From Biomes to Populations Flashcards
What is a biome?
General term embracing each region with its characteristic climate, day length, topography, flora and fauna
Distinct biological communities the have formed in response to a shared physical climate
What two abiotic factors did Robert Whittaker use to classify biomes?
Precipitation (average precipitation)
Temperature (average annual temperature)
Describe a tropical rainforest biome.
No dry season: all months have average precipitation of at least 60 mm
Mean monthly temp: over 10 degrees every month
Poor soils due to high levels of precipitation
High levels of biodiversity
What is a true rainforest?
True rainforests are typically found between 10 degrees North and 10 degrees South of the Equator
What percentage of biotic species are indigenous to rainforests?
40-75%
What percentage of all living plants and animal species live in tropical rainforests?
50%
Why are tropical rainforests among the most threatened biomes globally?
Large-scale habitat fragmentation caused by geological processes, climate change and human actions
Species extinction
What is habitat fragmentation?
Process by which habitat loss results in division of large, continuous habitats into a greater number of smaller patches of lower total area that are isolated from each other by matrix of dissimilar habitats
What does patch isolation (of habitats) reduce?
Population connectivity
Probability of population persistence
How much of the world is boreal forest/ taiga?
World’s largest biome aside from the oceans
29% of world’s forest cover
Describe where boreal forests are found and what they are characterised by.
Found through the high northern latitudes, about 50 degrees N to 70 degrees N
Characterised by coniferous forests: mostly pines, spruces and larches
What are temperatures and seasons like in boreal forests?
Low average temp (only tundra and permanent ice caps are colder)
Sub-Arctic climate: large temperature range between seasons
Long, cold winter: 5-8 months
Short summer: 1-3 months
What are the two major types of boreal forest/ taiga?
Southern: closed canopy forest
Northern: lichen woodland or sparse taiga
Describe Southern boreal forests.
Closed canopy forest
Many closely spaced trees with mossy ground cover
Clearings with shrubs and wildflowers common
Describe Northern boreal forests.
Lichen woodland or sparse taiga
Trees are more spaced and lichen ground cover
Forest cover often stunted in growth form
In North America, ice-pruned and asymmetric with diminished foliage on the windward side
What are temperate deciduous forests?
Dominated by trees that lose their leaves each year
Found in areas with warm moist summers and mild winters
What are the three major areas of temperate deciduous forests in the Northern Hemisphere?
North America: mainly Eastern
East Asia
Europe
Where are some smaller areas of temperate deciduous forests?
Australasia
North America (Western)
Southern South America
What are some typical trees in temperate deciduous forests?
Oak Maple Beech Elm Southern beech
Where is the diversity of tree species higher in temperate deciduous forests?
Where winters are milder
Mountainous regions that provide an array of soil types
Why have humans colonised temperate deciduous forests?
To harvest wood for timber and charcoal
What has been the impact of humans’ use of temperate deciduous forests?
Many forests became fragmented by fields and roads
Introduction of exotic diseases threatening forest trees
Animals like deer expand range and proliferate
Describe what a desert biome is like.
Barren area of landscape where little precipitation occurs
Little precipitation, sometimes none
Living conditions hostile to plant and animal life
Lack of vegetation exposes ground to denudation
What are the three types of desert climates?
Hot: between 30 degrees S and 30 degrees N
Mild: west coasts of continents, near tropical locations
Cold: polar climates
