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

Smoke-Cued Emergence in Plant Species of a Ponderosa Pine Forest: Contrasting

Greenhouse and Field Results

Scott R. Abella University of Nevada Las Vegas scott.abella@unlv.edu

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