Download Principles of ecosystem management

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
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.
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.
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.
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.
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 semidecayed 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.
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.
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.
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.
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 onehalf 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.
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.
• 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.
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.
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.
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 humandominated 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.
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.
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.
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.
Restoration Ecology
Restoration ecology seeks to repair or reconstruct ecosystems damaged
by humans or natural forces.
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 largescale construction.
• Re-creation attempts to construct a new biological community on a
site so severely disturbed that there is virtually nothing left to restore.
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?
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.
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.
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?
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?
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.
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.
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.
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.
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.
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.
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.