4. Terrestrial Biomes Flashcards
Define biome
Major divisions of land environment based on specific climate with common plant species. They usually evolve and boundaries can be subjective.
Define terrestrial biome
Large terrestrial regions on our planet with a similar climate and vegetation.
What distorts biome distribution away from the latitudinal arrangement of climate cells?
Tall mountain ranges (mountain shadows) and uneven distribution of wanted and land mass
What are terrestrial biomes defined by?
•Geography (latitudes/climate cells)
•Mean annual temperature (MAT)
•Mean annual precipitation (MAP)
•Predominant vegetation (food & habitat for the rest of the ecosystem)
What is a Walter Lieth diagram?
A chart displaying monthly mean average temperature and precipitation and their relative values. Provides information about a biomes seasonality, climate properties, and periods of drought
What absolute values are in a Walter Lieth diagram?
•Monthly/annual mean temperatures
•Monthly/annual mean precipitation
•How much of the year is frost free
•Variability of temperature and precipitation throughout the year
•Locality’s elevation above sea level
•Sum of annual precipitation
What relative information is in a Walter Lieth diagram?
•When periods of drought/excessive rain occur
What relationship between monthly precipitation and monthly average temperature indicates a drought and lack thereof respectively?
Drought: temperature >2× precipitation
Lack of drought: temperature <2× precipitation
Describe the biome characteristics of a tropical rainforest
•High annual & monthly mean temperatures
•High mean annual precipitation
•Low seasonality
Biomass-rich, evergreen forest vegetation.
Describe the biome characteristics of a desert
•Low or high mean annual temperature
•Very low mean annual precipitation
•Strong to moderate seasonality
•Sparse, short-stature, treeless vegetation
Describe the biome characteristics of a temperate grassland
•Low annual temperature
•Low annual precipitation
•Strong seasonality in temperature
•Tree-less vegetation, grasses and shrubs
•Very fertile soil (agriculture)
Describe the biome characteristics of a temperate forest
•Moderate annual temperature
•High annual precipitation
•Moderate seasonality in temperature
•Forest vegetation (deciduous & broadleaf or coniferous)
Describe the biome characteristics of a boreal forest
•Very low annual temperature
•Moderate annual precipitation
•Strong seasonality in temperature
•Coniferous forest vegetation
•Extensive wetland and peatland vegetation
Describe the biome characteristics of a tundra
•Very low annual temperature
•Moderate annual precipitation
•Moderate seasonality in temperature and precipitation
•Low shrub/grass vegetation, tree-less, permafrost
What is a Whittaker diagram?
A chart that displays biomes as a function of mean annual precipitation and mean annual temperature
Shows the MAT and MAP range for each biome
Why do desert biomes have such a wide range of temperature conditions?
Because of the existence of hot and cold deserts
What is a hot desert?
•Caused by the hot, dry air of Hadley cells
•Warm all year
What is a cold desert?
•Dry because of the rain shadow effect and continentality
•Found along higher latitudes
What is soil?
A complex mixture of organic and inorganic material. Most terrestrial life depends on it
How is soil formed?
Weathering
•Mechanical: breakdown of rock into smaller particles from water, wind, and plants
•Chemical: processes such as solution, hydrolysis, and oxidation
What are the 5 soil horizons?
O- organic
A- surface
B- subsoil
C- substratum
R- bedrock
What comprises the organic horizon of soil?
Accumulated organic material, especially decomposed plant and animal material. Dense roots
What comprises the surface horison of soil?
Well weathered fertile layer containing mineral and organic content. Mostly humidified organic content. Roots reach into the layer
What comprises the subsoil horizon of soil?
Mostly mineral material from upper layers, clay, iron, aluminum oxides deposited by water
What comprises the bedrock horison of soil?
Unweathered bedrock that will eventually become the rest of the soil
What are the 3 sublayers of the organic horizon of soil?
L- litter horizon
F- fermentation horizon
H- humic horizon
What comprises the litter horizon?
Plant elements with little to no decomposition
What comprises the fermentation horizon?
Moderately decomposed but still identifiable plant matter
What comprises the humic horizon?
Well humidified material decomposed by water. Plant material is difficult to identify
What influences the depth of soil? What is significant about deeper soil?
•Slope
•Weathering
•Parent materials
•Vegetation
Roots can penetrate deeper and the soil can hold more water/minerals
What do soil organisms do?
•Form soil structure
•Regulate soil moisture
•Perform gas exchange & carbon sequestration
•Nutrient cycling
•Decompose dead matter
•Control plant growth
