Lecture 7 CM Flashcards
Desert biome: dominant vegetation type
Many areas sand/ gravel/ rock only
succulent grasses and shrubs
Cactus (Americas)
Euphorbia (Africa, Asia)
Desert biome: vegetation structure
Usually present only in depressions/
above seasonally watered aquifers
Desert biome: soil structure
Poorly formed or absent
Desert biome:climate
Hot summer, cool/freezing winter
Desert biome: Rainfall
<5cm per annum
Desert biome: Net annual productivity
c. 315 Kcal m-2 yr-1 (Average)
Why does desert biome not have a soil structure?
continual and significant aerial movement of sand
What is the fastest expanding biome?
Desert due to climate change and human activity
Where is desert located?
20-40 degrees N and S
Example of a desert biome
Desert scrub of Pinyon Pine and Utah Juniper
Upper Reaches of the Colorado River Basin
Canyonlands National Park
Utah, USA
Dry tropical forest/scrub/savanna: dominant vegetation type
Semi-deciduous trees, sclerophyllous
shrubs and herbs, C4 grasses
Baboab (Adansonia), Australian bush
Dry tropical forest/scrub/savanna: vegetation structure
+/- scattered open canopy <c. 20m tall
<2m tall shrub and herb layer
Dry Tropical Forest/ Scrub/ Savanna: soil structure
Moderate depth, variable fertility
Dry Tropical Forest/ Scrub/ Savanna: Climate
Hot summer, mild winter
Dry Tropical Forest/ Scrub/ Savanna: Rainfall
100-200cm, seasonal*
Dry Tropical Forest/ Scrub/ Savanna: Net annual productivity
c. 7000 Kcal m-2 yr-1 (Average)
The dry tropical forest/scrub/savanna biome is prone to:
Droughts and frequent fires
Dry tropical forest/scrub/savanna biome location
0-30 degrees N and S
Which biome has the most constant change
Dry tropical forests/savanna biome
What results in the continual shifting of forest habitats in what is known as shifting mosaic
Seasonal fires and grazing of herbivores
Which biome has the greatest vertebrate biomass?
Savanna
The vertebrate biomass is supported by?
massive green biomass production on tropical
grasslands after seasonal monsoon rains
Seasonal shifts in monsoon winds trigger
mass herbivore
migrations from dry grasslands to wet grasslands
Carnivores are generally
more territorial and less mobile
- Grasses are much more tolerant of
grazing and fire than forest
Thus forests dominate only where grazing and fire are reduced –
however patterns at any one point in time are liable to change
Tropical rain forest biome: Dominant vegetation type
Evergreen broadleaf trees, highly
species diverse
Tropical rain forest: vegetation structure
main canopy 40-50m, emergent trees
50-70m, vines and epiphytes abundant,
several substories, usually sparse
shrub and herb layers
Tropical rain forest: Soil structure
frequently shallow, infertile
Tropical rain forest: Climate
Hot all year round
Tropical rain forest: Rainfall
> 150cm per annum, continuous
Tropical rain forest: Net annual productivity
c. 9000 Kcal m-2 yr-1 (Average)
Which biome is the most biologically productive?
Tropical rain forest
Tropical rainforest location?
0-20 degrees N and S
The tropical rainforest biome has no growth limitations other than?
physical disturbances e.g. too wet for fire
What biome has a key role in global water and carbon cycles?
Tropical rain forest
The tropical rain forest biome has every kind of life strategy evident, multi species relationships and dependencies are very complex an example of this is:
The Hornbill (a large, widely foraging fruit-eating bird)
* Hornbills eat figs, the seeds germinate in debris of large nest
* Using guano (droppings) for nutrition, fig seedling sends
adventitious roots through canopy to forest floor (30-40m down!).
Roots become woody, a ‘lace curtain’ stem develops around and
ultimately strangles the host tree on which nest has been built.
* Hornbills main food for eagles
* Hunting hornbills for pet trade kills both figs and eagles, and a
key relationship in the rainforest is destroyed
Among plants the tropical rain forest biome has many?
epiphytes (Orchids, Bromeliads)
* and a variety of unusual life strategies (carnivorous pitcher plants like
Nepenthes; strangler figs)
* and an abundance of ground-level monocots (like palms and gingers)
Tropical rain forest biome: Among animals
there are more vertebrate species here than any othe
biome (more than 50% of all species), in particular arboreal mammals and
frogs, and an abundance of bird species.
Tropical rain forest biome: Among insects
there are probably >1,000,000 species of beetles alone,
and every group is similarly diverse (Bugs, wasps, flies etc.)
Tropical rain forest biome: The dominant herbivores are
termites and ants
The mountain zone: High altitude habitats exist in?
Every biome
The mountain zone: The elevational ecological gradient is similar to
the latititudinal climate
gradient, but over a much shorter interval
Individual mountain ranges contain multiple biomes, up to and including
permanent ice-cover
Species endemism is higher in mountain areas because
habitats are very
restricted in area, and usually surrounded by very different vegetation (‘sky
islands’)
Mountain habitats are more susceptible to
disturbance/ destruction and
the effects of climate change compared to lowland areas
Mountain ranges
comprise a series
of sub-biomes at
different altitudes,
for example
the
North American
Rocky Mountains
Mountain sub biomes:
Lower montane zone
Montane zone
Subalpine zone
Alpine zone
Tropical alpine plants such as Espeletina hartwegiana (Andes,
Equador) have a specialised
frost-protection growth form and
are restricted to a narrow distributional range
This ecozone is surrounded by
tropical rainforest (at lower
elevations) and glaciers (at
higher elevations
