Reading for next lectures

1. Reading for next lectures • Textbook Chapters 8, 10, 12, 13

2. Seminars • Dr. Julia Koricheva, University of Turku, Finland. Direct and indirect costs of plant resistance to herbivores. EECB seminar Thurs Feb 26, 4:00 PM OSN 120

3. Outline • Herbivory in Australian woodland • Introduction to community ecology • Introduction to ecosystems ecology • Community concepts • Ecosystems analysis

4. Questions • How does herbivory affect woodland species? • Does habitat alter response to grazing or impact of herbivores? • Do different herbivores have different effects?

6. Photo: Taronga Zoo, Sydney NSW Photo: CSIRO Wildlife and Ecology

7. Burrendong Dam Study Area • Approx. 100 km2 in the Central West Slopes region, NSW, Australia near the center of White Box distribution. • Mosaic of eucalypt woodland, native pine woodland, cleared grassland, and alluvial flats.

8. Study Design • Fencing treatments established in January and February 1997 • 4 treatments (control, stock fence, kangaroo fence, rabbit fence) • 2 habitats (eucalypt woodland, cleared grassland)

9. Study Design 25m by 25m fences, four replicates Woodland Grassland control stock control stock kangaroo complete kangaroo complete Four Blocks Four Blocks

10. Study Design Transplants: Eucalyptus albens, Callitris glaucophylla, andThemeda australis. Planted in grassland and woodland plots in Apr 1998.

11. Summary • Three groups of grazing animals: • Four treatments: • Two habitats: • Three target species: • Monitored survival for all species, and created models based on size growth for trees.

13. Browse preferences Grassland Woodland

14. C S K R C S K R Eucalyptus mortality C-control S-Stock K-Kangaroo R-Rabbit # Trees Dead Grassland Woodland

15. C S K R C S K R Callitris Mortality 1-control 2-Stcock 3-Kangaroo 4-Rabbit C-control S-Stock K-Kangaroo R-Rabbit # Trees Dead Grassland Woodland

16. C S K R C S K R Woodland Grassland Themeda mortality C-control S-Stock K-Kangaroo R-Rabbit # Plants Dead

17. “Life history” transition diagram • Transitions between 5 size (height) classes for trees; final stage is “escape from herbivory”. • Models created for each habitat and treatment combination.

18. P 35 P 25 P P 15 P 14 24 P 13 P P P S P S S S S 23 34 45 12 3 5 1 2 4 P P P P P 22 33 44 55 54 P P P P 21 18 11 43 P P P 51 52 53 P 42 P 41 P 31 S S S S S S S S S S Matrix Two 1 2 3 4 5 Matrix One 1 2 3 4 5 P P P P P S [<25 cm] 0 P 0 0 0 S [<25 cm] 11 21 31 41 51 1 21 1 P P P P P S [25 - 49 cm] 0 P 0 0 0 S [25 - 49 cm] 12 22 32 42 52 2 22 2 P P P P P S [50 - 74 cm] 0 P 0 0 0 S [50 - 74 cm] 13 23 33 43 53 3 23 3 P P P P P S [75 - 100 cm] 0 P 0 0 0 S [75 - 100 cm] 14 24 34 44 54 4 24 4 P P P P P S [ >100 cm] 0 P 0 0 0 S [ >100 cm] 15 25 35 45 55 5 25 5

20. Summary • Plants in productive environment better able to compensate (more rapid growth) • High herbivory rate in unfenced low productivity habitats prevented “escape”. • This could have population consequences even though mortality was fairly low. • Differences in herbivore preference could be translated to community composition. • Interaction between competition and herbivory…tradeoff.

21. Community and ecosystems ecology • Community ecology: study of all organisms (plants?) in a given area. = synecology; species/organism based. • Ecosystems ecology: study of energy and matter flows, productivity, and cycling. Process/energy based.

22. Community and ecosystems ecology • Forest and range ecosystem function, management, and productivity can be viewed from either community or ecosystem viewpoint:

23. Historic community concepts Clements (1905): “super-organism” concept. • Plant species associate/co-occur in a predictable way, proceeding to a “climax” configuration determined by climate. • A community has emergent organism-like properties; can be classified into distinct idealized types. • In North America, 3 climax types: grassland, scrub and forest. Divided into subtypes (e.g. true grasslands VS sedge meadows; sagebrush VS desert scrub VS chaparral; coastal VS montane forest), then into “associations” (= communities). • Distinctions often driven by most obvious plant species (e.g. trees) • Basis for ecological site types, potential vegetation, and community classifications used by BLM and USFS

24. Historic community concepts II Gleason (1917): individualistic concept • Each species responds individually to environment and species around it. • There are no predictable associations or emergent “organismal” properties • Plant associations do exist – we can see them, describe them, relate them to environment; BUT they are due simply to juxtaposition of individual plants • “[the community] is not an organism, but merely a coincidence” • Some argue that Gleason downplays importance of site characteristics (soils, water, nutrients) too much…

25. Current understanding • Closer to Gleason’s than to Clements’s view • Communities are identifiable, but boundaries can be vague • “Climax” now used for communities undisturbed long enough to pass through several generations of dominant species • “Super-organsism” concept still shows up in some definitions of ecosystems and ecosystem management • “Ecological site” descriptions try to include ecosystem properties as well as vegetation composition

26. Ecosystems ecology • Concerned with nutrient fluxes, biogeochemical cycles, and energy balances. • Ecosystems analysis (p 358 text). • Long term monitoring of ecosystem (watershed). • Measurement of nutrient and water fluxes andcycling, as well as productivity. • Create nutrient budgets. • Other means of investigating: microcosms; computer simulations.