Biomes: Global Patterns of Life

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Biomes Global Patterns of Life
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Outline

• Terrestrial Biomes
• Marine Ecosystems
• Open Ocean
• Shallow Coasts
• Freshwater Ecosystems
• Lakes
• Wetlands
• Human Disturbance

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TERRESTRIAL BIOMES

• Biomes - Areas sharing similar climate,
  topographic and soil conditions, and roughly
  comparable communities.
• Temperature and precipitation are among the most
  important determinants in biome distribution.
• Most terrestrial biomes are identified by the
  dominant plants of their communities.

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Biomes
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Deserts

• Characterized by low moisture levels and
  precipitation that is infrequent and
  unpredictable from year to year.
• Wide daily and seasonal temperature fluctuations.
• Soils are easily disturbed by human activities,
  and slow to recover.
• Plants exhibit water conservation characteristics.

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Deserts
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Grasslands

• Communities of grasses, seasonal herbaceous
  flowering plants, and open savannas.
• Few trees due to inadequate rainfall.
• Large daily and seasonal temperature
  fluctuations.
• Frequent grass fires.
• Historic grazing by roaming herds of large
  ungulates.

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Grasslands
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Tundra

• Treeless
• Very short growing season, with cold harsh
  winters.
• Damage slow to heal.
• Arctic Tundra exhibits low productivity,
  diversity and resilience.
• Alpine Tundra receives intense solar radiation,
  hot daytime summer ground temperatures, and
  potential droughts.

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Tundra
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Conifer Forests

• Cone-Bearing
• Plants reduce water loss by evolving thin,
  needle-like evergreen leaves with thick waxy
  coating.
• Can survive harsh winters or extended droughts
  and accomplish photosynthesis even under poor
  conditions.
• Fire often plays role in maintenance.

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Conifer Forests

• Boreal Forest - Northern Conifer Forest
• Broad band of mixed coniferous and deciduous
  trees between 45 and 60 N latitude.
• Moist and cool climate with abundant streams and
  wetlands.
• Taiga - Northernmost edge of boreal forest
• Species-poor. Harsh climate limits productivity
  and resilience.
• Produce large peat bogs.

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Boreal Forest
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Conifer Forests

• Temperate Rainforest
• Wettest portion of coniferous forests of Pacific
  Northwest.
• Mild temperatures, and very abundant
  precipitation. (gt250 cm)
• Canopy condensation is major form of
  precipitation.

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Broad-Leaved Deciduous Forest

• Temperate regions support lush summer plant
  growth when water is plentiful.
• Deciduous leaves an adaptation to freezing
  temperatures.
• Eastern half of US was covered with broad leaf
  deciduous forest when European settlers arrived.
  Much of that was harvested a century ago for
  timber.
• Now large areas have re-grown and are again
  approaching old-growth status.

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Temperate Deciduous Forests
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Mediterranean

• Characterized by warm, dry summers and cool,
  moist winters.
• Fires are a major factor in plant succession.
• Referred to as chaparral in California.
• Biodiversity hotspot.
• Referred to as thorn scrub in Africa.
• Landscape dominated by acacias and other spiny
  plants.

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Tropical Moist Forests

• Humid tropical regions support one of most
  complex and biologically rich biomes.
• Ample rainfall and uniform temperatures.
• Cloud Forests - High mountains where fog and mist
  keep vegetation continually wet.

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Tropical Moist Forests

• Tropical Rainforests - More than 200 cm annual
  rainfall with warm-hot temperatures year-round.
• 90 nutrients tied up in living organisms.
• Rapid decomposition and nutrient cycling.
• Thin soil cannot support continued cropping, and
  cannot resist erosion.

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Tropical Rainforests
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Tropical Seasonal Forests

• Semi-evergreen and partly deciduous forests
  tending toward open woodlands and grassy
  savannas.
• Characterized by distinct wet and dry seasons
  with hot temperatures year-round

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MARINE ECOSYSTEMS

• Saltwater ecosystems cover vastly more total area
  and contain much greater volume of water than all
  freshwater bodies combined.
• Oceans hold bulk of worlds water.
• Aquatic ecosystems are influenced by local
  characteristics of climate, soil, and resident
  communities, and also by adjacent terrestrial
  ecosystems.

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Critical Characteristics

• Dissolved Substances
• Suspended Matter
• Depth
• Temperature
• Flow Rate
• Bottom Characteristics
• Internal Convective Currents
• Connectivity to Other Aquatic Ecosystems

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Marine Ecosystems

• Vertical stratification is an important aspect of
  many aquatic ecosystems.
• Organisms tend to form distinctive vertical
  sub-communities.
• Benthic - Bottom sub-community.
• Low oxygen levels.
• Pelagic - Water column

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Light Penetration
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Shallow Coasts

• Coral Reefs - Accumulated calcareous skeletons of
  colonial organisms (coral).
• Depth limited by light penetration.
• Among most endangered communities.
• Mangrove trees grow in salt water.
• Occur along calm, shallow, tropical coastlines.

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Tidal Environments

• Estuaries - Bays or semi-enclosed bodies of
  brackish water that form where rivers enter the
  ocean.
• Usually carry rich sediments.
• Fan-shaped sediment deposit (delta) formed on
  shallow continental shelves.

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Barrier Islands

• Barrier Islands - Low, narrow, sandy islands that
  form offshore from a coastline.
• Protect inland shores from surf.
• Prized for human development.
• Loss of vegetation triggers erosion.

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FRESHWATER ECOSYSTEMS

• Lakes
• Freshwater lakes have distinct vertical zones.
• Epilimnion
• Hypolimnion
• Benthos
• Thermocline - Distinctive temperature transition
  zone that separates warm upper layer and deeper
  cold layer.

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Wetlands

• Land surface is saturated or covered with water
  at least part of the year.
• Swamps - Wetlands with trees.
• Marshes - Wetlands without trees.
• Bogs and Fens - Waterlogged soils that tend to
  accumulate peat.
• Water usually shallow enough to allow full
  sunlight penetration.
• Trap and filter water, and store runoff.

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Wetlands
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HUMAN DISTURBANCE

• By some estimates, humans preempt about 40 of
  net terrestrial primary productivity.
• Temperate broad-leaved deciduous forests are the
  most completely human-dominated biome. Tundra
  and Arctic Deserts are the least disturbed.
• About half of all original wetlands in the US
  have been degraded over the past 250 years.

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Human Disturbance
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Summary

• Terrestrial Biomes
• Marine Ecosystems
• Open Ocean
• Shallow Coasts
• Freshwater Ecosystems
• Lakes
• Wetlands
• Human Disturbance

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