Chapter 4 - Climate and the world's biomes (CHAPTER + SLIDES) Flashcards
slides notes are included!!
The world’s climate
the earth’s surface would still be different even if the climate is the same all over
- the geography of the earths life is due to the climate
What controlls the climate?
Differential heating by sunlight AND the interaction of the atmosphere with the oceans & mountain ranges
=> the ridistribution of heat is done through aatmospheric movement.
Spinning of the earth impact on air motion
Coriolis effect: winds tend to go east and west
Rising and falling of air masses cause precipitation
Seasonality by the earths’s tilt is a complication within the model
Large scale climatic patterns are influenced by
1) Indecent sunlight at different latitudes
2) Atmospheric circulation
3) Ocean currents
4) Land topography.
Rain shadows
Mountain ranges
- side hit by winds, cool down and then precipitate
- whereas the downwind side has dry air and so deserts form
Ocean currents redistribute heat
- The cold water becomes hot and then recircles
- it is driven by the wind and affected by the coriolis effect
- the ocean density plays a role in the pattern and the current strength of the heat redistirbution
Biomes
Characteristic regions with particular types of vegetation
Biomes are areas dominated by plants with characteristic shapes, forms and phyisology
There is a mosaic of bioms
Tropical rain forest
Most diverse in resources
- covers 12% of the earth
- covers 50% of all terrestrial biomass
- has a high rate of primary production (800g of carbon dioxide fixed per square metre per year)
- high solar radiation (therefore the seeds only sproud after the canopy forms above them)
- Dramatically high species richness with not many single dominating species in communities
Tropical canopy
All action happens in the canopy
- plant forms that reach up to the canopy vicarously by tree climbing
Epiphytes
plants that grow on other plants
Species richness
the number of species
Tropical rain forests during the ice age
- the drought caused them to become ‘islands’ in a ‘sea’ of just savanna.
- this lead to lots of genetic isolation and so speciateion occured.
- the ice would retreat and then come back
- this generated a lot of YUMMY diversity for herbivores and plants
Flower diversity in tropical rain forests
Is equivalent to the polliantor diveristy
- has intense biological activity in the soil
- soil has lots of nutrients
- the regeneration of the soil can take centuries
Savanna
- warm
- rains reliably only during part of the year
- covers 9% of all land area
- is a grassland with small, scattered trees
- has limited moistures
- has fires and the grazing that lead to not much growth bc no rain
- favors the protective regenerative surfaces of organisms
- theres a seasonal glut and shrotage of food
Temperate grasslands
- natural vegetation over large areas (not antartica)
- has both tall and short grass
- has moderate rainfall, the soilsa re rich
used to be 9% but now its only 5% of land due to agriculture. - large populations of invertebrates
- the majority of this land has been transformed by humans.
Desert
- the rain timing is unpredictable
- covers 10% of the earths surface
- has 2 life styles
- freezing temperatures at night so greates frost tolerance. (therefore drought tolerance = frost tolerance)
- very few perennials grow there
- some small ants and rodents eat seeds
- the birds are nomadic and are driven by the need to find water
Desert oppotuinsitc life style
stiumlated gemination by the unpredictable rian timing.
- therefore those that do germinate grow fast and complete their life cycles after just a few weeks.
Desert long lived sluggish phisiological lifestyle
CAM photosynthesis, thick waxy cuticle, short leaves
- cacti and succulents
Temperate forest
- Varying altitudes
- 8% of terrestrial biosphere, mainly deciduoud
- patchiness is due to the tree deaths
- red oaks or sugar maple dominate them
- the vegetation provides foods for animals that are seasonal in occurance
- usually rich soils
- sometimes the soils become peat due to acidic waterlogging
- need for ecological succession process to recolonize agricultured lands
Low latitutes (temperate forests)
- full of evergreens
- winters are mild
- frosts and droughts are rare
- there are broad-leaved evergreen trees
Northern limits (temperate forest)
- Deciduous trees
- strong seasons
- short winter days
- six months of freezing temperatures
- deciduous trees, dormant after fall
Boreal Forests (Taiga)
- Coniferous. cold, short growing season
- 8% of land surface
- limitaed tree flora
- evergreen pines, birch, spruce (Further north)
- used to be an ice-sheet during the ice age.
- little vegitation which shows a slow recovery from the ice age
Permafrost
water in the soil frozen and now theres a permanent drought in taigas
Diversity in boreal forests (taiga)
Low diversity
- hence a greater change of pest outbreak
- likely to have a low resistance
- takes a 40 year recovery
- major fires can occur periodically (every 75-100years) which reset the field for ecological succession