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Mary Anne Sword Sayer 1 , Stanley J. Zarnoch 2 , and James D. Haywood 1

Physiological mechanisms of sustained growth despite crown scorch in a young longleaf pine plantation. Mary Anne Sword Sayer 1 , Stanley J. Zarnoch 2 , and James D. Haywood 1 U.S. Forest Service, Southern Research Station, 1 Pineville, Louisiana 2 Asheville, North Carolina.

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Mary Anne Sword Sayer 1 , Stanley J. Zarnoch 2 , and James D. Haywood 1

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  1. 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

  2. Presentation outline • Introduction • Longleaf pine (PinuspalustrisMill.) 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

  3. 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 • 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

  4. 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). • Range-Wide Conservation Plan for Longleaf Pine calls for an increase in longleaf acreage from 3.4 to 8 million by 2024. Loblolly pine Longleaf pine Photos: Glenn Hughes. Mississippi State University Extension Service. ghughes@ext.msstate.edu.

  5. Introduction • 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 ● 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. • Haywood (2011) New For 41:55-73. heat damage to shallow roots heat damage to vascular cambium heat damage to buds

  6. 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

  7. Objectives and hypothesis Hypothesis Sustained growth depends on maintenance of physiological factors that control whole-tree carbon fixation.

  8. Methods • Study site • Two western Gulf coastal plain,mesic, upland sites. • Palustris Experimental Forest, Calcasieu Ranger District, Kisatchie National Forest, Rapides Parish, LA. • Dominant understory vegetation included Schizachyriumscoparium, S. tenerum, Helianthus angustifolius, Heterothecagraminifolia. Study Sites longleafalliance.org Physiology of sustained longleaf pine growth in response to fire

  9. Methods • Study 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

  10. Methods • 3 vegetation management treatments • Control, C: No post-plant vegetation control. • Burning, B: Prescribed fire in May 2003 and May 2005. • Herbicide, H: Post-plant herbicide application for 2 to 3 years, and hand felling of recovering woody vegetation at age 4 or 5 years. 2nd flush bud intact 1st flush elongated • Experimental design: repeated measures RCBD with 5 blocks. Mid- to late May • Blocked by apparent soil permeability.

  11. 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 2005 Site 2 2003 Haywood (2010) New Forests 41:55-73. Physiology of sustained longleaf pine growth in response to fire

  12. Results- production Annual groundline basal area growth Why didn’t crown scorch reduce tree growth? • ANOVA 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.

  13. Results- foliage biomass • Destructive 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 one-third total height percentile. • Stem, branches, and age classes of foliage separated, dried, and weighed.

  14. Results- foliage biomass • ANCOVA of foliage biomass with GLD as a covariate Old 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. New foliage: 2003, 2004, 2005 Total foliage: 2003, 2004, 2005 Did rapid re-establishment of leaf area sustain sapling growth?

  15. 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 • 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.

  16. Results- mechanisms of foliage re-establishment • Short-term increase in fascicle-level gas exchange Amax1before and after prescribed fire in 2003 • Example 1 in 2003- • mild drought, • mean ΨJulypd -0.34 MPa. • morning vs. afternoon. • Example 2 in 2005- • mild to moderate drought, mean ΨJulypd -0.73 MPa. • uniform response. • By October, gas exchange rates were similar between • the C and B plots. Amax1before and after prescribed fire in 2005 13 saplings of mean height/plot, 10 dates in 2003-2005, detached fascicles, LiCor-6400 portable photosynthesis system, ANOVA.

  17. Results- mechanisms of foliage re-establishment • Short-term increase in fascicle-level gas exchange • Related to stomatal responses to water availability. Sapling VPD and gw on the Burn plots in 2005 • 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.

  18. Results- mechanisms of foliage re-establishment • Mobilization of stored root starch • Small woody roots • (2-10 mm diameter) were frozen and freeze dried. Seasonal pattern of southern pine root starch mobilization for flush growth accumulation for storage Root starch before and after prescribed fires1 • Root starch was mobilized more rapidly on the B plots than the C and H plots. 13 saplings of mean height/plot, 12 dates in 2003-2005, enzymatic assay by Dairyland Laboratories, Inc. in Arcadia, WI, ANOVA.

  19. Summary and Conclusions • Two potential mechanisms that sustain pine growth in frequently burned forests. • 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 re-establishment after scorch. • These mechanisms are season-dependent. • 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

  20. Summary andConclusions • 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.

  21. Mary Anne Sword Sayer, msword@fs.fed.us US Forest Service, Southern Research Station RWU-SRS-4158: Restoring and Managing Longleaf Pine Ecosystems

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