Turner et al. 2024 (Forest Ecology and Management)
RESEARCH BRIEF #51
A summary based on the following publication:
Turner, M.A., J.T. Bones, S.G. Marshall, and C.A. Harper. Canopy reduction and fire seasonality effects on deer and turkey habitat in upland hardwoods. Forest Ecology and Management, 553 (2024) https://doi.org/10.1016/j.foreco.2023.121657
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MANAGEMENT IMPLICATIONS
Canopy reduction paired with fire during either the early or late portion of the growing season resulted in increased understory sunlight and plant coverage compared to no treatment.
Late growing-season fires had lower intensity than early growing-season fires, impacting vegetation composition and structure differently.
Weather conditions should be considered carefully when applying fire during the growing season to help ensure desired fire intensity.
Using fire during different seasons in a management area can create diverse vegetation communities to support the varying needs of deer and turkeys throughout the year.
This study evaluated the responses of vegetation, white-tailed deer (Odocoileus virginianus) and wild turkeys (Meleagris gallopavo) to prescribed fire applied during different seasons (early vs. late growing season) following canopy reduction in an upland hardwood forest located in eastern Tennessee, USA. Gaining insights into how deer and turkeys respond to prescribed fire applied in different seasons could expand opportunities for implementing burns during various times of the year while maintaining essential habitat benefits for these species.
The study took place on the Chuck Swan State Forest and Wildlife Management Area. Forest stands evaluated were situated on south- to west-facing slopes, with overstory species including white oak (Quercus alba), north-ern red oak (Q. rubra), southern red oak (Q. falcata), yellow-poplar (Liriodendron tulipifera), red maple (Acer rubrum), hickory (Carya spp.), and blackgum (Nyssa sylvatica). The four stands included in the study were 70-140 years old, and no prior management had occurred since natural regeneration. Each stand was divided into three 1.6-ha (4-acre) treatment units, randomly assigned as control, cut + burn in the early growing season (EGS), or cut + burn in the late growing season (LGS). Control units remained untreated throughout the study.
A shelterwood with reserves harvest was conducted in the EGS and LGS units, approximately two years prior to prescribed fire application. Basal area was reduced to 13 m2/ha (57 ft2/acre), allowing approximately 30% sunlight to reach the understory. To enhance food resources for deer and turkeys, the harvest prioritized retaining oaks and soft mast producers, such as persimmon (Diospyros virginiana), black cherry (Prunus serotina), and blackgum.
LGS units were burned six times (average interval: 2.2 years) in September–October 2012–2022 before leaf-drop, whereas EGS units were burned six times (average interval: 2.2 years) in April–early May 2013–2023 after leaf-out. Burns for each treatment replicate were conducted on the same day to ensure consistent weather and timing. Low-intensity backing, flanking, and strip-heading fires were used, with slash removed from tree bases to minimize bole damage and with flame lengths less than1 m in height. Estimated burn coverage averaged 95% for EGS and 65% for LGS treatments.
The authors predicted that: 1) treated stands would have greater understory plant coverage, with the greatest visual obstruction following late growing-season fires because of extended regrowth time; 2) deer nutritional carrying capacity (NCC) would peak after early growing-season fires because younger regrowth is more nutritious than older vegetation following late growing-season fires; and 3) deer and turkey detections would reflect vegetation structure influenced by fire timing and intensity.
In each treatment unit, data were collected for fire temperature, understory vegetation coverage, deer forage, vegetative structure, and wildlife detections via camera traps. The relative maximum fire temperature was compared between EGS and LGS burns. The variation in coverage of forbs, grasses, brambles, vines, shrubs, and trees among treatments was evaluated. Visual obstruction and understory sunlight were assessed for differences across treatments. Variations in NCC were analyzed across treatments to assess differences in deer forage availability and quality. Camera-trap detections of deer and turkeys were analyzed to determine if they differed by treatment during May–June and July–August.
Canopy reduction combined with fire during either the EGS or LGS increased understory sunlight and plant coverage compared to the control (see Figures 1 and 2). Fire intensity was greater in EGS than in LGS, influencing plant composition and structure, as well as the resulting forage and cover resources available for deer and turkeys.
Visual obstruction from 0–1 m was greater in both EGS and LGS compared to the control, whereas obstruction from 0.5–1.5 m was greatest in LGS (see Figure 2). Denser understory vegetation increases visual obstruction below 2 m, offering deer essential bedding and fawning cover. For turkeys, understory vegetation plays a crucial role in providing nesting and brooding cover. Sites with dense cover at 0.5–1.5 m may improve nest survival, whereas brooding cover is optimized with enhanced understory cover 0–0.5 m with an open structure near ground level and good visibility above 0.5 m for predator detection.
Deer body size, antler growth, and reproductive success benefit from increased NCC. Both EGS and LGS treatments increased deer forage biomass relative to the control, but only EGS significantly enhanced deer NCC. There was an increase of approximately 30 kg/ha (27 lb/acre) in selected forbs in EGS compared to LGS, contributing to the greater NCC resulting from the greater crude protein content in most forbs.
Deer and turkey detections were greatest in EGS units during May-June. For deer, resprouting vegetation provides abundant food sources and fawning cover, whereas turkeys typically benefit from increased vegetation density < 1 m in height, combined with sufficient visibility above that level. During July-August, deer detections were similar between EGS and LGS, whereas turkey detections remained greatest in EGS.
This study demonstrates that prescribed burns during both early and late portions of the growing season in upland hardwood forests following canopy reduction provide distinct benefits for deer and turkeys. Canopy reduction paired with fire in either season increased understory vegetation compared to untreated areas. Late growing-season burns were less intense than early growing-season burns and had different effects on vegetation composition and structure. Careful consideration of weather conditions is essential to achieving desired fire intensity and ecological outcomes. Prescribed fire during different seasons can create a diverse vegetation mosaic that balances forage availability, cover, and structural diversity to meet the year-round needs of deer and turkeys.
Figures reprinted with permission from Forest Ecology and Management
