Craig A. Harper

Factors affecting salamander density and distribution within four forest types in the Southern Appalachian Mountains

Abstract We used a terrestrial vacuum to sample known area plots in order to obtain density estimates of salamanders and their primary prey, invertebrates of the forest floor. We sampled leaf litter and measured various vegetative and topographic parameters within four forest types (oak–pine, oak–hickory, mixed mesophytic and northern hardwoods) and three age classes (0–12, 13–39, and ≥40 years) over two field seasons within the Wine Spring Creek Ecosystem Management area in western North Carolina. We found salamanders preferred moist microsites across all forest types with the highest salamander densities occurring on sites with a northern and/or eastern exposure and within northern hardwood forests. Salamander densities were lowest on 0–12-year plots, yet were equal on 13–39 and ≥40-year plots, suggesting a much quicker recovery from the impact of clearcutting than reported by previous researchers. Overall invertebrate densities did not influence salamander density or distribution although, plots in which salamanders were captured, harbored significantly higher numbers of snails than plots in which salamanders were not captured. We discuss the importance of calcium to salamanders and snails as a possible source thereof.

Strategies for Managing Early Succession Habitat for Wildlife

Early succession plant communities consisting of a diverse mixture of grasses, forbs, and scattered shrubs are required by a variety of wildlife species. Early seral stages follow some form of disturbance but can become dominated by shrubs and trees rather quickly, especially in areas with abundant rainfall and relatively long growing seasons, such as the southeastern United States. In the absence of natural disturbance regimes, the quality and maintenance of these plant communities for wildlife is largely dependent upon management. Prescribed fire, disking, herbicide applications, and mowing are practices commonly used to maintain early succession plant communities for various wildlife species throughout this region. Prescribed fire consumes vegetative debris, provides open structure at ground level, and facilitates travel and foraging for wildlife throughout the field. Burning during the dormant season may promote cool-season grasses if they are present in the field. Burning in late March or early April generally promotes warm-season grasses and forbs. Late growing-season fire (September) will reduce woody encroachment and may encourage additional forb cover. Disking promotes vegetation decomposition, provides open structure at ground level, and generally promotes annual plant species. Disking in the fall and winter stimulates more forb growth than disking in the spring, which will stimulate undesirable nonnative warm-season grasses if present in the seedbank. Selective herbicides can influence plant composition and can be used to encourage grasses where forbs dominate, to promote forbs where grasses dominate, and to reduce woody cover. Mowing during midsummer encourages additional grasses in fields dominated by forbs but is not recommended for field maintenance because mowing produces thatch, which limits the ability of several wildlife species to travel and forage through the field, suppresses the seedbank, and destroys nests and young wildlife. Several practices can be used in combination to meet specific objectives. Succession should be set back every 2 to 4 yr, depending on plant response and focal wildlife species. It is important to intersperse disturbance in space and time, so that a variety of cover types are always available, even to those animals with small home ranges.

Forage Availability for White-Tailed Deer Following Silvicultural Treatments in Hardwood Forests

ABSTRACT Closed-canopy upland hardwood stands often lack diverse understory structure and composition, limiting available nutrition for white-tailed deer (Odocoileus virginianus) as well as nesting and foraging structure for other wildlife. Various regeneration methods can positively influence understory development; however, non-commercial strategies are needed to improve available nutrition in many stands, as some contain timber that is not ready to harvest and others are owned by landowners who are not interested in harvesting timber. Applications of herbicide and prescribed fire have improved availability of food and cover for deer and other wildlife in pine (Pinus spp.) systems. However, this strategy has not been evaluated in hardwood systems. To evaluate the influence of fire and herbicide treatments on available deer forage in upland hardwood systems, we measured forage availability and calculated nutritional carrying capacity (NCC) at 14% crude protein mixed diet, following 7 silvicultural treatments, including controls, in 4 mixed upland hardwood stands July–September 2007 and 2008. We compared NCC among forest treatments and within 4 paired warm-season forage food plots to evaluate the usefulness of food plots in areas where forests are managed. Nutritional carrying capacity estimates (deer days/ha) were greatest following canopy reduction with prescribed fire treatments in both years. Understory herbicide application did not affect species composition or NCC 1 year or 2 years post-treatment. Production of forage plantings exceeded that of forest treatments both years with the exception of early-maturing soybeans and retention cut with fire 2 years post-treatment. We encourage land managers to use canopy reducing treatments and low-intensity pre-scribed fire to increase available nutrition and improve available cover where needed in upland hardwood systems. In areas where deer density may limit understory development, high-quality forage food plots may be used to buffer browsing while strategies to reduce deer density and stimulate the forest understory are implemented.

Clarifying the role of fire in the deciduous forests of eastern North America: reply to Matlack

Fire is an important disturbance in ecosystems across the eastern deciduous forests of North America (Brose et al. 2014). Matlack (2013) provided an interpretation of historical and contemporary fire in this region. Although we applaud Matlack for correcting simplistic assumptions that fire was ubiquitous and all plant communities need to burn regularly to maintain biodiversity, we believe his interpretation of the role of fire is erroneous on several counts. Most problematic is his statement “ . . . it seems prudent to limit the use of prescribed burning east of the prairie-woodland transition zone.” Adherence to this overgeneralized advice would inevitably result in losses of native diversity across the eastern deciduous forest.

The Effects of Extreme Drought on Native Forage Nutritional Quality and White-tailed Deer Diet Selection

Abstract Forage availability is often used as a measure of habitat quality for Odocoileus virginianus (White-tailed Deer; hereafter “Deer”). Many studies have evaluated treatment effects on forage availability, but the effects of other abiotic factors, such as drought, on native forages and Deer diet selection are poorly understood. We measured diet selection and nutritional quality of commonly occurring forages following extreme drought (2007) and normal rainfall years (2008) in 4 closed-canopied hardwood stands in the Central Hardwoods region. Deer selected 6 forage species in both years of the study. Within these 6 species, crude protein (CP) and acid detergent fiber (ADF) were not different, and neutral detergent fiber (NDF) increased during the year of normal rainfall. Thirteen other commonly occurring forages showed a different trend, with CP negatively affected by drought and ADF and NDF unaffected. Less-selected species in the drought year and a greater selection-index cut-off value suggest Deer were more selective of species consumed during extreme drought because fewer plants met their nutritional requirements. Our data support the selective quality hypothesis, predicting Deer become more selective of plant species to meet nutritional requirements when resources are limited. Our data suggest more frequent and intense droughts predicted as a result of global climate change may influence diet selection of deer and decrease forage quality enough to limit lactation during the late-summer stress period in the Southeast.

Initial Effects of Prescribed Burning and Understory Fertilization on Browse Production in Closed-Canopy Hardwood Stands

Abstract Forage production for white-tailed deer Odocoileus virginianus is often limited in closed-canopy forests. We measured browse production and nutritional carrying capacity after prescribed burning and understory fertilization in closed-canopy hardwood stands one growing season after treatment in two physiographic regions of Tennessee. Nutritional carrying capacity estimates for prescribed burning, fertilization, and prescribed burning with fertilization were greater than in controls on the Cumberland Plateau. However, the cost per pound of forage produced after fertilization exceeded US

Vegetation and Avian Response to Oak Savanna Restoration in the Mid-South USA

26. In the Coastal Plain, fertilization did not affect nutritional carrying capacity, and prescribed burning and prescribed burning with fertilization lowered nutritional carrying capacity from controls. At both sites, prescribed fire had minimal effect on soil pH or soil phosphate and potash levels. Our results suggest prescribed fire and fertilization are of limited utility for increasing browse production in clos...

Comparison of Agricultural Seed Loss in Flooded and Unflooded Fields on the Tennessee National Wildlife Refuge

Abstract Oak (Quercus spp.) savannas are among the most imperiled ecosystems in the United States. Consequently, associated vegetation and avian communities are also in decline. Furthermore, restoration of savanna communities may be an important strategy for conserving avian species that require early successional habitat, a type underrepresented on regional landscapes. Therefore, we evaluated savanna restoration on twelve sites in the Mid-South USA. Specifically, we examined grass, forb, legume, and woody understory cover, regeneration and sapling density, and breeding bird use of the sites following mechanical overstory thinning and dormant-season fire using a hierarchical linear model. Total grass cover was negatively related to canopy cover (P < 0.01) and total forb cover was negatively related to total basal area (P  =  0.04). Oak regeneration density was positively related to canopy cover (P < 0.01), while oak competitor regeneration density was positively related to percent slope (P  =  0.01) and s...

Biomass and integrated forage/biomass yields of switchgrass as affected by intercropped cool- and warm-season legumes

Waterfowl exploit seed resources in agricultural fields to help meet the energy demands associated with migration, thermoregulation, and various life-history activities. Biologists commonly flood agricultural fields to increase the availability of seed for waterfowl and to provide hunting opportunities. Previous studies suggest that flooding may accelerate seed loss; however, simultaneous comparison of seed loss with unflooded fields has not been made. We compared rates of loss between seed contained in wire mesh bags placed in an unflooded agricultural field vs. seed submersed in a flooded field on the Tennessee National Wildlife Refuge from October 2007 to January 2008. Agricultural seed mass declined 40–300% more rapidly in the flooded than in the unflooded field. Corn, soybean, and grain sorghum seed mass declined 42%, 87%, and 46%, respectively, after 12 wk of continuous submersion, which was similar to previous studies that measured seed loss in flooded mesh bags. However, the rate of seed mass loss in unsubmersed mesh bags was 1.3–6.9 times lower than scattered seed lying on the ground under granivore exclosures in a separate experiment. We hypothesize lower rates of seed loss in mesh bags compared to scattered seed may be an artifact of the bags, which are commonly used in seed fate studies. Our results suggest biologists should delay flooding agricultural fields until immediately prior to the arrival of waterfowl and be aware that absolute estimates of seed loss from studies that use mesh bags may be biased negatively.

Poor soils and density-mediated body weight in deer: forage quality or quantity?

Switchgrass (Panicum virgatum L.) has potential as a biofuel feedstock for ethanol production on marginal soils not suitable for row crop production. Further, it is hypothesized that legumes may be interseeded into switchgrass to increase available soil nitrogen (N) and enhance switchgrass yields. Therefore the primary objective was to identify compatible legume species for intercropping with lowland switchgrass and determine if biomass yields and forage quality can be improved. Four cool- and two warm-season legume species were compared to application of 67 and 134 kg N ha−1 (59.8 and 119.6 lb N ac−1) during 2009 and 2010 over a range of soils at three research and education centers in Tennessee. Cool-season legumes were alfalfa (Medicago sativa L.), red clover (Trifolium pratense L.), crimson clover (Trifolium incarnatum L.), and hairy vetch (Vicia villosa L.), and warm-season legumes included Illinois bundle flower (Desmanthus illinoensis L.) and partridge pea (Chamaechrista fasciculata L.). Legumes were evaluated for establishment (plant densities) and their effects on switchgrass yield and forage quality under a one-cut biomass (single, postdormancy biofuel) and an integrated two-cut (biomass/forage [preanthesis]) system. In the one-cut system, switchgrass yields (16.6 Mg ha−1 [6.7 tn ac−1]) from the current recommended rate (67 kg N ha−1 [59.8 lb N ac−1]) exceeded (p < 0.05) legume treatment yields (average 13.5 Mg ha−1 [5.5 tn ac−1]). In the integrated harvest system, switchgrass yields from red (13.4 Mg ha−1 [5.4 tn ac−1]) and crimson clover (12.8 Mg ha−1 [5.2 tn ac−1]) intercrops were not different from 67 kg N ha−1 (14.5 Mg ha−1 [5.9 tn ac−1]). Crude protein levels were greater (p < 0.05) for 134 kg N ha−1 (119.6 lb N ac−1), compared to legume intercrops (except red clover). Partridge pea showed promise as a warm-season legume that can be grown compatibly with switchgrass for up to two years. Therefore, compatible legume-intercrop candidates, such as partridge pea and red clover, may enhance switchgrass yield and forage quality while displacing synthetic N in integrated biofuel/forage systems, but need to be further investigated in efforts to reduce nitrate (NO3) leaching and emissions from fertilizing.