Effects of longleaf pine planting density and other factors on stand structure and associated wildlife habitat

The primary objective of many longleaf pine (Pinus palustris) restoration programs is to enhance or restore habitat for wildlife dependent on herbaceous plant communities. Because herbaceous cover is inversely related to canopy cover, restoration programs often place restrictions on longleaf pine planting density. However, the influence of planting density on understory plant communities has been inadequately evaluated. Therefore, we initiated a study to examine the relative influences of planting density and other factors on overall understory composition and forage availability for white‐tailed deer (Odocoileus virginianus) and northern bobwhite (Colinus virginianus) in nine longleaf pine stands throughout the Coastal Plain of Alabama during 2017–2018. We found that coverage of herbaceous plants decreased 3.5%, coverage of woody plants decreased 2.4%, and coverage of northern bobwhite forage plants decreased 1.9% for each 1 m²/ha increase in longleaf pine basal area. However, planting density was not a significant predictor of current basal area, nor coverage of any functional group of plants we examined, likely because current longleaf pine density averaged only 46% (range = 30–64%) of seedling planting density. We did not detect an effect of prescribed fire on stand condition or understory plant communities, likely due to variability in fire timing and frequency. Our findings related to planting density were likely a function of low longleaf pine survival, which is not uncommon. Because of this and the inherent variability in growth rates for young longleaf pine stands, restoration programs should consider placing greater emphasis on post‐planting monitoring and management than planting density.     

Fine-scale resource selection and behavioral tradeoffs of eastern wild turkey broods

Resource heterogeneity across the landscape prompts animals to make behavioral tradeoffs to survive and reproduce. Behavioral thermoregulation can buffer organisms from thermal extremes but may conflict with other essential activities such as predator avoidance or foraging, and necessitate tradeoffs among resource requirements. We evaluated patterns of habitat selection relative to thermal conditions, forage availability, and concealment cover for female eastern wild turkeys (Meleagris gallopavo silvestris) with broods to assess potential tradeoffs among resource requirements. We quantified air temperature (°C), vegetation characteristics (e.g., visual obstruction), and arthropod biomass (g/m²) at locations used by broods across 5 study sites in the southeastern United States during May–July 2019–2020. We used conditional logistic regression to estimate brooding female resource selection at the second (home range) and third (within home range) orders. Specifically, we identified differences in selection between brooding and non-brooding females (second order), and factors influencing selection of sites used by brooding females during the day (when loafing and foraging) and night (roosting; third order). Brooding females selected sites with cooler temperatures (β = −0.22; 95% CI = −0.338–−0.102) and greater ground cover vegetation (β = 0.02; 95% CI = 0.013–0.033) than non-brooding females. Additionally, biomass of large prey (Orthoptera) was positively related to ambient temperature, suggesting that use of thermal refuge by brooding females may limit availability of large prey. Brooding females appeared to balance the tradeoff between thermal refuge and forage availability by altering habitat selection patterns within home ranges. Brooding females selected for herbaceous areas that provided greater biomass of large arthropods during the day, and avoided areas dominated by woody vegetation during both the day and night. We did not observe brooding females using locations where woody cover exceeded 27% of understory vegetation. Thermal refuge is an important component of brood habitat, but within thermally suitable areas brooding females can select sites with greater availability of large prey to meet energetic demands of broods. Evaluation of multiple spatial scales is key when assessing tradeoffs among resource needs and determining the potential of behavioral thermoregulation to buffer an organism's thermal environment and allow persistence in a warming climate.     

Effects of habitat and growing season fires on resprouting of shrubs in longleaf pine savannas

The effects of habitat and timing of growing season fires on resprouting of shrubs were studied in second-growth longleaf pine savannas of the west Gulf coastal plain in the southeastern United States. Within the headwaters of three different drainages of the Calcasieu River in the Kisatchie National Forest in western Louisiana, replicated permanent transects were established that extended from xeric upland longleaf pine savannas into downslope hydric seepage savannas. All shrubs were mapped and tagged, and numbers of stems were counted prior to any fires. Replicated prescribed fires were set early (June) and late (August) during the 1990 growing season; maximum fire temperatures were measured within both upland and seepage habitats within each transect. Shrubs were relocated; stems were recensused two and twelve months after the fires. At least some shrubs of all species resprouted from underground organs; none regenerated solely from seed banks in the soil. There was no reduction in total numbers of stems one year after fires compared to before fires, either in the upland or in seepage savannas. In addition, there was no reduction in total numbers of stems one year after early or late growing season fires. Fire-related mortality was restricted to small shrubs (< 18 stems) and was not associated with high fire temperatures. The rate of resprouting varied among species and between habitats. Resprouting occurred more rapidly in seepage than upland savannas, but more resprouts were produced in upland than seepage savannas one year after fires. In contrast to other upland species, Vaccinium arboreum and V. elliottii delayed resprouting more than two months following fire. Stems of Rhus copallina and Pyrus arbutifolia, species with long rhizomes, increased more after fires in June than fires in August. We suggest that growing season fires may block further recruitment of shrubs into longleaf pine savannas, but reduction in numbers of large shrubs may require additional management.     

Northern Bobwhite Non-Breeding Habitat Selection in a Longleaf Pine Woodland

Efforts to halt the decline of the northern bobwhite (Colinus virginianus; bobwhite) across its distribution have had limited success. Understanding bobwhite habitat requirements across the annual cycle and at varying scales is essential to aid efforts to conserve bobwhites. We monitored radio-tagged bobwhites from 2016 to 2018 on a 165-km² portion of Fort Bragg Military Installation in the Sandhills physiographic region of North Carolina, USA, to determine factors influencing non-breeding bobwhite habitat selection at multiple scales. We used generalized linear models (GLM) and generalized linear mixed models to assess bobwhite habitat selection at the microsite scale (the immediate vicinity of an animal) and the macrosite scale (across the study area), respectively, by comparing used points to available random points. At the microsite scale, bobwhites strongly selected areas with greater woody understory cover. Also, bobwhite selection increased with greater forb and switchcane (Arundinaria tecta) cover, but this effect plateaued at 65% forb cover and 50% switchcane cover. At the macrosite scale, bobwhites generally selected areas with greater understory cover within a 200-m radius but avoided areas with >55% understory cover; these areas primarily were located in the core areas of drainages with extensive ericaceous vegetation. Bobwhites selected areas with 3–6 m²/ha hardwood basal area in uplands, potentially because of the availability of mast, but avoided uplands when pine (Pinus spp.) or hardwood basal area exceeded 20 m²/ha or 12 m²/ha, respectively, likely because high basal area is associated with increased shading and subsequent loss of understory cover. In addition, bobwhites selected uplands 1 growing season (≥2-month period falling entirely between 1 Apr and 1 Oct) post-fire regardless of burn season. Overall, managers seeking to improve habitat quality for bobwhites in longleaf pine (Pinus palustris) woodlands should employ management practices that maintain available woody understory across the landscape to provide cover during the non-breeding season. © 2020 The Wildlife Society.     

Gopher Tortoise Response to Habitat Management by Prescribed Burning

ABSTRACT As quality of forested habitat declines from altered fire regimes, gopher tortoises (Gopherus polyphemus) often move into ruderal areas to the detriment of the animal and land manager. We evaluated effects of a dormant-and-growing-season prescribed fire on habitat and gopher tortoise use of degraded longleaf pine (Pinus palustris) forests surrounding military training areas. We burned 4 of 8 sites in winter 2001–2002 and again in April 2003. Changes in vegetation measured during 2001–2004 indicated that burn treatments did not increase herbaceous vegetation. Similarly, movement patterns, burrow usage, and home range of tortoises radiotracked from 2002–2004 did not differ between treatments. Woody cover initially was reduced in the forests postburn, and we found more new burrows in burned forest sites. Once shrub cover was reduced, tortoises started using forested habitat that had become overgrown. However, shrub reduction may be temporary, as woody stem densities increased postburn. Thus, the one-time use of fire to manage tortoise habitat may not rapidly restore the open canopy, sparse woody midstory, and abundant herbaceous vegetation that this species requires. Repeated prescribed fires or additional management techniques may be needed for complete restoration.     

Habitat Selection of Female Turkeys in a Managed Pine Landscape in Mississippi

Abstract: Intensive pine (Pinus spp.) management is a dominant form of forest management in the southeastern United States. Previous research has shown that managed pine forests provide suitable habitat for eastern wild turkeys (Meleagris gallopavo silvestris), but little research has examined seasonal habitat selection for female wild turkeys from a landscape perspective, particularly within managed pine landscapes. Therefore, we used a long-term (1986-1993) data set to describe seasonal habitat selection by female wild turkeys, using an information-theoretic approach from a landscape perspective, on an intensively managed pine landscape. Habitat use patterns during preincubation and autumn-winter were indicative of female wild turkeys moving between a bottomland hardwood-agricultural field complex during autumn-winter and upland managed pine stands during the remainder of the year. During spring and summer, female wild turkeys used landscapes primarily composed of intensively managed pine, including thinned and burned stands and roadsides. Our results confirm results of short-term, stand-based habitat analyses on our study area. We recommend variable fire return intervals of 3 to 7 years to improve habitat conditions for wild turkeys within intensively managed pine forests. Further research is needed to examine management actions, such as thinning, prescribed fire, and herbicide use, within the context of wild turkey use of intensively managed pine landscapes.     

Wild Turkey Nest Success in Pine-Dominated Forests of the Southeastern United States

Nest success is a primary component of productivity for wild turkeys (Meleagris gallopavo; turkeys) and there is concern that turkey productivity is declining across the southeastern United States. We evaluated the influence of nest site and landscape characteristics on risk of nest failure for turkeys in pine (Pinus spp.)-dominated forests across the southeastern United States. We used Cox proportional hazard models to evaluate daily hazard of nest failure associated with nest site and landscape metrics within 500-m and 1-km buffers centered on nests. Of 451 nests monitored (n = 320 females) between 2014 and 2018, 76% failed, with predation as the primary cause. Daily hazard of nest failure increased by 1.2% for each day that females delayed nest incubation following the mean nesting date (29 Apr; β_day = 0.010 ± 0.002 [SE]; hazard ratio [HR] = 1.01, 95% CI = 1.006–1.015). Environmental covariates associated with risk of nest failure included the maximum enhanced vegetation index (EVI) and distance to the nearest ecotone. Daily hazard increased with increasing distance away from an ecotone (β_ecotone = 0.16 ± 0.06; HR = 1.17, CI = 1.03–1.32) and with lower EVI around the nest (β_EVI = −0.30 ± 0.06; HR = 0.74, CI = 0.65–0.83). Additional nest site or landscape covariates were included in competitive models but did not influence risk of nest failure significantly. Our study highlights the importance of considering landscape context when designing and implementing land management actions intended to enhance wild turkey reproduction. Our findings suggest that landscape metrics thought to be important to turkeys in northern agro-forested landscapes may not be relevant to turkeys in pine ecosystems of the southeastern United States. © 2021 The Wildlife Society.     

Canopy thinning,not agricultural history,determines early responses of wild bees to longleaf pine savanna restoration

Longleaf pine savannas are highly threatened, fire‐maintained ecosystems unique to the southeastern United States. Fire suppression and conversion to agriculture have strongly affected this ecosystem, altering overstory canopies, understory plant communities, and animal populations. Tree thinning to reinstate open canopies can benefit understory plant diversity, but effects on animal communities are less well understood. Moreover, agricultural land‐use legacies can have long‐lasting impacts on plant communities, but their effects on animal communities either alone or through interactions with restoration are unclear. Resolving these impacts is important due to the conservation potential of fire‐suppressed and post‐agricultural longleaf savannas. We evaluated how historical agricultural land use and canopy thinning affect the diversity and abundance of wild bees in longleaf pine savannas. We employed a replicated, large‐scale factorial block experiment in South Carolina, where canopy thinning was applied to longleaf pine savannas that were either post‐agricultural or remnant (no agricultural history). Bees were sampled using elevated bee bowls. In the second growing season after restoration, thinned plots supported a greater bee abundance and bee community richness. Additionally, restored plots had altered wild bee community composition when compared to unthinned plots, indicating that reduction of canopy cover by the thinning treatment best predicted wild bee diversity and composition. Conversely, we found little evidence for differences between sites with or without historical agricultural land use. Some abundant Lasioglossum species were the most sensitive to habitat changes. Our results highlight how restoration practices that reduce canopy cover in fire‐suppressed savannas can have rapid benefits for wild bee communities.     

Hardwood management and restoration of longleaf pine ecosystems may affect raccoon daytime resting sites

Fire‐maintained Pinus palustris (longleaf pine) ecosystems are species rich and considered a top conservation priority in the southeastern United States. Ground‐nesting species such as Gopherus polyphemus (gopher tortoise) and Colinus virginianus (northern bobwhite) thrive in longleaf ecosystems. However, the generalist carnivore Procyon lotor (raccoon) is a significant predator of these endemic ground nesters. In forested ecosystems, raccoons prefer hardwood‐dominated habitats. Removal of hardwood trees, which is a common longleaf pine ecosystem restoration tool, affects habitat use of this predator. We examined 269 daytime resting sites (DRS) associated with 31 radio‐collared adult raccoons (18 M, 13 F) during 2014–2015 on a longleaf pine‐dominated site in southwestern Georgia. We developed 26 a priori models using an information theoretic approach to evaluate factors affecting use of DRS by raccoons. The top two models (ΔAIC < 2) had combined model weights of 0.75 and contained tree diameter, tree type, presence of nearby hardwood, and distances to pine, hardwood, mixed forest, and agriculture as predictors. However, the only informative variables were tree type and tree diameter. Raccoons used DRS in all available forest types, but were less likely to use pine trees (n = 7) relative to hardwoods (n = 247), and there was a positive relationship with tree diameter. Females used smaller trees farther from agriculture and primary roads, and were closer to wetlands than those used by males. Hardwood removal from within longleaf pine ecosystem affects habitat use of this predator, specifically DRS.     

Rio Grande Wild Turkey Habitat Selection in the Southern Great Plains

ABSTRACT We recorded telemetry locations from 1,129 radiotagged turkeys (Meleagris gallopavo intermedia) on 4 study areas in the Texas Panhandle and southwestern Kansas, USA, from 2000 to 2004. Analyses of telemetry locations indicated both sexes selected riparian vegetative zones. Females did not select grazed or nongrazed pastures for daily movements. However, females did select nongrazed pastures for nest sites on 2 study areas and males selected for grazed pastures at one study area during the breeding season. We compared nest sites (n = 351) to random sites using logistic regression, which indicated height of visual obstruction, percent canopy cover, and percent bare ground provided the highest predictive power (P ≤ 0.003) for characteristics describing nest-site selection. Nest-site vegetative characteristics between vegetative zones differed primarily in composition: upland zone nest sites had more (P ≤ 0.001) shrubs and riparian zone nest sites had more (P ≤ 0.001) grass. There were no differences in measured nest site vegetative characteristics between pasture types, but there were differences between available nesting cover in grazed and nongrazed pastures. Random plots in grazed pastures had less grass cover (P ≤ 0.001) and more bare ground (P = 0.002). Because of cattle impacts on average grass height and availability, grazing would likely have the highest impact on nesting in riparian zones due to turkey use of grass as nesting cover. An appropriate grazing plan to promote Rio Grande turkey nesting habitat would include grazing upland zones in the spring, when it likely has little impact on nesting-site selection, and grazing riparian zones following breeding season completion. Grazing at light to moderate intensities with periods of rest did not affect male turkey pasture use and may have continued to maintain open areas used by male turkeys for displaying purposes.