Fire and oak regeneration research Jeffrey S. Ward Department of Forestry & Horticulture CT Agricultural Experiment Station New Haven, CT
Thank you
Overview Short history of fire in Northeast An unplanned experiment Prescribed burning in shelterwoods Fire / stand structure interactions
New England and New York 1880 does not include CT, NH, and RI 200,000 Acres burned each year 150,000 100,000 50,000-1880 1900-1910 1929-1939 Period 1994-2005
Devastating early fires Charred red maple East Hartford 1905
Causes of early fires Forest pasture Railroad fires
40 30 20 10 0 1905-09 1915-19 1925-29 1935-39 1945-49 Annual acres burned (thousand) 1955-59 1965-69 1975-79 1985-89 1995-99 3500 3000 2500 2000 1500 1000 500 0 Fire rotation (years)
Acres (thousands) 2000 Connecticut s forest is changing 1750 1500 1250 1000 750 Miscellaneous Northern hardwood 500 Conifer 250 Oak 0 1938 1948 1958 1968 1978 1988 1998 2008 Year
The abundance of mature oaks in the current Connecticut forest is due, in part, to a history of periodic burning and short rotation clearcutting prior to 1920.
The Challenge Oak regeneration on better quality sites is often hampered by taller red maple and birch that develop in earlier phases of stand management, especially thinning and selection harvests. How could fire help?
Oak Maple Birch Birch Oak Maple Birch Oak JP Maple
Overview Short history of fire in Northeast An unplanned experiment Prescribed burning in shelterwoods Fire / stand structure interactions
Old-Series Plots (1927-2007) An unplanned experiment 1932 wildfire
1 Rod (5.03 m) 2 Chains (20.11 m)
Disturbance Histories Meshomasic plots Moderate to severe defoliation between stand ages 61-81 Turkey Hill - unburned section Light defoliation between ages 61-81 Turkey Hill - burned section Summer fire at stand age 32 Light defoliation between ages 61-81
1600000 1400000 1200000 1000000 800000 600000 400000 200000 0 Gypsy moth defoliations 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005
Upper canopy decline or mortality New regeneration
Oak density (stems/ha) 1200 1000 800 600 400 200 Oak OAK (Quercus) Single Multi Fire Gleason was right Different responses to disturbance has lead to different communities 0 1927 1937 1957 1967 1977 1987 1997 2007 Year of survey Maple density (stems/ha) 1200 1000 800 600 400 200 MAPLE (Acer) Maple Single Multi Fire Birch density (stems/ha) 1200 1000 800 600 400 200 BIRCH (Betula) Birch Single Multi Fire 0 1927 1937 1957 1967 1977 1987 1997 2007 Year of survey 0 1927 1937 1957 1967 1977 1987 1997 2007 Year of survey
General observations Burning increased oak Repeated defoliation favored black birch Minor defoliation favored red maple Ingrowth composition is influenced by disturbance type
Overview Short history of fire in Northeast An unplanned experiment Prescribed burning in shelterwoods Fire / stand structure interactions
Shelterwood burns Pilot Fuel modeling
Shelterwood Hot fire Increased oak Medium fire Shelterwood Some oak Cool fire No shelterwood No oak
Brose and Van Lear Virginia 80 70 60 Spring burning Central Virginia Oak Maple Mortality (%) 50 40 30 20 10 0 Low MedLow MedHigh High Fire intensity
How could fire influence species composition? Top-kill rates vary by species Resprouting rates vary by species Resprout height growth varies by species Post-fire seed input
Overview Short history of fire in Northeast An unplanned experiment Prescribed burning in shelterwoods Fire / stand structure interactions
Other studies Fire/fuel effects
Stand structure of 2000-2004 burns Clearcuts (4) Shelterwoods (2) Mt. laurel understory (3)
3-8 quincunx arrays per site 15 m (~50 ft) spacing
Temperature ( o F) 400 300 200 100 Fire intensity Lyme clearcut (Array C) SE SW NW NE Cen 0 0 3 6 9 12 15 18 21 24 27 30 Minutes
Fire survival sampling All stems > 2.5 dbh (6 cm dbh) All stems > 4.5 ft tall (140 cm)
Girdling greater for smaller stems 100% 75% 50% 25% 0% 4.5' 5.0' 5.5' 6.0' 0.5" 1" 2" 3" 4" 6" 8" 10" Proportion within size class 12" Girdling >90 76-90 51-75 26-50 10-25 <10 -----Height---- --------------------Dbh-------------------
Top-Kill Analysis (90% girdled) Logistic model: Top-Kill (%) = e x / (1+e x ) No difference among Acer, Quercus, Betula, Other tree, and Kalmia species groups. Stand structure, maximum temperature, and initial size were significant factors.
Top-kill increased with temperature 100% SHELTERWOOD, NO MOUNTAIN LAUREL TOP-KILL (> 90% GIRDLED) 80% 60% 40% 20% 0% 572 F (300 C) 392 F (200 C) 212 F (100 C) 140 F (60 C) 0 1 2 3 4 5 6 7 8 9 10 11 12 DBH (inches) Ht PsDbh 140 0.01 150 0.15 160 0.30 170 0.45 180 0.60 190 0.75 200 0.90
Top-kill differed by stand structure (> L IL 100% 80% ) D E L D IR G 60% % 0 9 Ḵ P O T 40% 20% 100 C (212 F) - MODERATE INTENSITY Mt. LAUREL UNDERSTORY CLEARCUT SHELTERWOOD 0% 0 5 10 15 20 25 30 DBH (CM)
New sprouts
Advanced regeneration is key for Red Maple and Oak
Sprouting differed by species group Top-killed stems with new sprouts 100% 80% 60% 40% 20% Proportion new new sprouts Oak Maple Birch 0% <160 cm tall >160 cm tall 1.0-2.4 cm dbh 2.5-4.9 cm dbh Pre-burn size class 5.0-9.9 cm dbh >= 10.0 cm dbh
Fires area a deer magnet
Overwhelming vegetation in clearcut burn
NUMBER OF NEW SPROUTS 16 12 8 4 A B B BC C D Red maples had more sprouts than oak (though oak had plenty) 0 BIRCH OAK OTHER SHRUB MAPLE Mt.LAUREL SPECIES GROUP 80 Height of oak and maple sprouts did not differ HEIGHT OF TALLEST NEW SPROUT (CM) 60 40 20 A A B B B B 0 BIRCH Mt.LAUREL OTHER OAK MAPLE SHRUB SPECIES GROUP
Overview Short history of fire in Northeast Long-term impact of 1932 wildfire Prescribed burning in shelterwoods Fire / stand structure interactions
Summary 1. Fire can have a profound, long-term influence on species composition. 2. Intensity and timing are important. 3. Larger stems more resistant to fire
Stand structure is important Clearcuts Mt. laurel understory Low success if: No oak regeneration to start Overstory removal is delayed Heavy fern cover Shelterwoods
Consider burning in young clearcuts
Oak Maple Birch Birch Oak Maple Birch Oak JP Maple
Oak Maple Birch Birch Oak Maple Birch Oak Maple Height of new sprouts similar, Oaks are now free-to-grow Root/shoot
Oak Maple Oak Birch Maple Oak Maple Free-to-grow oak seedlings have a better chance of persisting through canopy closure, and therefore, form part of the mature stand
Fire - alternative 1 st step for invasives 60% Brushsaw Clump mortality through July 2008 40% 20% Drum chopper Prescribed fire 0% < 3ft 3-4ft 4-5 ft 5-6 ft >6 ft Initial clump size (feet) 100% top kill
Fuel modeling/fire behavior Acknowledgements Division of Forestry Connecticut DEEP Partial Funding: Joint Fire Science Program McIntire-Stennis Program Patrick Brose & Thomas Schuler Northeastern Research Station USDA Forest Service
Jeff Ward - CAES (203) 974-8495 jeffrey.ward@ct.gov