1. Upland oak regeneration response to prescribed fire and canopy gap disturbances
Brian Izbicki, Dr. Heather D. Alexander and Dr. Brent R. Frey
Department of Forestry, Forest and Wildlife Research Center, Mississippi State University, MS
Abstract
Study Areas
Results: Seedling Growth
In upland oak forests of the Appalachian hardwood region, fire suppression contributes to extensive oak regeneration problems and compositional shifts toward shade tolerant species. Prescribed fire may maintain upland oak by removing competing species and increasing understory light. Single and multiple (2x, 3x) fires were implemented over 3-yr and 5-yr periods. Each growing season, canopy cover, growth, basal diameter and survival were quantified for six seedlings groups. Gap size and age, are being analyzed to identify influences on composition and regeneration dynamics if prescribed fire is unsuitable for all management objectives. Preliminary results suggest single fires are ineffective at creating beneficial conditions for oak regeneration while multiple fires promote oak growth relative to competing species. This study could direct how prescribed fire can preserve upland oak ecosystems and provides information on upland oak regeneration in canopy gaps with continued fire suppression.
Bernheim Arboretum and Research Forest 40 km SE of Louisville, KY
Sam D. Hamilton Noxubee National Wildlife Refuge Scattertown trail 45 km SW of Starkville, MS
Prescribed fire and canopy gap research
Canopy gap research
Prescribed Fire Regime
Canopy Gaps
Background
Site
‘08
‘09
‘10
‘11
‘12
‘13
’14
‘15
‘16
‘17*
Burns
Last burn (yrs)
Yoes X 1 4
Fire Tow. 2
East Rd.
Sal. 3
Knobs 5
Fern V.
Characteristics: slope, aspect, CWD, and present vegetation
Size: A=πLW/4
Age: release dated from increment cores
Composition and dynamics: perpendicular belt transects
Light: hemi-photos
Oak’s regeneration failure likely stems from decreased light and increased understory competition.
Evidence suggests regeneration problems are caused by fire suppression, necessitating reintroduction of fire for oak restoration.
Prescribed Fire Sampling Regime
6 seedling groups: white oak (Quercus alba), red oak (Q. coccinea, Q. rubra, Q. velutina), chestnut oak (Q. montana), hickory (Carya glabra, C. tomentosa), red maple (Acer rubrum) and American beech (Fagus grandifolia)
However, fire may not be successful, suitable or cost effective in today’s forests.
Expanded Gap
Open Gap
Seedling survival, height , annual growth, and basal diameter
Thus, understanding oak regeneration in canopy gaps may be important as upland oaks age, increasing the probability of overstory mortality.
10 m
Canopy cover: hemi- photos and densiometer
Densiometer
Allometric equations relating basal diameter to root biomass
Single fires ineffective at promoting oak growth; multiple fires increase oak growth
Canopy gaps change light conditions altering regeneration dynamics.
Hemi Photo
Red maple growth unaffected
Densiometer
Objectives and Hypotheses
Conclusions/Future Work
Assess effectiveness of single and multiple fires for oak regeneration and understand compositional trajectories of oak in canopy gap disturbances.
Multiple prescribed fire at high frequency may provide increased light to promote oak growth
Results: Canopy Cover
Single fires had no impact on canopy cover
Multiple fires reduced canopy cover ~10%
Canopy cover reduction short lived
Additional prescribed fires needed to reduce canopy cover
Canopy gaps may be important for upland oak regeneration in the absence of fire
(H1) Single fires will have no impacts on oak growth and survival; Multiple fires at high frequency will increase understory light and competitor mortality, leading to increased oak growth and survival.
(H2) As gap size and age increase, oak relative importance will increase and competing species relative importance will decrease.
(H3) Oak relative importance will be higher in open gap space; competing species will be higher in expanded gap space.
Canopy gap data will suggest how size and age impact species composition dynamics as upland oak ecosystems age with continued fire suppression
Acknowledgements
USDA McIntire-Stennis (MISZ )
MSU College of Forest Resources
Bernheim Arboretum and Research Forest
Sam D. Hamilton Noxubee National Wildlife Refuge
Josh Byers, Hardik Megat, William Webb, Alex Davis, Emily Babl, Homer Pena, Andrew Berry, Kelly Vowels, Rick Caldwell, and Christina Casto-Teltser