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Chapter 5 : Biomes, Landscapes, Restoration

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Title: Chapter 5 : Biomes, Landscapes, Restoration


1
  • Chapter 5 Biomes, Landscapes, Restoration
    Management
  • Major terrestial and aquatic biomes factors
    that determine their distribution
  • Humans disturbance of each ecossytem
  • Principles of landscape ecology and ecosystem
    management
  • Evaluation of the effects of restoration,
    replacement or substituting ecosystems and
    resources damaged by humans

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  • Terrestrial Biomes
  • Biomes are broad types of biological
    communities with similar climatic and topographic
    conditions with comparable
  • communities.
  • Temperature and precipitation are the two most
    important factors influencing the type of biome
    found in a location.

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  • Deserts
  • Desert biomes are characterized by low moisture
    levels and infrequent, unpredictable
    precipitation (2 - 4 in. annual precipitation)
  • Desert plants have adapted to prevent water
    loss (leaf adaptations, water-storage tissues,
    thick epidermal layers) and to discourage
    predation (thorns and spines).
  • Warm, dry descending air creates broad desert
    bands in continental interiors about 30o north
    latitude.
  • Not all deserts are hot. Those found at high
    latitudes and elevations can be cool or even
    cold.
  • Desert animals also have adapted to fight the
    heat and conserve water. Many have adopted
    burrowing behaviors to escape the sun, and many
    produce highly concentrated urine and feces in
    order to conserve water.
  • Desert soils are easily disturbed by human
    activities (off-roading, overgrazing, etc.) and
    take large amounts of time to recover.

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  • Grasslands Prairies and Savannas
  • Grasslands are moderately dry areas of
    abundant grasses, herbaceous flowering plants,
    and open savannas. Seasonal cycles for
    precipitation and temperature contribute to the
    rich growth.
  • Grasslands have few trees due to inadequate
    rainfall and frequent grassfires.
  • In some parts of the world, native people
    use fire to create grasslands for grazing while
    in other parts, fire suppression has greatly
    reduced the amount of native grasslands.

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  • Tundra
  • Climates in high mountain areas or at far
    northern or southern latitudes are often too
    harsh for trees. This treeless landscape, called
    tundra, is characterized by a very short growing
    season, harsh winters, and the potential for
    frost any month of the year.
  • The arctic tundra is a biome of low
    productivity, low diversity, and low resilience.
    Only the upper layer of soil thaws during the
    summer while the lower is permafrost and
    impermeable to plant roots.
  • The alpine tundra differs from the arctic
    tundra. High, thin mountain air permits intense
    solar radiation causing many plants to have deep
    pigmentations. The sloping of the land allows for
    better drainage, increasing the chances of
    drought. There is also a wide day-night
    temperature range.
  • Although the tundra may swarm with life during
    the brief growing season, few species are able to
    survive the harsh winter. Dominant tundra plants
    are mosses, lichens, grasses, sedges, and dwarf
    shrubs. Flocks of migratory birds and
    bloodsucking insects reside in the arctic
    wetlands. Larger animals (musk ox, caribou,
    mountain goats) must be specially adapted to deal
    with the climate and sparse food supply.
  • Damage to the tundra is slow to heal because of
    the short growing season. For example, truck tire
    ruts and bulldozer tracks from the oil and
    natural gas industries may take centuries to
    repair.

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  • Conifer Forests
  • Coniferous forests are characterized by limited
    moisture which has caused the vegetation to
    develop thin, needlelike evergreen leaves with a
    thick waxy coating.
  • The boreal (northern coniferous forest)
    stretches in a broad band of mixed coniferous and
    deciduous trees around the world between 45o and
    60o north latitude. Among the dominant conifers
    are spruce, pine, hemlock, cedar, and fir. Mosses
    and lichens form most of the ground cover.
  • Wetlands abound in this biome, especially on
    recently glaciated landscapes. The taiga is the
    far northern border between the coniferous forest
    and the arctic tundra.
  • Cold temperatures and wet soil inhibit full
    decay of organic matter. This semi-decayed matter
    is called peat.
  • The southern pine forest is characterized by a
    warm, moist climate and sandy soil.
  • The coniferous forests of the Pacific coast are
    characterized by mild temperatures and abundant
    precipitation which results in luxuriant plant
    growth and huge trees.
  • The wettest part of the coastal forest becomes
    temperate rainforest.

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  • Broad-Leaved Deciduous and Evergreen Forests
  • Forests of broad-leaved trees where rainfall
    is plentiful are called deciduous forests. Trees
    found here are able to produce summer leaves and
    shed them at the end of the growing season. These
    include oak, maple, birch, ash, and elm trees.

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  • Mediterranean/Chaparral/Thorn Shrub
  • Mediterranean climates are characterized by
    warm, dry summers and cool, moist winters.
    Evergreen shrubs, scrub oaks, and pines dominate
    this landscape.
  • Fires play an important role in plant
    succession here.
  • In California, this landscape is called
    chaparral (Spanish for thicket) and is inhabited
    by jackrabbits, mule deer, chipmunks, lizards,
    and bird species.
  • In drier areas, this landscape is dominated by
    spiny plants giving it the name thorn shrub.
  • This biome is considered to be a hotspot for
    biological diversity.

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  • Tropical Moist Forests
  • Tropical moist forests are characterized by
    ample rainfall and uniform temperatures.
  • Cool cloud forests are found high in
    mountains and cannot resist erosion from the
    abundant rains.

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  • Tropical Seasonal Forests
  • Tropical regions characterized by distinct
    wet-dry seasons with hot temperatures all year
    round give rise to tropical seasonal forests.
    These areas are dominated by semi-evergreen or
    partly deciduous forests tending toward open
    woodland or grassy savannas.
  • Tropical rainforests occur where rainfall is
    abundant (200 cm per year) and temperatures are
    hot year round.
  • The soil of these forest types tends to be old,
    thin, and nutrient poor yet the number of species
    present is mind-boggling. It is estimated that
    one-half to two-thirds of all terrestrial plants
    and insects live in tropical forests.
  • Nutrient cycling is also unique here. Almost
    all nutrients are tied up in the bodies of
    organisms.
  • The forest relies on rapid decomposition and
    recycling of dead organisms to maintain nutrient
    supplies.

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  • Aquatic Ecosystems
  • Freshwater and Saline Ecosystems
  • Freshwater ecosystems include standing waters of
    ponds and lakes as well as flowing waters of
    rivers and streams.
  • Freshwater ecosystems are influenced by
    climate, soil, resident communities, and by the
    terrestrial ecosystems surrounding them.
  • Availability of essentials for life is
    influenced by dissolved substances, suspended
    matter, depth, temperature, flow rate, bottom
    characteristics, internal convective currents,
    and connections with other aquatic systems.
  • Vertical stratification is an important aspect
    of standing water ecosystems, especially in
    regard to gradients of light, temperature,
    nutrients, and oxygen. Stratification of these
    essentials results in the stratification of
    biological communities in the water as well.

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  • The bottom sub-community is called the benthos
    and is made up of low oxygen tolerating
    organisms.
  • Deep lakes are stratified into an upper
    epilimnion, a middle thermocline, and a lower
    hypolimnion.
  • Humans utilize freshwater systems a great deal
    for food, recreation, transportation, and
    industrial uses.
  • Not all freshwater systems have what we think
    of as "fresh" water. Some may be salty (Dead Sea,
    Great Salt Lake) while others may contain high
    levels of minerals or be highly alkaline.

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  • Estuaries Wetlands Transitional Communities
  • Estuaries are bays of brackish water that form
    where rivers enter the ocean.
  • They contain rich sediments that support a
    multitude of aquatic life and are important as
    "nurseries" to a variety of species.
  • A fan shaped sediment deposit at the mouth of a
    river is called a delta.
  • Wetlands are ecosystems in which the land
    surface is covered by standing water at least
    part of the year.
  • There are three types of wetlands swamps
    (contain trees), marshes (no trees), and bogs and
    fens (may or may not have trees, tend to
    accumulate peat, low productivity).
  • Wetlands are major breeding, nesting, and
    migration staging areas for waterfowl and
    shorebirds.
  • Wetlands perform a variety of useful functions
    including detoxification of substances in water,
    clarifying water, and helping replenish
    underground aquifers.
  • Wetland areas are being destroyed or degraded
    by human processes at an alarming rate.

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  • Shorelines and Barrier Islands
  • Ocean shorelines are also particularly rich in
    life-forms, many of which grow attached to solid
    substrates such as exposed rock.
  • Barrier islands are low, narrow, sandy islands
    that form offshore from a coastline.
  • They protect inland shores from the onslaught
    of the surf. Human activity also destroys these
    fragile ecosystems quite easily.
  • Coral reefs form in clear, warm, tropical seas.
    They are the
    accumulated skeletons of innumerable tiny
    colonial animals called
    corals. They support a wide
    variety of interesting organisms. Reefs
    are among the
    most endangered biological communities on earth.

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  • Human Disturbance
  • Humans have become the dominant organisms over
    most of the earth and have damaged or disturbed
    more than half the world's ecosystems.
  • Conversion of natural habitat to human use is
    the largest single cause of loss of biodiversity.
  • Temperate broad-leaved forests are the most
    completely human-dominated of any major biome.
  • Mediterranean climates are also generally
    desirable for human habitation, leading to
    conflict between human preferences and biological
    values.
  • Tundra and arctic deserts are among the least
    disturbed biomes in the world. That is changing,
    however, with the discovery of large reserves of
    oil and natural gas.

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  • Landscape Ecology
  • Landscape ecology is the study of reciprocal
    effects of spatial pattern on ecological
    processes. Reciprocal effects refers to the
  • fact that complex spatial patterns shape, and are
    in turn shaped by, the ecological processes that
    occur in them.
  • Landscape ecology considers humans important
    elements of most landscapes and take them into
    account in their studies.

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  • Patchiness and Heterogeneity
  • Landscape ecologists claim that if we look
    closely, all landscapes consist of similar
    mosaics of discrete, bounded patches with
    different abiotic or biotic composition. Often a
    predominant or continuous cover type acts as a
    matrix in which other patch types appear to be
    embedded.
  • Landscape heterogeneity can exist across a wide
    range of scale from Yellowstone Park to the
    effects of soil crumb size and insect burrows in
    a few square centimeters of soil.

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  • Landscape Dynamics
  • Time and space are of special concern in
    landscape ecology.
  • The boundaries between habitat patches are
    considered especially significant by landscape
    ecologists. Edges can induce, inhibit, or
    regulate movement of materials, energy, or
    organisms across a landscape.
  • There are many similarities between
    landscape ecology and conservation biology.

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Restoration Ecology Restoration ecology seeks
to repair or reconstruct ecosystems damaged by
humans or natural forces.
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  • Defining Some Terms
  • Restoration involves active manipulation of
    nature to re-create species composition and
    ecosystem processes as close as possible to the
    state that existed before human disturbance.
  • Rehabilitation refers to an attempt to
    rebuild elements of structure or function in an
    ecological system without necessarily achieving
    complete restoration to its original condition.
  • Remediation is a process of cleaning
    chemical contaminants from a polluted area by
    physical or biological methods.
  • Reclamation is used to describe chemical or
    physical manipulations carried out in severely
    degraded sites, such as open pit mines or
    large-scale construction.
  • Re-creation attempts to construct a new
    biological community on a site so severely
    disturbed that there is virtually nothing left to
    restore.

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  • Conflicting Views of Restoration
  • There are conflicting views over the
    effectiveness and ideology of different
    approaches to protecting nature. Two of the
    different camps are preservationists and
    restorationists.
  • Preservationists argue that the best
    strategy is to avoid destructive projects in the
    first place. Restorationists counter that we are
    unlikely to preserve more than small areas in
    pristine form. They believe that we should use
    science to repair damage done by destructive
    projects.
  • An important question to consider is the
    place of humans in nature. Are we members of the
    biological community or are we separate from it?

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  • Tools of Restoration
  • There are many different ways to approach
    restoration. Curtis Prairie at the University of
    Wisconsin-Madison was restored through intensive
    horticultural and animal control methods.
  • Sometimes, an alien species must be removed
    before native species may take hold again. For
    example, in Hawaii, feral pigs that root out
    native plants and eat native birds are being
    hunted and removed.
  • Successional restoration uses fire to
    discourage invasion of exotic species. In
    southern Kansas, fire and native bison have been
    introduced to restore a 16,000 ha tall grass
    prairie.

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Letting Nature Heal Itself Sometimes to
reestablish a healthy ecosystem, all we have to
do is walk away and leave it alone. The DMZ
between North and South Korea is a perfect
example. An area shattered by war that has been
left alone for almost 50 years has become a
thriving wild life refuge.
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Authenticity An important question in
restoration is authenticity. How important is it
to restore a particular place to an exact replica
of its original ecosystem? If a similar, healthy
community can be restored, is that good enough or
must an exact replica be created?
35
Back To What? Another important question is
what our goals in restoration should be. For
example, if a preserve is damage due to a
hurricane or fire, should we use science to tidy
up the area or let natural processes take care of
it? Also, if pollen grains preserved in sediment
near a river show the area was a marsh 1000 years
ago, should we restore the area to marshland?
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Creating Artificial Ecosystems Sometimes
artificial ecosystems may be created to solve
human problems. For example, Arcata, California,
created a wetland to deal with it sewage waste
from the city. The wetland allowed for
detoxification of the water and for a beautiful
nature preserve.
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Ecosystem Management Ecosystem management is a
relatively new discipline in environmental
science that attempts to integrate ecological,
economic, and social goals in a unified systems
approach to make environmental management
decisions.
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  • Table 5.2 -- Principles of ecosystem management
  • Managing across whole landscapes, watersheds,
    or regions over an ecological time scale.
  • Considering human needs and promoting
    sustainable economic development and communities.
  • Maintaining biological diversity and essential
    ecosystem processes.
  • Utilizing cooperative institutional
    arrangements.
  • Integrating science and management.
  • Generating meaningful stakeholder and public
    involvement and facilitating collective
    decision-making.
  • Adapting management over time, based on
    conscious experimentation and routine monitoring.

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  • A Brief History of Ecosystem Management
  • While the term ecosystem management is
    relatively new, a few ecologists had the
    foresight to advocate many specific elements of
    this science fifty years ago.
  • In 1970, environmental policy expert Lynton
    Caldwell wrote that we should use ecosystems as
    the basis for public land policy.
  • Currently, many state and federal natural
    resource agencies in the United States are
    attempting to implement ecosystem management as
    their guiding policy.

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  • Principles and Goals of Ecosystem Management
  • There are several important differences between
    the current integrated approach to ecosystem
    management and traditional policies of the past.
  • Hierarchical context A focus on any one level
    of the biodiversity hierarchy is insufficient.
    Ecosystem managers must see interconnections
    between all levels.
  • Ecological boundaries Rather than divide
    administrative units by political boundaries,
    natural units should be managed in an integrated
    fashion.
  • Data collection and routine monitoring To
    function correctly, ecosystem management requires
    ongoing research and data collection so that
    successes and failures may be recognized and
    evaluated.
  • Adaptive management Ecosystem management
    assumes that scientific knowledge is provisional
    and regards management plans as learning
    processes or continuous experiments where
    incorporating the results of previous actions
    allows managers to remain flexible and adapt to
    uncertainty.
  • Organizational change Implementing ecosystem
    management requires changes in agency structure
    and ways of doing business.
  • Humans in nature People cannot be separated
    from nature.
  • Values Regardless of the role of scientific
    knowledge, human values play a dominant role in
    ecosystem management goals.

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  • Table 5.3 -- Ecosystem management goals maintain
    viable populations of native species in situ.
  • Represent, within protected areas, all native
    ecosystem types across their natural range of
    variation.
  • Protect essential ecological processes such as
    nutrient cycles, succession, hydrologic
    processes, etc.
  • Manage over long enough time periods to sustain
    the evolutionary potential of species and
    ecosystems.
  • Accommodate human use and occupancy within these
    constraints.

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  • Critiques of Ecosystem Management
  • There are many criticisms of ecosystem
    management. Many ecologists say that due to their
    chaotic, unpredictable nature, we will never
    understand ecosystems and developing policies to
    manage them is a waste of time.
  • Many people also fear that effective
    ecosystem management will allow humans to believe
    we can do damage to nature and that at may be
    repaired.
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