ESC 305.01 Global Climate Change Chapter 6.1 Impacts on Terrestrial Ecosystems - PowerPoint PPT Presentation

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ESC 305.01 Global Climate Change Chapter 6.1 Impacts on Terrestrial Ecosystems


Deforestation will probably have serious long-term irreversible effects on the climate of the Amazon Basin. ... The ecosystem has living (biotic) and non-living ... – PowerPoint PPT presentation

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Title: ESC 305.01 Global Climate Change Chapter 6.1 Impacts on Terrestrial Ecosystems

ESC 305.01Global Climate Change Chapter 6.1
Impacts on Terrestrial Ecosystems
  • An ecosystem is a collection of compounds and
    processes within a section of the biosphere.
  • The ecosystem has living (biotic) and non-living
    (abiotic) components.
  • When studying an ecosystem, the interactions
    between living and nonliving sections are
  • Biotic part of an ecosystem includes all living
    organisms, from the smallest (viruses and
    bacteria) to the top predator.

  • Abiotic part of an ecosystem includes soil, rock,
    water, air, as well as the physical
    characteristics like temperature, humidity,
    slope, etc.

  • Climate, primarily temperature and precipitation,
    determine the geographic distribution of major
    terrestrial ecosystems (biomes) from deserts to
    rain forests.
  • Local and regional differences in soil types,
    watershed conditions and sun exposure influence
    the success of different plants.
  • However, seasonal patterns of rainfall and
    temperature dictate the type of plant
    associations that dominate an area.

  • Assocations we call
  • Tundra
  • Desert
  • Grassland
  • Rainforest
  • Each plant association has an optimum climate
    space, that is, a specific combination of
    temperature and precipitation conditions in which
    it best thrives.

  • Terrestrial ecosystems are sub-sections of
    tundra, taiga, temperate forest, tropical
    rainforest, savanna, and desert biomes.
  • The geographic distributions of major terrestrial
    ecosystems are largely governed by patterns of
    temperature precipitation.
  • Biomes are distinctive ecological systems
    characterized primarily by the nature of their

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  • Terrestrial ecosystems are an integral part of
    the global carbon cycle.
  • Grasslands and forests sequester atmospheric
    carbon (CO2) through photosynthesis and store it
    temporarily as organic carbon.
  • Below ground, organic carbon is decomposed by
    micro-organisms and released back into the
  • Both of these processes are influenced by
    temperature and could be altered by global

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  • Forests and other terrestrial biomes provide
    habitats for a diversity of plants and animals.
  • If the forest is damaged or removed, habitat loss
    can endanger the survival of the associated
    living organisms.
  • Climate change can directly affect many plants
    and animals by altering the growing season or
    temperature patterns that trigger life cycle

Impacts seen todayRetreat of glaciers
  • Over the past 150 years, the majority of mountain
    glaciers monitored have been shrinking.
  • Many glaciers at lower latitudes are now
    disappearing, and scientists predict that, under
    some plausible warming scenarios, the majority of
    glaciers will be gone by the year 2100.

Impacts as seen todayRetreat of glaciers
  • As glaciers continue to shrink, summer water
    flows will drop sharply, disrupting an important
    source of water for irrigation and power in many
    areas that rely on mountain watersheds.

Impacts as seen todayRetreat of glaciers
Impacts as seen todayRetreat of glaciers
Impacts as seen todayRetreat of glaciers
Impacts as seen todayRetreat of glaciers
Impacts as seen todayRetreat of glaciers
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Impacts as seen todayRetreat of glaciers
  • Many glaciers in the European Alps and North
    America have lost 30 to 40 of their glacial
    area and about half of their total volume between
    the 1850s and 1980s (Haeberli and Beniston,
  • The Himalayan Glaciers on the Tibetian Plateau
    have been among the most affected by global

Impacts as seen todayRetreat of glaciers
  • The Himalayas provide more than half of the
    drinking water for 40 of the worlds population
    through seven Asian river systems that all
    originate on the same plateau.

Pressures to Ecosystems
  • Land use changes
  • Pollutant and nutrient discharges
  • Overharvesting
  • Introduction of exotic species
  • Natural climate variability

  • Climate change is an additional pressure with the
    following results
  • Lengthening of vegetative growing season (by 1.2
    to 3.6 days per decade) in the high northern
  • Warming of lakes and rivers as a result of
    shortening duration of ice cover,
  • Shift in vegetation range in mountain regions,
  • Increased mortality and range contraction of
    wildlife as a result of the heat stress.

  • Satellite data reveal that between 1970 and 1990,
    the overall Northern Hemisphere winter snow cover
    decreased by about 10 (Folland et al., 1990).
  • Land use conversion and intensive use of land has
    resulted in decreased soil fertility and
    increased land degradation, as well as
  • Land degradation already affects more than 900
    million people in 100 countries (mostly
    developing countries).

  • SRES scenarios indicate increased droughts,
    higher intensity of rainfall, more irregular rain
    patterns and more frequent tropical summer
    drought in the mid-latitude continental
  • Optimum temperature and precipitation patterns
    defining the current distribution of vegetation
    types can be measured.
  • Global climate models can predict future
    geographic shifts in defined climate spaces.
    Thus, the possible geographic distribution of
    available future habitat for a vegetation type
    can be mapped.

  • Impact of future greenhouse effect on global
    vegetation and climate was predicted through use
    of coupled atmosphere-ocean-land model FOAM-LPJ
    (Center for Climatic Research, University of
  • According to the model, tropical rainforests will
    suffer due to high temperatures and reduced
  • Boreal forests will continue to shift poleward.

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  • Predictions by Ecological Models (MAPSS and BIOME
  • The Tundra decreases by as much as 1/3 to 2/3 of
    its present size, under all scenarios and with
    both ecological models.
  • The boreal forest expands in size under all
    scenarios, ranging from 108 to 133 of its
    present size.
  • Temperate forests increase in area (107 to 158

  • BIOME3 shows a competitive displacement of
    tropical savannas by neighboring forests, due to
    the superior competitive ability in the model of
    the trees over the grasses under elevated CO2.
  • The total area of grasslands and shrub lands in
    these simulations remains largely unchanged or
    expands by as much as 27 , depending on the

  • MAPSS (Mapped Atmosphere-Plant-Soil System) is a
    global vegetation distribution model that was
    developed to simulate the potential biosphere
    impacts and biosphere-atmosphere feedbacks from
    climatic change.
  • Model output from MAPSS has been used extensively
    in the Intergovernmental Panel on Climate
    Change's (IPCC) regional and global assessments
    of climate change impacts on vegetation and in
    several other projects.

Worldwide MAPSS ( Source US Forest Service)
  • Greenhouse warming will increase the frequency of
    disturbance weather events (summer/autumn drought
    thunderstorms) that impact mid-latitude
    temperate forests (Overpeck et al., 2001).
  • In temperate and boreal forests of North Anerica
    and Russia, a number of studies suggest that the
    climate change induced increases in forest fire
    seasonal severity, seasonal length, and areal
    extent (Stocks et al., 1998).

  • An increase in forest fires is already
    responsible for increasing releases of CO2 into
    the atmosphere.
  • Climate change will radically increase species
    loss and reduce biodiversity, particularly in the
    higher latitudes of the Northern Hemisphere
    (Malcom and Markham, 2000).
  • Global warming has the potential to significantly
    alter 35 of the worlds existing terrestrial
    habitats during this century.

  • Deforestation will probably have serious
    long-term irreversible effects on the climate of
    the Amazon Basin.
  • Once removed, the Amazon forest will be unable to
    re-establish itself.
  • Deforestation of tropical rainforests elsewhere
    will probably have similar effects on regional

  • Increasing atmospheric CO2 generally increases
    photosynthetic rates in individual plants.
  • However, the plants do not necessarily benefit
    from this increased productivity.
  • When several species are grown together,
    increased competition and nutrient availability
    diminishes any benefit of enhanced atmospheric

  • The geographic distributions of major terrestrial
    ecosystems are largely governed by patterns of
    temperature and precipitation.
  • There can be little doubt that climate change
    during this century will significantly alter the
    distribution and abundance of terrestrial
  • Climate change appears to be responsible for many
    documented life cycle changes in plants and
    animals over the past 50 years or more.
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