of food.
what is NPP (net primary productivity)
A measure of how much new plant and animal growth - or biomass - is added to a biome each year, measured in grams per square metre per year
when is productivity greater
when there is plenty of sunlight
high temperatures
precipitation
direct threats to the TRF
Deliberate cutting down of trees for timber to make roads or to convert the forest into farmland
- Cattle ranches (60 percent)
- small scale subsistence agriculture(30 percent)
- fires, mining, urbanisation, road construction, dams (3 percent)
- Logging, legal and illegal (3 percent)
- Large-scale commercial agriculture including soybeans (1 percent)
Indirect threats to TRF
Come from pollution
global warming
disease
Reasons for deforestation
- Poverty, in many LICs locals cut down small areas of forest for land to farm since they have no other way of making a living
- Debt, some countries may cut down trees, export timberor grow cash crops to pay off debt
- Economic development - most tropical forests are in the developed world, in order to develop their economies, forests are sacrificed in the place of roads, expanding cities, and to dam rivers and build hydroelectric power (HEP) stations
- Demand for resources, tropical forests contain raw materials eg timer, oil, gas, iron ore and gold…to get these, forest must be destroyed and land is also needed to feed growing population
Examples of places where TRF are being destroyed for commercial reasons
- Mineral exploitation - eg Colton mining in the Democratic Republic of Congo; Colton is a mineral used in mobile phones, it is dug from ground from shallow mines
- Hydroelectric Power (HEP) eg Tucural Dam in Amazon, Brazil
Different rates of deforestation?
one cause is due to poverty eg in some LICs like Burundi
also the palm oil industry in Indonesia
Protection of forest in some MICs which lower deforestation rates
Isolation eg in places that are inacessable
global warming
Rising population plus resource consumption add greenhouse gases to the atmosphere which causes Climate change
Effects of’ Global Warming TF
Plants flowering earlier
Birds migration patterns are changing
The Arctic tundra is warming rapidly
Vegetation zones are shifting towards the Poles by 6km every year
How droughts put the forest ecosystem under stress
during the leaf litter so decomposer organisms causing leaves in the canopy to die, reducing the food supply and affecting food webs
what is making droughts more common and severe
deforestation
-with less trees, there is less evaporation and transpiration meaning less clouds and less rain
Fear with droughts
Is that they will become more common and rainforests will suffer permanent damage and die back
as this happens they could become sources of carbon dioxide , not carbon dioxide sinks, accelerating global warming and forest fires even more and some think that 60 percent of th Amazon could become a tiny savanna
Why is deforestation of Taiga less problematic than that of rainforest?
Biome is very vast, in spite of Canadian and Russian deforestation, only 8 percent of intact taiga has been lost
- Much of taiga is isolated and out of. sight in the frozen northern latitudes
- Few ‘cute’ and cuddly’ species under threat that people get excited about
how forest fires are a problem in (cold and wet) taiga
summers can be hot and dry
thick carpet of pine needle litter helps start a fire
summer storms generate lightning strikes
coniferous trees contain sticky resin which burns easily
Fire is an important and natural part of the taiga ecosystem, how does it allow the forest to regenerate itself?
Aspen and birch tree sprout from burned stumps
Black spruce, pine cones open when burned, releasing seeds
how too much fire will cause long-term reduction in biodiversity
forests will not regenerate properly as trees will not mature between fires
fire tolerant species begin to dominate, reducing biodiversity
Trees that cannot tolerate fire decline and so do the birds and insects that feed on them
three consequences of pests and diseases
they reduce commercial value of forest, preventing it being sold as timber
They drastically alter the ecosystem - killing
tree species alters food web
They change the landscape from dense forest to a more open landscape with fewer trees
> Biodiversity is reduced because only forest trees that can resist pests and diseases grow in this area
Spruce bark beetle - for taiga I think
2.5 hectares of spruce in taiga have been destroyed due to them
large storms due to global warming make them fly off and infect new areas
Warmer winters - global warming - stop many of them dying in the winter
White pine blister rust - for taiga i think
A fungal disease attacking white pine trees invasive species (from Europe to North America) Once economically important tree for commercial logging in Canada but blister rust devastated the trees and prevented them from regrowing
Formation of acid rain
Fossil fuels are burnt, releasing sulphur dioxide and nitrogen dioxide into the air
These react with water in clouds to form sulphuric and nitric acids
Precipitation carries these acids down to surface
Effects of acid rain
- makes lakes so acidic that fish and aquatic plants die
- weakens trees
- damages needles (especially spruce) and their ability to photosynthesize
- Damage to tree roots as aluminium compounds released when soil becomes too acidic
- damaged soil contains less essential plants nutrients (eg less calcium and magnesium)
- Weaker roots cannot take up nutrients
- Weak trees are more vulnerable to disease and insect attack
> biodiversity is reduced as forests become stressed
> some trees ide, reducing food availability for other species
> plants that tolerate acidic soil are reduced
what is CITES (Convention on International Trade in Endangered Species of wILD fAUNA AND flora)
is an international agreement between governments with the aim to ensure that international trade in specimens of wild animals and plants does not threaten their survival
what is REDD Programme (Reducing Emissions from Deforestation and Forest degradation)
Promotes involvement of all stakeholders (companies?) including indigenous people and other forest - dependent communities, in national and international implementation to reduce the rate of deforestation and replant forest areas.
