Different biomes, lecture 32 Flashcards
Types of tropical forests
3
tropical rainforest
subtropical forest
monsoon forest
Why are there several types of forest in the tropics?
varying climate
Effects of varying climate on types of forest biomes in the tropics
seasonality
diversity - species and structure
Climatic aspects of tropical rainforest
high and constant temp. and humidity
Seasonality of tropical rainforest
not very seasonal
so
dry and wet season - last roughly 6 months each
Flora characteristics of tropical rainforest
- tall tress with buttress bases
- 2 understory levels typically smaller trees
- shrub and herb layers not well developed
- epiphytes and lianas (vines) are common and climb trees for light access
- high tree species diversity
In a tropical forest biome are plants evergreen or deciduous?
how does this affect leaf loss
nearly all are evergreen,
therefore leaf loss is at irregular intervals and not connected to climatic fluctuations
Subtropical forest biome
Humid tropical areas characterised by a moderate difference between summer and winter.
Seasonality in subtropical forest biome
a wet-dry type rather than hot-cold type
Subtropical forest biome distribution
outside the equatorial zone but are within or border the tropical zone
Stratification of sub tropical forest compared rainforests
simpler stratification in subtropical, only one understory layer
In a subtropical forest biome are plants evergreen or deciduous?
how does this affect leaf loss
plants tend to be evergreen,
but
may lose their leaves during dry season
Monsoon forest biome
Occurs in regions in the tropics, whose total annual rainfall is high (higher than tropical forest)
Seasonality in monsoon forest biome
pronounced wet and dry periods,
inc. the monsoon
Stratification of monsoon forests
simple,
single understory tree layer
In a monsoon forest biome are plants evergreen or deciduous?
canopy is deciduous
understory is evergreen
Temperate rainforest
Located between the poles and the tropics, in the temperate region, the coldest of the rainforests.
Seasonality of the temperate rainforest biome
definite seasonality in temp. and rainfall
Rainfall in temperate rainforest biome
high rainfall but very heavy fog which is possibly a more important water source for vegetation
Species diversity of temperate rainforests
lower than other rainforests but higher than other temperate forests
Temperate rainforest biome canopies
canopies include tallest trees in the world such as the sequoia family (giant redwoods)
Tropical savanna
intermediate between forest and grassland found in the tropics
Rainfall in the tropical savanna
very non-uniform
Vegetation/ fauna in the tropical savanna
- small trees are present but sparsely distributed, no continuous canopy
- Grasses are most common plants and may reach 2m
Some tropical savanna’s have the same climatic regimes as forests, why are savanna’s found?
- Fire and grazing of animals is widespread
- This gives grasses competitive advantage over tree species and maintains the savanna biome
Deserts (desert shrub)
Desert biomes exist in the driest environments
Desert biome climate
- temperature range across different deserts from very hot to very cold
- dry
Desert biome vegetation
- Shrubs and cacti, well adapted to conserving water
- Rapidly growing annuals, entire life cycle on water from one rainy spell
Variety in the desert biome
great variety as found in both subtropical areas and arctic
Mediterranean woodland and shrubland
climate
warm, dry summers and cold, moist winters
Where is the Mediterranean woodland and shrubland found
Europe, California, Australasia
Vegetation/ flora in the Mediterranean woodland and shrubland
- Low evergreen trees/ tall shrubs (3-4m high) with small hard needles or slightly broader leaves
- Matorral (chaparral, maquis) results form degradation of evergreen woodland
Species diversity in the Mediterranean woodland and shrubland biome
Species diversity lower than temperate deciduous forest and higher than dryer grassland
What is an important factor in the Mediterranean woodland and shrubland biome
fire
How are plants adapted to fire in the Mediterranean woodland and shrubland biome
regeneration
Temperate grasslands seasonality
Seasonality is pronounced for temperature and rainfall, rainfall concentrated in summer
Temperate grasslands stratification and species diversity
Stratification reduced to single story, but species diversity may be high as a deciduous forest
Vegetation/ flora in temperate grasslands
- Trees form ‘gallery forests’ - strip close to stream
- Two basic groups of grasses:
Moister areas - tall grasses over 1m
Drier regions - short grasses <1m
How are the grasses in temperate grassland maintained?
grazing
Seasonality and rainfall in the temperate deciduous forest biome
Seasonality is extremely well marked, hot-cold type
Precipitation can be uniform throughout the year
Stratification in the temperate deciduous forest biome
Tree canopy is diverse but dominated by two or three species
Understory tree layer patchy but quite well developed
Flora other than trees in the temperate deciduous forest
- Shrubs are common and species diverse
- Often two separate herb assemblage:
Spring flowers, bloom before trees come into leaf and gone by summer
Plants adapted to low light levels of forest floor and last until autumn
Boreal coniferous forest
Found only in the northern hemisphere, a forest made up of coniferous trees
Climate for the boreal coniferous forest
Cold regions with high rainfall and strongly seasonal climates - long winters, fairly short summers
Species diversity for the boreal coniferous forest
low (as not many species can survive) and pure stands of trees and shrubs common
Stratification in the boreal coniferous forest
Understory tree uncommon, but the shrubs layer rich and mosses and lichens
Productivity and resilience of the boreal coniferous forest
- Productivity and community stability lower than in any other forest biome
- Sensitive to pests, low resilience of the systems a result of climate
Tundra
The coldest biome which mostly found north of the arctic circle (arctic tundra) or above where trees grow in the mountainous regions (alpine tundra)
Tundra soil
Very cold ecosystems - water permanently frozen in subsoil - permafrost
Flora in the tundra
Plant adapted to very short growing season and extreme cold
Trees are absent except near rivers
Where permafrost melted deeply: scrub and heath
Mostly just a herb layer, grasses and sedges
Lichens cover exposed rocks
Species diversity and vulnerability in the tundra
Diversity is very low, as are growth rates, thus community is extremely vulnerable/ fragile
Aquatic biomes are less subject to .. than terrestrial biomes
climate
Freshwater aquatic biomes classified by
(<1% salt concentration)
Rivers
Lakes
Estuaries
Marine biomes classified by
(>1% salt concentration)
Difference in depth and light availability:
- Intertidal zones
- Coral reefs
- Oceanic pelagic
- Abyssal zones (no light)
Marine biome covers how much of the Earth’s surface
75%
