Biomes: Global Patterns of Life

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Biomes Global Patterns of Life

• Glaciers shrinking in a warming world
  Chacaltaya Glacier, Bolivia

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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.
• Plants share adaptations, but are different
  species in different continents.s

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Surface temperatures over time
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Patterns of sea level, 1993-2000
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Dominant mixes of ecosystems show global patterns
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Human Disturbance
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For Discussion

• With climate change, the distributions of many
  species are expected to change.
• What mechanisms might be examined to test this?
• hint how is this related to concepts of niche?
• With climate change, the distributions of biomes
  are expected to change.
• How is this different from question 1?
• What mechanisms would lead to this?

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Questions

• How does climate influence the form of dominant
  ecosystems?
• How can we agree on defining dominant ecosystems?
• How do humans directly influence biomes?
• Can areas of biomes collapse?
• Collapse irreversible change to simpler state

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Climate influences dominant growth forms of
natural vegetation
hundreds of species
tens of species
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Tundra
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Boreal Forest
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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.
• Taiga - Northernmost edge of boreal forest
• Species-poor. Harsh climate limits productivity
  and resilience.
• Temperate Rainforest
• Wettest portion of coniferous forests of Pacific
  Northwest.

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Temperate Deciduous Forests
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Grasslands (Steppe)
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Deserts
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Tropical Seasonal Forests
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Tropical Rainforests
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AQUATIC BIOMES

• Saltwater ecosystems cover vastly more total area
  and contain much greater volume of water than all
  freshwater bodies combined.
• Aquatic ecosystems are influenced by light
  penetration (depth), salt content and nutrients.
  
• For lakes and streams, also influential are
  adjacent terrestrial ecosystems.
• For coral ecosystems, temperature also is limiting

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Light Penetration
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How do biomes change through time?
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Temperature and moisture have varied Biomes 3.5
ky in the past
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North America 9 ky in the past
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present vegetation and 18 ky
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Biomes 28 ky in the past
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If change is natural why should we be concerned
about modern climate change?
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What would we mean by collapse?

• Can humans contribute to collapse?
• What actions and consequences would be involved?
• alter temperature
• alter water availability
• alter ability of organisms to disperse to adjust
  to change
• alter ability of organisms to evolve quickly
• Some examples

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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.