biomes and global climate (terrestrial lecture 6) Flashcards
What is climatic zonation of biomes?
Alexander von Humboldt, 1806:
Areas with similar climates across the world also support vegetation with similar life forms
- biomes are associated w climate
Why does climate cool with altitude (orographic effects)?
Temperature:
- pressure decreases at higher elevation
- adiabatic cooling
Rainfall:
- moist air cools with elevation
- condensation, rain, rainshadow
Why does climate cool as latitude increases?
The sun’s rays are less direct on the Earth’s axes, more direct at equator. At high latitudes the same amount of rays are spread over a wider area
Why does rainfall vary globally?
- global air & ocean circulation patterns
- orographic effects
- land-sea temperature differences
Biome characteristics:
- tropical rainforest
tropical rainforest:
- hot & wet year round
- mean annual temp over 25C
- mean precipitation over 100mm/month
- evergreen broadleaf trees
How are biome distribution and climate related?
- biome distributions are determined by climate but boundaries are unclear
- there is considerable overlap b/w climate space and biomes across different continents, but there are also differences: environmental history, evolutionary history of floras
Biome characteristics:
- mediterranean
mediterranean:
- hot dry summer
- warm, wet winter
- evergreen broadleaf shrubs
Biome characteristics:
- savannah
savannah:
- hot summer
- winter dry season
- maintained by fire/herbivores but not climate
- broadleaf trees (evergreen/drought deciduous)
- C4 grasses
Biome characteristics:
- temperate forest
temperate forest:
- warm summer, cold winter
- cold deciduous broadleaf trees
Biome characteristics:
- boreal forest
boreal forest:
- warm summer, v v v cold winter
- needleleaf evergreen trees/winter deciduous needleleaf trees
Biome characteristics:
- tundra
- cool summer, v v v cold winter
- no trees
- shrubs/grasses/sedges
