Responses of early-successional songbirds to a two-stage shelterwood harvest for oak forest regeneration

Background: The early stage of forest succession following disturbance is characterized by a shift in songbird com- position as well as increased avian richness due to increased herbaceous growth in the forest understory. However, regeneration of woody species eventually outcompetes the herbaceous understory, subsequently shifting vegetation communities and decreasing availability of vital foraging and nesting cover for disturbance-dependent birds, ulti- mately resulting in their displacement. These early stages following forest disturbance, which are declining through- out the eastern United States, are ephemeral in nature and birds depend on such disturbances for nesting and other purposes throughout their lives. Methods: We investigated the use of a two-stage shelterwood method to manage long-term persistence of seven early successional songbirds over a 13-year period in an upland hardwood forest within the southern end of the mid- Cumberland Plateau in the eastern United States. Results: Canopy and midstory gaps created after initial harvest were quickly exploited by tree growth and canopy cover returned to these areas, accelerating the displacement of early-successional species. Woody stem densities increased substantially following stage two harvest as advanced tree regeneration combined with the re-opening of the overstory layer increased resource competition for early-successional plants in the understory. Carolina Wren (Thryothorus ludovicianus), Eastern Towhee (Pipilo erythrophthalmus), Indigo Bunting (Passerina cyanea), and Yellow- breasted Chat (Icteria virens) were characterized by immediate increases following initial harvest in 2001; while the American Goldfinch (Spinus tristis), Prairie Warbler (Setophaga discolor), and White-eyed Vireo (Vireo griseus) did not show an immediate response. Stage two harvest in 2011 rejuvenated vegetation which benefitted focal species, with six of seven species showing increases in densities between 2010 and 2012. Conclusion: The two-stage shelterwood method created conditions advantageous to early-successional birds by helping to re-establish understory vegetation through periodic disturbance to the canopy layer. This method provides evidence that early-successional species can be managed long-term (\u3e 15 years) while using relatively small spatial disturbance through the two-stage shelterwood method

Stand dynamics of an oak woodland forest and effects of a restoration treatment on forest health

a b s t r a c t Woodland restoration has been conducted in many countries, primarily in Mediterranean regions, but has only recently been attempted on publically and privately owned lands in the eastern United States. We reconstructed historical stand dynamics and tested the immediate effects of an oak (Quercus) woodland restoration treatment on forest health, inferred from tree-ring widths (TRW). The stands were upland white oak (Q. alba) and chestnut oak (Q. prinus) dominated and were located on the Cumberland Plateau of eastern Kentucky, USA. The stands regenerated primarily under a severe disturbance regime concurrent with peak industrial logging approximately 100 years ago. A relatively high percentage of trees (38 percent) recruited under large canopy gaps or clearings, indicative of a severe disturbance; however, gap-phase dynamics was also an important process in oak recruitment to the canopy. Primarily small (<31 cm DBH) and young (<110 years old) trees were removed during the restoration treatment, and mean DBH of residual trees was 13 cm larger than harvested trees. Residual trees were 22 years older than harvested trees, but this difference was not significant. The largest and oldest trees represented important legacy trees that could provide desirable forest biodiversity attributes. Residual trees had larger TRWs than harvested trees, beginning in the 1930s, and these differences increased over time. Residual trees also had larger TRW during two recent drought events (1986 and 1999), but recovery following drought was similar between residual and harvested trees. Managers can use well established silvicultural techniques to obtain desired stand structural conditions, while selecting healthy trees that have better response to stress factors such as drought. The oak woodland restoration treatment may help to maintain residual overstory trees until oak regeneration can be recruited to provide sustainability towards the next generation. Published by Elsevier B.V

Heartland Virus in Lone Star Ticks, Alabama, USA

We detected Heartland virus (HRTV) in lone star nymphs collected in 2018 in northern Alabama, USA. Real-time reverse transcription PCR selective for the small segment of the HRTV genome and confirmatory sequencing of positive samples showed high identity with HRTV strains sequenced from Tennessee and Missouri

Responses of early-successional songbirds to a two-stage shelterwood harvest for oak forest regeneration

Abstract Background The early stage of forest succession following disturbance is characterized by a shift in songbird composition as well as increased avian richness due to increased herbaceous growth in the forest understory. However, regeneration of woody species eventually outcompetes the herbaceous understory, subsequently shifting vegetation communities and decreasing availability of vital foraging and nesting cover for disturbance-dependent birds, ultimately resulting in their displacement. These early stages following forest disturbance, which are declining throughout the eastern United States, are ephemeral in nature and birds depend on such disturbances for nesting and other purposes throughout their lives. Methods We investigated the use of a two-stage shelterwood method to manage long-term persistence of seven early successional songbirds over a 13-year period in an upland hardwood forest within the southern end of the mid-Cumberland Plateau in the eastern United States. Results Canopy and midstory gaps created after initial harvest were quickly exploited by tree growth and canopy cover returned to these areas, accelerating the displacement of early-successional species. Woody stem densities increased substantially following stage two harvest as advanced tree regeneration combined with the re-opening of the overstory layer increased resource competition for early-successional plants in the understory. Carolina Wren (Thryothorus ludovicianus), Eastern Towhee (Pipilo erythrophthalmus), Indigo Bunting (Passerina cyanea), and Yellow-breasted Chat (Icteria virens) were characterized by immediate increases following initial harvest in 2001; while the American Goldfinch (Spinus tristis), Prairie Warbler (Setophaga discolor), and White-eyed Vireo (Vireo griseus) did not show an immediate response. Stage two harvest in 2011 rejuvenated vegetation which benefitted focal species, with six of seven species showing increases in densities between 2010 and 2012. Conclusion The two-stage shelterwood method created conditions advantageous to early-successional birds by helping to re-establish understory vegetation through periodic disturbance to the canopy layer. This method provides evidence that early-successional species can be managed long-term (> 15 years) while using relatively small spatial disturbance through the two-stage shelterwood method

Temporal patterns of ground flora response to fire in thinned Pinus-Quercus stands

The ground flora stratum affects stand structure, resource acquisition, nutrient cycling, and taxonomic richness in forest ecosystems. Disturbances, such as thinning and prescribed fire, alter forest understory growing conditions that generally increase ground flora cover and richness. We studied annual changes in ground flora assemblages over three growing seasons post-fire in thinned and frequently burned (three-year rotation) Pinus-Quercus stands. Our results corroborated trends from other studies that indicated greater ground flora richness and cover after thinning and burning compared to thin-only treatments. We also found that the stratum experienced relatively rapid succession between growing seasons that complimented the tolerance succession model. Forbs had reduced cover and richness from increasingly difficult growing conditions over time and were replaced by woody plants, shrubs, and seedlings. This likely occurred from changing competition dynamics that favored quick growth in the first growing season and long-term investment in vertical growth in the third growing season. The successful regeneration pathways also fit ground flora regeneration models and added a unique pathway to strengthen the predictive power of these models. As many stand management goals are focused towards improving biodiversity, prescribed fire and thinning may be used to increase understory richness in Pinus-Quercus stands.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

The effects of intermediate-scale wind disturbance on forest composition, structure, and succession with implications for management

Forest disturbances are discrete events in space and time that disrupt the biophysical environment and impart lasting legacies on forest composition, structure, and stand development. Intermediate-scale disturbances may promote stand heterogeneity, including uneven-aged structure, and their effects can range in size and distribution from small, patchy gaps to the removal of large portions of overstory vegetation. These events are often classified along gradients of intensity, which in this study were defined using post-tornado aerial photographs and visual assessments in the field. The specific objectives of this study, which took place two growing seasons after an EF1 tornado, were to quantify and compare canopy structure, understory light regimes, woody species composition, and species diversity along a gradient of canopy disturbance and to analyze the influence of intermediate-scale disturbance on the successional trajectory of an upland hardwood forest. We found no significant differences in tree layer Shannon diversity among the control (no storm damage), moderately, or severely disturbed plots. We found significant differences (P < 0.01) in percent of intercepted PAR between the control and severe classes and between moderate and severe classes. This disturbance acted primarily as a release mechanism for advanced regeneration and stems in the midstory. Our results can be used to refine silvicultural prescriptions that attempt to minimize the disparity between managed and unmanaged stands and to promote intra-stand heterogeneity. (Published By University of Alabama Libraries

Influence of gap-scale disturbance on development and succession in a Cumberland plateau quercus-pinus forest

Quercus-Pinus forests of the eastern US span > 13 million ha. It is important for managers to understand the methods used to sustain Pinus spp. in these mixtures or progress toward a more natural mixture of hardwoods. Understanding developmental and successional patterns in this forest type can help assess the need to actively manage natural processes, or to inform silvicultural prescriptions to achieve management goals. Little research has been conducted on localized disturbance processes in Quercus-Pinus forests. I examined 60 canopy gaps in a Quercus-Pinus forest on the Cumberland Plateau in Alabama to analyze their influence on development and succession. Most canopy gaps (53%) were single treefall events caused by snapped stems. The majority of gap maker trees (56%) were Pinus individuals while 44% were hardwoods. Most gaps (58%) closed by height growth of subcanopy trees. The majority of these gap filler taxa were hardwoods: Quercus (39%), Carya (14%), Pinus (14%), Nyssa Sylvatica (12%), and other (15%). Significant positive relationships existed between gap size and sapling diversity (r² = 0.15, P = 0.002), tree diversity (r² = 0.21, P = 0.0002), and total stem diversity (r² = 0.29, P < 0.0001). The number of Pinus gap makers and the number of gaps projected to fill by subcanopy recruitment of hardwoods indicated the forest was in the latter stages of a composition shift from Pinus to a much stronger Quercus component. To maintain a Pinus component, managers would likely need to create canopy gaps larger than those documented here and remove hardwood competition from the regeneration layer. (Published By University of Alabama Libraries

Gap dynamics in mature, mesic quercus stands on the Cumberland Plateau, Alabama

Gap scale disturbances are important processes in forest stand development in the southern Appalachian Highlands. Canopy gaps within secondary forest throughout the southern Appalachian Highlands have been documented as critical mechanisms in canopy tree replacement and stand regeneration. I quantified gap characteristics, gap formation and closure mechanisms, and intra-gap tree and sapling distribution patterns for 60 canopy gaps in secondary mesic, Quercus stands on the Cumberland Plateau in north Alabama. Snag-formed gaps were the most common. We documented the influence gap formation mechanisms had on gap size, which ultimately contributed to gap closure. The projected closure mechanism was significantly related to the area of the gap whereby smaller gaps usually closed via lateral crown expansion and larger gaps typically closed by subcanopy recruitment. Based on the results, I hypothesized that gaps exceeding 200 m2 had higher probabilities of closing via subcanopy recruitment rather than lateral crown expansion. Several gaps projected to close by subcanopy recruitment were doing so through Quercus capture. However, Quercus capture of gaps was restricted to upper slope position with low understory competition from shade tolerant species and adequate light levels based on the ratio of gap diameter to peripheral canopy height. Liriodendron tulipifera was projected to capture seven gaps, all of which were smaller than the hypothesized minimum gap area for capture by the species. The majority of gaps were projected to close via lateral crown expansion. Based on the composition of saplings and trees in gap environments, I project the forest to transition from a Quercus dominated system to one with much stronger Fagus grandifolia and Acer saccharum components. My study fills a void in the literature on the role of canopy gaps in secondary, mesic Quercus stands that established just prior to 1900 for the southern Appalachian Highlands region. (Published By University of Alabama Libraries