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Smoke-Cued Emergence in Plant Species of a Ponderosa Pine Forest: Contrasting
Greenhouse and Field Results
Scott R. Abella University of Nevada Las Vegas [email protected]
http://faculty.unlv.edu/abellas2/
School of Life Sciences
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.
Introduction
Fire effects, smoke technology
Seed, seed bank, field research
Many factors could affect response
Most field research in Australia
Mixed results
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
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
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
Results
Seed Experiment
• Overall positive effect, no neg. effect
• Promoted 5/8 Penstemon (P < 0.01)
0
10
20
30
40
50
60
70
80
Control Smoke
Em
erg
en
ce
(%
)
Penstemon barbatus Error bars = 1 SD
USDA Plants Database
t = -2.56, P = 0.03
t = -2.41, P = 0.04
Seed Bank Experiment
67% increase of emergents
60% increase in richness
Seed Bank Experiment
• Smoke results in general increase
• Composition (MRPP, P = 0.36)
Relative seed density (%) Control Smoke Erigeron flagellaris 11 12 Erigeron divergens 5 7 Carex geophila 4 5 Muhlenbergia montana 0 1
0
4
8
12
16
20
24
Control Smoke
Grazed
Ungrazed
(b) 9 m2
No
. sp
ecie
s
0
2
4
6
8
10
12
Grazed
Ungrazed
No
. sp
ecie
s(a) 1 m2
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
aaaaaaaaa
Ordination, Sørensen comparison No effect on community composition
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
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%
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.
• Smoke only one component of fire
• Heat1, pine charred wood2
• Fire cues relative to altered post-fire/thinning environments
1Huffman, D.W. 2006. West. North Am. Nat. 66:365-373. 2Abella, S.R., et al. 2007. CJFR 37:552-567.
Uses:
• Seed bank assays
• Pre-tmt of seeds
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