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Fire severity and succession: spatial and temporal patterns and implications for herbivores

Fire severity and succession: spatial and temporal patterns and implications for herbivores. Fire severity. Patterns of vegetation dominance in the second decade of succession. Implications for herbivores. Post-fire residual organic layer depth as a metric of fire severity.

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Fire severity and succession: spatial and temporal patterns and implications for herbivores

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  1. Fire severity and succession: spatial and temporal patterns and implications for herbivores

  2. Fire severity Patterns of vegetation dominance in the second decade of succession Implications for herbivores

  3. Post-fire residual organic layer depth as a metric of fire severity • Carbon loss • Permafrost thaw • Post-fire soil moisture and temperature • Resprouting potential / seed availability • Post-fire seedling recruitment and establishment Shallow organic layer = high severity Deep organic layer = low severity

  4. Time Low severity burn Seedling recruitment and establishment phase Black spruce self replacement (Johnstone and Kasischke 2005) Mature black spruce High severity burn Time Persistent deciduous canopy presence?

  5. STUDY SITES • 1987 Granite Creek Burn- GC87 • 1994 Hajdukovich Creek Burn- HC94 • 1999 Donnelly Flats burn- DF99 • 1990 Tok burn – TK90

  6. Study sites in 1994 Hajdukovich Creek burn OL depth >8cm

  7. OL depth 4-8 cm

  8. OL depth 0-4 cm

  9. Changes in stand density and biomass from 8 yrs to 14 yrs post-fire Aspen • Stem density decreased • by 60 % • Biomass per unit area • increased ~2 fold • Average individual • biomass increased • ~ 3 fold

  10. Spruce • Stem density was • unchanged • Biomass per unit area • increased 40 fold • Average individual • biomass increased • ~ 30 fold

  11. Shenoy et al. 2011, FEM 261, pp 381-90 Fire severity effects on species recruitment and establishment patterns are persistent

  12. Fire severity- species composition relationships across multiple burns

  13. Shenoy et al .2011 Divergent successional trajectories are developing at two ends of the fire severity spectrum

  14. Growth rates of black spruce and aspen in low versus high severity sites (HC94 burn) Black spruce Aspen

  15. Willow biomass Biomass (g m-2)B Organic layer depth

  16. Persistent shift in forest composition Low severity High severity OL depth ~14 cm OL depth < 1 cm

  17. Forage availability in HC94 burn In high severity sites: Density of forage species (aspen, willow, birch) Browse production Browse removal per ha (x6) Browsing pressure was high throughout HC94 burn Rachel Lord thesis 2008

  18. Browse production and removal in HC94 burn Adapted from Paragi and Kellie 2008 ADFG

  19. High moose densities in the HC94 burn Kalin Kellie (ADFG) personal communication Densest moose populations (within GMU 20D) in areas that burned 11-30 years ago Maier et al. 2005, CJFR Vol.35 pp2233-2243

  20. Implications of variation in fire severity for herbivores FIRE Deciduous: coniferous biomass Forage availability Moose population density Fire severity Nutrition Forage accessibility Growth rates of aspen and spruce Site architecture Hunter success

  21. Thank you! Thank you! Knut Kielland Jill Johnstone Eric Kasischke Roger Ruess Field work: Kirsten Barrett Matt Borr Cameron Carroll Ben Cook Cassidy Phillips Adrian Rocha

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