Paradigm Shifts in Conservation Ecology: Exploring Population Dynamics and Biodiversity

1. DOMINANT AND EMERGING PARADIGMS IN CONSERVATION ECOLOGY The meaning of "paradigm" as a scientific "world view"How and why paradigms change

2. Dominant paradigms of previous decadesAn old and enduring question: "What controls population dynamics?"

3. 1. Population dynamics driven by the environment, especially weather • Thrips, roses, weather • Popular in Europe and Australia • Emphasizes stochastic (chance) over deterministic, not directly density-dependent • Useful in degree-day models for biological control

4. thrips Thrip damage on roses Severe winters increase mortality of deer but increase survival of grizzly bear and wolf young

5. 2. Population dynamics driven by competition • Common idea in New World • Influence of Darwin and Hutchinson • Fundamental vs realized niche gave rise to idea of community matrix and field tests • Deterministic generally but stochastic processes can be important

6. African grazing animals: Competition can have strong temporal component Plants frequently compete for nitrogen in temperate zone and phosphorus in tropics

7. 3. Population dynamics driven by predator x prey • Wildlife management • Early interest from presumed conflict with human hunters; livestock death • Ideas: search-handling, prey dispersal, predator satiation, prey refugia • Keystone predator, competition, diversity • Deterministic and stochastic

8. Starfish as keystone predators may reduce competition from mussels and enhance biodiversity. Crown of thorns starfish may reach large numbers and reduce coral biodiversity.

9. Large area required Genetics and behavior Refugia for prey Predators can be prey

10. The other old and enduring question, "Why are there so many species?" Evolutionary Versus Ecological time

11. Biodiversity in evolutionary time • Biogeography (ancient legacies) • Stable environments facilitate narrow niches, hence more species packing (rainforests and deep ocean??) • Speciation following dispersal barriers • Speciation following major extinctions

12. Biodiversity cycles over geological time. Rainforest diversity ?? Deep ocean vents have rich diversity

13. Biodiversity in ecological time • Environments that are both highly productive and heterogeneous have high biodiversity (not always) • Stable competitive environments should have fewer species due to displacement (note contrast with speciation) • Highly variable environments dominated by colonizing species, diversity low

14. Emerging Paradigms • New emphasis on spatial and temporal scale-dependent processes • Coupling population dynamics with ecosystem analyses

15. Metapopulation of mountain lions in So California. Some are sinks (e.g.,Laguna)

16. Stability at the large scale is dependent on non-stability processes acting at smaller scales • Coupling bottom-up with top-down processes (forest example) • Communities are comprised of a mix of weakly and strongly interacting species (esp. protect keystone species/resources)

17. Stability at the large scale is dependent on non-stability processes acting at smaller scales (forest example) • Coupling bottom-up with top-down processes (forest example) • Communities are comprised of a mix of weakly and strongly interacting species (esp. protect keystone species/resources; sometimes conflicts with people, sometimes stewardship)

18. Forest canopy looks homogeneous and stable at this scale

19. Spatial heterogeneity is evident from digitized image (left) and very evident from enhanced spectral imagery (below)

20. At a smaller scale you may pick out particular causes of spatial heterogeneity. Pine bark beetles kill trees (left) which eventually result in forest patches of different ages (below)

21. At the smallest scale critically important processes of nutrient uptake take place that influence productivity and additional spatial heterogeneity.

22. To understand forest structure and change you need to understand top-down processes (disease, fire, beetles) and bottom-up processes (nutrient uptake). Spatial and temporal scales are very different.

23. Ecosystems are open so landscape scale is important (from small ponds to “dead zones” • Ecosystems have characteristic disturbance regimes (complicated by changing environment) • Rare episodic events can leave legacy (Mt St Helen eruption) • Legacies generally important (pig and cattle drive example)

24. Intermediate Disturbance Hypothesis originated with Connell’s observation of tree falls in Australian rainforests.

25. Frequency distribution of gaps created by tree falls gave rise to the Intermediate Disturbance Hypothesis…important in forest management Boulders of different sizes (=different stability) used to test Intermediate Disturbance Hypothesis

27. Disturbance patches may be small, as in this leaf-cutter ant colony.

28. Or very large. This is Mt. Saint Helens, 1970, pre-eruption

29. Mt. Saint Helens after the 1980 eruption

30. Disturbances have a natural history and a legacy of effects. Time of eruption in spring was important. Many small animals survived in pocket gopher burrows. Seeds of many plants were stored in marmot burrows.

31. Hurricane Dean Monday afternoon…heading towards the Sian Kaan reserve as a category 5 storm. Dean’s path over the ocean leaves cool and nutrient-rich waters.

32. H. Dean cat. 4 skirts the south coast of Jamaica

33. H. Dean and house destruction in Kingston, Jamaica

34. Sian Kaan Biosphere Reserve. About 30 miles north of the eyewall of H Dean. This is the zone of greatest wind and ocean surge forces.

35. Indigenous maya living in the Sian Kaan Biosphere Reserve harvest conch and spiny lobster on a sustainable schedule.

36. Spiny lobster

37. Why H Dean did little damage to Sian Kaan….mangroves absorb the storm energy

38. Typical dense stand of mangroves along estuary

39. Mangroves protecting the Sian Kaan lagoon where conch and lobster are harvested. The mangroves provide a critical “environmental service”…a rapidly emerging paradigm or focus in conservation biology.

40. Mangroves destroyed to make a shrimp pond. An economically and environmentally important ecosystem (environmental service) is replaced by a short-term economic activity. Shrimp ponds in mangroves are often drug-laundering operations.

41. Shrimp ponds can be sustainably operated in mangrove regions if they are located on mudflats.

42. Finding the appropriate economic and environmental value of ecosystems as environmental services is a major focus of conservation. • Watersheds • Riparian forests • Salt marshes • Many other examples

43. Ecosystem Services People are both players and stakeholders in conservation initiatives and ecosystem processes in general. Recognizing and measuring “Ecosystem Services” (natural and economic value of the environment) is an increasingly important goal for conservation ecologists.

45. Decline of pollinators represents loss of a major environmental service.

46. Why are pollinators declining so rapidly??? 36% of honeybee hives lost 2007. Native bee decline?? Disease (several exotic) Chemicals to control varroa mites make honeybees susceptible to disease Pollutants Future…Climate change uncouples flower phenology from bee emergence.

47. Many scientists now believe that disease is an important component in shaping populations and communities

48. Domestic cats are hosts for toxoplasmosis. Lethal to sea otters and of increasing concern for humans (zoonotic). Avian malaria especially serious for island populations that lack resistance. Mosquito vector feeding on Hawaiian Honeycreeper.

49. But like other themes in conservation, disease is also investigated in a larger environmental context.

50. Mystery of lion population crashes