23 Conservation + Restor

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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

I. Conservation Planning: Approach 1: Single Species

Focus on rare, endangered species.

Focus on dynamics and genetics of small populations

II. Conservation Planning: Approach 2 Preserve areas/habitats

Hotspots: high # species + high # endemic species (only found there)

III . Principles of design planning 1: for large expanse of uniform habitat

A. Larger area better than small

Why larger better? see ICA 8 from Part 2

B. SLOSS: single large better than equal size of separate small

C. Fragmentation into small patches brings:

reductions in: total area, interior/edge ratio, habitat heterogeneity, connectivity

makes migration difficult with changing climate

D. Plan for migration via corridors and ‘stepping stones’

Advantages:

1. Support more species by reducing chance of stochastic extinction.

2. Promote genetic diversity.

3. Buffer populations against disturbance.

4. Avoid ‘edge effects’.

5. Offer freedom to migrate without going outside of normal habitat

Disadvantages:

1. Risk spread of disease, weeds, invasive species between patches.

2. Predators learn corridor route.

3. Disrupt local adaptations and cause outbreeding depression.

E. Circular (> interior/edge ratio) better than rectangular

IV. 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’

V. 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

Greater species diversity enhances chance of recovery from disturbance

VI. Consider population ecology

A. Small populations: greater risk of extinction due to

Stochastic events

Subpopulations more isolated

Subpopulations with more synchronized fluctuations

B. Deterministic models

Based on large size; no variation in average birth and death rates

C. 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.

D.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

IRESTORATION 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.

I. Restoration Ecology:

A Use research to understand ecological processes in highly disturbed ecosystems

B 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

C Relevant disciplines: Population, Community, Landscape, Ecosystem Ecology

D Intertwined dimensions: Society, Politics, Economics, Policy

Ecological Theory Relevant to Restoration:

II. Population level –

A Vulnerability of small populations

Stochastic extinction

Genetic variation/inbreeding depression

B Minimum population viable size

C Metapopulation dynamics

D Use of locally adapted genotypes

III.Community Ecology

A Species-Area relationship

B Island Biogeography Theory

C Fragmentation and patch size requirements of different groups of organims

D Disturbance dimensions + Intermediate disturbance hypothesis

E Succession

1 Species-species Iinteractions as they influence community development

Facilitation

Inhibition

Tolerance

2 Causes of succession: site availability species availability species performance

3 Contributing processes: disturbance dispersal ecophysiology

propagules life history

resources stress

competition

allelopathy

herbivory

4 Model of restoration as managing succession:

design a disturbance, control colonization, control species performance

5Community Assembly

F 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 for greatest diversity of animals

IV.Landscape Ecology

A Take into account: Patch size + longevity, disturbance frequency, habitat requirements

B Spatial concepts;

Large areas sustain more species than small areas.

Many small patches in an area will help sustain regional diversity.

C Patch shape is as important as size.

D Fragmentation of habitats, communities, and ecosystems reduces diversity.

E Isolated patches sustain fewer species than closely associated patches.

F Species diversity in patches connected by corridors > than for disconnected patches.

G A heterogeneous mosaic of community types sustains more species & is more likely to

support rare species than a single homogeneous community.

H Ecotones between natural communities support a variety of species from both

communities and species specific to the ecotone.

V.Ecosystem Ecology

Havestrong productivity to ensure sufficient energy flow to higher trophic levels.

Ensure functional nutrient cycles

Consider sources and sinks for energy flow and nutirent cycles

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