Climate and Life on Earth I: The terrestrial biosphere Flashcards
At the global scale, variations in climatic factors, especially temperature and rainfall, determine
the distribution and diversity of the major terrestrial ‘biomes’, alongside their primary
productivity
Describe some of the local conditions and resources that vary within biomes
- topography
- geology
- soil
- influence community patterns and productivity at a smaller scale
- change on a variety of timescales (ecological succession progresses, climate change), tracked by changes in their associated ecological communities.
List some biomes
- ice sheet and polar desert
- tundra
- taiga
- temperate broadleaf forest
- temperate steppe
- subtropical rainforest
- Mediterranean vegetation
- monsoon forest
- arid deser
- xeric shrubland
- dry steppe
- semiarid desert
- grass savanna
- tree savanna
- subtropical and tropical dry forest
- tropical rainforest
- alpine tundra
- montane forests
primary productivity
- the rate at which biomass is produced per unit area/volume through photosynthesis
- measured in a rate of energy production per unit area, or as a mass of carbon or dry organic matter
- paralogue of the extent to which biomes capture carbon from atmosphere
What determines the distribution and characteristics of ecological communities at a global scale?
- climate (temperature)
- precipitation
- biomes
biomes
zones dominated by plants with characteristic shapes, forms and physiological processes
Describe the Whittaker Biome Classification
distribution of terrestrial biomes can be explained largely by temperature and rainfall
Give some Mediterranean biomes
- “Garrigue”, S. France
- “Chapparal”, California
- “Fynbos”, South Africa
Describe the meso-scale changes with elevation (and aspect)
- civilisation up to 1800m and 35 degrees
- rainforest up to 3000m and 25 degrees
- moorlands up to 4000m and 20 degrees
- alpine desert up to 5000m and 15 degrees
- eternal ice above 5000m and up to -25 degrees
- e.g. Mt. Kilimanjaro, Tanzania
Categorise civilisation
- villages
- agriculture
- livestock breeding
- plantations
Categorise rainforest
- dense vegetation
- frequent rainfall
Categorise moorland
- grasslands
- upland moors
Categorise alpine deser
- stone
- lava desert
Categorise eternal ice
- ice
- glacier
Ecosystems depend upon
the energy that is being harvested by plants, algae, and other primary producers
Gross primary productivity (GPP)
- total fixation of energy by photosynthesis
- some GPP will be respired by autotroph, and lost from the ecosystem as respiratory heat
Net primary productivity (NPP)
- energy fixed by photosynthesis not lost to ecosystem as respiratory heat
- all NPP passes through a live consumer system or a decomposer system
secondary productivity
heterotrophs produce biomass
Different biomes have
differing annual NPPs
List some marine NPPs
- trade winds domain (tropical and subtropical): 13.0
- westerly winds domain (temperate): 16.3
- polar domain: 6.4
- coastal domain: 10.7
- salt marshes, estuaries and macrophytes: 1.2
- coral reefs: 0.7
List some terrestrial NPPs
- tropical rainforests: 17.8
- broadleaf deciduous forests: 1.5
- mixed broadleaf and needleleaf forests: 3.1
- needleleaf evergreen forests: 3.1
- needleleaf deciduous forest: 1.4
- savannas: 16.8
- perennial grasslands: 2.4
- broadleaf shrubs with bare soil: 1.0
- tundra: 0.5-0.8
- desert: 8.0
- cultivation: 56.4
Which is the marine biome with the lowest NPP
coral reefs
Which is the marine biome with the highest NPP
Westerly winds domain (temperate)
Which is the terrestrial biome with the lowest NPP
tundra
Which is the terrestrial biome with the highest NPP
cultivation, the tropical rainforests
Give a measure of the human domination of the biosphere
appropriation of NPP
Describe human appropriation of potential NPP
- 23.8%
- 53% from harvesting
- 40% by land-use-induced productivity changes
- 7% by human-induced fires
In terrestrial systems, NPP is primarily limited by:
- intensity of solar radiation received
- availability of water
- temperature
- availability of nutrients
Different regions of the planet receive
different amounts of solar radiation
Give some regions of the planet
- artic circle
- tropic of Cancer
- equator
- tropic of Capricorn
- antarctic circle
Plants living in different regions have
- differing degrees of efficiency in using solar radiation
- other resources (water) cause these efficiencies
Precipitation levels in a region
- affect NPP
- e.g. tallgrass prairie
ANPP
above-ground NPP
Water use will be affected by
temperature
Describe the correlation between precipitation (mm) and ANPP (gm-2)
- strong linear correlation
- y = 0.38x + 176.83
- P = 0.0003 (significant)
- r^2 = 0.62
Describe the effects of increasing temperature
- photosynthesis
- increases rate of evaporation
- increases rate of decomposition (releases nutrients)
Productivity is only possible when
plants are able to photosynthesise
Describe the relationship between maximum ecosystem GPP (%) and day of the year in temperature, coniferous and boreal systems
normally distributed
Which nutrients are usually limiting?
phosphorus and nitrogen
What is a plant called if it is limited by both phosphorus and nitrogen
co-limited
Describe the fate of primary producers
energy and nutrients captured is then consumed by heterotrophs
Describe a trophic pyramid
- sun’s energy captured by primary producers
- herbivorous consumers
- 1st level carnivorous consumers
- 2nd level carnivorous consumers
- 3rd level carnivorous consumers
- apex carnivores
- heat energy lost at each stage
- matter decomposed at each stage
List some primary producers
phytoplankton, seaweed
List some herbivorous consumers
zooplankton, cockles
List some 1st level carnivorous consumers
- juvenile stages of fish and jellyfish
- small fish, crustaceans and sea stars
List some 2nd level carnivorous consumers
larger fish
List some 3rd level carnivorous consumers
squid
List some top carnivores
shark, dolphin, albatross
Climate plays a major role in determining
how different sorts of ecological communities are distributed across the globe
