Transcript Physiological mechanisms of sustained growth despite crown scorch in a young longleaf pine plantation

PHYSIOLOGICAL MECHANISMS OF
SUSTAINED GROWTH DESPITE
CROWN SCORCH IN A YOUNG
LONGLEAF PINE PLANTATION
Mary Anne Sword Sayer1, Stanley J. Zarnoch2, and
James D. Haywood1
U.S. Forest Service, Southern Research Station,
1Pineville, Louisiana
2Asheville, North Carolina
2011 Ecological Society of America Annual Meeting, August 7-12 2011, Austin Texas
PRESENTATION OUTLINE
 Introduction
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Longleaf pine (Pinus palustris Mill.) and fire
Longleaf pine restoration
Obstacles to longleaf pine restoration
 Experimental

results from central Louisiana
Physiological mechanisms that sustain the growth of
forests that are frequently burned.
 How
does season of fire impact these
physiological mechanisms?
PHYSIOLOGY OF SUSTAINED LONGLEAF PINE GROWTH IN RESPONSE TO FIRE
INTRODUCTION


Range once extended from
east Texas to the Atlantic
coastal plain of the U.S.
Now found on 3.8% of its
historical range.
Range-Wide Conservation Plan for Longleaf Pine 2009. americaslongleaf.com
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Adapted to, and benefits
from frequent low intensity
fire.
Ecosystem flora and fauna
are perpetuated by fire.
Repeated fire every 2 to 5
years is used to manage
longleaf pine ecosystems.
PHYSIOLOGY OF SUSTAINED LONGLEAF PINE GROWTH IN RESPONSE TO FIRE
INTRODUCTION
 Increased
interest in restoring longleaf pine
Regeneration success is likely.
 Highly diverse ecosystems with 29
federally listed TES.
 May be more tolerant of climate
change than other southern pines
(e.g., hurricanes, drought).


Loblolly pine
Longleaf pine
Photos: Glenn Hughes. Mississippi State University Extension Service.
[email protected].
Range-Wide Conservation
Plan for Longleaf Pine
calls for an increase in
longleaf acreage from 3.4
to 8 million by 2024.
INTRODUCTION

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Successful longleaf pine restoration depends on fire as a tool.
Obstacles must be overcome for fire to be welcome on private lands.
Growth responses to fire are inconsistent and may be negative.
● Out of prescription
● Introducing fire / heavy fuel load
heat damage to shallow roots
heat damage to vascular
cambium
heat damage to buds
● Unknown reasons
Negative
○ Boyer (1987) South J Appl For
11:154-157.
○ Johansen and Wade (1987) South
J Appl For 11:180-184.
○ Haywood (2009) For Ecol Manage
158:195-305.
○ Weise et al (1987) Res Note SE-347.
Neutral
○ Brockway and Lewis (1997) For Ecol
Manage 96:167-183.
○ Weise et al (1987) Res Note SE-347.
○ Ford et al (2010) Can J For Res
40:1410-1420.
o Haywood (2011) New For 41:55-73.
OBJECTIVES AND HYPOTHESIS
 To
determine if there are physiological
variables that sustain growth after
prescribed fire.
 To
determine if the seasonal variation of these
physiological variables is related to forest
production.
 To
help land managers sustain forest production by
manipulating these physiological controls using
silviculture.
PHYSIOLOGY OF SUSTAINED LONGLEAF PINE GROWTH IN RESPONSE TO FIRE
OBJECTIVES AND HYPOTHESIS
Hypothesis
Sustained growth depends on maintenance of
physiological factors that control whole-tree
carbon fixation.
METHODS
 Study
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site
Two western Gulf coastal plain, mesic, upland sites.
Palustris Experimental Forest, Calcasieu Ranger
District, Kisatchie National Forest, Rapides Parish, LA.

Study Sites
Dominant understory
vegetation included
Schizachyrium
scoparium, S. tenerum,
Helianthus angustifolius,
Heterotheca graminifolia.
longleafalliance.org
PHYSIOLOGY OF SUSTAINED LONGLEAF PINE GROWTH IN RESPONSE TO FIRE
METHODS
 Study
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
site
Sites prepared by chopping or shearing/windrowing
and burning.
Treatment plots, 22 x 22 m (0.048 ha).
Planted with container longleaf pine, 1.8 x 1.8 m.
Age 6 years
Age 7 years
Site 1
 2 blocks
 age 13 yrs in November 2010
 Ruston and Malbis fine sandy
loams, Gore silt loam
Site 2
 3 blocks
 age 14 yrs in November 2010
 Beauregard silt loam
METHODS
3
vegetation management treatments
 Control, C: No post-plant vegetation control.
 Burning, B: Prescribed fire in
May 2003 and May 2005.
2nd flush
 Herbicide, H: Post-plant
bud intact
herbicide application for 2 to
3 years, and hand felling of
1st flush
recovering woody vegetation
elongated
at age 4 or 5 years.
 Experimental
design: repeated
Mid- to late May
measures RCBD with 5 blocks.
 Blocked by apparent soil permeability.
RESULTS- CROWN SCORCH
 2003
●
40-70% scorch
● 480 kJ/s/m2
● mild drought
 2005
● 90% scorch
● 755 kJ/s/m2
● mild to moderate
drought
Site 2 2003
Site 2 2005
Haywood (2010) New Forests 41:55-73.
PHYSIOLOGY OF SUSTAINED LONGLEAF PINE GROWTH IN RESPONSE TO FIRE
RESULTS- PRODUCTION
Annual groundline basal area growth
Why didn’t
crown scorch
reduce tree
growth?
 ANOVA
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of annual groundline basal area growth
H plots greater than C and B plots.
Magnitude of differences was less during drought.
Regardless of scorch, no difference between C
and B plots.
RESULTS- FOLIAGE BIOMASS
 Destructive
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harvest in 2003, 2004, and 2005
Late summer, 4
months post-burning
in 2003 and 2005.
3 saplings per plot
(45 per year).
1 sapling per onethird total height
percentile.
Stem, branches,
and age classes of
foliage separated,
dried, and weighed.
RESULTS- FOLIAGE BIOMASS
 ANCOVA
of foliage biomass with GLD as a covariate
Old foliage: 2003, 2004, 2005
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New foliage: 2003, 2004, 2005
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Total foliage: 2003, 2004, 2005
Old foliage: B plots less than
C and H plots.
New foliage: No difference
among B, C, and H plots.
Total foliage: No difference
between C and B plots.
Foliage was re-established
four months after crown
scorch.
Did rapid re-establishment
of leaf area sustain sapling
growth?
RESULTS- FOLIAGE BIOMASS
 ANOVA of pct foliage biomass by age class
● 2003 and 2005: pct of 2nd flush foliage was greater on
the
B plots than the C and H plots.
Percentage of foliage biomass by age class
2nd flush
bud intact
singed 1st flush foliage
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2005: pct of 1st flush foliage was greater on the B plots
compared to the C and H plots.
1st and 2nd flush foliage growth may have been
accelerated on the B plots compared to the C and H plots.
RESULTS- MECHANISMS OF FOLIAGE RE-ESTABLISHMENT
 Short-term
increase in fascicle-level gas exchange
Amax1 before and after prescribed fire in 2003
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Amax1 before and after prescribed fire in 2005
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Example 1 in 2003o mild drought,
mean ΨJuly pd -0.34 MPa.
o morning vs. afternoon.
Example 2 in 2005o mild to moderate drought,
mean ΨJuly pd -0.73 MPa.
o uniform response.
By October, gas exchange
rates were similar between
the C and B plots.
saplings of mean height/plot, 10 dates in 2003-2005, detached fascicles, LiCor-6400 portable photosynthesis system, ANOVA.
RESULTS- MECHANISMS OF FOLIAGE RE-ESTABLISHMENT
 Short-term
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increase in fascicle-level gas exchange
Related to stomatal responses to water availability.
Sapling VPD and gw on the Burn plots in 2005
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o
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gw decreased
as leaf water
status
decreased.
Leaf water
status and gw
increased after
burning.
Prescribed burning in May led to an increase in leaf water
status and gas exchange for up to a 3-month period.
RESULTS- MECHANISMS OF FOLIAGE RE-ESTABLISHMENT
 Mobilization
of stored root starch
Seasonal pattern of southern pine root starch
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Small woody roots
(2-10 mm diameter)
were frozen and freeze
dried.
●
Root starch was
mobilized more rapidly
on the B plots than the
C and H plots.
mobilization
for flush growth
accumulation
for storage
Root starch before and after prescribed fires1
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saplings of mean height/plot, 12 dates in 2003-2005, enzymatic assay by Dairyland Laboratories, Inc. in Arcadia, WI, ANOVA.
SUMMARY AND CONCLUSIONS
 Two
potential mechanisms that sustain pine
growth in frequently burned forests.
1.
2.
Increased leaf water status and gas exchange for up to
three months after burning.
Mobilization of stored root starch for the growth of new
foliage after burning.
These mechanisms may accelerate foliage reestablishment after scorch.
 These mechanisms are season-dependent.
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Increased leaf water status is most beneficial during
summer and early fall.
Root starch is least available for mobilization between
August and December.
PHYSIOLOGY OF SUSTAINED LONGLEAF PINE GROWTH IN RESPONSE TO FIRE
SUMMARY AND CONCLUSIONS
 Post-fire
benefits to leaf area re-establishment and
growth are available when the first flush is
elongated but the second flush is intact and
protected at the time of the burn.
A
new study comparing spring and fall burning is
underway to verify the physiological benefits of
season of burning.
Mary Anne Sword Sayer, [email protected]
US Forest Service, Southern Research Station
RWU-SRS-4158: Restoring and Managing Longleaf Pine Ecosystems