Download Lecture 21 ICA 4 RESTORATION ECOLOGY 1. Why is Illinois in

Lecture 21 ICA 4 RESTORATION ECOLOGY
1. Why is Illinois in great need of restoration of habitats? It has nearly the lowest among
all 50 states in % of natural areas remaining.
2. What is restoration ecology? Study of how to understand ecological processes in
highly disturbed ecosystems in order to know how to enhance their complexisty and
long-term persistence
What ecological disciplines are relevant to address restoration problems?
Population, Community, Landscape, and Ecosystem Ecology
3. What is meant by ecosystem structure? = Species diversity; food web complexity
by ecosystem function? = Energy flow + cycling of matter
4. Differentiate among:
Reclamation: increase diversity in highly disturbed ecosystem
Rehabilitation: reintroduce ecosystem function
Restoration: reestablishment of functions and characteristic species, communities,
and structure
Reconstruction: starting restoration from scratch
5. What social disciplines intersect with restoration ecology? economics; politics,
policy; social sciences
6. What principles of population ecology are relevant for restoration ecology?
Vulnerability of small populations
Watch for genetic inbreeding depression; aim for high genetic diversity.
Source of colonists: need to use locally adapted genotypes
Stochastic extinctions; maintain a minimum viable population size (500)
Take meta-population theory into account; how connected will local restored area
be to other subpopulations for sources of immigrants and gene flow?
7. How is a species-area curve relevant to restoration ecology?
It helps to identify the number of species gain as area of restored area increases; it
also indicates the area above which no further gains in species is likely.
8. How is Island Biogeography Theory relevant to restoration ecology?
The restored area is probably an island in a non-hospitable matrix. The equilibrium
number of species in the restored area may depend on area size and extent of
proximity to large‘ mainland’ source area of immigrants.
9. What is the ‘take-home’ message about the influence of patch size on different
biotic components of the community? Some components of a community’s
biodiversity are more sensitive than others to patch size for maintaining their
presence.
10. What are three dimensions of importance in describing a disturbance?
Frequency Severity
Spatial extent
11. How much disturbance will be favorable for maintaining the most species in a
restored area? Why? “Intermediate’ level because too low disturbance will allow
competitive exclusion to occur; too high disturbance will lower species number to
the few species that have evolved to deal with such a high level of stress.
12. What is an example of reversible vs. permanent conversion of habitat by a
natural disturbance? Fire (reversible); Volcanic eruption (long-term)
anthropogenic event? Logging (reversible); Shopping mall (permanent)
13. Why is succession theory relevant to restoration ecology?
Many areas undergoing restoration have been ‘set back’ to earlier stages of
succession; e.g. they may have only soil and dormant seeds in soil and no
vegetation.
Restoration can rely, in part, on natural succession to aid in restoration of the land.
14. How do species-species interactions influence restoration efforts?
Facilitation can be used to accelerate restoration; e.g. planting of nurse crops may
bring soil restoration more quickly.
Inhibition by one species of other species’ entry and success is to be avoided. E.g.
early prairie construction may bring in warm season grasses that inhibit cool
season grasses and forbs.
15. What is community assembly? The ‘rules’ followed as a community develops in
terms of which components/species occur in the mature community; it is often
determined by random variation in species’ colonization and / or subsequent
species interactions.
How does it differ from succession? Succession is deterministic (predictable?) and
is driven by internal interactions and the environment. Assembly is stochastic. The
particular supply of colonists determines the outcome so that many different stable
assemblies are possible.
16. What are three general ‘causes’ of succession? A Site availability; B species
availability; and C species performance (once arrived)
17. What are contributing processes to each cause?
A. disturbance
B. dispersal; progagules; resources
C. Ecophysiology; life history; stress; competition; allelopathy; herbivory
18. Give an example of a modifying factor for each cause.
A. Size, severity, time, spatial pattern
B. Landscape configuration; dispersal agents; time since disturbance; soil;
C. Germination requirements, PS rate; growth rate; reproduction timing/mode;
resource availability; soil chemistry; microbes; neighboring species; climate;
plant defenses.
19. Comment on this statement: “Restoration is the practice of managing succession”.
A restoration ecologist may let ‘nature’ undergo some natural succession or try to
manipulate/manage the path of vegetation development on the site. By managing,
he/she can design the nature of the disturbance (e.g. fire), control what species
colonize (by artificial plantings), and control species performance (by weeding, using
herbicides, fertilizers, etc.)
20. What are examples of how restoration is put into practice?
Designed disturbance: Use burning, bulldozing; clipping; plowing, correct soil
properties
Controlled colonization: Use broadcast seeding; drilling; direct planting;
Controlled species performance: Use fertilization, herbicide, irrigation, topsoil,
mowing, removal of invasive species;
21. What principles are related to species diversity and a stable restored community?
Increase in structural diversity of vegetation increases species diversity.
Full restoration of native plant communities sustains diverse wildlife populations.
High diversity of plant species ensures year-round food supply for the greatest
diversity of wildlife.
Top-down control of trophic abundances may ultimately affect species abundances.
Cascade effects (indirect effects extended through multiple levels) will occur.
Keystone organisms (non-redundant species, key species that maintain stability /
diversity) may need to be deliberately introduced and maintained.
22. How is landscape ecology relevant to restoration ecology?
A restored area cannot be viewed in isolation (as a postage stamp all alone). It
exists in the context of its surrounding landscape that will influence its long-term
success.
What spatial principles are relevant in designing a restoration project?
Large areas sustain more species than small areas.
Many small patches in an area will help sustain regional diversity
Patch shape is as important as size.
Fragmentation of habitats, communities, and ecosystems reduces diversity.
Isolated patches sustain fewer species than closely associated patches.
Species diversity in patches connected by corridors > than for disconnected patches.
A heterogeneous mosaic of community types sustains more species & is more likely
to support rare species than a single homogeneous community.
Ecotones between natural communities support a variety of species from both
communities & species-specific to the ecotone.
23. Why must ecosystem ecology be considered in designing a restoration project?
NPP + energy flow must be considered if the restored area is to be sustained.
The area is affected by processes in the abiotic component of the restored area, in
addition to the biotic community restored. The community will not thrive if the
cycles are not functional.