LECTURE 23
CONSERVATION BIOLOGY 2 + RESTORATION ECOLOGY
MAJOR CONCEPTS
1. Conservation Biology relates to land use and landscape structure.
2. Habitat destruction and fragmentation cause 67% of all cases of recent extinctions.
3. Hotspots for immediate conservation: high # species + high # endemic species
4. Plan areas/habitats to preserve: A) if large uniform area available:
SLOSS: single large better than equal size of separate small
5. Plan areas/habitats to preserve: B) if diversity of area available:
Several small diverse better than one large uniform.
6. Plan for migration via corridors and ‘stepping stones’ in both types.
7. Consider community structure (e.g. top-down control, cascade effects, keystone sp.).
8. Large nearby subpopulations may rescue a small population from going extinct.
9. Chance events may cause small populations to go extinct.
Conservation Biology: Relate to Land Use and Landscape Structure
Conservation Planning: Approach 1: Single Species
Focus on rare, endangered species.
Focus on dynamics and genetics of small populations
Conservation Planning: Approach 2 Preserve areas/habitats
Hotspots: high # species + high # endemic species (only found there)
Deterministic causes of extinctions: the ‘evil quartet’
Habitat destruction and fragmentation (67% of all cases)
Problems associated with fragmentation
Introduction of exotic species
Eliminate native species and alter ecosystem function
Islands, disturbed habitats, and those near people especially vulnerable
Overexploitation
Often changes species composition
Chains of linked extinctions
Principles of design planning 1: (for large expanse of uniform habitat)
Larger area better than small
Why larger better?
SLOSS: single large better than equal size of separate small
Plan for migration via corridors and ‘stepping stones’
Advantages?
Disadvantages?
Circular (> interior/edge ratio) better than rectangular
Principles of design planning 2: (for creating out of diverse area)
Several small diverse better than one large uniform
Plan for migration via corridors and ‘stepping stones’
Consider community structure
Top-down control of trophic abundances
Cascade effects: indirect effects extended through multiple levels
Can have chain of extinctions if highly dependent
Keystone organisms must be preserved
Non-redundant species, key species that maintain stability/diversity
Population level….
Small populations: greater risk of extinction due to
Stochastic events
Subpopulations more isolated
Subpopulations with more synchronized fluctuations
Deterministic models
Based on large size; no variation in average birth and death rates
Stochastic (random) models
Randomness affects populations
Catastrophe
Temporal variation in environment
Stochastic (random sampling) processes
Chance events may cause small populations to go extinct
Probability of extinction
increases over time
decreases with larger initial population size
Small populations can go extinct due to random fluctuations in population size.
Rescue effect: immigration from large subpopulation keeps a declining population
from inbreeding and going extinct (source provides emigrants to sink)
Need corridors to connect source and sink
Summary 6-16
RESTORATION ECOLOGY
MAJOR CONCEPTS
1. Restoration ecology is an applied discipline dependent on firm understanding of
basic ecological processes.
2. It also is tightly embedded in a social context.
3. All subdisciplines of ecology from population through ecosytem contain principles
relevant for enhancing success of restoration projects.
Restoration Ecology: use research to understand ecological processes in highly disturbed
ecosystems  apply understanding to:
enhance their complexity and long-term persistence
increase diversity
reintroduce ecosystem function
biomass (energy flow; productivity) + nutrient content (cycles)
reestablish characteristic species, community structure + function
Relevant disciplines: Population, Community, Landscape, Ecosystem Ecology
Intertwined dimensions: Society, Politics, Economics, Policy
Ecological Theory Relevant to Restoration:
Population level –
Vulnerability of small populations
Stochastic extinction
Genetic variation/inbreeding depression
Minimum population viable size
Metapopulation dynamics
Use of locally adapted genotypes
Community Ecology
Species-Area relationship
Island Biogeography Theory
Fragmentation and patch size requirements of different groups of organims
Disturbance dimensions
Intermediate disturbance hypothesis
Succession
Species-Species Interactions as they influence community development
Facilitation
Inhibition
Tolerance
Causes of succession: site availability species availability species performance
Contributing processes: disturbance
dispersal
ecophysiology
propagules
life history
resources
stress
competition
allelopathy
herbivory
Community Assembly
Model of restoration as managing succession:
design a disturbance, control colonization, control species performance
Community Structure and Stability
Top-down control of trophic abundances
Trophic cascade effects: indirect effects extended through multiple levels
Chain of extinctions if highly dependent
Keystone organisms must be preserved
Non-redundant species, key species that maintain stability/diversity
Increase in structural diversity of vegetation increases species diversity.
Full restoration of native plant communities sustains diverse animal populations.
High diversity of plant species year-round food supply for greatest diversity of animals
Landscape Ecology
Take into account: Patch size + longevity, disturbance frequency, habitat requirements
Spatial concepts;
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
and species specific to the ecotone.
Ecosystem Ecology
Must have strong productivity to ensure sufficient energy flow to higher trophic levels.
Must ensure functional nutrient cycles
Must consider sources and sinks for energy flow and nutirent cycles