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School of Life Sciences

School of Life Sciences. Smoke-Cued Emergence in Plant Species of a Ponderosa Pine Forest: Contrasting Greenhouse and Field Results

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School of Life Sciences

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  1. School of Life Sciences Smoke-Cued Emergence in Plant Species of a Ponderosa Pine Forest: Contrasting Greenhouse and Field Results Scott R. AbellaUniversity of Nevada Las Vegas scott.abella@unlv.edu http://faculty.unlv.edu/abellas2/

  2. Introduction • Importance of seed germination • Seed exposure to smoke • Smoke-stimulated germination • Butenolide compound1 1Flematti, G.R., et al. 2004. A compound from smoke that promotes seed germination. Science 305:977.

  3. Introduction • Fire effects, smoke technology • Seed, seed bank, field research • Many factors could affect response • Most field research in Australia • Mixed results

  4. Objective • Frequent-fire ponderosa pine forests • Determine effects of smoke at 3 scales: (i) seed, (ii) seed bank, (iii) field • Grazing interaction in field experiment

  5. Methods Seed Experiment • 61 native species • Liquid smoke applied to soil Seed Bank Experiment • 9 sites, 2 plots per site averaged • 0-5 cm mineral soil • 10-month emergence period

  6. Field Experiment • 9 thinned sites, two 20 × 25 m plots • Regen Direct (Forest Flavors, Inc.) 10 m2 exclosure and paired area open to grazing on each plot Split-plot design with covariate Pre-tmt, 15 months post-tmt

  7. Results Seed Experiment • Overall positive effect, no neg. effect • Promoted 5/8 Penstemon (P < 0.01) Penstemon barbatus Error bars = 1 SD USDA Plants Database

  8. Seed Bank Experiment 67% increase of emergents 60% increase in richness t = -2.56, P = 0.03 t = -2.41, P = 0.04

  9. Seed Bank Experiment • Smoke results in general increase • Composition (MRPP, P = 0.36) Relative seed density (%) Control SmokeErigeron flagellaris11 12Erigeron divergens57Carex geophila 4 5Muhlenbergia montana 0 1

  10. (b) Richness/m2 (b) Richness/m2 aaaaaaaaa Field Experiment Split-plot analysis of cover, richness Smoke P = 0.24-0.73 Interaction NS Grazing P = 0.04-0.09 Covariate Sig. C c c (a) 1 m2 No. species No. species (b) 9 m2

  11. Ordination, Sørensen comparison No effect on community composition

  12. Discussion • Study limitations – e.g., • variable seed genetic sources • greenhouse conditions • Smoke enhanced emergence in seed and seed bank greenhouse experiments, but not in field experiment

  13. Field outcome • smoke application rate – within range of Australian studies of varying outcomes • timing: June 22-23 application corresponded to historical fires • Precip: 112% in 2005 tmt year, 72% 2006 post-tmt but July-Aug 128%

  14. Field outcome • Seed bank composition – Penstemon uncommon • Time since fire1 • Other cues • Thinning 1Van Horne and Fulé. 2006. Comparing methods of reconstructing fire history using fire scars in a southwestern United States ponderosa pine forest. CJFR 36:855-867.

  15. Smoke only one component of fire • Heat1, pine charred wood2 • Fire cues relative to altered post-fire/thinning environments • Uses: • Seed bank assays • Pre-tmt of seeds 1Huffman, D.W. 2006. West. North Am. Nat. 66:365-373. 2Abella, S.R., et al. 2007. CJFR 37:552-567.

  16. Acknowledgments Sam Crace (“Charcoal Sam”), Forest Flavors, Inc., Kentucky, donated Regen Direct Judy Springer, Kyle Christie, Brian Zimmer, and students/staff at NAU ERI for help with fieldwork Don Normandin, Matt Tuten, and Luke Brandy installed exclosures Brad Blake and Phil Patterson, NAU research greenhouse J.J. Smith, Keith Pajkos, and NAU Centennial Forest Wally Covington and the NAU ERI

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