Ecological Restoration - University of Windsor

download report

Transcript Ecological Restoration - University of Windsor

Ecological Restoration
• Ecological restoration refers to the rehabilitation,
reclamation, re-creation and recovery of degraded
lands. These efforts may be conducted on either a smallscale (e.g. tree planting) or may involve major human and
technical efforts (e.g. re-creation of wetlands, acid lake
neutralization).
• Restoration can be claimed to begin with Aldo Leopold’s
restoration of oak openings and prairie at the University of
Wisconsin Arboretum.
• The 4 r’s above indicate
different possibilities and
end
points of the process
• If no action is taken, the ecosystem might moderately improve or might get
somewhat worse.
• If only a few ecosystem processes or species are ‘restored’, but the system
remains far from its pristine state, the effect is called enhancement.
• If the ecosystem is significantly improved but remains quite distinct from its
pre-degradation condition, the effect is called rehabilitation. This is
frequently the objective in areas that have been strip mined (e.g. oil sands
in Alberta).
• Reclamation stabilizes land and restores sufficient soil to revegetate the
land, without attempting to restore the condition before mining.
• Replacement builds a new community that meets some set of conservation
objectives, but is unlike the one degraded. Constructed wetlands around
the Great Lakes fit into this category.
• Finally, restoration rebuilds an ecosystem little different than the pristine
ecosystem that was degraded.
• This approach represents what is done to the physical environment and to
plants in restoration. For animals there are translocation and
reintroduction (using captive-bred animals).
• All this suggests that with sufficient economic support, virtually
any ecosystem could be restored. However, it is inappropriate to
assume that true restoration is always or even frequently
possible
• However, sometimes real progress is made:
The dry forest in northeastern Guanacaste, Costa Rica, has been
actively under restoration.
1980
2000
• One of the important keys to restoration of Guanacaste dry
forest has been fire suppression. With fires (accidental and
intentional) large areas were maintained as pasture. Dry forest
trees were able to grow once more once fire was suppressed.
• In other systems, like prairie grasslands, fire is a tool used to
maintain and restore areas. Some fires happen accidentally,
and others are carefully controlled for management and/or
restoration.
• An accidental fire during the 1970s in what is now the Ojibway
Prairie Preserve shows you how rapidly the plant community
recovers.
Ojibway Prairie Preserve
spring, two years ago, just before the fire
2 weeks after the
fire
4 weeks after the fire
10 weeks after the fire
When a restoration project is to be implemented,
what are the important considerations?
The flow chart is useful in determining what is possible biologically
and physically, but there are steps not included in the flow chart:
• Site assessment – what was there, and what is there
now? What is the ownership and other legal
restraints on restoration? What can be learned from
other similar ecosystems in the region?
• Setting the goals – true restoration is rarely even
approachable; what are realistic goals for a project?
Funding limits, stakeholder interests, and physical
constraints examined in the flowchart all interact in
determining realistic goals.
• Designing the project – design needs to take into account
subjects you’ve seen in this course: genetics, population
biology, demography, community ecology, species (or trophic
level)
interactions, weather, and conditions of the physical
environment. Simple steps may have far reaching
consequences.
• The dry forest of Guanacaste required only re-establishment
of a natural fire regime and facilitation of seed dispersal from
forest remnants.
• In another example from the text, restoration of vernal pools
in California was achieved by using topsoil retained from
development to re-inoculate pools with natural microbial flora
and fauna.
• Implementing the project – what is done to reach the
restoration goals?
• Hydraulic shovels, bulldozers, and other heavy machinery can
be used to move earth or modify the landscape.
exp: Detroit River bank close to downtown. The objective is to
restore a ‘natural’ riverbank for both aesthetic and biological (fish
habitat) reasons.
• In other cases, e.g. restoring prairies, much of the work is done
with hand tools (shovels, hoes,…)
How is the success of a restoration program evaluated?
• One such method for objectively determining the success of a
restoration program is through a measure called the 'Index of
Biological Integrity'. This index feeds information from a suite
of indicators.
• For aquatic systems these might include: fish species richness,
presence of indicator taxa (e.g. those (in)tolerant of low
oxygen concentration), incidence of abnormalities, disease etc.
• IBI values for different times can be plotted to determine
whether progress has been made following implementation of
remedial action plans (RAPs).
• On the Great Lakes, 43 sites have been identified where water
quality is deemed degraded. For each of these Area of
Concern (AOC) sites (e.g. Detroit River, Hamilton Harbour,
Wheatley Harbour), RAPs are designed to identify and resolve
problems impairing water quality.
• Cultural Eutrophication and its attendant water quality
problems (e.g. anoxia) is one of the leading reasons why we
have Areas Of Concern on the Great Lakes (others are
due mainly to industrial activities and their waste products).
• Lake Erie faced a problem as a result of nutrient inflow,
mainly from the Detroit River and untreated sewage.
• The western basin of the lake experienced a slow increase in
nutrient loading until about 1940. The loading shot up from
sewage and agricultural fertilizer inflows until the mid-1960's;
human population in the watershed increased from 3.8 to 11
million between 1910 and 1960 (Sweeney 1993).
• By the mid 1960's, people were greatly concerned by surface
mats of the cyanobacterium Aphanizomenon
flos aquae and low oxygen levels in the west
and central basins.
• Anoxia caused massive invertebrate and fish die-offs. Mats
of the nuisance alga Cladophora glomerata washed ashore
with the dead fish. Beaches were closed to swimmers and
drinking water was tainted.
• All of this was due mainly to increased phosphorus levels in
the lake – from 7.5 µg/L in 1948 to 36 µg/L in 1962.
• Public outrage finally forced joint US-Canada efforts
(creation of the International Joint Commission) to reduce
inflows of phosphorus to the lake. The major sources were
municipal inflows from Detroit and Toledo.
• Overall inflow declined from 14,000 and 1,500 tonnes of
phosphorus per year in 1972 (USA and Canadian contributions,
respectively) to ~1800 and <200 tonnes per year in 1990 (Dolan
1993). These values were below the guidelines set for
improvement of water quality.
• Water quality improved dramatically, but we have seen
backsliding in the past decade in part due to diffuse input (runoff
from fields) and in part due to recirculation of nutrients by
invasive zebra mussels
Closed: western
Open: central
Ludsin et al. 2001.
• When we move from the large scale projects to attempts to
conserve individual species, different problems arise.
• A number of 'species restoration' projects have been quite
successful. For example, the California condor, peregrine falcon,
and Whooping crane have all increased in breeding programs so
that individuals are being released into the wild.
• However, re-introductions have sometimes been politically
controversial, and in other cases scientific questions have been
raised…
Re-introduction requires careful consideration of
genetic consequences. What are the concerns?
1.Captive-bred plants (or animals) may have been
subjected to much different selection pressures than
natural ones. When placed in the wild, they may not
tolerate new, natural selection pressures; when their
genes are mixed into wild populations, they may
weaken adaptations of wild populations.
2.There may be outbreeding depression when captivebred and wild populations reproduce.
3.Breeding between groups may “break up coadapted
gene complexes”.
4. Depending on relative numbers of natural and
captive-bred, reintroduced organisms, genetic
diversity and effective population size may be
negatively affected. Here’s a theoretical N for
small (40) and large (400) natural populations with
reintroduction from a captive population:
5. One reason for introducing fairly large numbers of
captive-bred individuals is maintenance of genetic
diversity. Successful introductions tend to be large
or to cause rapid increase in total population size.
Animal re-introductions have a slightly different set
of problems when compared to plants. Animals that
attract sufficient interest and support for this
expensive approach are typically charismatic species,
and frequently top predators. As a result, they are
significant concerns for human populations in areas
of re-introduction. Think of the black-footed ferret
and the Florida panther.
Because they are key species, the IUCN (1995)
developed guidelines (steps) for animal reintroduction:
1.Examine feasibility. That means ensuring that
species biology is suitable, there is a suitable
source of animals for the project, and that whatever
threats drove the population to endangerment or
extirpation are not still present.
2.Make sure there is suitable habitat for reintroduction within the historic range of the
species, and that protected status can be provided
for the re-introduced population.
3.Evaluate the genetics (similarity to natural
population, genetic diversity) of potentially reintroductions.
4.This is the political reality! – valuate support and
opposition to reintroduction, and that both longterm economic and political support is available.
5.Design the reintroduction to ensure potential for
long-term adaptive management. Since there have
been only a few re-introduction programs, more
about what makes such projects successful needs to
be known. The design should permit experimental
tests of methodology.
6.Make sure that, if necessary in adaptive
management, intervention is possible.
Why Protect and Restore?
In part, because it is required by legislation. Your text
covers American legislation, here we’ll review the
Canadian Acts:
Canada Water Act –
An Act to provide for the management of the water
resources of Canada, including research and the
planning and implementation of programs relating
to the conservation, development and utilization of
water resources. This is the act that prohibits
pollution in Federal waters, including waste
disposal.
Canada Wildlife Act (1985) –
The provisions of this Act respecting wildlife apply
to (a) any animal, plant or other organism
belonging to a species that is wild by nature or that
is not easily distinguishable from such a species;
and (b) the habitat of any such animal, plant or
other organism. It includes wildlife conservation
and wildlife research. The Minister of Environment
establishes advisory committees to determine status
and actions regarding rare and endangered species.
Actions are generally limited to ‘public lands’ and
marine areas.
Canadian Environmental Protection Act (1999) –
An Act respecting pollution prevention and the
protection of the environment and human health in
order to contribute to sustainable development. In
this act the government acknowledges the need to
integrate environmental, economic and social
factors in making decisions. With regard to
pollution, the ‘watchword’ is “virtual elimination of
persistent and bioaccumulative toxic substances”
and management if their release into the
environment cannot be prevented”. The
precautionary principle is embedded in the act.
There are many components to the Environmental
Protection Act. This is where the rules for strip mine
(and oil sands) reclamation and restoration are.
Regulations on PCBs, import and export of
hazardous materials, ozone-reducing substances
(CFCs), paper mill effluents (mostly mercurial
compounds), and phosphorus release from sewage
treatment are among a much larger number of
component parts of the act.
Migratory Birds Convention Act (1994) –
No person shall, without lawful excuse, (a) be in
possession of a migratory bird or nest; or
(b) buy, sell, exchange or give a migratory bird or
nest or make it the subject of a commerce.
Additionally, it’s illegal for vessels to foul nests,
birds, or their habitats. It’s not clear whether anyone
has been charged after spills.
Species At Risk Act (2002) –
An Act respecting the protection of wildlife species
at risk in Canada. The Government of Canada has
ratified the United Nations Convention on the
Conservation of Biological Diversity. This act
provides legal protection for species at risk and
complements existing legislation. A committee set
up by the Minister of Environment, the Committee
on the Status of Endangered Wildlife in Canada
(COSEWIC) advises the minister about species that
are in need of legal protection and/or recovery. The
act also recognizes shortcomings in designing
conservation plans:
1.knowledge of wildlife species and ecosystems is
critical to their conservation, and
2.the habitat of species at risk is key to their
conservation.
Wild Animal and Plant Protection and Regulation of
International and Interprovincial Trade Act ( 1992) –
This is the act that legislates Canada’s acceptance of
the terms of the CITES treaty.
References
Dolan, D.M. 1993. Point source loadings of phosphorus to Lake Erie: 1986-1990.
Journal of Great Lakes Research 19:212-223.
Gore, J.A., Jr. and F.D. Shields. Jr. 1995. Can large rivers be restored? Bioscience
45:142-153.
Ludsin, S. A. M. W. Kershner, K. A. Blocksom, R. L. Knight, and R. A. Stein. 2001.
Life after death in Lake Erie: Nutrient controls drive fish species richness,
rehabilitation. Ecological Applications 11:731-746.
Makarewicz, J.C. 1993. Phytoplankton biomass and species composition in Lake Erie,
1970 to 1987. Journal of Great Lakes Research 19:258-274.
Nicholls, K.H., G.J. Hopkins, and S.J. Standke. 1999. Reduced chlorophyll to
phosphorus ratios in nearshore Great Lakes waters coincide with the
establishment of dreissenid mussels. Canadian Journal of Fisheries and
Aquatic Sciences 56:153-161.
Sweeney, R.A. 1993. 'Dead' sea of North America? - Lake Erie in the 1960s and
1970s. Journal of Great Lakes Research 19:198-199.