• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 2
  • 1
  • Tagged with
  • 9
  • 3
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

XERIC LIMESTONE PRAIRIES OF EASTERN UNITED STATES

Lawless, Patrick Joseph 01 January 2005 (has links)
Xeric limestone prairies (XLPs) are open, nonforested communities dominatedby native, C4 perennial grasses. In eastern United States, they occur on shallow, rockycalcareous soils in various physiographic provinces from Missouri and Pennsylvaniasouth to Arkansas and Georgia. Floristic, vegetation, and physical environmental datawere collected from 18 XLPs in Kentucky and used in conjunction with data collected inother studies to provide a synthesis for XLP vegetation in eastern United States and acomparison of this vegetation type with limestone cedar glades and deep-soil barrens.XLPs occur on 33 soil series in five orders (Alfisols, Mollisols, Ultisols, Inceptisols, andVertisols) and on limestone, dolomite, and calcareous shale of Cambrian through Tertiarysystems. In Kentucky, XLPs are restricted to the Interior Low Plateaus, where they aremost frequent on the Upper Mississippian Salem Limestone in the KnobstoneEscarpment and Knobs. Three hundred and thirty-five taxa were recorded in the 18 sitessampled in Kentucky, of which 20 (6.0%) are nonnative and 24 (7.2%) state-listed asrare. The majority of the flora is intraneous C3 hemicryptophytes. Thirteen taxa areendemic to XLPs of eastern United States, but none to those in Kentucky. The native, C4perennial grass Schizachyrium scoparium was dominant in 10 of 12 community types inKentucky identified at a scale of 100-m2 and in 21 of 23 studies of XLPs in easternUnited States. The C4 annual grass Sporobolus vaginiflorus had high frequency values inthe majority of sites in Kentucky, where it often was dominant in the most shallow-soilzones. Variability among XLPs in Kentucky and among the floras of XLPs in differentregions is largely attributable to differences in forb species composition. Soil depth is theprimary abiotic source of variability in XLP community types in Kentucky and in manyother regions of eastern United States. Dendrochronological and aerial photographicstudies support the conclusion that the vast majority of XLPs are not primarycommunities. XLPs on the Cambrian Ketona Dolomite in the Ridge and Valley in BibbCounty, Alabama, are perhaps the only sites which represent an edaphic climax.
2

Distribution of Tardigrades Within a Moss Cushion: Do Tardigrades Migrate in Response to Changing Moisture Conditions?

Nelson, Diane R., Adkins, Rebecca G. 01 January 2001 (has links)
The distribution of tardigrades within the layers of the cushion moss Grimmia alpicola Hedwig, 1801 was investigated. The aim of this study was to determine the tardigrade species present within the moss layers during both wet and dry periods and to determine if migration occured in response to changing moisture conditions. Samples of the moss were removed from concrete caps on brick fence posts before and after rainfall and separated into two sections (top and bottom). The tardigrades from each layer and moisture condition were identified to species. Data for each species were statistically analyzed with a two-way analysis of variance (ANOVA) to compare the numbers of individuals present in the top and bottom layers of the moss under both wet and dry conditions. Five tardigrade species were identified, including two species new to science: Macrobiotus sp. n.: Milnesium tardigradum Doyère, 1840: Echiniscus viridissimus Peterfi, 1956; Echiniscus perviridis perviridis Ramazzotti, 1959; and Echiniscus sp. n. The new species will be described in a forthcoming paper. No significant differences were found in the numbers of the individuals of four of the five species in each layer within the moss or for each moisture condition. Only one species, E. viridissimus, was significantly more frequent in the top layer of the moss, regardless of moisture condition. Migration within the moss cushion was not detected in any of these five species as a result of changes in moisture conditions. In xeric moss species, it may not be beneficial for tardigrades to migrate to avoid desiccation. Instead, they apparently undergo anhydrobiosis in both the top and bottom layers of the moss cushion.
3

DIVERSITY, COMMUNITY STRUCTURE SHIFTS, AND PATCH CHARACTERISTICS IN NATURAL XERIC FOREST OPENING COMMUNITIES.

Barfknecht, David Francis 01 December 2022 (has links) (PDF)
During European settlement, the vast majority of grasslands in Illinois were converted for agricultural purposes. Some of the remaining natural areas in southern Illinois include natural xeric forest openings (i.e., barrens, glades, outcrops), that have transitional community compositions representative of previously extensive grasslands and adjacent hardwood forests. Previous research in these forest openings show that the communities are largely driven by edaphic conditions and vary spatially across southern Illinois. While most of these communities are currently protected and established as nature preserves, threats to these natural xeric forest openings continue to persist, such as climate change and exotic invasion. These threats are capable of altering taxonomic, phylogenetic, and functional diversity and community composition. The overall goals of this research were to 1) determine metapopulations and metacommunity structure in a local group of sandstone outcrop communities (a subset of natural xeric forest opening communities), 2) expand resolution to a regional scale to include natural xeric forest openings with several substrates to investigate changes in taxonomic, phylogenetic, and functional diversity and community composition since surveys conducted in 1988, and 3) include spatial analyses to characterize autocorrelation structure of diversity and environmental variables and biological turnover of natural xeric forest openings at a global scale. Sandstone outcrop communities at Jackson Hollow in Pope County, Illinois had several metapopulation species based on Hanski’s incidence functional model. These metapopulation species were more often members of the Asteraceae and Poaceae than members of other plant families, and were often exotic in origin with short-lived lifecycles. These metapopulation species were also neither dominant species or singletons within sandstone patches. Based on the Elements of Metacommunity (EMS) Framework, positive coherence, species turnover, and boundary clumping indicate that these sandstone outcrop communities are predictable communities where species replace one each other regularly as groups of species and respond similarly to environmental gradients. Furthermore, diversity metrics were all positively correlated with each other, but not with patch characteristics. In addition, total species and metapopulation species were positively associated with phylogenetic and functional diversity, but metapopulation species were positively associated with non-standardized phylogenetic and functional indices. When looking at several natural xeric forest openings across southern Illinois and comparing them based on substrate types and between surveys in 1988 and 2019, taxonomic, phylogenetic, and functional compositions were distinct based on substrates, but were stable and resilient across surveys. Sandstone and shale communities were the most similar based on composition, followed by limestone communities compared to sandstone and shale communities, and then loess communities being the most dissimilar from all other communities. Environmental variables that best explained differences in community composition were canopy cover, soil acidity, photosynthetically active radiation, and soil depth. Diversity variables that best explained differences in community composition were phylogenetic nearest taxon index, Faith’s phylogenetic diversity, and dominant species richness. Ninety-four different species were either significant indicators for specific substrates, or 2019 surveys. While no cases of phylogenetic signal were observed based on functional traits, substrate types, or surveys, three cases of functional signal based on dominant communities were observed in sandstone communities in 2019, shale communities in 2019, and overall shale communities across 1988 and 2019 surveys. When applying spatial analyses to these natural xeric forest openings to understand autocorrelation structure and biological turnover, soil depth was the only environmental variable that exhibited significant spatial autocorrelation, as previous glacial events caused loess hill prairies in the northwestern extent of this study to have deeper soil due to Quaternary loess deposition. However, several diversity metrics exhibited spatial structure based on 1988 and 2019 surveys (1988: dominant species richness, Pielou’s evenness, Shannon-Weiner diversity, Faith’s phylogenetic diversity, and distance-based functional diversity; 2019: dominant species richness, Pielou’s evenness, Shannon-Weiner diversity, Faith’s phylogenetic diversity, and phylogenetic nearest taxon index). In addition, climate variables daily mean temperature and total annual precipitation exhibited spatial structure. Most variables were spatially clustered at local site scales and spatially dispersed at larger scales and spatially over-dispersed at a regional scale. Generalized dissimilarity models constructed based on elevation, soil, and climate variables showed that models based on both functional composition and 2019 surveys best explained biological turnover compared to taxonomic and phylogenetic and 1988 models. Several variables included in models differed based on aspects of biological turnover or surveys, but temperature annual range and soil bulk density variables were common across all models. However, differences between total deviance explained and null deviances show that geographic distance between natural xeric forest openings was overwhelmingly the most influential variable contributing to biological turnover. Given these observations, natural xeric forest openings at local scales persist as distinct habitat patches amidst a landscape that largely constitutes an inhospitable matrix to colonizing species, yet certain species are able to migrate between patches. The resulting community assembly of individual patches is determined by both colonizing species and environmental gradients across the landscape. Despite simultaneous threats to diversity and composition in natural xeric forest openings at a regional scale, substrate continues to drive community assembly, in that certain species are characteristic indicators of these substrates. Furthermore, the most recent surveys in sandstone and shale communities exhibited functional signals. However, these natural xeric forest openings are spatially structured based on soil depth due to glacial history, certain metrics of diversity, and climate variables. Along with these occurrences of spatial autocorrelations, different aspects of biological turnover are best predicated by geographic distance as well as unique combinations of climate and soil variables between different aspects of diversity and surveys.
4

Early impacts of midstory hardwoods and overstory density on longleaf seedling establishment on xeric sites

Henry, Jacob Colin 10 August 2018 (has links)
Competition from hardwood species has long been considered a constraint on longleaf pine (Pinus palustris). However, evidence suggests that hardwood midstories may improve longleaf regeneration on xeric sites. Additionally, overstory retention for red-cockaded woodpecker (Leuconotopicus borealis; RCW) habitat may be inadvertently contributing to regeneration failures. Experimental plots in the North Carolina Sandhills were planted with containerized longleaf seedlings across a gradient of overstory density, and hardwoods were chemically controlled by treating at planting, treating after one year, or left untreated. Seedling survival (percent), growth (mass), and brown spot needle blight (percent infected seedlings; BSNB) were measured after two years. Seedling survival, growth, and BSNB infection rates were inversely related to overstory density. Midstory treatments did not significantly affect seedling survival, growth, or BSNB infection rates. Early results did not show facilitative effects from a hardwood midstory, but indicated overstory densities greater than 12 m2/ha negatively impact longleaf regeneration.
5

Endemismo e conservação de refúgios xéricos pleistocênicos da Serra do Itapetinga / Endemism and conservation of the xeric pleistocene refuges of serra do Itapetinga

Zorzi, Vinicius Gaburro de 24 August 2016 (has links)
Nas paisagens de montanha da região sudeste brasileira, áreas de afloramentos rochosos denunciam ao observador a natureza geológica de uma vegetação cuja existência local e distribuição relacionam-se às características de profundidade do solo e a efeitos da topografia. A serra do Itapetinga é uma elevação localizada ao norte da cidade de São Paulo onde afloram mais de 100 corpos pertencentes ao Neoproterozóico e que abrigam formações vegetais pleistocênicas persistentes pertencentes aos “complexos rupestres de granito”. Esta vegetação se encontra refugiada em sítios cujas condições edáfica e climática propiciam elevada diversidade biológica, além de endemismos e espécies pecilohídricas. Tais nuances edáficas e microclimáticas possibilitam a formação de microhabitats dotados de peculiaridades interessantes a grupamentos específicos de plantas. Dentre estes, as ilhas de solo constituem formações vegetais isoladas por matriz de rocha e que podem ser utilizadas como modelo de ilhas ecológicas em estudos de comunidades. As formas de vida prevalentes nos campos rupestres do sudeste brasileiro são determinadas por plantas hemicriptófitas e caméfitas. A proporção de fanerófitas varia em função da existência de microhabitats que propiciem o acúmulo de sedimentos, além de aumentar abruptamente no perímetro da rocha. A importância de terófitas é reduzida em relação a todas as demais formas, remetendo normalmente a ervas de comportamento ruderal. Apesar de sua ocorrência proporcionalmente menor nos afloramentos do sudeste brasileiro, plantas geófitas, após as hemicriptófitas, constituem a forma de vida mais frequente nas ilhas de solo - os microhabitats mais representativos da flora rupestre. O desaparecimento recente de tal vegetação relaciona-se diretamente com o aumento da procura do local para atividades de contemplação da natureza, para esportes de aventura e para coleta de plantas ornamentais, sendo comum o uso do fogo nas atividades relacionadas à contemplação e para controle do crescimento da vegetação em propriedades locadas na serra do Itapetinga e em seu entorno. Este estudo objetivou determinar a composição e a estrutura da vegetação nos afloramentos rochosos do Itapetinga, procedendo a análise das fontes de distúrbios sobre os ecossistemas para identificar evidências de impactos atuantes sobre tais comunidades vegetais rupestres. Para tal, procederam-se em 10 afloramentos coletas de plantas para identificação de morfotipos, atribuição de formas de vida e microhabitats utilizados pelas plantas, além de levantamentos de atividades humanas e evidências de impacto para utilização da matriz Pressão-Estado-Impacto-Resposta. As famílias mais representativas foram Asteraceae, Poaceae, Orchidaceae e Myrtaceae. As plantas hemicriptófitas, geófitas, helófitas e litófitas, aproximaram as proporções de formas de vida observadas das proporções esperadas para as classes de Raunkier, o que corrobora para a caracterização de uma fisionomia essencialmente campestre. A análise de matriz mostrou a prevalência de impactos negativos sobre positivos e a significância de atividades turísticas, esportivas e de infraestrutura em sua geração. Os afloramentos que concentram a riqueza rara e ameaçada são os que concentram o uso pela população, de forma que estratégias para a conservação destes relictos de vegetação perpassam invariavelmente por mudanças na forma de uso das rochas e de seu entorno / In the mountain landscapes of Brazilian Southeast, outcrops report to the observer the geological details of a vegetation whose its local existency and distribution is related to characteristics such as soil depth and effects of the topography. Serra do Itapetinga is an elevation located in the north of the city of São Paulo, where over a hundred of corps belonging to the Neoproterozoic spring out and contain persistent Pleistocene vegetation groups as part of the “granite cave formations”. This vegetation finds itself sheltered in sites in whose soil and climate conditions provide great biological diversity, besides endemisms and poikilohydry species. These soil and microclimate nuances allow the formation of microhabitats equipped with interesting peculiarities and specifc groups of plants. Among them, the soil islands compose vegetal formations cut off by a rock matrix that might be used as a model of ecological islands when studying communities. The forms that lives prevailing in the rupestrian fields of Brazilian southeast are determined by hemichryptophyte and chamaephyte plants. The proportion of phanerophyte varies according to the existence of microhabitats that propitiate accumulation of sediments, besides abruptly rise in the rock perimeter. The importance of therophyte is reduced in comparison with all the other forms, normally referring to species with ruderal behavior. Besides its smaller presence in the outcrops of Brazilian southeast, geophyte plants, after the hemichryptophyte, represent the most frequent form of life in the soil islands - the most characteristic microhabitats of the rupestral flora. The recent disappearance of this vegetation form is strictly related to the increase of the search of these locations for observation of nature, adventure sports and harvest of native plants, where the fire use is common for clearing lands. This study aimed to determinate the vegetation structures and composition on the outcrops of Itapetinga, followed by the analysis of the disturbance sources on ecosystem to identify the evidences of impact on the ancestry vegetation communities. Ten different outcrops were studied within its relation with the local human interference in other to identify evidences of impact. The more representative groups were Asteraceae, Poaceae, Orchidaceae and Myrtaceae. The study showed the expected proportions for the Raunkier classes which supports characterization of an essentially rural physiognomy. The analysis showed the prevalence of negative impact and significant touristic, sportive and infrastructure activities. The outcrops that concentrate rare and threatened richness are the ones frequented by the public in what way conservation strategies intervene changes in the rock use and its surroundings
6

Vegetation von Inselbergen in Zimbabwe : Struktur, Diversität und ökogeographische Differenzierung einer tropischen Lebensgemeinschaft /

Seine, Rüdiger. January 1996 (has links)
Thesis--Rheinische Friedrich-Wilhelms-Universität Bonn, 1996. / Includes bibliographical references (p. 317-327).
7

Endemismo e conservação de refúgios xéricos pleistocênicos da Serra do Itapetinga / Endemism and conservation of the xeric pleistocene refuges of serra do Itapetinga

Vinicius Gaburro de Zorzi 24 August 2016 (has links)
Nas paisagens de montanha da região sudeste brasileira, áreas de afloramentos rochosos denunciam ao observador a natureza geológica de uma vegetação cuja existência local e distribuição relacionam-se às características de profundidade do solo e a efeitos da topografia. A serra do Itapetinga é uma elevação localizada ao norte da cidade de São Paulo onde afloram mais de 100 corpos pertencentes ao Neoproterozóico e que abrigam formações vegetais pleistocênicas persistentes pertencentes aos “complexos rupestres de granito”. Esta vegetação se encontra refugiada em sítios cujas condições edáfica e climática propiciam elevada diversidade biológica, além de endemismos e espécies pecilohídricas. Tais nuances edáficas e microclimáticas possibilitam a formação de microhabitats dotados de peculiaridades interessantes a grupamentos específicos de plantas. Dentre estes, as ilhas de solo constituem formações vegetais isoladas por matriz de rocha e que podem ser utilizadas como modelo de ilhas ecológicas em estudos de comunidades. As formas de vida prevalentes nos campos rupestres do sudeste brasileiro são determinadas por plantas hemicriptófitas e caméfitas. A proporção de fanerófitas varia em função da existência de microhabitats que propiciem o acúmulo de sedimentos, além de aumentar abruptamente no perímetro da rocha. A importância de terófitas é reduzida em relação a todas as demais formas, remetendo normalmente a ervas de comportamento ruderal. Apesar de sua ocorrência proporcionalmente menor nos afloramentos do sudeste brasileiro, plantas geófitas, após as hemicriptófitas, constituem a forma de vida mais frequente nas ilhas de solo - os microhabitats mais representativos da flora rupestre. O desaparecimento recente de tal vegetação relaciona-se diretamente com o aumento da procura do local para atividades de contemplação da natureza, para esportes de aventura e para coleta de plantas ornamentais, sendo comum o uso do fogo nas atividades relacionadas à contemplação e para controle do crescimento da vegetação em propriedades locadas na serra do Itapetinga e em seu entorno. Este estudo objetivou determinar a composição e a estrutura da vegetação nos afloramentos rochosos do Itapetinga, procedendo a análise das fontes de distúrbios sobre os ecossistemas para identificar evidências de impactos atuantes sobre tais comunidades vegetais rupestres. Para tal, procederam-se em 10 afloramentos coletas de plantas para identificação de morfotipos, atribuição de formas de vida e microhabitats utilizados pelas plantas, além de levantamentos de atividades humanas e evidências de impacto para utilização da matriz Pressão-Estado-Impacto-Resposta. As famílias mais representativas foram Asteraceae, Poaceae, Orchidaceae e Myrtaceae. As plantas hemicriptófitas, geófitas, helófitas e litófitas, aproximaram as proporções de formas de vida observadas das proporções esperadas para as classes de Raunkier, o que corrobora para a caracterização de uma fisionomia essencialmente campestre. A análise de matriz mostrou a prevalência de impactos negativos sobre positivos e a significância de atividades turísticas, esportivas e de infraestrutura em sua geração. Os afloramentos que concentram a riqueza rara e ameaçada são os que concentram o uso pela população, de forma que estratégias para a conservação destes relictos de vegetação perpassam invariavelmente por mudanças na forma de uso das rochas e de seu entorno / In the mountain landscapes of Brazilian Southeast, outcrops report to the observer the geological details of a vegetation whose its local existency and distribution is related to characteristics such as soil depth and effects of the topography. Serra do Itapetinga is an elevation located in the north of the city of São Paulo, where over a hundred of corps belonging to the Neoproterozoic spring out and contain persistent Pleistocene vegetation groups as part of the “granite cave formations”. This vegetation finds itself sheltered in sites in whose soil and climate conditions provide great biological diversity, besides endemisms and poikilohydry species. These soil and microclimate nuances allow the formation of microhabitats equipped with interesting peculiarities and specifc groups of plants. Among them, the soil islands compose vegetal formations cut off by a rock matrix that might be used as a model of ecological islands when studying communities. The forms that lives prevailing in the rupestrian fields of Brazilian southeast are determined by hemichryptophyte and chamaephyte plants. The proportion of phanerophyte varies according to the existence of microhabitats that propitiate accumulation of sediments, besides abruptly rise in the rock perimeter. The importance of therophyte is reduced in comparison with all the other forms, normally referring to species with ruderal behavior. Besides its smaller presence in the outcrops of Brazilian southeast, geophyte plants, after the hemichryptophyte, represent the most frequent form of life in the soil islands - the most characteristic microhabitats of the rupestral flora. The recent disappearance of this vegetation form is strictly related to the increase of the search of these locations for observation of nature, adventure sports and harvest of native plants, where the fire use is common for clearing lands. This study aimed to determinate the vegetation structures and composition on the outcrops of Itapetinga, followed by the analysis of the disturbance sources on ecosystem to identify the evidences of impact on the ancestry vegetation communities. Ten different outcrops were studied within its relation with the local human interference in other to identify evidences of impact. The more representative groups were Asteraceae, Poaceae, Orchidaceae and Myrtaceae. The study showed the expected proportions for the Raunkier classes which supports characterization of an essentially rural physiognomy. The analysis showed the prevalence of negative impact and significant touristic, sportive and infrastructure activities. The outcrops that concentrate rare and threatened richness are the ones frequented by the public in what way conservation strategies intervene changes in the rock use and its surroundings
8

Local and regional factors influencing dung beetle assemblage structure across an environmental gradient in Botswana

Tshikae, Balatlhane Power 19 October 2011 (has links)
The taxonomic composition, structure, and diversity of current local species assemblages results from an interacting complex of historical, regional ecological and local ecological factors. Structural differences between such current species assemblages are primarily determined by changing ecological conditions across spatial gradients. These conditions may change abruptly or they may represent a gradual divergence. Across the Botswana Kalahari basin there is a gradual northeast-southwest aridity and dung type gradient, which was demonstrated to strongly influence dung beetle assemblage structure at six study sites from Chobe National Park to the Central Kalahari Reserve to the Kgalagadi Transfrontier Park using carrion and four dung types as bait (pig, elephant, cattle, sheep). Regional patterns were primarily influenced by climate (rainfall) while dung type mainly showed a local influence on patterns of variation. Four distinct biogeographical groups were defined for the study region comprising widespread, northeast/widespread, northeast, and arid southwest Kalahari-centred species. Biogeographical diversity was higher in the more mesic NE than the arid SW but varied somewhat between bait types. In the SW, Kalahari endemics dominated all bait types. In general, abundance and species richness declined along the aridity gradient although the pattern was uneven due to low numbers in the north of the Central Kalahari Game Reserve. Species showed high turnover (beta – diversity), particularly between the moister NE and the Kalahari/Savanna ecotone. Hierarchical Analysis of Oblique Factors showed statistically distinct separation between assemblage structure at the six study sites and that the proportion of mesic NE shared influence on assemblage composition declined towards the SW where there was an increase in Kalahari endemics. Similarly the proportion of arid SW shared influence declined towards the NE. Plotting these results onto a map showed that the point of intersection between shared NE or SW influence lay very close to the ecotone between SW (Kalahari Xeric Savanna) and NE-centred ecoregions (Acacia-Baikiaea Savanna) defined for the area by Olson et al. (2001). In terms of dung type diversity, increasing aridity across the Kalahari represents a gradient of diminishing resources with the loss of large dung types to the SW and increasing dominance of dung pellets. Several different patterns of response were shown using different methods. Four principal patterns of bait type association were indicated by one method. Another method showed that, rather than diminishing numbers of competing species leading to widening niche widths to the SW, niche widths were narrowest at the Kalahari / mesic Savanna ecotone. Using several other multivariate techniques, three different patterns of dung type resource partitioning were demonstrated that paralleled the aridity gradient, one common to the NE and two to the SW. The historical, regional and local ecological factors influencing these patterns of dung beetle assemblage structure are discussed as well as implications and recommendations for conservation. / Thesis (PhD)--University of Pretoria, 2011. / Zoology and Entomology / unrestricted
9

UNDERSTORY RESPONSE TO SHELTERWOOD AND BURN TREATMENTS IN A DRY QUERCUS FOREST IN INDIANA

Sarah J Rademacher (12469245) 27 April 2022 (has links)
<p>  </p> <p>Alterations to the historic fire regime have contributed to widespread regeneration failure in <em>Quercus</em> L. (oak) forests of the eastern United States. Composition has shifted from <em>Quercus</em> and other fire-adapted species to dominance by mesophytic species. While land managers often focus efforts on restoring <em>Quercus</em> regeneration, the herbaceous layer experiences reduced cover and diversity of herb and graminoid species resulting from the increased woody stem density in fire-suppressed forests. Declining abundance of <em>Quercus</em> species and diversity in the herbaceous layer reduce the overall habitat quality and ecosystem functions provided by the forest. A combination of overstory harvests and prescribed burning are often conducted to restore the plant community in <em>Quercus</em> forests affected by mesophication. Initiated in 2010, our study on the Hoosier National Forest in Indiana conducted shelterwood and midstory (mechanical, chemical, or none) harvests followed by prescribed burning on a less productive site, while leaving a more productive site unburned. Our objective was to evaluate the survival and competitive response of <em>Quercus</em> spp. within the regeneration layer and whether diversity and cover increased in the herbaceous layer following treatments. Using nested circular plots, we measured seedling survival and resprout response, in addition to regeneration density before and after treatments. We measured the percent cover of herbaceous-layer species within quadrats and calculated species richness, evenness, and diversity. Using multiple mixed-effects models, ANOVA, and NMDS ordination, we evaluated woody species regeneration and herbaceous-layer composition before and after treatments. Post-treatment, monitored <em>Quercus</em> spp. seedlings at the burned site displayed greater survival (> 94%) and resprouting (> 92% of monitored stems), which exceeded most competing species, including<em> Acer</em> spp. (~ 59% survival and resprouting) and <em>Fraxinus americana </em>(72% survival and resprouting). <em>Q. alba</em> seedling (< 3.8 cm DBH) densities doubled after burning; it was one of the most abundant species (9,864 stems ha-1) at the burned site. NMDS ordination indicated a clear shift in regeneration species composition with the burn driving a shift away from mesophytic species towards greater importance of <em>Quercus</em> species. Additionally, our burned site had significantly increased herbaceous-layer richness, Shannon diversity index, and total cover compared to pre-treatment. Percent cover increased across all plant functional groups within the herbaceous layer, with trees/shrubs exhibiting the greatest increase. Herbaceous-layer composition at the burned site significantly shifted toward greater importance of graminoids and herbs post-treatment. Post-treatment, the unburned site contained fewer, and less competitive, <em>Quercus</em> seedlings compared to non-<em>Quercus</em> competitors and displayed no significant compositional shifts in seedling species composition post-harvest. Our unburned site exhibited significant, but minor, increases in herbaceous-layer richness, evenness, diversity, and total cover. Herbaceous-layer composition at the unburned site was significantly different post-treatment, shifting towards greater importance of vines, trees/shrubs, and herbs. The more-productive unburned site would likely require multiple burns to produce adequate competitive <em>Quercus</em> seedlings to perpetuate dominance in the developing stand. Burning would also likely result in greater increases in herbaceous-layer diversity compared to harvesting alone. Conversely, the shelterwood, followed by a single burn, on the less productive site had a more substantial effect on the herbaceous layer, and likely produced an adequate density of <em>Quercus</em> reproduction to ensure future dominance by the genus.</p>

Page generated in 0.0552 seconds