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Vegetation Types of North America

Vegetation Types of North America. Handy descriptors. Growth form spectrum : % spp. phanerophytes, chamaephytes, hemicryptophytes, geophytes, therophytes. Handy descriptors. Precipitation/Evapotranspiration (P/E) Ratio Precip.: . Evapotranspiration (potential evapotranspiration):

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Vegetation Types of North America

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  1. Vegetation Types of North America

  2. Handy descriptors • Growth form spectrum: % spp. phanerophytes, chamaephytes, hemicryptophytes, geophytes, therophytes

  3. Handy descriptors • Precipitation/Evapotranspiration (P/E) Ratio • Precip.: • . • Evapotranspiration (potential evapotranspiration): • Ratio > 1 wet, < 1dry • NPP: Net primary productivity

  4. Tundra • Hi latitude (arctic) or hi elev. (alpine) • 20% N. America (lavender) • Cold! Growing season <3 mo. Lo NPP. • Lo precip.: high P/E ratio (why?)

  5. Growth Form Spectrum: Tundra • Solution: grow low (no trees!) • Growth form % • Phanerophytes 0 (min.) • Chamaephytes 23 • Hemicryptophytes 61 (max.) • Geophytes 15 • Therophytes 1 (min.)

  6. Tundra • Special growth form: cushion plant Alpine tundra

  7. Conifer forest • Covers more N. America (lt. green)

  8. Conifer forest • Several types: boreal forest (hi latitude)

  9. Conifer forest • Other conifer forests (hi altitudes): • Spruce-fir (S. Appalachians) • Mixed conifer: Rockies, Cascades/Sierra Nevada Spruce-fir forest Mt. Mitchell, N. Carolina

  10. Conifer forest • Cold winters: growing season 3-4 mo. • P/E > 2 Lake Tahoe (6624 ft. elev.) June 1983 9,000 ft

  11. Conifer forest • Highest LAI (9-11): conifers+ summer herbs

  12. Conifer forest • Soils: acid, leached (E & Bh horizons) • Order: Spodosol • CEC: hi or lo?

  13. Growth Form Spectrum: Conifer Forest • Growth form % • Phanerophytes 15 • Chamaephytes 9 • Hemicryptophytes 51 • Geophytes 19 • Therophytes 6

  14. Ecotone between conifer forest/tundra • Timberline or treeline: tree

  15. Ecotone between conifer forest/tundra • Twisted tree form: krummholz • Enforced by environment (review: how test?)

  16. Ecotone between conifer forest/tundra • Flagging: pruning

  17. Ecotone between conifer forest/tundra • Why timberline? Lack NPP=Gross Ps-resp.

  18. Deciduous forest • Our trips

  19. Deciduous forest • Greatest rainfall • P/E= • Greatest NPP Liriodendron: 1990 Plant Ecology trip to Joyce Kilmer Memorial Forest, North Carolina

  20. Growth Form Spectrum: Deciduous forest • Growth form % • Phanerophytes 26 (tied max.) • Chamaephytes 3 (min.) • Hemicryptophytes 44 • Geophytes 20 • Therophytes 7

  21. Deciduous forest: Review Spring herbs Summer green herbs Late-summer herbs Semievergreen herbs

  22. Deciduous forest: Review • Seed dispersal by ants (term?): Herbs (30-70%!) Viola seed: name of “food body?”

  23. Deciduous forest: Review • Disturbance

  24. Deciduous forest: Review • Physical • Chemical • Behavioral • Crypsis (camouflage/mimicry) • Associational • Plant Defenses

  25. Deciduous forest: Review • Relationship?

  26. Grasslands • Central/Western North America

  27. Grasslands • Several types: shortgrass, mixed grass, tallgrass Palouse grassland Grassland-forest ecotone Annual grassland Desert grassland

  28. Grasslands • P/E ratio • LAI = • NPP 2nd highest

  29. Grasslands • Soils: thick dark A horizon! • Order?

  30. Growth Form Spectrum: Grassland • Growth form % • Phanerophytes 2 • Chamaephytes 23 • Hemicryptophytes 46 • Geophytes 3 • Therophytes 14

  31. Grass life forms • Annual, bunchgrass, sod-forming (fire resistant)

  32. Grass review • Community history

  33. Grass review • Herbivore counterdefenses

  34. Grass Ps types • Latitude gradient: C3 (cool-season) north, C4 (warm-season) south

  35. Grass Ps types • C4 review….. PEP Carboxylase Rubisco

  36. Carbon isotope ratios C4 • Enzyme affinity CO2 • Rubisco: less • PEP carboxylase: more • C3 delta C-13; • C4 delta C-13; • More negative = • more discrimination

  37. Herbivore Feeding Preferences Ex., rhinos Africa Black rhino: more rare (3,600).

  38. Herbivore Feeding Preferences White rhino: less rare (11,700).

  39. Herbivore Feeding Preferences Rhino poaching:

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