BIOMES

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BIOMES I. Climatic Determinants II. FORESTS III.
Grasslands
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III. Grasslands A. Shrub Forest - Savannah
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III. Grasslands A. Shrub Forest - Savannah 1.
Abiotic Conditions
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III. Grasslands A. Shrub Forest - Savannah 1.
Abiotic Conditions TEMP Uniformly warm annual
temp gt 20C a bit more seasonality due to warmer
temps during arid dry season
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III. Grasslands A. Shrub Forest - Savannah 1.
Abiotic Conditions TEMP Uniformly warm annual
temp gt 20C a bit more seasonality due to warmer
temps during arid dry season RAINFALL seasonal
- closer to tropical margins rainfall determines
tree density, from shrub forest ot tropical
savannah with a few trees to true grassland
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III. Grasslands A. Shrub Forest - Savannah 1.
Abiotic Conditions TEMP Uniformly warm annual
temp gt 20C a bit more seasonality due to warmer
temps during arid dry season RAINFALL seasonal
- closer to tropical margins rainfall determines
tree density, from shrub forest ot tropical
savannah with a few trees to true grassland
EVAPOTRANSPIRATIONAL STRESS high, especially in
dry season selects for C4 grasses
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III. Grasslands A. Shrub Forest - Savannah 1.
Abiotic Conditions TEMP Uniformly warm annual
temp gt 20C a bit more seasonality due to warmer
temps during arid dry season RAINFALL seasonal
- closer to tropical margins rainfall determines
tree density, from shrub forest ot tropical
savannah with a few trees to true grassland
EVAPOTRANSPIRATIONAL STRESS high, espcially in
dry season selects for C4 grasses LIGHT Never
limiting, no winter and no big trees creating
shade
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III. Grasslands A. Shrub Forest - Savannah 1.
Abiotic Conditions TEMP Uniformly warm annual
temp gt 20C a bit more seasonality due to warmer
temps during arid dry season RAINFALL seasonal
- closer to tropical margins rainfall determines
tree density, from shrub forest ot tropical
savannah with a few trees to true grassland
EVAPOTRANSPIRATIONAL STRESS high, espcially in
dry season selects for C4 grasses LIGHT Never
limiting, no winter and no big trees creating
shade SOILS low permeability - calcium
carbonate hardpan creates waterlogged surface in
wet
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III. Grasslands A. Shrub Forest - Savannah 1.
Abiotic Conditions TEMP Uniformly warm annual
temp gt 20C a bit more seasonality due to warmer
temps during arid dry season RAINFALL seasonal
- closer to tropical margins rainfall determines
tree density, from shrub forest ot tropical
savannah with a few trees to true grassland
EVAPOTRANSPIRATIONAL STRESS high, espcially in
dry season selects for C4 grasses LIGHT Never
limiting, no winter and no big trees creating
shade SOILS low permeability - calcium
carbonate hardpan creates waterlogged surface in
wet DISTURBANCE fire - selects for grasses
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III. Grasslands A. Shrub Forest - Savannah 1.
Abiotic Conditions TEMP Uniformly warm annual
temp gt 20C a bit more seasonality due to warmer
temps during arid dry season RAINFALL seasonal
- closer to tropical margins rainfall determines
tree density, from shrub forest ot tropical
savannah with a few trees to true grassland
EVAPOTRANSPIRATIONAL STRESS high, espcially in
dry season selects for C4 grasses LIGHT Never
limiting, no winter and no big trees creating
shade SOILS low permeability - calcium
carbonate hardpan creates waterlogged surface in
wet DISTURBANCE fire - selects for grasses
NUTRIENTS and CYCLING Most nutrients bound in
biomass rapid decomposition and rapid
absorption. Little litter accumulation.
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III. Grasslands A. Shrub Forest - Savannah 1.
Abiotic Conditions 2. Biota
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III. Grasslands A. Shrub Forest - Savannah 1.
Abiotic Conditions 2. Biota Arid conditions and
fire select for C4 grasses
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• III. Grasslands
• A. Shrub Forest - Savannah
• 1. Abiotic Conditions
• 2. Biota
• Arid conditions and fire select for C4 grasses
• Large grazers dominate harvest energy by
  processing huge amounts of forage quickly, or by
  ruminating (bacterial gut flora). Migratory

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III. Grasslands A. Shrub Forest - Savannah B.
Temperate Grassland (Prairie)
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III. Grasslands A. Shrub Forest - Savannah B.
Temperate Grassland (Prairie) 1. Abiotic
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III. Grasslands A. Shrub Forest - Savannah B.
Temperate Grassland (Prairie) 1. Abiotic TEMP
seasonal extremes - continental climate limits
growing season to 120-300 days depending on
latitude and temperature extremes.
Des Moines, Iowa
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III. Grasslands A. Shrub Forest - Savannah B.
Temperate Grassland (Prairie) 1. Abiotic TEMP
seasonal extremes - continental climate limits
growing season to 120-300 days depending on
latitude and temperature extremes. RAINFALL
Summer rain is predictably seasonal. Rainfall is
too low to leach cations from soil but can be
high enough to support significant plant
productivity.
Des Moines, Iowa
Cheyenne, WY
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increasing rainfall
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III. Grasslands A. Shrub Forest - Savannah B.
Temperate Grassland (Prairie) 1. Abiotic TEMP
seasonal extremes - continental climate limits
growing season to 120-300 days depending on
latitude and temperature extremes. RAINFALL
Summer rain is predictably seasonal. Rainfall is
too low to leach cations from soil but can be
high enough to support significant plant
productivity. EVAPOTRANSPIRATIONAL STRESS high,
especially in dry season selects for C4 grasses
but C3 grasses still plentiful
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III. Grasslands A. Shrub Forest - Savannah B.
Temperate Grassland (Prairie) 1. Abiotic TEMP
seasonal extremes - continental climate limits
growing season to 120-300 days depending on
latitude and temperature extremes. RAINFALL
Summer rain is predictably seasonal. Rainfall is
too low to leach cations from soil but can be
high enough to support significant plant
productivity. EVAPOTRANSPIRATIONAL STRESS high,
especially in dry season selects for C4 grasses
but C3 grasses still plentiful LIGHT Never
limiting, no winter and no big trees creating
shade
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III. Grasslands A. Shrub Forest - Savannah B.
Temperate Grassland (Prairie) 1. Abiotic TEMP
seasonal extremes - continental climate limits
growing season to 120-300 days depending on
latitude and temperature extremes. RAINFALL
Summer rain is predictably seasonal. Rainfall is
too low to leach cations from soil but can be
high enough to support significant plant
productivity. EVAPOTRANSPIRATIONAL STRESS high,
especially in dry season selects for C4 grasses
but C3 grasses still plentiful LIGHT Never
limiting, no winter and no big trees creating
shade SOILS deep and rich
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III. Grasslands A. Shrub Forest - Savannah B.
Temperate Grassland (Prairie) 1. Abiotic TEMP
seasonal extremes - continental climate limits
growing season to 120-300 days depending on
latitude and temperature extremes. RAINFALL
Summer rain is predictably seasonal. Rainfall is
too low to leach cations from soil but can be
high enough to support significant plant
productivity. EVAPOTRANSPIRATIONAL STRESS high,
especially in dry season selects for C4 grasses
but C3 grasses still plentiful LIGHT Never
limiting, no winter and no big trees creating
shade SOILS deep and rich DISTURBANCE fire -
selects for grasses
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III. Grasslands A. Shrub Forest - Savannah B.
Temperate Grassland (Prairie) 1. Abiotic TEMP
seasonal extremes - continental climate limits
growing season to 120-300 days depending on
latitude and temperature extremes. RAINFALL
Summer rain is predictably seasonal. Rainfall is
too low to leach cations from soil but can be
high enough to support significant plant
productivity. EVAPOTRANSPIRATIONAL STRESS high,
especially in dry season selects for C4 grasses
but C3 grasses still plentiful LIGHT Never
limiting, no winter and no big trees creating
shade SOILS deep and rich DISTURBANCE fire -
selects for grasses NUTRIENTS and CYCLING moist
grasslands are richest soils on Earth, rich in
nutrients and organics
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III. Grasslands A. Shrub Forest - Savannah B.
Temperate Grassland (Prairie) 1. Abiotic 2.
Biota
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III. Grasslands A. Shrub Forest - Savannah B.
Temperate Grassland (Prairie) 1. Abiotic 2.
Biota The height and density of grasses
correlates with rainfall, which changes the soil
conditions.
increasing rainfall
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III. Grasslands A. Shrub Forest - Savannah B.
Temperate Grassland (Prairie) 1. Abiotic 2.
Biota The height and density of grasses
correlates with rainfall, which changes the soil
conditions. Perennial C4 grasses dominate.
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III. Grasslands A. Shrub Forest - Savannah B.
Temperate Grassland (Prairie) 1. Abiotic 2.
Biota The height and density of grasses
correlates with rainfall, which changes the soil
conditions. Perennial C4 grasses dominate.
Again, large grazers and predators dominate the
food webs.
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III. Grasslands A. Shrub Forest - Savannah B.
Temperate Grassland (Prairie) 1. Abiotic 2.
Biota The height and density of grasses
correlates with rainfall, which changes the soil
conditions. Perennial C4 grasses dominate.
Again, large grazers and predators dominate the
food webs.
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III. Grasslands A. Shrub Forest - Savannah B.
Temperate Grassland (Prairie) C. ArcticTundra
ALPINE
ARCTIC
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III. Grasslands A. Shrub Forest - Savannah B.
Temperate Grassland (Prairie) C. Arctic Tundra 1.
Abiotic
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III. Grasslands A. Shrub Forest - Savannah B.
Temperate Grassland (Prairie) C. Arctic Tundra 1.
Abiotic TEMP Cold most of the year, with a
growing season less than 100 days. The summer
does have long days, but light intensities are
still low due to oblique angle.
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III. Grasslands A. Shrub Forest - Savannah B.
Temperate Grassland (Prairie) C. Arctic Tundra 1.
Abiotic TEMP Cold most of the year, with a
growing season less than 100 days. The summer
does have long days, but light intensities are
still low due to oblique angle. RAINFALL
Precipitation is very low, less than 25cm/year.

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III. Grasslands A. Shrub Forest - Savannah B.
Temperate Grassland (Prairie) C. Arctic Tundra 1.
Abiotic TEMP Cold most of the year, with a
growing season less than 100 days. The summer
does have long days, but light intensities are
still low due to oblique angle. RAINFALL
Precipitation is very low, less than 25cm/year.
EVAPOTRANSPIRATIONAL STRESS high, largely due
to desiccating effects of dry, strong cold winds
and water frozen as ice most of year.
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III. Grasslands A. Shrub Forest - Savannah B.
Temperate Grassland (Prairie) C. Arctic Tundra 1.
Abiotic TEMP Cold most of the year, with a
growing season less than 100 days. The summer
does have long days, but light intensities are
still low due to oblique angle. RAINFALL
Precipitation is very low, less than 25cm/year.
EVAPOTRANSPIRATIONAL STRESS high, largely due
to desiccating effects of dry, strong cold winds
and water frozen as ice most of year. LIGHT
Limiting most of year growing season very short

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III. Grasslands A. Shrub Forest - Savannah B.
Temperate Grassland (Prairie) C. Arctic Tundra 1.
Abiotic TEMP Cold most of the year, with a
growing season less than 100 days. The summer
does have long days, but light intensities are
still low due to oblique angle. RAINFALL
Precipitation is very low, less than 25cm/year.
EVAPOTRANSPIRATIONAL STRESS high, largely due
to desiccating effects of dry, strong cold winds
and water frozen as ice most of year. LIGHT
Limiting most of year growing season very short
SOILS shallow just above permafrost boggy in
summer very slow decomposition - mats of peat
that transfer little nitrogen to soil
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III. Grasslands A. Shrub Forest - Savannah B.
Temperate Grassland (Prairie) C. Arctic Tundra 1.
Abiotic TEMP Cold most of the year, with a
growing season less than 100 days. The summer
does have long days, but light intensities are
still low due to oblique angle. RAINFALL
Precipitation is very low, less than 25cm/year.
EVAPOTRANSPIRATIONAL STRESS high, largely due
to desiccating effects of dry, strong cold winds
and water frozen as ice most of year. LIGHT
Limiting most of year growing season very short
SOILS shallow just above permafrost boggy in
summer very slow decomposition - mats of peat
that transfer little nitrogen to soil
DISTURBANCE winter, freez-thaw cycles, storms,
exposure
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III. Grasslands A. Shrub Forest - Savannah B.
Temperate Grassland (Prairie) C. Arctic Tundra 1.
Abiotic TEMP Cold most of the year, with a
growing season less than 100 days. The summer
does have long days, but light intensities are
still low due to oblique angle. RAINFALL
Precipitation is very low, less than 25cm/year.
EVAPOTRANSPIRATIONAL STRESS high, largely due
to desiccating effects of dry, strong cold winds
and water frozen as ice most of year. LIGHT
Limiting most of year growing season very short
SOILS shallow just above permafrost boggy in
summer very slow decomposition - mats of peat
that transfer little nitrogen to soil
DISTURBANCE winter, freez-thaw cycles, storms,
exposure NUTRIENTS and CYCLING soils nutrient
poor and shallow
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peeling back the soil and vegetation to the top
of the permafrost
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• III. Grasslands
• A. Shrub Forest - Savannah
• B. Temperate Grassland (Prairie)
• C. Arctic Tundra
• 1. Abiotic
• 2. Biota
• No trees - above treeline.

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III. Grasslands A. Shrub Forest - Savannah B.
Temperate Grassland (Prairie) C. Arctic Tundra 1.
Abiotic 2. Biota No trees - above treeline.
Perennial grasses, mosses, and lichens dominate
the growing season is even too short for annual
herbs to really get going.
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• III. Grasslands
• A. Shrub Forest - Savannah
• B. Temperate Grassland (Prairie)
• C. Arctic Tundra
• 1. Abiotic
• 2. Biota
• No trees - above treeline.
• Perennial grasses, mosses, and lichens dominate
  the growing season is even too short for annual
  herbs to really get going.
• Mammals tend to remain all year, relying on thick
  fur to weather winters. Some migration into the
  boreal forest does occur.

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• III. Grasslands
• A. Shrub Forest - Savannah
• B. Temperate Grassland (Prairie)
• C. Arctic Tundra
• 1. Abiotic
• 2. Biota
• 3. Alpine Tundra

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• III. Grasslands
• A. Shrub Forest - Savannah
• B. Temperate Grassland (Prairie)
• C. Arctic Tundra
• 1. Abiotic
• 2. Biota
• 3. Alpine Tundra
• Elevational treelines vary with latitude, being
  900m at 65N, 2100m at 49N, 3300m at 40N, and
  4200m at 19N.

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• III. Grasslands
• A. Shrub Forest - Savannah
• B. Temperate Grassland (Prairie)
• C. Arctic Tundra
• 1. Abiotic
• 2. Biota
• 3. Alpine Tundra
• Elevational treelines vary with latitude, being
  900m at 65N, 2100m at 49N, 3300m at 40N, and
  4200m at 19N.
• However, the presence of cold-hardy trees is also
  critical. In Brazil near 22S, the treeline is
  below 2000m because there are no cold-tolerant
  trees in the region.

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• III. Grasslands
• A. Shrub Forest - Savannah
• B. Temperate Grassland (Prairie)
• C. Arctic Tundra
• 1. Abiotic
• 2. Biota
• 3. Alpine Tundra
• Elevational treelines vary with latitude, being
  900m at 65N, 2100m at 49N, 3300m at 40N, and
  4200m at 19N.
• However, the presence of cold-hardy trees is also
  critical. In Brazil near 22S, the treeline is
  below 2000m because there are no cold-tolerant
  trees in the region.
• Short growing season and a long cold winter, but
  lots of precipitation, lower oxygen, high UV
  radiation, and unpredictable storms makes this a
  very different environment from arctic tundra.

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• III. Grasslands
• A. Shrub Forest - Savannah
• B. Temperate Grassland (Prairie)
• C. Arctic Tundra
• 1. Abiotic
• 2. Biota
• 3. Alpine Tundra
• Elevational treelines vary with latitude, being
  900m at 65N, 2100m at 49N, 3300m at 40N, and
  4200m at 19N.
• However, the presence of cold-hardy trees is also
  critical. In Brazil near 22S, the treeline is
  below 2000m because there are no cold-tolerant
  trees in the region.
• Short growing season and a long cold winter, but
  lots of precipitation, lower oxygen, high UV
  radiation, and unpredictable storms makes this a
  very different environment from arctic tundra.
• Soils lack permafrost but are thin and "new".
  Well drained (water runs downslope and does not
  pool) and summer droughts can occur.
• Dominant plants are perennial grasses and cushion
  plants.

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• III. Grasslands
• IV. Deserts

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• III. Grasslands
• IV. Deserts
• 1. Abiotic

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• III. Grasslands
• IV. Deserts
• 1. Abiotic
• TEMP Temperatures can vary dramatically,
  depending on time of day, time of year, and
  latitude. Below freezing temperatures are
  possible in high latitude deserts.

Tomboktou, Mali (Sahara)
Alice Springs, Australia
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• III. Grasslands
• IV. Deserts
• 1. Abiotic
• TEMP Temperatures can vary dramatically,
  depending on time of day, time of year, and
  latitude. Below freezing temperatures are
  possible in high latitude deserts.
• RAINFALL The common limiting variable is water -
  deserts have less than 25cm/year, on average. In
  warm deserts, the potential evaporation is much
  greater than the precipitation. In Phoenix, AZ,
  potential evapotranspiration is 130 cm a year,
  but rainfall is only 18 cm/year.

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• III. Grasslands
• IV. Deserts
• 1. Abiotic
• TEMP Temperatures can vary dramatically,
  depending on time of day, time of year, and
  latitude. Below freezing temperatures are
  possible in high latitude deserts.
• RAINFALL The common limiting variable is water -
  deserts have less than 25cm/year, on average. In
  warm deserts, the potential evaporation is much
  greater than the precipitation. In Phoenix, AZ,
  potential evapotranspiration is 130 cm a year,
  but rainfall is only 18 cm/year.
• EVAPOTRANSPIRATIONAL STRESS very high
  desiccating conditions exceed rainfall

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• III. Grasslands
• IV. Deserts
• 1. Abiotic
• TEMP Temperatures can vary dramatically,
  depending on time of day, time of year, and
  latitude. Below freezing temperatures are
  possible in high latitude deserts.
• RAINFALL The common limiting variable is water -
  deserts have less than 25cm/year, on average. In
  warm deserts, the potential evaporation is much
  greater than the precipitation. In Phoenix, AZ,
  potential evapotranspiration is 130 cm a year,
  but rainfall is only 18 cm/year.
• EVAPOTRANSPIRATIONAL STRESS very high
  desiccating conditions exceed rainfall
• LIGHT not limiting during growing season

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• III. Grasslands
• IV. Deserts
• 1. Abiotic
• TEMP Temperatures can vary dramatically,
  depending on time of day, time of year, and
  latitude. Below freezing temperatures are
  possible in high latitude deserts.
• RAINFALL The common limiting variable is water -
  deserts have less than 25cm/year, on average. In
  warm deserts, the potential evaporation is much
  greater than the precipitation. In Phoenix, AZ,
  potential evapotranspiration is 130 cm a year,
  but rainfall is only 18 cm/year.
• EVAPOTRANSPIRATIONAL STRESS very high
  desiccating conditions exceed rainfall
• LIGHT not limiting during growing season
• SOILS little vegetation cover and slow
  decomposition mean little organic inputs - very
  patchy (under bushes). Otherwise, mineral soil is
  exposed (lithosol). Rainfall does not generate
  enough soil mositure to leach cations capillary
  action may even bring them near to surface and
  form a calcium and magnesium hardpan called
  caliche. These salts exacerbate desiccation.

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• III. Grasslands
• IV. Deserts
• 1. Abiotic
• TEMP Temperatures can vary dramatically,
  depending on time of day, time of year, and
  latitude. Below freezing temperatures are
  possible in high latitude deserts.
• RAINFALL The common limiting variable is water -
  deserts have less than 25cm/year, on average. In
  warm deserts, the potential evaporation is much
  greater than the precipitation. In Phoenix, AZ,
  potential evapotranspiration is 130 cm a year,
  but rainfall is only 18 cm/year.
• EVAPOTRANSPIRATIONAL STRESS very high
  desiccating conditions exceed rainfall
• LIGHT not limiting during growing season
• SOILS little vegetation cover and slow
  decomposition mean little organic inputs - very
  patchy (under bushes). Otherwise, mineral soil is
  exposed (lithosol). Rainfall does not generate
  enough soil mositure to leach cations capillary
  action may even bring them near to surface and
  form a calcium and magnesium hardpan called
  caliche. These salts exacerbate desiccation.
• DISTURBANCE desiccation, temperature extremes,
  severe drought, fire

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• III. Grasslands
• IV. Deserts
• 1. Abiotic
• TEMP Temperatures can vary dramatically,
  depending on time of day, time of year, and
  latitude. Below freezing temperatures are
  possible in high latitude deserts.
• RAINFALL The common limiting variable is water -
  deserts have less than 25cm/year, on average. In
  warm deserts, the potential evaporation is much
  greater than the precipitation. In Phoenix, AZ,
  potential evapotranspiration is 130 cm a year,
  but rainfall is only 18 cm/year.
• EVAPOTRANSPIRATIONAL STRESS very high
  desiccating conditions exceed rainfall
• LIGHT not limiting during growing season
• SOILS little vegetation cover and slow
  decomposition mean little organic inputs - very
  patchy (under bushes). Otherwise, mineral soil is
  exposed (lithosol). Rainfall does not generate
  enough soil mositure to leach cations capillary
  action may even bring them near to surface and
  form a calcium and magnesium hardpan called
  caliche. These salts exacerbate desiccation.
• DISTURBANCE desiccation, temperature extremes,
  severe drought, fire
• NUTRIENTS and CYCLING very poor

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• III. Grasslands
• IV. Deserts
• 1. Abiotic
• 2. Biota

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• III. Grasslands
• IV. Deserts
• 1. Abiotic
• 2. Biota
• Xerophyllic plants adapted to extreme drought
  stress dominate (CAM plants)

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• III. Grasslands
• IV. Deserts
• 1. Abiotic
• 2. Biota
• Xerophyllic plants adapted to extreme drought
  stress dominate (CAM plants)
• strong diurnal patterns in animal and plant
  activity (CAM)

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• III. Grasslands
• IV. Deserts
• 1. Abiotic
• 2. Biota
• Xerophyllic plants adapted to extreme drought
  stress dominate (CAM plants)
• strong diurnal patterns in animal and plant
  activity (CAM)
• Plant density tightly linked to water
  availability.

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• III. Grasslands
• IV. Deserts
• V. Summary - Terrestrial Biomes
• NET PRIMARY PRODUCTIVITY (total photosynthesis -
  respiration)