What is an ecosystem?
A large, relatively distinct region characterised by similar climatic conditions and plants.
What is a biome?
A series of similar, but unconnected ecosystems examined across the globe.
What is climate?
Weather conditions over a long period of time.
What are the main determinants of vegetation type and why?
Temperature and moisture, because they affect photosynthesis.
Name two Tundra climates you know of…
Arctic and Alpine
What distinguishes an arctic tundra?
-extreme northern latitudes wherever snow melts seasonally - encircles the North Pole
-Only in Northern hemisphere
Permafrost
- Limits depth of root penetration (woody species)
little organic matter in soil
- Low temps
- Flat topography
- Bogs, ponds and low lakes in summer
Species characterised by low species richness and low growth rates
What distinguishes an alpine tundra?
Similar to artic, but
No permafrost
More rain and wind that artic
Regenerates very slowly after disturbance
What are the grasslands you know of? What separates them?
Tropical (Savannah)
Temperate
Temp
What distinguishes grassland?
Average rainfall allows only grass to grow
rainfall low/erractic
fire or drought prevents larger plants from growing
What distinguishes tropical grassland?
Scattered shrubs and stunted trees
- Year round high temps
- Low percipitation, dry and rainy periods
- Fire during dry season
- animals migrate
- plants have fire adapted features
What distinguishes temperate grassland?
-Summers are hot, sry and have occasional drought and fires
-Winters are cold, rainfall uncertain (grass dies off)
-High winds, evaporation is rapid
-Soil held together with mats of roots
- Often ploughed
Overgrazing and mismanagement has led to desert
What distinguishes a desert?
Deserts are dry areas - found both in temperate (cold deserts) and tropical regions (warm deserts)
- Cover 30% of the Earths land
• low rainfall main reason for deserts
• Generally receive < 25 cm rain per year
• Very fragile environment, slow regrowth
• evaporation is rapid
Low water vapour results in daily temperature extremes of heat and cold
Occur where dry air which has lost its moisture over the tropics drops back to earth
- Or in the middle of continents
What distinguishes a tropical desert?
- commonly next to no life
- Few plants
What distinguishes a temperate desert?
-Temperatures hot in summer cold in winter
Plants have evolved strats to capture and conserve water - waxy covering (cut downs evap rate), deep roots, reduced leaves
What adaptations and behaviours do desert animals have to survive?
Escape heat in barrows
Have adaptations to conserver water
Reptiles have thick outer coverings
Minimise water loss
Some become dormant during extreme heat and drought
What distinguishes a forest?
-Areas with moderate to hill rainfall usually cover with forest
- Smaller form of vegetation and various species of trees
Dependent on climate(temp)
What distinguishes a tropical forest?
Found near equator where hot air rises and drops moistures
Has warm annual mean temp
Humid, heavy rainfall daily
Evergreen - etremely high growth
Number and name the layers of a tropical forest…
- emergent layer
- canopy
- Understory
- Shrub
- Ground layer
What sort of niches are found in tropical forests?
Narrow/specialised
What kind of pollination must be used in tropical forests? Why?
Little Wind, therefore wind pollination impossible
-plants develop folowers that attract particular insects, birds, or bats
Deciduous forests are distinguished by….
Moderate average temps that change significalantly during four seasons
Survive winter by dropping leaves
Few species than tropical forests
- More ground plants
Range of niches for animal life with more ground species and less specialised
Name the layers of a deciduous forest…
- Canopy, partly open
- Understory of shorter shade tolerant plants
Forest floor with ferns, mosses and low growing plants
- Understory of shorter shade tolerant plants
What distinguishes an evergreen forest?
- Less common
- Occcur with ample rainfall or moisture
Mild temps
- Occcur with ample rainfall or moisture
Name the layers of an evergreen forest…
- Emergent
- 30-50m tall trunks
- Hardwood canopy
- 20m Flowering trees, broad leaves
- Subcanopy
- 10-15m Wide assort of small and large trees
- Shrub
- Most carry defence against browsing
- Floor
Moist, dark
What distinguishes a mangrove forest?
Grows in costal ecosystems
Define a swamp…
Swamplike
What is the fate of swamp?
- Can’t survive after germination due to drainage/dryland plants
- Other species invading due to drainage
Cut down for farmland, housing
- Other species invading due to drainage
What defines a boreal forest
- Only in northern hemispher
- Cold, long, dry short winter days (no permafrost)
- Short summer, mild-warm temps, long days
- Tiny needle shaped, wax covered leaves, able to withstand intense cold and drought of winer
- Evergreen - allows photsynthesis to begin as soon as warm temps return
- Two layers - long canopy and ground layer
- Few species
What are the deficits of a boreal forest?
- Not well suited to agriculture, short growing season
- Forestry
- Acid rain and air pollution
Suceptible because slow growth