Wednesday, March 7, 2012 CC-BY-NC
Post Midterm - Lecture 1 - biomes + anthropogenic biomes

Maintainer: admin


1.1biomes as a function of temp and precipitation

  • saturation Curie - Amt of moisture in the air is a function of temp (cold air can't hold much water)
  • increase of precipitation - increase in biomass
  • moisture is limiting reactant in productivity
  • ecological niche


  • northernmost/southernmost - antarctic is mostly an ice sheet, so we mostly just talk about the north
  • much more tundra in the north than in the south
  • long winters, short growing season
  • winter: mostly dark
  • summer: can get very hot, summer radiation is 80% of montreal radiation - short but intense growing season
  • 10 degree celcius summer isotherm (tree-line). above this latitude, it is unfavorable for trees to grow
  • <250mm precipitaiton annually
  • treeless, mostly grasses, ligands, dwarf woody plants, mosses
  • most vegetation is annual
  • perennial vegation is insulated by snow in the winter (in the snow, temp is around freezing)
  • landscape is very young (as compared with when the glaciers receded)
    • thus, most stuff grows on the rocks
  • animals: insects or rodents. note: animals have to graze on limited material. the only exceptions are animals that get food from the oceans


  • 10 dgree isotherm, but instead of latitude (like arctic), it's elevation
  • Himalayas is largest
  • slope and aspect play important role
  • slope: rook slides, avalanches, regular disturbances kill of plants
  • aspect: which direction are facing (north vs south)
  • plants are self pollinating (don't rely on insects), plants are bulblets - instead of seeds - survive over winter
  • fewer large animals in alpine vs arctic (less water, no access to oceans)


  • just below tundra
  • worlds largest forest biome
  • circumvoyla - same ecosystem all the way around the world
  • spruce, firs, mosses, ligands, lemmings, boles, caribou, moose
  • trees are relatively small, <30m
  • trees: thin+spindly (so ice + snow doesn't break the branches)
  • permafrost in northern taiga - usually 2-3m active soil, then solid ice below that
  • drunken trees - melting permafrost
  • trees are rather young - disturbance factors: fires in summer, insect infestations, ice and snow, limiting area, outgrow itself (roots can only go so far)
  • peatlands - anaerobic respiration, breaking down carbon very slowly. leaves don't break down as quickly -> thus a huge carbon store
  • peatlands - methane production

1.5temperate rainforest

  • rare ecosystem (BC, New zealand)
  • lots of rain
  • dominated by conifers
  • located on oceans, don't have freezing regions
  • confiers are better than deciduous for colder conditions
    • conifers: year round productivity (they don't drop their leaves)
  • epiphytes - grow on trees (like moss on trees)
  • redwoods - CA, tall, old
  • douglas firs - 400 yrs
    • cuz: tall because: lack of disturbance (no ice storms, no fires)


  • mcgill nature reserve
    • one of oldest beech maple forest in region
  • deciduous - take advantage of summer productivity
  • fire - rejuvenation of soil, germination of seeds
  • east to west - gets drier, gets more to open grasslands

1.7temperate grasslands/prairie

  • too dry for trees, still enough moisture for grasslands
  • great plans, parries, the 'step?' in central asia
  • hot in summer, cold in winter
  • defined by grasses: tend to be annual (hars winters), very deep roots (droughts in summer) - very productive soil
  • high abundance in diversity of large mammals (horses, bison, deer, kangaroo)
  • fires: common, important, thunderstorms, returns nutrients to soil

1.8temperate scrubland/chaparral (mediteranean)

  • dry
  • near oceans - hot but moderate
  • vegetation: dense scrub
  • southern cal, Mediterranean, chile, south africa
  • wine country
  • natural vegetation is aromatic (sage, lavender)
  • fire is common, vegetation is < 50 yrs old
  • santa anna winds in socal - massive brushfires
  • citrus, grapes, olives


  • <50 cm a year
  • air is trying to suck out water from every surface
  • extremely dry, can be very hot or very cold (mongolia)
  • hot in day, cold at night
  • 4 causes of aridity
  • 1) high pressure zones (hadley and farell cells)
  • 2) away from oceans, no source of moisture (australian outback), no winds bringing moisture
  • 3) topographic rain shadow (nevada, arizona) - air coming on other side of mountain is dry - all water gets dropped on other side of mountain
  • 4) cold ocean currents (northern chile) - make air very dry (can't hold alotta water)
  • landscape: sand (sahara) or rocky
  • lack water: erosian+disturbance is caused by wind (prevents vegetation)
  • specialized plants to adapt (mesophytes, zerophytes)
  • plants: spines (protection from animals), no leaves, or very thick waxy leaves (prevent evaporation)
  • most animals are nocturnal (less evaporation, to hot during the day)

1.10savanna and seasonal forest

  • distinct with isolated trees
  • 65% africa, 60% of …
  • large Amt of rainfall - extremely seasonal (dry wet seasonality) - really dfines the savanna
  • plants are well adapted to drought (dry hot period), grasses w/deep roots, trees w/waxy leaves
  • grasses dominate due to disturbances (mostly fire)
  • thick bark, thick leaves - resistant to fire
  • grass can grow back from roots after a fire
  • c4 plants, rather than c3 - well adapted to hot temps
  • large animals: antelope, wildebeest, zebra, giraffe, rhinos, cheetahs, lions
  • great migrations - migrate with shifting precipitation with interopical convergence zone

1.11humid tropical forest

  • warm temps, lots of ramie
  • hadley cells meet - intertropical convergence zone
  • most productive ecosystem - not limited by temp or by precipitation
  • multiple layers or ecosystems
  • central america, south america, southeast asia, congo
  • diversity: perhaps due to age, perhaps due to amt of energy
  • 10% of land area, 50-90% of species
  • limiting factor: nutrients - soils are nutrient poor - very old - weathering for ~10s of thousands yrs old - nutrients are leached out by runoff - most of nutrients is almost all in vegetation - high rate of nutrient recycling (if a tree falls, its nutrients gets picked up quickly)
  • lungs of the earth (terrestrial)

2human impact

2.1erle ellis - describing anthropogenic biomes

2.1.1data sets

  • population density, croplands, pastures, irrigation, rices, tree cover -> define anthromes


  • 3 kinds:
  • 1) used (dense settlements, villages, croplands, rangelands)
  • 2) seminatural
  • 3) wild


  • don't have people
  • tundra, deserts, alpine
  • 19% of global tree cover
  • unproductive regions
  • boreal forest - classic example
  • still not pristine (logging, hydro dams/reservoirs, mining, oil+gas (tar sands) : resource extraction


  • populated and remote regions
  • 45% tree cover
  • semiwild
  • new england, USA


  • grazing lands, dry areas
  • residential or populated or remote
  • original vegetation, animals


  • 25% tree cover
  • remote, residential,


  • densely populated but primarily agriculture
  • anthromes: rice, irrigated, pastoral, rained

2.6urban and dense

  • also includes suburban - lawns naturally wouldn't be there

2.7glaol summary

  • 80% population in urban/village
  • land: 23% wildlands, 77% antrhopogenic biomes
  • net primary productivity: 11% wildlands, 89% anthropogenic


  • embeddedness - % of land not used by humans where humans exist
  • intensification - moderate: ecosystem is largely intact, substantial: range lands, new animals, major change: croplands, profound: villages, maximal: urban areas
  • china, nigeria, germany, indue, east asia - completely changed
  • age of novel ecosystems dependent on new world vs old world
  • biggest change over last 300 yrs is in asia - transition to villages