1. Ecosystem Restoration Repaying the Ecological Debt

2. Conceptual issues After manipulation of a natural system, have three choices:

4. Ecosystem Restoration Restoration – bring back to pre-disturbance condition Rehabilitation – partial replacement of original ecosystem Enhancement – alternative ecosystem Note: to understand above scenarios of recovery have to consider two biological factors of colonization and succession

5. Colonization and Succession - Both are ecosystem changes with time 1. Colonization – arrival of new species in an empty patch Colonization of “bare” areas based on MacArthur and Wilson theory of island biogeography  CONSIDER DENUDED PATCHES AS ISLANDS Ex. Clear-cuts, strip mine are islands in a “sea” of mixed deciduous forest

6. Time (t) Species (s) Seq G = ____ = colonization rate ∆S ∆t S = Seq (1-e -Gt ) 1.Number of species depends on colonization rate (G) 2.G starts out high, gets smaller and smaller 3.Colonization rate based on two relationships

7. inhospitable terrain “islands” (clear-cut, toxic waste site, strip mine) Species source (mainland, deciduous forest) ▲ Longer distance from source (mainland) = lower # of species

8. inhospitable terrain Larger patches = higher probability of being “hit” by propagules ▲ Increased size/area = increased # of species on islands

10. Seq

11. Factors Affecting Colonization Rates Proximity to source Kind of organism (vagility) Reproductive rate (r- vs K- selection) Air, water currents (rafting) Residual disturbance, toxics Competition Habitat diversity and quality Generalist/Specialist Immigration Extinction Note: once reach equilibrium  dynamics become interactive = succession

12. Time (t) Species (s) Seq Non-interactive Interactive = succession

13. Succession Orderly change in community composition over time Usually follows colonization  especially studied in plant communities Two models –r–relay floristics –i–initial floristics

14. Relay floristics Crop Weeds | Grassland | Shrubland | Forest Abandonment Years Species

15. Initial floristics Crop Weeds | Grassland | Shrubland | Forest Abandonment Years Species

16. Implications for Reserve Design better worse A B C D E F

17. Significance to restoration of altered ecosystems Relay floristics – ongoing process based on external input Initial floristics – happens all at once based on internal input ▲Might have to manage system to help recovery - stock fish - soil stabilization with annual plants - etc.

18. Tionesta Natural Area, Allegheny National Forest, PA Photo by R. Grippo