Paper 3 Flashcards
Ecosystem
All of the living things in a given area, interacting with each other and with their non living environments
Biome
A very large ecosystem. (The rainforests are one biome, deserts are another)
Biosphere
The biosphere is made up of the parts of the earth where life exists. The biosphere extends from the deepest root systems of trees,to the dark environment of ocean trenches
What are the factors affecting biomes?
Temperature
Precipitation
Altitude
Geology
Prevailing winds
Latitude
Relief rainfall
How does temperature affect biomes?
Near the equator, sunlight is more intense and therefore warmer
Near the equator the sun rays are at high angle in the sky all year round
Latitude increases toward poles, winters are longer and colder, climate is more seasonal
Polar areas, sunshine intensity is low lack of heat and light limits plant growth
How does precipitation affect a biome?
Earth can be divided into high and low air pressure precipitation zones
Precipitation is high at the rising parts of these cells because air pressure is low
Descending parts of cells- air pressure is high but precipitation is low
How does altitude affect a biome?
Height affects biomes in three ways:
Temperature drops by 6.5C for every 1000m increase
At high altitudes, below freezing temperatures are common, limits types of plants that grow
Rainfall usually increases with height
How does geology affect a biome?
Rocks undergo chemical weathering
Soil contains all the nutrients needed by plants to survive
In areas where the geology creates dry soil conditions percolating rainwater passes through relatively easily
Many different bacteria, algae and fungi do important jobs that make life possible
How does prevailing winds affect a biome?
Other major biomes are controlled not so much by temperature but by the amount and seasonal distribution of rainfall.
The drier lands found further inland are said to be in a rain shadow
Inland areas isolated from the sea suffer from low rainfall because winds blowing off the oceans quickly lose moisture, especially if the air passes over high mountains
How does relief rainfall affect a biome
Warm moist air from the prevailing wind rising
Local factors
Differences that alter animal and plant species in a biome, from one we would expect
Examples of local factors
Rock and soil type
Water availability and drainage
Altitude
Biotic
Living part is made up of plant (flora) and animal (fauna)
Abiotic
Non living part includes the atmosphere, water, rock and soil
Role of ecosystems?
The role of ecosystems in maintaining a healthy atmosphere is globally important
Slash and burn farming?
Used by 500 million worldwide
Farmers clear small areas of forest by cutting then burning
Ash from burning adds nutrients to the soil
Land is farmed for 5-6 years, after the soil becomes infertile and farmers move to a new area
Ecosystem services for indigenous people?
Efe people of ituri tropical rainforest (30 000 people)
Move around so have small temporary homes
Wood for cooking fires comes from forest
Hunt animal
Gather food from forest
Sell extra meat then trade/ but items
Plants and wild honey to make traditional medicines
Carbon sink?
Natural stores for carbon containing chemical compounds like carbon dioxide or methane.
Where is carbon stored in the biosphere
Biomes store carbon as biomass
When plants and animals die the dead biomass ends up in the soil
How could more carbon end up in the atmosphere
Humans destroy biomes
How can the nutrient cycle be put at risk?
Removing biomass
Heavy rain and surface run off can wash away litter
Deforested areas are at risk from soil erosion removing another store
Geometric growth
Doubling in each generation
How does the growth of food production differ? (M)
Food production will only increase arithmetically
What is the outcome of this population/ resource growth? (M)
Population would eventually outstrip food supply
