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Grassland birds have experienced protracted population declines, primarily due to loss and degradation of native grasslands. Restoration of native grasses may benefit grassland birds, but such restoration within the eastern United States has been limited. Production uses of native grasses (e.g., hay, pasture, biofuel feedstock) provide market-based incentives that could lead to more extensive use of these grasses than existing conservation-focused practices, potentially influencing breeding birds. Therefore, we compared breeding bird (n = 9 target species) relative abundance among 4 types of native warm-season grass (NWSG) agricultural production fields: forage (hay and pasture; n = 22 and 7, respectively), seed (n = 21), biofuel (n = 15), and a control (idle fields in conservation programs or practices; n = 37) in Kentucky and Tennessee, 2009–2010. We detected 2 145 birds, with field sparrow (Spizella pusilla, 43%) and red-winged blackbird (Agelaius phoeniceus, 27%) encountered most often. Relative abundance did not differ between production types and controls except for field sparrow (lower on seed production fields) and northern bobwhite (Colinus virginianus, lower on hay production fields). Species richness equaled or exceeded that of control fields for all production categories. We documented negative relationships between relative abundance and landscape-scale forest cover for four species (field sparrow, grasshopper sparrow [Ammodramus savannarum], eastern meadowlark [Sturnella magna], and red-winged blackbird) and positive relationships with amount of pasture and hay cover for four species (northern bobwhite, grasshopper sparrow, eastern meadowlark, and red-winged blackbird), reinforcing the importance of nonforested environments for these species. We conclude that production stands could be a viable approach for increasing NWSG available for breeding birds and, when established in the appropriate landscape context, can provide benefits similar to those provided by conservation programs.

QUESTIONS: A paradoxical co‐existence challenges woodland and savanna restoration worldwide: How are shade‐intolerant, flammable herbaceous layers promoted while maintaining the shade‐casting, more fire‐sensitive woody regeneration that sustains overstorey structure? Where restoration success consisted of robust, diverse herbaceous layers and vigorous, well‐stocked Pinus echinata regeneration (hereafter, shortleaf‐bluestem response), we asked: are there targetable conditions of overstorey, understorey, topography, and proximity to mature Pinus echinata that simultaneously maximize desired woody and herbaceous understorey components? Do these conditions and dependent responses differ across canopy disturbance level and fire season? LOCATION: Cumberland Plateau, Tennessee, USA (36°04′8.11″ N, 84°50′38.36″ W). METHODS: We measured 12 shortleaf‐bluestem response and 17 explanatory condition variables at 345 plots spanning an experimental restoration gradient (canopy disturbance level and fire season combinations). We ordinated variation and identified response thresholds using a multivariate regression tree. Differences across tree groupings and splits associated response thresholds with specific explanatory conditions. RESULTS: Pockets of substantial Pinus echinata regeneration (>3,000 stems/ha), C₄ grass density (>40,000 ramets/ha), and herbaceous diversity (increase from 22 to 205 species) occurred 7–14 years after canopy disturbance and 3–8 fires. Such shortleaf‐bluestem response was maximized at 3 m²/ha residual tree basal area, 11% canopy closure, reduced midstorey density (5,000 small‐sapling stems/ha), and southwesterly aspects within 70 m of mature Pinus echinata. In contrast, shortleaf‐bluestem response was negligible at 11.3 m²/ha basal area and 68% canopy closure. Fire season, snag basal area, slope, and slope position effects were minimal. CONCLUSIONS: We identified specific conditions fostering the co‐existence of desired herbaceous and woody understorey components, addressing a major woodland and savanna restoration challenge and expanding on previous threshold concept applications by simultaneously considering multiple desired responses. Results can direct the restoration of imperiled shortleaf‐bluestem communities east of the Mississippi River, USA, where work has been scarce or ineffective, and similar approaches could inform fire‐dependent woodland and savanna restoration worldwide.

Preparing agricultural producers to cope with volatile weather changes, specifically drought, requires a better understanding of forage water-use efficiency (WUE) potentials. Options to improve farm resiliency to drought may include the use of C4 annual and perennial forages, which have greater production efficiency during drought than commonly used C3 forages. Our objective was to measure WUE through real-time gas exchange measurements of photosynthesis and transpiration in (1) a greenhouse study and (2) under field-grazing conditions. Growth parameters, instantaneous water use efficiency (iWUE), and mass-based WUE (mWUE) data were collected under greenhouse conditions in Study 1 for the following species: crabgrass (Digitaria sanguinalis cv. &lsquo, Red River&rsquo, ), switchgrass (Panicum virgatum cv. &lsquo, Alamo&rsquo, ), big bluestem (Andropogon gerardii cv. &lsquo, OZ-70&rsquo, ), indiangrass (Sorghastum nutans cv. &lsquo, Rumsey&rsquo, ), eastern gamagrass (Tripsacum dactyloides cv. &lsquo, Pete&rsquo, ), bermudagrass (Cynodon dactylon cv. &lsquo, Vaughn&rsquo, s #1&rsquo, ), sorghum-sudangrass (Sorghum bicolor (L.) &times, Sorghum sudanese (P.) cv. &lsquo, Greengrazer&rsquo, ), and tall fescue (Schedonorus arundinaceus (Schreb.) Dumort). Study 2 occurred from 2014 to 2016, and evaluated iWUE of crabgrass, switchgrass, bermudagrass, eastern gamagrass, and a big bluestem/indiangrass mix under field conditions. Overall, in situ iWUE of crabgrass, switchgrass, eastern gamagrass, and bermudagrass did not differ, while iWUE of the big bluestem/indiangrass was less than switchgrass and crabgrass, an advantage for these species if the standardized precipitation index drops below zero. Bermudagrass, switchgrass, sorghum-sudangrass, pearl millet, and indiangrass had comparable mWUE values under greenhouse-simulated drought. These results will aid in the development of forage species recommendations for mitigating drought and improving resiliency.

In oak-dominated communities throughout eastern North America, fire exclusion and subsequent woody encroachment has replaced the “glitter” of once robust and diverse wildflower and grass layers with leaf-litter dominance. Restoring the important herbaceous components of Eastern oak ecosystems could involve pairing heavy canopy disturbance with growing-season fire, but potential negative effects warrant research. Beginning with 20 ha replicates of closed-canopy forest at three sites across Tennessee and North Carolina, USA, we monitored groundcover response to combinations of thinning (none; light: 14 m2 ha−1 residual basal area; and heavy: 7 m2 ha−1) and seasonal fire (none; March: pre leaf expansion; and October: pre leaf abscission) from 2008 to 2016. Before treatments, woody plants and leaf-litter-dominated groundcover and herbaceous plants were rare (

Declines in native warm season grasslands have been linked to grassland bird population decline due to habitat loss including conversion to non-native grasses. Rotational grazing (ROT) and patch-burn grazing (PBG) are two possible tools to restore native warm-season grasses (NWSG) on working-lands in the Mid-South USA and thus aid in the recovery of grassland bird populations. This project compares ROT, PBG, and before treatment implementation to assess their effects on grassland-associated bird species. At three research sites between KY and TN, 14–10 ha NWSG pastures were established and randomly assigned 7 pastures each to ROT and PBG treatment and monitored avian relative abundance during the breeding season from 2014 to 2017. Avian call count data and vegetation characteristics were collected in 2014 and treated as a before treatment year. Following 2014, ROT and PBG treatments were implemented across each respective research site. We used the open N-mixture model framework to estimate avian relative abundance related to year, treatments, research site, and landscape and within-field variables. Avian species richness and diversity were calculated for each treatment, research site, and year. Landscape variables, within-field variables, and research sites exerted more influence on relative abundance than ROT or PBG. Grassland-associated bird species relative abundance and species richness/diversity were affected by habitat disturbances (both ROT and PBG) but varied by species and site. Field sparrows [Spizella pusilla] had the highest increase in relative abundance (9.68 ± 1.24 birds/point count location or 1.77 ha) while northern cardinals [Cardinalis cardinalis] exhibited a significant decrease in relative abundance (3.44 ± 1.54 birds/point count location) following treatment implementation on specific research sites. Species diversity and richness did not differ between ROT and PBG treatments. However, a site and year difference were observed for both estimates. Using ROT and/or PBG to create habitat disturbances can alter within-field variables (i.e., vegetation height) which, taken into context with landscape variables, could impact grassland bird populations and diversity depending on grassland bird species habitat requirements. Our research provided the baseline information for ROT and PBG impacts on grassland birds in the east/southeastern USA. However, we believe future research should focus on breeding and annual fecundity to better understand how populations will change over time and how working lands conservation might aid this conservation effort without a reduction in livestock productivity.

Establishing herbaceous groundcover is essential for oak woodland and savanna restoration. In the Appalachian region, woody vegetation in the understory can persist through many fires and interfere with achieving this goal. Herbicide applications could reduce such vegetation and interact with canopy-disturbance and fire to accelerate restoration. In stands thinned to woodland (16 m2 ha−1, 75% canopy closure) or savanna (5 m2 ha−1, 24% canopy closure) conditions and burned biennially in the fall (October) or spring (March), we economically applied triclopyr (Garlon® 3A) to understory woody plants using foliar and cut-surface techniques in the fall between fires. From 2011 to 2013, only minor differences in vegetation were observed between areas managed with canopy-disturbance and fire (CF) and areas where herbicides were also used (CFH). Small-sapling (≥1.4 m tall

Native grasses, such as switchgrass (SG; L.), big bluestem (BB; Vitman), indiangrass (IG; Nash), and eastern gamagrass (EG; [L.] L.) may be capable of providing desirable summer forage for cattle as well as a source of biomass for renewable energy. To evaluate that potential, experiments were conducted at 2 locations in Tennessee comparing weaned beef () steers (268 ± 25 kg initial BW) during early-season grazing (Early; 30 d, typically corresponding to May, followed by postdormancy biomass harvest) and full-season grazing (Full, mean duration = 98 d). For Exp. 1, which compared SG, a blend of BB and IG (BBIG), and EG, ADG was greater ( < 0.05) for BBIG (1.02 kg/d) than SG (0.85 kg/d), and both were greater ( < 0.05) than EG (0.66 kg/d). Grazing days for SG and EG were similar (389 and 423 animal unit days [AUD]/ha, respectively) and exceeded ( < 0.05) that of BBIG (233 AUD/ha) during Full. In Exp. 2 (SG and BBIG only), rates of gain were comparable to that of Exp. 1, but AUD were 425 (SG) and 299 (BBIG) AUD/ha. Such rates of gain and grazing days indicate that these grasses can provide desirable summer forage for growing cattle. Early produced 211 to 324 kg BW gain/ha, depending on experiment and forage, followed by dormant-season harvests of 7.5 to 10.5 Mg/ha of biomass, indicating a potential for beef cattle forage and biomass production on the same land resource. Native grasses provided productive summer pasture and good rates of gain on growing cattle and could contribute to forage programs, especially where cool-season grasses currently predominate.

The removal of fire’s influence on plant community succession has resulted in the near disappearance of oak (Quercus spp.) woodlands and savannas from the Appalachian region. Negative trends in associated plant and wildlife species could be reversed if these communities are restored, but management has been limited by inadequate canopy disturbance, resprouting of woody plants, and a lack of empirical research. To address these issues, we evaluated herbaceous and woody vegetation response (2008–2012) on the Cumberland Plateau in Tennessee to 5 replicated treatments involving canopy reduction (14 m2 ha−1 [woodland] or 7 m2 ha−1 [savanna] residual basal area) and fire-season (mid-March [spring] or early October [fall]) combinations and unmanaged controls. All categories of woody vegetation except large-saplings (⩾1.4 m tall and ⩾7.6 but

Surface coal mining and subsequent reclamation of surface mines have converted large forest areas into early successional vegetative communities in the eastern United States. This reclamation can provide a novel opportunity to conserve northern bobwhite (Colinus virginianus). We evaluated the influence of habitat management activities on nest survival, nest-site selection, and brood resource selection on managed and unmanaged units of a reclaimed surface mine, Peabody Wildlife Management Area (Peabody), in west-central Kentucky, USA, from 2010 to 2013. We compared resource selection, using discrete-choice analysis, and nest survival, using the nest survival model in Program MARK, between managed and unmanaged units of Peabody at 2 spatial scales: the composition and configuration of vegetation types (i.e., macrohabitat) and vegetation characteristics at nest sites and brood locations (i.e., microhabitat). On managed sites, we also investigated resource selection relative to a number of different treatments (e.g., herbicide, disking, prescribed fire). We found no evidence that nest-site selection was influenced by macrohabitat variables, but bobwhite selected nest sites in areas with greater litter depth than was available at random sites. On managed units, bobwhite were more likely to nest where herbicide was applied to reduce sericea lespedeza (Lespedeza cuneata) compared with areas untreated with herbicide. Daily nest survival was not influenced by habitat characteristics or by habitat management but was influenced by nest age and the interaction of nest initiation date and nest age. Daily nest survival was greater for older nests occurring early in the breeding season (0.99, SE

Switchgrass (Panicum virgatum L.) and guinea grass (Panicum maximum Jacq.) have been proposed as sustainable alternatives to fossil fuels in subtropical and tropical environments, respectively; although still requiring non-renewable inputs, notably, fertilizer-nitrogen (N). Furthermore, climatic intensification forecasts suggest southeastern USA may emulate more tropical or subtropical growing conditions resulting in altered N dynamics and plant physiology. Objectives were to determine: (i) effects of biochar (1 and 2Mgha−1), two intercropped legumes [sunn hemp (Crotalaria juncea L.) and pigeon pea (Cajanus cajan L.) intercrops] versus inorganic N [67kgha−1and 0kgha−1] on feedstock and soil characteristics and biomass yield; (ii) how feedstock composition is affected over three harvest dates; and, (iii) switchgrass adaptation to more extreme (tropical) growing conditions. For both species, yield and feedstock composition were influenced by harvest timing (P0.05). In general, initial harvests had greater digestible 5- and 6-carbon sugars and N, P, and K tissue levels, whereas in subsequent harvests, higher acid- and neutral-detergent fiber levels were observed, suggesting lesser potential fermentability. Desired feedstock characteristics can therefore be manipulated by harvest timing. Yield results suggest pigeon pea and sunn hemp intercrops, and biochar (1Mgha−1) may result in equivalent yields as N fertilizer per harvest (P

Biomass production systems using native warm-season grasses can allow for an early-season harvest (for forage) followed by a dormant harvest (for biomass). A study was conducted to investigate the impact of harvest timing and grass species on the chemical composition of harvested forage and biomass. The three-species composite treatments were switchgrass (SG) (Panicum virgatum L.); a two-way blend of big bluestem (Andropogon gerardii V.) (BB) and indiangrass (Sorghastrum nutans L.) (IG); and a three-way mixture of SG, BB, and IG. Harvest treatments were a biomass harvest (BH) in late fall, early-boot (EB) harvest (for forage) followed by BH, or early-seedhead harvest (ESH) (for forage) followed by BH. Forage harvested at EB had greater crude protein and less neutral detergent fiber (NDF) and acid detergent fiber (ADF) compared with ESH (P = 0.05). The ADF and NDF content of biomass was greatest for BH and was reduced in biomass regrowth after EB, with the later ESH resulting in the largest decrease in fiber content. Total macronutrient removal of N, P, and K was increased in the dual-use system. Results indicated that it is possible to alter the composition of biomass provided for bioenergy production by taking an early-season forage harvest.

Grassland birds have declined more than any other guild in the United States because of loss and degradation of native grasslands. The United States Department of Agriculture Farm Bill programs have restored some native warm-season grasses (NWSG), but populations of many grassland bird species continue to decline. Market-based NWSG uses focused on hay, pasture, and biofuel feedstock may be more appealing to landowners, and may still provide grassland bird habitat on the landscape. We examined breeding grassland bird occupancy of 102 NWSG production fields including 5 treatments (control [n = 37], grazing [n = 7], hay [n = 22], seed [n = 21], and biofuel [n = 15] production) in Kentucky and Tennessee during 2009–2010 breeding seasons. We used a robust design model in Program MARK to determine occupancy and detection rates for grassland birds. We modeled occupancy differences among treatments and sites (i.e., KY, TN), and included covariates (i.e., field-level vegetation metrics and landscape composition at 3 scales [250 m, 500 m, and 1 km]) for eastern meadowlark (Sturnella magna), field sparrow (Spizella pusilla), grasshopper sparrow (Ammodramus savannarum), northern bobwhite (Colinus virginianus), and red-winged blackbird (Agelaius phoeniceus). Covariates that influenced occupancy included treatment (field sparrow, 2009 only), site (eastern meadowlark, grasshopper sparrow, and northern bobwhite), percent NWSG cover (positive, red-winged blackbird), and percent forest cover within 250 m (negative for eastern meadowlark, grasshopper sparrow, northern bobwhite, and red-winged blackbird) or within 1 km (negative, field sparrow). Our results suggest that forest cover in the surrounding landscape negatively influences species occupancy, and species occupancy generally did not differ among NWSG production treatments. These treatments could be an alternative means to provide grassland bird habitat within an agriculture production landscape. © 2016 The Wildlife Society.

Oak (Quercus spp.) woodlands and savannas throughout the Mid-South, USA have become closed-canopy forests through succession in the absence of fire, contributing to declines in disturbance-dependent avian species. Restoration could ameliorate these trends, but effects of such management practices on avian communities of the Mid-South are poorly understood. We implemented an experiment on the Cumberland Plateau, Tennessee with treatments involving fall (Oct) or spring (Mar) fire with woodland (14 m2/ha) or savanna (7 m2/ha) residual basal area and unmanaged control stands (20 ha each). We conducted fixed-radius point counts 3 times annually (2010–2012) and analyzed trends in naive occupancy for 41 species. For 20 species with adequate data (10 early-, 10 late-successional), we performed multiple-season, robust-design occupancy modeling and accounted for detection bias. We then used mixed-model polynomial regression to define relationships between occupancy and measures of live and dead basal area, midstory density, and herbaceous groundcover. Restoration substantially altered forest structural characteristics but did not affect the occupancy of most late-successional species. In contrast, the presence of early-successional species increased as live basal area decreased and herbaceous groundcover increased. Only 3 of 41 species (hooded warbler [Setophaga citrina], ovenbird [Seiurus aurocapilla], and worm-eating warbler [Helmitheros vermivorum]) exhibited reduced occupancy as woodland and savanna conditions were approached. The presence of all other species, including 13 regionally and 2 continentally declining, remained constant or increased as restoration progressed. Woodland conditions of 10 m2/ha live basal area and 20% herbaceous groundcover maximized occupancy of early-successional species with little consequences for late-successional species. Proceeding further toward savanna conditions negatively affected species associated with lower strata of mature-forests but further increased the presence of some early-successional species. Midstory density and dead basal area were poor predictors of occupancy and thus may be necessary but not sufficient in promoting early-successional species. Our results suggest implementing oak woodland and savanna management in the Mid-South could benefit disturbance-dependent birds of high conservation priority with minimal negative impacts on the presence of late-successional species. © 2016 The Wildlife Society.

109 Determining alternative organic N fertilizer sources and levels over a range of soils that are C-neutral is fundamental to producing a sustainable bioenergy feedstock. Specifically, inorganic N fertilizers have prices linked to petroleum markets, require fossil energy for their production, and can degrade surface and ground water (Pimentel et al., 2008; Ashworth et al., 2015). One likely replacement of synthetic N fertilizer is the use of legumes in biofuel production systems (Snapp et al., 1998). An additional inorganic N alternative is biochar or the by-product of switchgrass and other lignocellulosic biomass from thermochemical conversion processes such as pyrolysis (Lehmann and Joseph, 2009). Biochar applications to soil may increase C sequestration and plant nutrient retention, thereby decreasing chemical fertilizer inputs (Mullen et al., 2010). However, in order for legumes and biochar to be employed for feedstock production, a protocol for the most economical and nutrient efficient system is needed. Soil fertility and crop yield can be increased by leguminous green manure intercrops through increases in soil organic C, N, and P compared with weedy fallows and nonleguminous cover crops (Tonitto et al., 2006). However, the extent of this in warm temperate intercropping systems is unknown, especially for switchgrass production. Smithson and Giller (2002) found that biologically fixed N from legumes can reach levels up to 450 kg N ha-1 per crop. Tonitto et al. (2006) concluded in a meta-analysis that legumes could supply up to 350 kg N ha-1 yr-1 in a fairly continuous distribution, with 50% of the studies having 50 to 150 kg N ha-1 yr crop-1. At this level of N, legume intercrop systems can meet N requirements for switchgrass production. These results demonstrate the potential for N2–fixing crops to support crop yields while reducing reactive mononitrogen oxide emissions and decreasing nitrate leaching by up to 40% (Tonitto et al., 2006). Biofuels

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 hypothe- sized 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 switch- grass 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 inte- grated biofuel/forage systems, but need to be further investigated in efforts to reduce nitrate (NO 3 ) leaching and emissions from fertilizing.

Heifer rearing is one of the largest production expenses for dairy cattle operations, which is one reason milking operations outsource heifer rearing to custom developers. The cost of harvested feedstuffs is a major expense in heifer rearing. A possible way to lower feed costs is to graze dairy heifers, but little research exists on this topic in the mid-south United States. The objectives of this research were to determine the cost of feeding bred dairy heifers grazing native warm-season grasses (NWSG), with and without legumes, and compare the cost of grazing with the cost of rearing heifers using 3 traditional rations. The 3 rations were corn silage with soybean meal, corn silage with dry distillers grain, and a wet distillers grain-based ration. Bred Holstein heifers between 15- and 20-mo-old continuously grazed switchgrass (SG), SG with red clover (SG+RC), a big bluestem and Indiangrass mixture (BBIG), and BBIG with red clover (BBIG+RC) in Tennessee during the summer months. Total grazing days were calculated for each NWSG to determine the average cost/animal per grazing day. The average daily gain (ADG) was calculated for each NWSG to develop 3 harvested feed rations that would result in the same ADG over the same number of grazing day as each NWSG treatment. The average cost/animal per grazing day was lowest for SG ($0.48/animal/grazing d) and highest for BBIG+RC ($1.10/animal/grazing d). For both BBIG and SG, legumes increased the average cost/animal per grazing day because grazing days did not increase enough to account for the additional cost of the legumes. No difference was observed in ADG for heifers grazing BBIG (0.85 kg/d) and BBIG+RC (0.94 kg/d), and no difference was observed in ADG for heifers grazing SG (0.71 kg/d) and SG+RC (0.70 kg/d). However, the ADG for heifers grazing SG and SG+RC was lower than the ADG for heifers grazing either BBIG or BBIG+RC. The average cost/animal per grazing day was lower for all NWSG treatments than the average cost/animal per day for all comparable feed rations at a low, average, and high yardage fee. Results of this study suggest that SG was the most cost-effective NWSG alternative to harvested feeds for bred dairy heifer rearing.

Across the Southeastern U.S., including the Cumberland Plateau of Tennessee, prescribed fire and overstory thinning are being used to restore areas of closed-canopy hardwood forest to open woodland and savanna. We used acoustic recording of bat echolocation call sequences to examine bat activity (relative use of an area for foraging) in hardwood forest stands subject to 4 prescribed fire and residual basal area treatments (spring prescribed fire with woodland [SpW] and savanna [SpS] residual basal areas, and fall prescribed fire with woodland [FaW] and savanna [FaS]) basal areas, as well as untreated controls, during summer of 2013 and 2014. When possible, we classified recorded echolocation call sequences to species using automated identification software (Sonobat™ 3.1.4, SonoBat™ Inc., Arcata, California). To minimize errors in species classification of recorded bat passes, we combined similar species in groups based on call characteristics prior to conducting analyses. Total bat activity (P ⩽ 0.001), as well as LABO/NYHU (eastern red bat [Lasiurus borealis] and evening bat [Nycticeius humeralis]; P = 0.001), EPFU/LANO (big brown bat [Eptesicus fuscus] and silver-haired bat [Lasionycteris noctivagans]; P ⩽ 0.001), PESU (tricolored bat [Perimyotis subflavus]; P = 0.001), and LACI (hoary bat [Lasiurus cinereus]; P = 0.005) activity was generally higher in SpS and FaS stands, where overstory basal area was lower, than in control, SpW, and FaW stands, where overstory basal area was higher (P ⩽ 0.001). Our results suggest these treatments reduce clutter (physical obstructions to flight and foraging including foliage, branches, and stems), leading to improved foraging conditions for bats, particularly larger bodied species with lower call frequencies that are adapted to fly and forage in open conditions. We found no evidence nocturnal flying insect prey abundance or biomass influenced activity of bats in treatment stands, indicating clutter is more important than prey availability in determining habitat use by bats in this system. Our study provides support for continued use of prescribed fire and overstory thinning to restore hardwood forest to woodland and savanna and as a strategy to maintain and enhance habitat for forest bats in the Southeastern U.S.

Establishment failures linked to seed dormancy are a challenge to wide-scale use of switchgrass (Panicum virgatum L.) for biomass feedstock and forage production. One prospective strategy for breaking dormancy is dormantseason planting. The objectives of this study were to evaluate (i) three switchgrass dormantseason planting dates (1 December, 1 February, and 15 March) vs. a growing-season (1 May) control; (ii) two seeding rates (6.7 and 10.1 kg pure live seed [PLS] ha−1); and (iii) highand lowdormancy seed lots. Treatments were assigned in a split-plot design with three replications at two locations in Tennessee in 2008 and 2009. Neither seeding rate nor seed-dormancy level affected plant density or yield (P > 0.05). However, a seeding date  year interaction impacted first-year density at both locations. Although patterns differed by year for the two locations, density of March plantings equaled or exceeded (P < 0.05) those at other dates for both locations and years. These variations in density did not carry over to impact yield in year two. A sigmoidal regression of seedling density vs. yield was significant (P < 0.001) albeit not strong (R2 = 0.13); yield response approached an asymptote above ~8 plants m−2. Results suggest March planting dates, using standard seeding rate recommendations (6.7 kg PLS ha−1) irrespective of seed-dormancy rates, may be more reliable than planting in May. Thus, a broader establishment window than traditionally used may be practical. However, results should be validated over a broader range of soils and climatic conditions, especially over a winter severity gradient. P.D. Keyser, A.J. Ashworth, F.L. Allen, and G.E. Bates Center for Native Grasslands Management, Univ. of Tennessee Institute of Agriculture, 2431 Joe Johnson Drive, 252 Ellington Plant Sciences Building, Knoxville, TN 37996; P.D. Keyser, Dep. of Wildlife and Fisheries, Univ. of Tennessee Institute of Agriculture, 2431 Joe Johnson Drive, 252 Ellington Plant Sciences Building, Knoxville, TN 37996; and A.J. Ashworth, F.L. Allen, and G.E. Bates, Dep. of Plant Sciences, Univ. of Tennessee Institute of Agriculture, 2431 Joe Johnson Drive, 252 Ellington Plant Sciences Building, Knoxville, TN 37996. Received 6 Mar. 2015. Accepted 24 Aug. 2015. *Corresponding author (pkeyser@utk.edu). Abbreviations: ETREC, East Tennessee Research and Education Center; HRREC, Highland Rim Research and Education Center; PLS, pure live seed; Trmt, seeding treatment. Published in Crop Sci. 56:1–10 (2016). doi: 10.2135/cropsci2015.03.0144 © Crop Science Society of America | 5585 Guilford Rd., Madison, WI 53711 USA All rights reserved. Published November 6, 2015

The objective was to determine the breakeven price for switchgrass (SG) (Panicum virgatum L.), a mix of big bluestem (Andropogon gerardii Vitman) and Indiangrass (BBIG) (Sorghastrum nutans L. Nash), and a combination of SG and BBIG (SG/BBIG) produced under three harvest treatments. Two-harvest treatments included a forage harvest at early boot (EB) and at early seedhead (ESH) plus a biomass harvest at fall dormancy (FD). The third harvest treatment was a single biomass harvest at FD. Mixed models were used to determine if there were differences in yield, crude protein, and nutrient removal for each of the native warm-season grass (NWSG) treatments at each harvest. The EB plus FD harvest system would be preferred over the ESH plus FD harvest system for all NWSG treatments. BBIG was the only NWSG treatment with a breakeven price for biomass that decreased with an EB harvest. For all three NWSG treatments, a producer would be better off harvesting once a year for biomass than twice for forage and biomass. The cost of harvesting and replacing the nutrients for the forage harvest was greater than the revenue received from selling the forage.

2419 The Green Revolution of the mid-20th century boosted food security, thanks to improved crop genetics and the use of fossil fuel-intensive inputs such as N fertilizer. Modern extensions of the Green Revolution promote agricultural and energy sustainability via reductions of environmental impacts (e.g., greenhouse gases and water contamination) and the production of renewable biofuels. Use of N2–fi xing legume species to replace fossil fuel-based N fertilizers exemplifi es a convergence of agricultural and energy sustainability. Th e manufacture and use of synthetic N fertilizers are signifi cant causes of greenhouse gases emissions and off -fi eld movements of N to natural waters (Peoples et al., 1995; Peoples and Baldock, 2001). Furthermore, N2O, a byproduct of nitrifi cation (of NH4) and denitrifi cation (of NO3) during synthetic N fertilizer transformations in soils, is approximately 300 times more potent as a greenhouse gases than CO2 (Schlesinger, 1991). Although interseeding N2–fi xing legumes has been practiced with many tropical crops and temperate pastures, no legumes have been identifi ed as promising companion species for supplying N to switchgrass. Further, switchgrass has been touted as an environmentally benign feedstock for biofuels, although it does require N to assure satisfactory yields, albeit at modest levels. Recommended annual N applications of 67 kg ha–1 for switchgrass growth (Mooney et al., 2009) indicate that potential exists to further improve environmental benefi ts if such inputs are replaced with BNF (Ashworth et al., 2015). Legumes fi x atmospheric N2 into NH4 in root nodules via symbiosis with Rhizobium-type bacteria but legumes also take up plant-available soil N, resulting in a mixture of soil-derived and atmosphere-derived N in the total N mass of the plant agronomy, soils & environmental Quality

Intercropping legumes may reduce inputs and enhance sustainability of forage and feedstock production, especially on marginal soils. This approach is largely untested for switchgrass (Panicum virgatum L.) production, yet producer acceptance should be high given the traditional use of legumes in forage/agricultural systems. Our objectives were to evaluate three cool-season and two warm-season legumes and their required densities to influence yield and supply nitrogen (N) compared to three inorganic N levels (0, 33, and 66 kg N ha -1 (0, 30, and 60 lb N ac -1 )) at three locations in Tennessee (Knoxville (Sequatchie Silt Loam), Crossville (Lilly Loam), and Milan (Loring B2 Series)). Fall of 2010 seeded, cool-season legumes (red clover (Trifolium pratense L.), hairy vetch (Vicia villosa L.), ladino clover (Trifolium repens L.)), arrowleaf clover (Trifolium vesiculosum L.), and a spring of 2011 seeded, warm-sea- son legume (partridge pea (Chamaecrista fasciculate L.)) were interseeded into switchgrass at three (high, medium, and low) seeding rates each in two experiments. Harvest treatments were annual single, postdormancy biofuel (Experiment One) or integrated forage-biofuel (preanthesis and postdormancy; Experiment Two). Year one yield impacts were minimal. During the second harvest year, legumes increased yield versus Year 1; in general, yields for 33 and 67 kg N ha -1 did not differ from those for red clover, hairy vetch, ladino clover, or partridge pea (p < 0.05). Arrowleaf clover yields were not different from 0 kg N ha -1 . Forage biomass yields were generally more responsive to legumes (p < 0.05) than the biomass regime. Legume persistence after three years was generally greatest for ladino clover and partridge pea. Forage quality (switchgrass only) in some cases was positively influenced by legume treatments, notably hairy vetch and partridge pea (p < 0.05). Intercropping selected legumes in switchgrass may enhance forage quality and yield while reducing nonrenewable inputs, fertilizer costs, and emissions/runoff to air and groundwater.

2321 The development of renewable energy sources has become an issue of increasing importance and consequently has grown over the last three decades (Lynd et al., 1991; Sanderson et. al., 1996; McLaughlin and Kszos, 2005). It has been estimated that more than 21 million ha of SG might be needed annually for biomass production (English et al., 2006). If SG or other dedicated herbaceous energy crops were planted at this scale, there could be a significant portion of land currently being used for forage production being displaced by biomass crops (English et al., 2006; Graham et al., 2008; Sanderson and Adler, 2008). To address this issue, dualharvest forage/biomass systems have been explored with interest in using SG for biomass (Sanderson et al., 1999; Guretzky et al., 2011; Mosali et al., 2013). This approach could allow producers the flexibility to divert some biomass production into forage, exploit biomass markets, select alternative harvest options, and the potential to increase profitability (Sanderson and Adler, 2008). Where forage is a priority, growing-season harvests should occur earlier in the growing season when forage has a higher nutritive value (Mitchell et al., 2001; Guretzky et al., 2011; Richner et al., 2014). Several studies have examined dualharvests (i.e., growing-season plus dormant-season) in SG but those harvests occurred in late June or mid-July, when plants had flowered and nutritive value had fallen below optimum levels (Grabowski et al., 2004; Thomason et al., 2005; Fike et al., 2006; Guretzky et al., 2011). In the southern Great Plains, Sanderson et al. (1999) concluded a May/dormant harvest combination was the best approach for a dual-harvest system. In another study from the southern Great Plains, Guretzky et al. (2011) recommended dual-harvest use of SG if the first harvest was taken early in the growing season and the biomass harvest was taken after the first killing frost. In the northern Great Plains, Vogel et al. (2002) recommended an early harvest Climatology & Water Management

Native warm-season grasses (NWSGs) have demonstrated potential to reduce summer forage variability, and furthermore, there has been growing interest in the use of NWSGs as lignocellulosic biomass crops. Th e objective of this research was to determine if there was a diff erence in net returns for full-season summer grazing beef steers (Bos taurus) on three NWSGs. Additionally, the expected price for biomass that a beef producer would need to break even between using the dual-purpose early-season grazing and biomass system and the full-season grazing system was calculated for these three NWSGs. Weaned beef steers grazed switchgrass (Panicum virgatum L.) (SG), a big bluestem (Andropogon gerardi Vitman) and indiangrass [Sorghastrum nutans (L.) Nash] mixture (BBIG), and eastern gamagrass [Tripsacum dactyloides (L.) L.] at Grand Junction (AP) and Highland Rim (HR), TN, from 2010 to 2012. Th e dual-purpose grazing occurred for 30 d beginning in early May, with subsequent growth harvested as biomass post-dormancy, and full-season grazing occurred for 90 d beginning in early May. Budgets were developed for each NWSG to calculate net returns, and mixed models were used to determine diff erences in beef yield and net returns across each NWSG and location. Expected yield and net returns to full-season grazing were not diff erent among NWSGs at AP. However, net returns to full-season grazing were higher for BBIG than SG at HR. A profi t-maximizing, risk-neutral individual would increase net returns by grazing any of the NWSGs over marketing calves at weaning. Th e breakeven biomass prices ranged between US$10 and US$98 Mg–1 depending on the NWSG and location.

More than 600,000 ha of mine land have been reclaimed in the eastern United States, providing large contiguous tracts of early successional vegetation that can be managed for northern bobwhite (Colinus virginianus). However, habitat quality on reclaimed mine land can be limited by extensive coverage of non-native invasive species, which are commonly planted during reclamation. We used discrete-choice analysis to investigate bobwhite resource selection throughout the year on Peabody Wildlife Management Area, a 3,330-ha reclaimed surface mine in western Kentucky. We used a treatment-control design to study resource selection at 2 spatial scales to identify important aspects of mine land vegetation and whether resource selection differed between areas with habitat management (i.e., burning, disking, herbicide; treatment) and unmanaged units (control). Our objectives were to estimate bobwhite resource selection on reclaimed mine land and to estimate the influence of habitat management practices on resource selection. We used locations from 283 individuals during the breeding season (1 Apr–30 Sep) and 136 coveys during the non-breeding season (1 Oct–Mar 31) from August 2009 to March 2014. Individuals were located closer to shrub cover than would be expected at random throughout the year. During the breeding season, individuals on treatment units used areas with smaller contagion index values (i.e., greater interspersion) compared with individuals on control units. During the non-breeding season, birds selected areas with greater shrub-open edge density compared with random. At the microhabitat scale, individuals selected areas with increased visual obstruction >1 m aboveground. During the breeding season, birds were closer to disked areas (linear and non-linear) than would be expected at random. Individuals selected non-linear disked areas during winter but did not select linear disked areas (firebreaks) because they were planted to winter wheat each fall and lacked cover during the non-breeding season. Individuals also selected areas treated with herbicide to control sericea lespedeza (Lespedeza cuneata) throughout the year. During the breeding season, bobwhites avoided areas burned during the previous dormant season. Habitat quality of reclaimed mine lands may be limited by a lack of shrub cover and extensive coverage of non-native herbaceous vegetation. Managers aiming to increase bobwhite abundance should focus on increasing interspersion of shrub cover, with no area >100 m from shrub cover. We suggest disking and herbicide application to control invasive species and improve the structure and composition of vegetation for bobwhites. © 2015 The Wildlife Society.

Management strategies designed to reduce the negative impacts of overabundant Odocoileus virginianus (White-tailed Deer) populations on forest regeneration may be influenced by changes in both population density and timber harvest. However, there is conflicting evidence as to how such changes in per capita resource availability influence home-range patterns. We compared home-range patterns of 33 female White-tailed Deer from a low-density population at a site with abundant browse to patterns of a sample of >100 females prior to a 75% reduction in population density and a doubling in timber harvest area. Home-range and core-area sizes were approximately 3 times larger than were found prior to population decline and timber harvest increase, consistent with predictions related to intraspecific competition. We also observed greater site fidelity than previously exhibited, although this may be an artifact of increased home-range sizes. Our results support previous research suggesting that White-tailed...

Habitat management for northern bobwhite (Colinus virginianus) should affect vital rates, but direct linkages with survival are not well documented; therefore, we implemented an experiment to evaluate those responses. We conducted our experiment on a reclaimed surface mine, a novel landscape where conditions were considered sub-optimal because of the dominance of non-native vegetation, such as sericea lespedeza (Lespedeza cuneata), which has been reported to provide marginal habitat for northern bobwhite and may negatively affect survival. Nonetheless, these areas have great potential for contributing to bobwhite conservation because of the amount of early successional cover they provide. Our study site, a 3,330-ha reclaimed surface mine in western Kentucky, consisted of 2 tracts (Sinclair and Ken, 1,471 ha and 1,853 ha, respectively) that served as replicates with each randomly divided into a treatment (i.e., habitat manipulation through a combination of disking, burning, and herbicide application) and an undisturbed control (n = 4 experimental units). Habitat treatments were applied October 2009 to September 2013. We used radio telemetry to monitor northern bobwhite (n = 1,198) during summer (1 Apr–30 Sep) and winter (1 Oct–31 Mar), 2009–2013. We used the known-fate model in Program MARK to evaluate treatment effects on seasonal survival rates. We included biological, home-range, landscape, and microhabitat metrics as covariates to help improve model sensitivity and further elucidate experimental impacts. Survival varied annually, ranging from 0.139 (SE = 0.031) to 0.301 (SE = 0.032), and seasonally (summer, 0.148 [SE = 0.015]; winter, 0.281 [SE = 0.022]). We found a treatment effect (β = 0.256, 95% CI = 0.057–0.456) with a seasonal interaction (β = −0.598, 95% CI = −0.898 to −0.298) with survival being higher in summer (0.179 [SE = 0.022] vs. 0.109 [SE = 0.019]) and lower in winter (0.233 [SE = 0.025] vs. 0.355 [SE = 0.035]) on treatment than control units. Among habitat covariates, litter depth (β = −0.387, 95%CI = −0.5809 to −0.1930) was the most influential effect (negative) on survival. Additional experiments across a wider range of habitat conditions may be required to determine management intensity or duration thresholds required to elicit greater changes in survival for northern bobwhite populations. Published 2015. This article is a U.S. Government work and is in the public domain in the USA.

Many wildlife management prescriptions are either implicitly or explicitly designed to improve habitat quality for a focal species, but habitat quality is often difficult to quantify. Depending upon the approach used to define and identify high-quality habitat, management decisions may differ widely. Although individual-level measures of habitat quality based on per capita reproduction (e.g., average nesting success, number of young produced per pair) are most common in the literature, they may not align with population-level measures that reflect number of young produced within a defined area. Using data on the cerulean warbler (Setophaga cerulea) collected in the Cumberland Mountains (Tennessee, USA; 2008–2010) as an example, we illustrate how lack of concordance between individual- and population-level measures of habitat quality can have real-world management implications. © 2015 The Wildlife Society.

Native warm-season grasses (NWSG) currently are being promoted for livestock forage and biofuels feedstock in the Mid-South. However, there are no published data on how NWSG managed with livestock in the Mid-South may affect habitat for wildlife. We conducted a study to evaluate habitat for grassland songbirds and northern bobwhite (Colinus virginianus) in response to two cattle grazing treatments in NWSG pastures across three sites in Tennessee, 2010 and 2011. We evaluated vegetation composition and structure along with invertebrate availability during the primary nesting season for grassland songbirds and the typical brood-rearing season for the northern bobwhite. Grazing treatments included full-season (May to August) grazing and early-season (30 days beginning in May) grazing, after which subsequent growth was taken as a biofuel harvest postdormancy. Forage treatments included big bluestem/indiangrass mixture, switchgrass, and eastern gamagrass. Vegetation composition was dominated by the planted forages in all pastures. All forage types and both grazing treatments provided suitable structure for grassland songbirds and bobwhite during the primary nesting season. Full-season grazing maintained suitable structure through the brooding period, with greater openness at the ground level and angle of obstruction, as well as optimal vegetation height (

Forested streamside management zones (SMZs) provide numerous societal benefits including protection of water quality and enhancement of in-stream and riparian habitats. However, values of residual timber in SMZs are often ignored, yet maintenance of unnecessarily wide SMZs can potentially reduce merchantable timber. Therefore, forestland owners, managers, and logging contractors are interested in determining minimum SMZ widths and stocking levels that can effectively maintain water quality while minimizing residual SMZ stand values. A larger SMZ efficacy study evaluated the efficacy of 7.6-m SMZs with no thinning, 15.2-m SMZs with no thinning, 15.2-m SMZs with thinning, and 30.2-m SMZs without thinning within 16 operational clearcuts. All SMZs widths provided effective sediment control (Lakel et al. 2010). The substudy presented here evaluated residual values in the SMZs of the larger study. Analyses examined immediate values associated with foregoing removal of SMZ timber and provide insight into future SMZ management issues. Across 16 harvested tracts, SMZs accounted for approximately 12% of the total harvest area with an average SMZ residual timber value of $1,064.78/ha. This study supports the financial benefits of partial harvests within the SMZs that remove higher value trees as typically recommended or permitted by best management practice guidelines. However, partial harvests may promote less valuable shade-tolerant species. Results also indicated that almost one-half of the SMZs had notable wind and/or ice damage within 2 years of installation. Financial analysis including opportunities for a tax credit indicate that longer term management of SMZs may be financially feasible if valuable products continue to be thinned from these stands along with rotational harvesting of the adjacent upland stands. Overall, results indicate that society and landowner short-term goals for typical southern Piedmont sites can generally be achieved by leaving 15.2-m SMZs and thinning the stands where practical.