1. Outline Community Ecology Ecosystem Ecology
Indirect effects, Keystone species, Invasive species
Biodiversity: importance and evaluation
The new paradigm in ecology: communities in flux
Conservation of species interactions
Ecosystem Ecology
Ecosystem services
Biodiversity and ecosystem services
Ecosystems of special concern (Marine and Tropical)

2. Successful Biological Control

3. Is Biodiversity Important?
Conservation Biology Perspective
Inherently valuable
Utilitarian Perspective
Natural resources: Genetic libraries; natural design
Ecological Role
Invasibility
Stability
Ecosystem Function

4. Diversity and Invasibility
Tilman, D Community invasibility, recruitment limitation, and grassland biodiversity. Ecology 78:
Seeds from up to 54 plant species (native but mostly rare) were added to patches of native grassland
The % seeds established was negatively correlated with species diversity
Conclusion: Invasibility may decrease with biodiversity

5. Diversity and Stability
Year to year variability in species abundance higher in species rich plots
Year to year variability in total biomass lower in species rich plots
Effect of drought lower in spp. rich plots
Tilman, D Biodiversity: Population versus ecosystem stability. Ecology 77:

6. Diversity and Stability
Hypothetical Mechanism: When climatic variations harm some spp., unharmed spp. increase. This compensatory increases stabilize ecosystem processes (i.e. productivity) but cause populations to be more variable
This was apparent for both EV (non-drought years) and “catastrophes” (drought years)

7. What is “Stability” Historical Modern Operational
Constancy of ecological communities
Modern
Resilience
Operational
Variation in community or ecosystem processes

8. Tentative Conclusions
At the community level, species diversity may . . .
Increase stability (reduce invasibility)
Decrease stability (year-to-year variation in population abundance)

9. The “New” Paradigm in Ecology
Clements, F. E Nature and structure of the climax. Journal of Ecology 24:
Climax succession
Gleason, H. A The individualistic concept of the plant association. Bulletin of the Torrey Botanical Club 53: 7-26.
“Random” succession

10. The Land Ethic and Stability
"A thing is right when it tends to preserve the integrity, stability, and beauty of the biotic community. It is wrong when it does otherwise." - Aldo Leopold

11. Intermediate Disturbance Hypothesis
Number of species
Disturbance rate

12. Community Ecology and Conservation
classical paradigm contemporary paradigm
Natural systems closed open, subject to change
by natural/human events
Stable states 1 more than 1
Metaphor balance of nature flux of nature
Conservation any natural unit is manage process and
implication conservable; keep context, not species;
humans out humans included

13. Community Ecology and Conservation: Nested Communities

14. Community Ecology and Conservation: Nested Communities4 8 5 1 15 19 16 13 3 18 12 9 11 7 6 14 10 2 17 Eu x Ed Ml Mf Sp Op Sb