global biogeographical patterns Flashcards
what are the three earth realms
atmos
lithos
hydros
what is biogeography?
Biogeography is the study (identification, explanation, analysis) of the distribution of living organisms in space and through time
what questions does biogeo address?
‘How many types of living things are there?’
‘Where are these living organisms found?’ ‘
Are there clear patterns of distribution?’
‘What factors control such patterns?’
‘How have these patterns changed over time?’
‘How do people affect organisms and their distribution patterns?’
define limiting factor
factors in the environment which control, or limit, the abundance of a particular organism or group
what are the four types of limiting factors?
climate = temp, moisture, humidity, wind, light, shade
soil = nutrients, salinity, pH, texture, physical space
other organisms = predation, grazing, food availability, competition
humans = land use trans, into of aliens, pollutions, mis-management
why is climate the master factor?
temp and moisture
- Climate factors can control or influence the distribution of organisms – especially clear at the global scale
temperature as a limiting factor
- endothermic reactions (metabolic reactions for ex) rate doubles with every 10 degree increase in temp
- there is a threshold - 50 degrees - metabolism is impossible and 0 degrees
- organisms are classified based on ability to maintain body temps
- photosynthesis is an endothermic reaction - temp strongly influences bio productivity
what are endotherms
produce their own body heat
what are ectotherms
acquire heat from environ
what are homeotherms
maintain a constant body temp
poikilotherms
body temp adjusts based on temp of environ
photosynthesis equation
6CO2 + 6H20 - C6H12O6 + 6O2
photosynthesis reaction in words
carbon dioxide +water = gluscose + oxgen
most obvious example of importance of temp thresholds determining the distribution
existence in the northern hemisphere of the so called arctic tree line
cooler conditions - tree growth is retarded and only small shrubs and herbs thrive
explain how moisture may be a limiting factor
protoplasm - 95% h2o - water is an obvios and highly potent biogeog factor
- Moisture availability very dependent on precipitation inputs (and evaporation outputs) - highly variable in space and time.
Organisms are classified according to their adaptations to water availability: e.g. hydrophytes, mesophytes, xerophytes, halophytes.
define protoplasm
he colourless material comprising the living part of a cell, including the cytoplasm, nucleus, and other organelles.
list the categories of plants in order of moisture requirement
xerophyte
mesophyte
hydrophyte
what is a halophyte
plant adapted to growing in saline conditions
what is a biome
a grouping of terrestrial ecosystems on a given continent that are similar in vegetation type and structure, in their associated animal communities and in their physical environmental characteristics
what is a bio-climatic zone
concept that summarises large-scale vegetation formations and at the same time recognise associated physical environmental characteristics – a holistic or integrating concept.
what is considered to be the dominant environmental determinant
climate
what are the defining factors of a biome
- Large-scale terrestrial ecosystems identified at the global, continental/sub-continental scale.
- scale ; 1: 10 000 000
- named after the dominant vegetation
- Predominant environmental determinant is climate (therefore geology, soils etc. have local importance but not at the global or continental scale).
- natural
- plants and animals have adapted to that environ challenges of that biomes
where is the tundra
in the high north of the world
explain the physical constraints of life in a cold climate
- low temps
- limited day length
- low solar radiation input
- low moisture
- permanently frozen subsoil
- active layer in summer - solifluction mass wasting
describe the tundra
Treeless ‘tundra’ (northern European word) region occupies 25 million km2 at high latitudes – almost all in the northern hemisphere. High altitude equivalent in the tropics (e.g. South American Andes)
further constraints of living i the tundra
poor drainage
patterned ground produced by frost heaving
solifulction: lobes and terrraces
life in cold climates - desctribe the biogeog responses of plants
- impoverished- few species can survive the environ
- structurally simple plants
- Characteristic plants are small herbs and shrubs which sprout from underground each year (perennial): often dwarf and with cushion form (provides protection against desiccating wind and maximises opportunity to be snow-covered in winter).
- Few plants with ‘annual’ (as opposed to perennial) life cycle
life in cold climates - desctribe the biogeog responses of animals
- low diversity
- hibernation
- thick furs or fat
- unique camouflage
one massive impact of humans on tudra
permafrost thaw
explain the physical conditions of life in a cold climate
- consistently warm
- aseasonal precip
- ideal
constraints of a tropical climate
- high daily temp
- temporary moisture stress
- competition from pathogens
- leaches soild
- nutrient poor soils
- only a thin layer of rich soil
where do these tropical environs occur?
Tropical vegetation formations occur between Cancer and Capricorn; i.e. approx 15-20 degrees either side of equator. 17 million km2
if the soils are so poor why is rain forest so productive
- efficient nutrient cycle
- ## addition of exogenus nutrients - dust
life in tropical climates - desctribe the biogeog responses
- highly productive
- high diversity
- complex stratified structure
- evergreen
Leathery, waxy, dark green leaves with ‘drip tips’, giant leaves
describe the complex stratified structure of the tundra
emergents
canopy
ground layer
how is stability of large trees maintained
- buttress roots
- stilt roots
major human impact
deforestation
what are the physical constraints of life in african arid climates
- dry and highly variable
- precip is intense and short and therefore doesnt seep into soil
- Climate in hot deserts: high temperatures and also associated with high diurnal and annual temperature ranges, low cloud cover, low humidity and windiness (therefore high potential evaporation).
- Substrates often sandy or rocky.
life in arid climates - desctribe the biogeog responses
- limited biodiversity
- special adaptations required
name and explain the different types of plant adaptations and give an example
- drought escaping- annuals- only grow when moisture available - namaqaland daisies
- drought enduring - perennial and evergreen with deep roots - welwitschia mirabilis
- drought evading - perennial, dormant during drought, loose leaves, Karoo bushes
- drought resisting - perennials, succulents that store water or have specialised photosynthesis - plants that use CAM
what does CAM stand for
crassulacean acid metabolism
explain crassulacean acid metabolism
stomata are open in cooler and more humid night-time hours, permitting the uptake of CO2 to be fixed and stored as a four-carbon acid (i.e. malate) so that during the hotter and drier day-time hours the CO2 is released providing the enzyme rubisco with high concentration of CO2 while the stomata are closed to reduce water loss through evapotranspiration.
human impact on arid zone
desertification - land degradation in arid zone
where is the fynbos biome
A ‘mediterranean-type’ climate dominated by summer drought. Mean annual rainfall 250 to 2000 mm - dependent largely on altitude.
physical constraints of the fynbos biome
Soils are shallow, nutrient-poor and are acidic (i.e. infertile) because underlying geology (especially on hard, quartzitic TMG sandstones)
plant communities of the fynbos biome
- true’ fynbos (heathland) e.g. mountain fynbos (characterised by proteas, ericas and restios)
- non-fynbos’ communities, e.g. renosterveld and afromontane forest.
- amazing diversity
major determining factor of the types of vegetation
underlying geology and rainfall
vegetation on malmes shale and granite
renosterveld
veg on TMG sandstones
mountain fynbos
veg on sandy flats
acid sandy plane fynbos
veg on calcareous dunes
dune fynbos/strandveld
proteaceae details
proteaceae:
- silver tree
- suikerbossie
- protea
- mimetes
- leucospermum
- Serruria florida
the other fynbos plant
erica
restios
renoster bos
afromontane forest
two things that fynbos is adapted to
environ
fire
describe fynbos adaptation to environ
- nutrient-poor, shallow soils
- summer aridity and windiness
- fire (frequency, timing, intensity)
describe adaptations to fire and other methods used for seed dispersal
- fire kills most fynbos plants therefore adaptation is through recruitment of the next generation by seed dispersal, germination and seedling establishment
- seed (often canopy-stored) released by fire - serotiny)
- seed dispersal by ants and rodents (myrmecochory)
- other adaptations include fire survival by ‘resprouting’
- geophytes with bulbs/rhizomes
fynbos adaptations for summer aridity
Leaf (foliar) adaptations
- designed to reduce transpirational moisture loss through stomata
- reduced leaf area
- stomata protected or ‘buried’
- folded leaf structure
human influence on fynbos biome
- agriculture
- commercial forestry in mountain catchments
- alien vegetation - austrailian species
- urbaisation
- conservation
name the major culprits of alien invasion
Rooikranz port jackson willow black wattle silky hakea pine
