Dissertations / Theses on the topic 'Stand structure'
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1
Moss, Ian. "Stand structure classification, succession, and mapping using LiDAR." Thesis, University of British Columbia, 2012. http://hdl.handle.net/2429/41931.
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In this dissertation, a consistent, reasonably precise, verifiable system of stand structure classification was developed and demonstrated. The goal was to provide a foundation for better communication amongst forest management professionals. A novel distance metric and classification algorithm were introduced. The distance metric was based on similarity in reversed cumulative stems and basal area per ha by diameter (DBH; 1.3 m above ground). This distance metric: (1) uses commonly available information; (2) avoids the separation of data into arbitrary DBH classes; and (3) represents a broad range of simple to complex stand structures. Using 421 plots established across a range of Interior Douglas-fir (Pseudotsuga menziesii var. glauca (Beissn.) Franco) and lodgepole pine (Pinus contorta var. latifolia (Engelm.) Critchfield) stands in the Cariboo region of British Columbia, Canada, a 17-class system of classification was constructed. Whole stand statistics, cumulative distributions, and stand structure/distribution indices were used to evaluate the results. The classes were reasonably precise, with meaningful partitions separating single layered versus complex stands. The utility of the classification system was investigated for diagnosing potential patterns of succession. Over 100 simulated stand structure progressions were simulated using plot data input into an individual-tree growth model. Similar progressions in stand structure classes were assigned common pathways. Four general patterns of succession were observed: (1) a high density single layered pathway; (2) a moderate density single layered pathway; (3) a moderate density complex pathway; and (4) a moderate density, mixed complex-single layered pathway. Lastly, the feasibility of using aerial Light Detection and Ranging (LiDAR) for stand structure classification in forest inventory was assessed. LiDAR was reasonably effective in distinguishing structural classes on the basis of cumulative distributions in basal area or gross volume with respect to DBH, but it was less successful when the distributions in numbers of stems per ha were included. Further study using additional LiDAR metrics beyond those used in this study are needed to improve the use of LiDAR for stand structure classification. This stand structure classification system has potential for a wide variety of forest management applications, including improvement of linkages between strategic and tactical planning and implementation.
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O'Hara, Kevin L. "Thinning even-aged Douglas-fir stands : effects of density and structure on stand volume growth /." Thesis, Connect to this title online; UW restricted, 1987. http://hdl.handle.net/1773/5522.
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Nicholas, N. S. "Stand structure, growth, and mortality in southern Appalachian spruce-fir." Diss., Virginia Tech, 1992. http://hdl.handle.net/10919/38365.
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Nicholas, Niki Stephanie. "Stand structure, growth, and mortality in southern Appalachian spruce-fir /." This resource online, 1992. http://scholar.lib.vt.edu/theses/available/etd-06062008-165928/.
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Karlsson, Kjell. "Growth allocation and stand structure in Norway spruce stands : expected taper and diameter distribution in stands subjected to different thinning regimes /." Uppsala : Dept. of Bioenergy, Swedish University of Agricultural Sciences, 2005. http://epsilon.slu.se/200575.pdf.
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Stiers, Melissa [Verfasser]. "Quantifying stand structure and structural complexity along a management gradient in temperate forests / Melissa Stiers." Göttingen : Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2020. http://d-nb.info/1218780762/34.
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Linder, Per. "Stand structure and successional trends in forest reserves in boreal Sweden /." Umeå : Swedish Univ. of Agricultural Sciences (Sveriges lantbruksuniv.), 1998. http://epsilon.slu.se/avh/1998/91-576-5606-1.gif.
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Bauer, John M. "Fire history and stand structure of a central Nevada pinyon-juniper woodland." abstract and full text PDF (free order & download UNR users only), 2006. http://0-gateway.proquest.com.innopac.library.unr.edu/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:1436023.
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Gonzalez, Rubio Hector Larsen David R. "Stand structure development effects on wood quality of Melina (Gmelina arborea roxb.)." Diss., Columbia, Mo. : University of Missouri--Columbia, 2009. http://hdl.handle.net/10355/6171.
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Title from PDF of title page (University of Missouri--Columbia, viewed on Feb 15, 2010). The entire thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file; a non-technical public abstract appears in the public.pdf file. Dissertation advisor: Dr. David Larsen Vita. Includes bibliographical references.
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Danzer, Shelley Rae 1951. "Fire history and stand structure in the Huachuca Mountains of Southeastern Arizona." Thesis, The University of Arizona, 1998. http://hdl.handle.net/10150/278665.
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Historically, wildfires in mixed conifer forests of Southwestern sky islands were frequent events. Dendrochronological methods were used to reconstruct fire regimes and stand age structures in the Huachuca Mountains of Southeastern Arizona. Pre-settlement (i.e., before ca. 1870) fire intervals ranged from 4 to 10 years, with many fires spreading over the entire sample area. Stand age distributions show an increase in more shade-tolerant tree species. Although ponderosa pine is still the dominant overstory tree species, recent recruitment is predominantly southwestern white pine and Douglas-fir. Establishment of Ft. Huachuca in 1877 was a precursor to extensive use of timber, mineral, range and water resources in the Huachuca Mountains. The fire regime was altered at this time, with only one subsequent widespread surface fire recorded in 1899. Settlement era land-use practices may be responsible for changes in stand structure and composition.
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Brashears, Mark Benjamin. "Changes in stand structure and species diversity following clearcutting in central Appalachian hardwoods." Morgantown, W. Va. : [West Virginia University Libraries], 2001. http://etd.wvu.edu/templates/showETD.cfm?recnum=2092.
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Thesis (M.S.)--West Virginia University, 2001.Title from document title page. Document formatted into pages; contains v, 45 p. : ill. (some col.), maps. Includes abstract. Includes bibliographical references (p. 24-27).
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Baker, Patrick John. "Age structure and stand dynamics of a seasonal tropical forest in western Thailand /." Thesis, Connect to this title online; UW restricted, 2001. http://hdl.handle.net/1773/5558.
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Considine, Cody Douglas. "Fire History and Current Stand Structure Analysis of a Midwestern Black Oak Sand Savanna." OpenSIUC, 2009. https://opensiuc.lib.siu.edu/theses/91.
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Management and restoration of black oak dominated sand savannas often rely on historic vegetative descriptions (settler accounts, surveyor notes, aerial photographs). It is commonly assumed that fire alone maintains savanna structure and composition, however little information is known about the specific fire frequency needed to maintain these systems. The objective of this study was to quantify and correlate characteristics of stand structure with fire history of the Kankakee Sands savannas in northeastern Illinois. Fire history chronologies were determined through dendrochronological methods from 289 dated fire scars identified on 58 black oak (Quercus velutina) trees located throughout four wooded sites. Tree and woody structure was characterized in 30 circular plots (0.04 hectares) in three sites and 26 circular plots in one site that were placed at 25-meter intervals along randomly established permanent line transects in the summer of 2007. The structure analysis consisted of the development of tree age-size relationships among presently dominant and suppressed trees in relation to fire history. Variations in tree and woody structure were strongly related to fire dynamics among the four study sites. Specifically, components such as tree density (n = 114; r = 0.46; P < 0.0001), basal area (n = 114; r = 0.35; P < 0.0001), and total woody stem density (n = 114; r = 0.42; P < 0.0001) all increased as a function of fire-free interval. In addition, sites with shorter fire-free intervals were associated with a higher percentage of hollow tree boles (n = 104 r = -0.31 P < 0.0015) and visible fire scar wounds (n = 104 r = -0.43334 P < 0.0001). While the results of this study suggest fire had a significant role in structuring these four wooded sites, the data also indicated other historic disturbances coupled with individual site characteristics may be integral components in structuring these dynamic systems. For instance, fire-free intervals less than two years maintained conditions of openness, as was referenced to 1939 historic aerial photographs, but eliminated potential future canopy trees. Under these conditions, a dramatic shift in community structure toward prairie vegetation is likely, as no smaller trees were present to assume canopy dominance. Fire-free intervals greater than two years were associated with transition to closed canopy forests. Therefore, management considerations pertaining to fire with the addition of other historic disturbances, including grazing and or selective cutting, are proposed to balance historic canopy openness and promote regeneration of characteristic savanna species.
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McElhinny, Chris, and chris mcelhinny@anu edu au. "Quantifying stand structural complexity in woodland and dry Sclerophyll Forest, South-Eastern Australia." The Australian National University. Centre for Resource and Environmental Studies, 2005. http://thesis.anu.edu.au./public/adt-ANU20060322.133914.
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In this thesis I present and test a methodology for developing a stand scale index of structural complexity. If properly designed such an index can act as a summary variable for a larger set of stand structural attributes, providing a means of ranking stands in terms of their structural complexity, and by association, their biodiversity and vegetation condition. This type of index can also facilitate the use of alternative policy instruments for biodiversity conservation, such as mitigation banking, auctions and offsets, that rely on a common currency the index value that can be compared or traded between sites. My intention was to establish a clear and documentable methodology for developing a stand scale index of structural complexity, and to test this methodology using data from real stands.¶
As a starting point, I reviewed the literature concerning forest and woodland structure and found there was no clear definition of stand structural complexity, or definitive suite of structural attributes for characterising it. To address this issue, I defined stand structural complexity as a combined measure of the number of different structural attributes present in a stand, and the relative abundance of each of these attributes. This was analogous to approaches that have quantified diversity in terms of the abundance and richness of elements. It was also concluded from the review, that stand structural complexity should be viewed as a relative, rather than absolute concept, because the potential levels of different structural attributes are bound within certain limits determined by the inherent characteristics of the site in question, and the biota of the particular community will have evolved to reflect this range of variation. This implied that vegetation communities with naturally simple structures should have the potential to achieve high scores on an index of structural complexity.¶
I proposed the following five-stage methodology for developing an index of stand structural complexity:
1. Establish a comprehensive suite of stand structural attributes as a starting point for developing the index, by reviewing studies in which there is an established relationship between elements of biodiversity and structural attributes.
2. Develop a measurement system for quantifying the different attributes included in the comprehensive suite.
3. Use this measurement system to collect data from a representative set of stands across the range of vegetation condition (highly modified to unmodified) and developmental stages (regrowth to oldgrowth) occurring in the vegetation communities in which the index is intended to operate.
4. Identify a core set of structural attributes from an analysis of these data.
5. Combine the core attributes in a simple additive index, in which attributes are scored relative to their observed levels in each vegetation community.¶
Stage one of this methodology was addressed by reviewing a representative sample of the literature concerning fauna habitat relationships in temperate Australian forests and woodlands. This review identified fifty-five studies in south-east and south-west Australia, in which the presence or abundance of different fauna were significantly (p<0.05) associated with vegetation structural attributes. The majority of these studies concerned bird, arboreal mammal, and ground mammal habitat requirements, with relatively fewer studies addressing the habitat requirements of reptiles, invertebrates, bats or amphibians. Thirty four key structural attributes were identified from these fifty-five studies, by grouping similar attributes, and then representing each group with a single generic attribute. This set, in combination with structural attributes identified in the earlier review, provided the basis for developing an operational set of stand level attributes for the collection of data from study sites.¶
To address stages two and three of the methodology, data were collected from one woodland community Yellow Box-Red Gum (E. melliodora-E. Blakelyi ) and two dry sclerophyll forest communities Broadleaved Peppermint-Brittle Gum (E. dives-E. mannifera ), Scribbly Gum-Red Stringybark (E. rossii E. macrorhyncha ) in a 15,000 km2 study area in the South eastern Highlands Bioregion of Australia. A representative set of 48 sites was established within this study area, by identifying 24 strata, on the basis of the three vegetation communities, two catchments, two levels of rainfall and two levels of condition, and then locating two sites (replicates) within each stratum. At each site, three plots were systematically established, to provide an unbiased estimate of stand level means for 75 different structural attributes.¶
I applied a three-stage analysis to identify a core set of attributes from these data. The first stage a preliminary analysis indicated that the 48 study sites represented a broad range of condition, and that the two dry sclerophyll communities could be treated as a single community, which was structurally distinct from the woodland community. In the second stage of the analysis, thirteen core attributes were dentified using the criteria that a core attribute should:¶
1. Be either, evenly or approximately normally distributed amongst study sites;
2. Distinguish between woodland and dry sclerophyll communities;
3. Function as a surrogate for other attributes;
4. Be efficient to measure in the field.
The core attributes were: Vegetation cover <0.5m Vegetation cover 0.5-6.0m; Perennial species richness; Lifeform richness; Stand basal area of live trees; Quadratic mean diameter of live stems; ln(number of regenerating stems per ha+1); ln(number of hollow bearing trees per ha+1);ln(number of dead trees per ha+1);sqrt(number of live stems per ha >40cm dbh); sqrt(total log length per ha); sqrt(total largelog length per ha); Litter dry weight per ha. This analysis also demonstrated that the thirteen core attributes could be modelled as continuous variables, and that these variables were indicative of the scale at which the different attributes operated.¶
In the third and final stage of the analysis, Principal Components Analysis was used to test for redundancy amongst the core attributes. Although this analysis highlighted six groupings, within which attributes were correlated to some degree, these relationships were not considered sufficiently robust to justify reducing the number of core attributes.¶
The thirteen core attributes were combined in a simple additive index, in which, each attribute accounted for 10 points in a total index value of 130. Attributes were rescaled as a score from 0-10, using equations that modelled attribute score as a function of the raw attribute data. This maintained a high correlation (r > 0.97, p< 0.0001) between attribute scores and the original attribute data. Sensitivity analysis indicated that the index was not sensitive to attribute weightings, and on this basis attributes carried equal weight. In this form my index was straightforward to apply, and approximately normally distributed amongst study sites.¶
I demonstrated the practical application of the index in a user-friendly spreadsheet, designed to allow landowners and managers to assess the condition of their vegetation, and to identify management options. This spreadsheet calculated an index score from field data, and then used this score to rank the site relative to a set of reference sites. This added a regional context to the operation of the index, and is a potentially useful tool for identifying sites of high conservation value, or for identifying sites where management actions have maintained vegetation quality. The spreadsheet also incorporated the option of calculating an index score using a subset of attributes, and provided a measure of the uncertainty associated with this score.¶
I compared the proposed index with five prominent indices used to quantify vegetation condition or habitat value in temperate Australian ecosystems. These were: Newsome and Catlings (1979) Habitat Complexity Score, Watson et al.s (2001) Habitat Complexity Score, the Site Condition Score component of the Habitat Hectares Index of Parkes et al. (2003), the Vegetation Condition Score component of the Biodiversity Benefits Index of Oliver and Parkes (2003), and the Vegetation Condition Score component of the BioMetric Assessment Tool of Gibbons et al. (2004). I found that my index differentiated between study sites better than each of these indices. However, resource and time constraints precluded the use of a new and independent data set for this testing, so that the superior performance of my index must be interpreted cautiously.¶
As a group, the five indices I tested contained attributes describing compositional diversity, coarse woody debris, regeneration, large trees and hollow trees these were attributes that I also identified as core ones. However, unlike these indices, I quantified weeds indirectly through their effect on indigenous plant diversity, I included the contribution of non-indigenous species to vegetation cover and did not apply a discount to this contribution, I limited the direct assessment of regeneration to long-lived overstorey species, I used stand basal area as a surrogate for canopy cover, I quantified litter in terms of biomass (dry weight) rather than cover, and I included the additional attributes of quadratic mean diameter and the number of dead trees.¶
I also concluded that Parkes et al. (2003), Oliver and Parkes (2003), and Gibbons et al. (2004), misapplied the concept of benchmarking, by characterising attributes in terms of a benchmark range or average level. This ignored processes that underpin variation at the stand level, such as the increased development of some attributes at particular successional stages, and the fact that attributes can respond differently to disturbance agents. It also produced indices that were not particularly sensitive to the differences in attribute levels occurring between stands. I suggested that a more appropriate application of benchmarking would be at the overarching level of stand structural complexity, using a metric such as the index developed in this thesis. These benchmarks could reflect observed levels of structural complexity in unmodified natural stands at different successional stages, or thresholds for structural complexity at which a wide range of biota are present, and would define useful goals for guiding on-ground management.
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Considine, Cody D. "Fire history and current stand structure analysis of a midwestern black oak sand savanna /." Available to subscribers only, 2009. http://proquest.umi.com/pqdweb?did=1967969431&sid=1&Fmt=2&clientId=1509&RQT=309&VName=PQD.
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Nordh, Nils-Erik. "Long term changes in stand structure and biomass production in short rotation willow coppice /." Uppsala : Dept. of Crop Production Ecology, Swedish University of Agricultural Sciences, 2005. http://epsilon.slu.se/2005120.pdf.
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Barrocas, Eva de Gouveia. "Contribution to the study of holm oak stand dynamics." Master's thesis, Universidade de Évora, 2021. http://hdl.handle.net/10174/30090.
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The holm oak is an emblematic species of the montado, a complex and biodiverse multifunctional, agro-silvopastoral system. Signs of the decline of the montado crown cover have been reported. This research followed an integrative approach to investigate how crown cover influences stand structure, natural regeneration, soil conditions, and litter layer in pure holm oak stands. Two new methodologies were created: STRUX Index that facilitates structure classification, and Natural Regeneration Classification that studies the viability of natural regeneration. The results showed that a higher crown cover was linked to uneven-aged structure, higher values of above-ground biomass, higher number of established natural regeneration, and a tendency for higher values of soil organic carbon and litter layer. Furthermore, it was observed a positive correlation between natural regeneration, litter layer, and soil organic carbon together with a negative correlation with soil pH This study brings a positive perspective on the preservation of holm oak stands; Contribuição para a dinâmica de povoamento em montado de azinho
A azinheira é uma espécie emblemática do montado, sistema agro-silvopastoril, multifuncional e de elevada biodiversidade. Como a área de montado regrediu nas últimas décadas, tornou-se urgente compreender a dinâmica dos montados de azinho. Através de uma abordagem integrada, foi estudada a contribuição do grau de coberto para a dinâmica da estrutura dos povoamentos. Duas novas metodologias foram criadas: o Índice STRUX, para a classificação da estrutura do povoamento, e a Classificação de Regeneração Natural, para avaliar a viabilidade e qualidade da regeneração natural. Os resultados indicaram que valores superiores de grau de coberto estão relacionados com a estrutura irregular, com mais biomassa florestal e com mais regeneração natural instalada. Foi observada uma correlação positiva entre a regeneração natural, a manta morta e o carbono orgânico e uma correlação negativa com o pH do solo. Este estudo contribuiu para uma perspetiva positiva sobre a resiliência do montado de azinho.
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Matthews, Jeff Michael. "Effects of Wildfire Intensity on Invasives, Stand Structure and Fuel Loading in Shenandoah National Park." Thesis, Virginia Tech, 2004. http://hdl.handle.net/10919/35924.
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As invasive species are so prominent, the influence of wildfire intensity on fuel loading, invasives, species richness, diversity, and evenness were studied at Shenandoah National Park. Most National Parks identify invasive species as the biggest threat to their goal of maintaining native ecosystems. Eight study sites were stratified into three burn classes (high intensity, low intensity, and control), and three transects were randomly located so that nested plots and fuel transects were measured at a distance of 50 ft (15 m), 150 ft (45 m), and 250 ft (75 m) from a road or trail. Field sampling was conducted between May 15, 2004 and June 30, 2004. A subsample of these plots were used to determine specific gravity and quadratic mean diameter for each size class of fuel and to determine the bulk density of the duff and litter layers. High intensity wildfires initially reduced species diversity and evenness in the tree and herbaceous strata, but after 14 years tree species diversity and evenness returned to levels found in unburned areas, while herbaceous strata diversity was not associated with time since burn. Low intensity wildfires resulted in the greatest impacts in the shrub stratum. Presence of invasive species was associated with more even and diverse vegetation in all strata, perhaps because invasive species were relatively sparse. Fuel loadings were reduced initially by high intensity wildfires, but quickly returned to the same level as unburned areas. Although these initial findings indicate that invasive species will not persist after wildfire disturbance, continual monitoring by National Parks would be prudent.Master of Science
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Scheuermann, Cynthia M. "Forest Stand Structure and Primary Production in relation to Ecosystem Development, Disturbance, and Canopy Composition." VCU Scholars Compass, 2016. http://scholarscompass.vcu.edu/etd/4653.
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Temperate forests are complex ecosystems that sequester carbon (C) in biomass. C storage is related to ecosystem-scale forest structure, changing over succession, disturbance, and with community composition. We quantified ecosystem biological and physical structure in two forest chronosequences varying in disturbance intensity, and three late successional functional types to examine how multiple structural expressions relate to ecosystem C cycling. We quantified C cycling as wood net primary production (NPP), ecosystem structure as Simpson’s Index, and physical structure as leaf quantity (LAI) and arrangement (rugosity), examining how wood NPP-structure relates to light distribution and use-efficiency. Relationships between structural attributes of biodiversity, LAI, and rugosity differed. Development of rugosity was conserved regardless of disturbance and composition, suggesting optimization of vegetation arrangement over succession. LAI and rugosity showed significant positive productivity trends over succession, particularly within deciduous broadleaf forests, suggesting these measures of structure contain complementary, not redundant, information related to C cycling.
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Ackerman, Simon Alexander. "The effect of irregular stand structures on growth, wood quality and its mitigation in operational harvest planning of Pinus patula stands." Thesis, Stellenbosch : Stellenbosch University, 2013. http://hdl.handle.net/10019.1/85874.
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Thesis (MScFor)--Stellenbosch University, 2013.ENGLISH ABSTRACT: The practice of combining row and selective thinning in commercial pine plantation silviculture carries the risk of unwanted irregularities in tree distribution within the stand. This situation is aggravated with poor tree selection during marking. The potential consequences of poor tree selection are gaps created along row removals, which are necessary for access to harvesting operations. These gaps lead to spatially asymmetric growing space among adjacent trees. The effect of irregular stand structures on tree morphology and growth are investigated in this study, and are based on two stands of Pinus patula, (Schiede ex Schlechtendal et Cham.) in Langeni plantation, South Africa. This study focuses on two aspects. Firstly, a comparison between trees grown in all-sided and one-sided spatial competition situations in order to assess if there are differences in growth and selected quality parameters. Secondly, the mitigation of irregular structures using a simulation based study on changing the planting geometry in order to investigate the effect on harvesting in terms of stand impact, simulated harvesting productivity and harvesting system costs. Results showed that trees grown in an irregular competitive status have significantly larger crown diameters, crown lengths, longer and thicker branches, disproportionately one sided crown growth and a reduction in space-use efficiency. Simulations indicated that changing planting geometry from the current 2.7m x 2.7m to 2.3m x 3.1m and 2.4m x 3m would result in up to a 20% reduction of machine trail length and fewer rows being removed for machine access. The simulation of harvesting thinnings showed that various planting geometry alternatives increased harvesting productivity by 10% to 20% and reduced overall thinning harvesting cost by up to 11%. This study successfully investigated the factors that potentially negatively affect saw timber quality and volume production of the stand at final felling. It also illustrated the applicability of simulation methods for testing harvesting scenarios and developing economically viable alternatives.
AFRIKAANSE OPSOMMING: Die praktiese kombinasie van ryuitdunning en seleksiedunning in kommersiële denneplantasies dra die risiko van ongewensde onreelmatighede in die verspreiding van bome in die opstand. Hierdie situasie word vererger deur swak boomseleksie tydens die merk van dunnings. Die potensiële gevolge van swak boomseleksie is die ontstaan van onreelmatige gapings tussen boomkrone, veral langs die rydunnings, wat nodig is vir toegang tydens die ontginning van die hout. Dit lei daartoe dat die bome langs die dunningsrye asimmetriese ruimtes het om in te groei. Die effek van onreelmatige opstandstrukture op boom-morfologie en -groei word in hierdie studie ondersoek in twee Pinus patula, (Schiede ex Schlechtendal et Cham.) vakke te Langeni plantasie, Suid-afrika. In die studie word daar gefokus op twee aspekte. Eerstens word bome wat onder toestande van eweredige ruimetlike kompetisie groei vergelyk met die wat onder toestande van eensydige ruimtelike kompetisie groei om sodoende vas te stel of daar verskille is in die groeipatroon aan die hand van geselekteerde gehalteparameters. Tweedens word daar gefokus op die verbetering van onreelmatige opstandstrukture deur gebruik te maak van ’n simulasie-gebasseerde studie om veranderinge in die aanplantingsgeometrie te ondersoek met die doel om die effek van plantspasieering op ontginningsimpakte, gesimuleerde ontginningsproduktiwiteit en -sisteem koste te bepaal. Die resultate het getoon dat bome wat onder toestande van onreelmatige spasieering en kompetisie groei krone met groter deursnee asook langer lengtes ontwikkel, langer en dikker takke het, disproporsionele, eensydige kroongroei en ’n reduksie in ruimte-gebruik toon, wat die groeidoeltreffendheid nadelig beinvloed. Simulasies met betrekking tot die verandering in boomaanplantgeometrie vanaf die huidige 2.7m x 2.7m na 2.3m x 3.1m en 2.4m x 3m het gedui op ’n reduksie van 20% in die masjienpadafstand en na minder rye wat uitgehaal moes word om die toegang van masjiene moontlik te maak. Die simulasie van die ontginning van dunnings het getoon dat verskillende aanplantgeometriealternatiewe die ontginningsproduktiwiteit met 10% tot 20% verbeter het, en die algehele dunningsoeskoste met tot 11% verminder het. In hierdie studie is die faktore, wat die gehalte van saaghoutkwaliteit en volume tydens die finale oes van die plantasie potensieel negatief mag beinvloed, suksesvol ondersoek. Dit illustreer ook die geskiktheid van simulasietoepassings vir die toets van ontginningsalternatiewe en die ontwikkelling van meer ekonomies voordelige praktyke .
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Brown, Peter Leonard. "Stand structure, canopy architecture and thinning response in mature Queensland maple (Flindersia brayleyana F. Muell.) plantations /." St. Lucia, Qld, 2001. http://www.library.uq.edu.au/pdfserve.php?image=thesisabs/absthe16432.pdf.
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Zeller, Laura Isabel [Verfasser], Hans [Akademischer Betreuer] Pretzsch, Thomas [Gutachter] Knoke, and Hans [Gutachter] Pretzsch. "Interactions between forest stand structure, tree species composition, and stand productivity in spatial, temporal, and silvicultural context / Laura Isabel Zeller ; Gutachter: Thomas Knoke, Hans Pretzsch ; Betreuer: Hans Pretzsch." München : Universitätsbibliothek der TU München, 2020. http://d-nb.info/1214808549/34.
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Klinka, Karel, Pal Varga, Louise E. M. de Montigny, and Christine Chourmouzis. "The structure of single- and mixed-species, second-growth stands of Western hemlock and Western redcedar." Forest Sciences Department, University of British Columbia, 2001. http://hdl.handle.net/2429/708.
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The structure of a forest stand is characterized by: (a) species composition, (b) age, (c) size (diameter and height), and (d)
spatial (horizontal and vertical) arrangement of the trees. Depending on the species, site, and disturbance history, the
stand structure varies with time, thus providing a snapshot of a particular development stage.
Research on growth and stand structure has shown that the spatial distribution of trees is one of the key determinants of
stand productivity. Forest inventories and ecological surveys carried out in British Columbia (BC) have shown that the
structure of naturally established, unmanaged stands varies from simple (single-species, single-storied, and even-aged) to
complex (multi-species, multi-storied, and uneven-aged). Only a few studies have quantitatively characterized this range
of structural complexity, with nearly all studies focusing on old-growth stands.
BC forest policy requires that harvested areas be regenerated with a mixture of tree species whenever a mixture is suited
to the site. This policy is based upon the assumption that under appropriate conditions, increases in stand productivity,
reliability, and/or biodiversity can be attained in mixed-species stands. This assumption has not yet been tested for forest
ecosystems. One mechanism by which different tree species can reduce crown competition for light is through vertical
separation (the development of multiple canopy strata). Canopy stratification is not easily recognized in mixed-species
stands, particularly when species have similar shade tolerance and height growth patterns, and no quantitative methods
have been developed to detect stratification.
The diameter frequency distribution of two-storied stands have been characterized by inverted J-shaped as well as modal
curves. Although it would be more appropriate to characterize stand structure by height frequency distributions, these
distributions have not been developed. We suggest that (i) a stand is stratified if there are distinct, quantitatifiable modes
in the size distribution; either diameter, height, or crown height, and (ii) height or crown height distributions will be the most
sensitive measures.
To characterize the structure of western hemlock (Tsuga heterophylla (Raf.) Sarg.) (Hw) and western redcedar (Thuja
plicata Donn ex D. Don in Lamb.) (Cw) second-growth stands, and to investigate its influence on tree growth, we (1)
described and compared size (diameter, height, and crown height) frequency distributions in single- and mixed-species
stands, (2) determined whether mixed-species stands develop a stratified canopy, and (3) examined whether interactions
between hemlock and redcedar affect tree growth.
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Muñoz, Aguilar Raúl Santiago. "Sliding mode control of the stand alone wound rotor synchronous generator." Doctoral thesis, Universitat Politècnica de Catalunya, 2010. http://hdl.handle.net/10803/5960.
Full textAbstract:
En esta Tesis ha sido analizado el control de la màquina sincrónica de rotor bobinado actuando en isla. Para esta configuración, la velocidad mecànica determina la frecuencia, y la tensión de rotor se utiliza para fijar la amplitud de la tensión de estator. Debido a que la constante de tiempo eléctrica es mucho más ràpida comparada con la constante de tiempo mecánica, la velocidad mecánica fue considerada constante y externamente regulada y la investigación se enfocó en la regulación de la amplitud de la tensión de estator.Cuatro diferentes controladores basados en técnicas de modos deslizantes fueron diseñados en el marco de referencia dq. Las leyes de control obtenidas regulan la amplitud de la tensión de estator independientemte del valor de la carga. Adicionalmente, sólo las medidas de tensión y posición del rotor (para calcular la transformada dq) son necesarias. La estabilidad de los puntos de equilibrio obtenidos fueron probados al menos utilizando anàlisis de pequeña señal.
Se realizó la validación por simulación y experimental de cada controlador en diferentes escenarios. Los resultados obtenidos validan los diseños y muestran las principales ventajas y desventajas de el sistema en lazo cerrado.
El capítulo 2 cubre los problemas de modelado de la màquina sincrónica de rotor bobinado. Partiendo de las ecuaciones trifásicas generales, y utilizando la transformada de Park, se encontraron el modelo en dq del generador sincrónico de rotor bobinado (WRSG) en isla, alimentando tanto carga resistiva como inductiva. Los puntos de equilibrio del sistema obtenido fueron analizados y calculados, luego se definió el objetivo de control. Finalmente, se obtuvieron modelos lineales aproximados y sus respectivas funciones de transferencia.
Los controladores PI son los más usados en la industria porque ofrecen buen desempeño y son sencillos de implementar. En el capítulo 3, se obtuvieron las reglas de sintonización para el controlador PI, y se analizaron estos resultados con el objetivo de proponer nuevos controladores que mejoraran el desempeño de la clásica aproximación PI.
El esquema de control en modos deslizantes para la WRSG conectada a una carga resistiva fue diseñado en el capítulo 4. Éste, también incluye un completo análisis de estabilidad del sistema en lazo cerrado.
El capítulo 5 presenta dos diseños basados en modos deslizantes para regular la amplitud de la tensión de estator para el WRSG actuando en isla. Ambos diseños usan la componente d de la tensión de estator en la función de conmutación. El primer caso es un control anidado, donde un lazo externo PI es añadido para proveer la referencia de la componente d de la tensión. En la segunda aproximación un término integral es añadido a la superficie de conmutación.
El caso de alimentar una carga inductiva es estudiado en el capítulo 6. El controlador requiere una extensión dinámica debido a que la amplitud de la tensión de estator es una salida de grado relativo cero. Como resultado, un controlador robusto, que no depende de los parámetros de la máquina ni de los valores de carga es obtenido.
En el capítulo 7 los resultados de simulación y experimentales para los controladores diseñados para el WRSG actuando en isla son presentados. En primer lugar, una descripción completa del banco es presentada. Esta incluye detalles de la etapa de adquisición de datos y de la DSP utilizada. En segundo lugar, se hace la descripción del procedimiento de simulación. Luego, las simulaciones y experimentos, que contienen diferentes escenarios, con cambios de referencia y variaciones de carga para cada controlador son presentados.
The control of the stand-alone the wound rotor synchronous generator has been analyzed in this dissertation. For this islanded configuration, the mechanical speed determines the frequency, and the rotor voltage is used to set the stator voltage amplitude. Due to the electrical time constant is so fast compared with the mechanical time constants, the mechanical speed was considered constant and externally regulated and the research was focused on the stator voltage amplitude regulation.
Four different controllers based on sliding mode control techniques were designed in the dq reference frame. The obtained control laws regulate the stator voltage amplitude irrespectively of the load value. Furthermore, only voltage and rotor position measures (to compute the dq transformation), are required. The stability of the obtained equilibrium points was proved at least using small-signal analysis.
Simulation and experimental validation of each controller containing several scenarios were carried out. The obtained results validate the designs and show the main advantages and disadvantages of each closed loop system.
Chapter 2 covers the modeling issues of the wound rotor synchronous machine. From the general three-phase dynamical equations, and using the Park transformation, the dq-model of the stand-alone wound rotor synchronous generator feeding both a resistive and an inductive load are obtained. Equilibrium points of the obtained systems are analyzed and, after defining the control objective, the desired equilibrium points are computed.
Finally, linear approximated models are obtained and their transfer functions are also presented.
PI controllers are the most used in the industry because they offers good performance and are easily implementables. In Chapter 3 we obtain the tuning rule for the PI controller, and we analyze these results in order to propose new controllers which improve the classic PI approach.
The sliding mode control scheme for the WRSG connected to a resistive load is designed in Chapter 4. It also includes a complete stability analysis of the closed loop system.
Chapter 5 presents two sliding mode designs to regulate the stator voltage amplitude for a stand-alone wound rotor synchronous generator. Both use the stator voltage d-component error in the switching function. The first case is a nested controller, where an outer PI loop is added to provide the proper d-voltage component reference. In the second approach an integral term is added to the switching function.
The case of feeding an inductive load is studied in Chapter 6. The controller introduces a dynamic extension because the stator voltage amplitude is a zero relative degree output. As result, a robust controller, which neither depends on the machine parameters nor on the load values, is obtained.
In Chapter 7 the simulation and the experimental results of the designed controllers for the stand-alone wound rotor synchronous generator are presented. Firstly, a complete description of the bench is provided. It also includes details of the data acquisition stage and the used DSP card. Secondly, the description of the simulation procedure is commented. Then, the simulation and experiments which contains several scenarios, with reference change and load variations evaluated for each controller are presented.
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Oaten, Dustin Kyle. "Biodiversity within dry forests of the interior of British Columbia : the role of aspen and stand structure." Thesis, University of British Columbia, 2007. http://hdl.handle.net/2429/32147.
Full textAbstract:
The dry interior forests of British Columbia are composed of contiguous coniferous
forests dominated by Douglas-fir (Pseudotsuga menziesii), with a small portion consisting of
trembling aspen (Populus tremuloides). These aspen trees are of particular interest as there is
evidence that they may support a relatively abundant and diverse faunal community.
However, this potential has not been extensively explored within these forests. Two
bioindicator taxa, small mammals and cavity-nesting birds, were investigated within aspen
stands near Kamloops, British Columbia, Canada during 2005 and 2006, and were compared
to neighbouring Douglas-fir and mixedwood stands. Seven thousand ninety seven captures
of 12 small mammal species were made during 15,761 trap nights, with 48% of captures
within aspen stands. Seven species were numerically dominant within these stands including
the deer mice (Peromyscus maniculatus), southern red-backed vole (Clethrionomys gapperi),
long-tailed vole (Microtus longicaudus), montane vole (Microtus montanus), meadow vole
(Microtus pennsylvanicus), and the northwestern chipmunk (Tamias amoenus). Eight stand
level attribute variables were highly correlated with total small mammal abundance: percent
aspen, total plant cover, number of grass species, snag density (stems/ha), CWD volume
(m³/ha), plant richness, and shrub and herb cover. Fourteen cavity-nesting bird species were
detected 1541 times during 288 point count surveys, with 48% of detections within aspen
stands. Four species dominated the counts: three weak secondary cavity excavators and a
single primary cavity excavator. The total abundance of cavity-nesting bird species was
correlated with total volume of CWD (m³/ha), snag volume (m³/ha), snag density (stems/ha),
downed CWD volume (m³/ha) and percent aspen. Overall, the pure stands of aspen supported
the largest numbers and diversity of small mammals and birds; these results highlight the
importance of aspen stands as they may serve as biodiversity 'hotspots' within dry interior
British Columbia forests. Forest managers should incorporate the maintenance of these
stands into their long-term management plans.Forestry, Faculty of
Graduate
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Kenefic, Laura. "Leaf Area, Stemwood Volume Growth, and Stand Structure in a Mixed-Species, Multi-Aged Northern Conifer Forest." Fogler Library, University of Maine, 2000. http://www.library.umaine.edu/theses/pdf/KeneficLS2000.pdf.
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Busse, Nielsen Anders. "Understanding and communicating forest stand structures : lifting barriers for nature-based forest management." Hørsholm : Forest & Landscape, 2006. http://www.sl.kvl.dk/upload/flr36.pdf.
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Alexander, M. Ross, and M. Ross Alexander. "Determining the Role of Stand Structure in Shaping Climate-Growth Relationships in Eastern Temperate Forests of the US." Diss., The University of Arizona, 2017. http://hdl.handle.net/10150/624527.
Full textAbstract:
Forests play an integral role in regulating the exchange of carbon between the atmosphere and the terrestrial biosphere. These ecosystems only cover for about 30% of the land surface, forests account for almost half of the annual carbon uptake. The amount of carbon sequestered by forest ecosystems is largely dependent upon favorable climate conditions that promote increases in growth. Under the lowest emissions scenario, the United States is projected to undergo an almost 2˚C increase in temperature by the end of the century and it is important that we assess the contemporary climate-growth relationships of multiple forest types to better evaluate the stability and persistence of this vital carbon sink. Tree rings have been used to assess forest response to macroclimate conditions, but often the trees sampled for these analyses are only the most dominant individuals in the forest. This excludes individuals found in the understory of complex forest systems, such as those in the temperate forests of the eastern United States, and climate-growth relationships calculated from only dominant individuals may not be representative of the entire stand. Recent studies have shown that structural complexity of the forest canopy can significantly alter the microclimate conditions at which understory trees grow. Altered growth responses of the understory trees could increase the resilience of complex forest systems to the changes in temperature that are expected by the end of the century.
Here, I apply dendrochronology methods to quantify climate-growth relationships of canopy strata in temperate forests of the eastern United States. Many different forest types are found in this region and have been the focus of numerous species-specific studies on climate growth relationships. However, the integrated response of co-occurring species within canopy units is not often investigated, despite measures of productivity being an integration of ecosystem processes. I present research that investigates the differential climate sensitivities of canopy strata, and I present a means to more accurately represent biomass estimates calculated from tree-ring data.
The first study quantifies the climate sensitivities of different canopy strata from five temperate forests in the eastern US. We used a generalized additive model (GAM) to assess the influence that growing season mean temperature, growing season precipitation, and tree size have on dominant (uppermost), intermediate, and understory (lowermost) canopy strata. We found that differential climate sensitivities do exist between canopy strata, causing each canopy class to respond to extreme climate conditions in a different manner. For example, during the hottest and wettest years dominant and intermediate trees show slight increases in growth, whereas understory trees show significant decreases in growth. These results suggest that the climate and competitive environments created within stratified canopy layers may provide an added degree of ecosystem stability in the face of changing climate conditions.
The second study assesses the spatial coherence of climate-growth relationships between canopy layers from the eastern temperate forest region. We collected increment cores from sites in Missouri, Indiana, Ohio, Michigan, Massachusetts, and Maine and we found that site groupings were relatively consistent between canopy layers. Dominant and intermediate trees showed a strong correlation with temperature that also coincides with the forest types and species distributions that are observed across the region. However, understory trees show stronger relationships with precipitation. Sites from the northeast US and Michigan displayed muted climate relationships, likely due to having both coniferous and hardwood species present. The midwest sites, composed of mostly hardwood species, showed relatively strong, negative temperature relationships in the dominant and intermediate canopy layers, but understory trees displayed strong positive relationships with temperature. These results suggest that although macroclimate conditions influence species distributions and affect the dominant trees, understory trees are likely responding to microclimate conditions. This also suggests that regions with increased functional diversity and complex canopy structure may be better buffered against changing climate conditions.
Finally, we identify four main sources of uncertainty in estimating aboveground biomass from tree-ring data. Tree rings are being used more frequently to estimate the annual uptake of biomass by forested ecosystems. However, these calculations require several steps and assumptions that affect the overall accuracy of the biomass estimates. The error range around tree-ring estimates of aboveground biomass is seldom reported. We illustrate how increment upscaling, allometric, stand density, and mortality uncertainties can affect biomass estimates from a well-studied site in the Valles Caldera in northern New Mexico. We found that dominant sources of uncertainty change depending upon whether cumulative or incremental biomass is calculated. At the cumulative level, choice of allometric equation and tree mortality estimates dominate the uncertainty, whereas inter-annual variability in the tree-ring record dominates incremental biomass estimates. Despite the calculations that are required to translate linear ring-width measurements into biomass quantities, the underlying climate-growth relationships recorded within the tree rings are not significantly altered. Tree-rings provide a means for non-destructively quantifying the aboveground biomass in a forest and reporting the accompanying uncertainties will facilitate more accurate comparisons between disparate forest types.
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Daggett, R. Howard. "Long-Term Effects of Herbicide and Precommercial Thinning Treatments on Species Composition, Stand Structure, and Net Present Value in Spruce-Fir Stands in Maine: The Austin Pond Study." Fogler Library, University of Maine, 2003. http://www.library.umaine.edu/theses/pdf/DaggettRH2003.pdf.
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Abolt, Rena Ann Peck 1968. "Fire histories of upper elevation forests in the Gila Wilderness, New Mexico via fire scar and stand age structure analyses." Thesis, The University of Arizona, 1997. http://hdl.handle.net/10150/278601.
Full textAbstract:
Fire scar analysis to identify fire events and stand age structure analysis to identify fire effects on survivorship of trees were used to reconstruct surface and crown fire regimes in upper elevation forests of the Gila Wilderness, NM. Fire regimes varied across forest type, but not necessarily across elevation. Prior to the twentieth century, (from 1706 to 1904), the mean return interval for large fires was 8 years. During the twentieth century, (from 1904 to 1995), the mean fire return interval for large fires was 46 years. The virtual end of historically frequent fire regimes due to livestock grazing and fire suppression since the turn of the century has affected successional pathways of forest types across elevations, favoring later successional forest species and structures.
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Win, Maung Aye. "Ecological Studies on Locally-managed Mangrove Forests in Taninthayi Region, Myanmar." Kyoto University, 2020. http://hdl.handle.net/2433/253396.
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Godin, Aaron Michael. "Soil nutrient status and fungal community structure of high and low phosphatase microsites in a mixed Douglas-fir paper birch stand." Thesis, University of British Columbia, 2013. http://hdl.handle.net/2429/45476.
Full textAbstract:
Phosphorus (P) plays an important role in driving primary production in terrestrial
ecosystems. However, the majority of P in soil is covalently bound to complex
organic compounds and is largely inaccessible to plants. Soil fungi facilitate the
release of mineral P from organic forms, through the release of extracellular
phosphatase enzymes. To date, very little work has been done to identify fungal
communities physically located with phosphatase activity in situ in the field. In the
current study, I examined soil nutrient status and fungal communities associated with
high and low phosphatase areas. I used an enzyme imprinting method to detect mmscale
phosphatase activity from soil profiles in a mixed Douglas fir and paper birch
stand in British Columbia. Small (0.05 g) soil samples were removed from areas of
high and low phosphatase activity at five root windows. Total extractable P (p=0.95),
inorganic phosphate (p=0.87), and soluble organic P (p=0.20) were not different
between areas of high and low phosphatase activity across all windows, suggesting
that P availability alone was not important in driving phosphatase activity. However,
percent total carbon (p=0.05) and percent total nitrogen (p=0.05) were higher in
microsites with high phosphatase activity. This implies that higher levels of carbon
and nitrogen, especially relative to P, stimulated phosphatase activity. Additions of
carbon (C) and nitrogen (N) to randomly-selected microsites, to test this hypothesis,
were inconclusive. I used pyrosequencing to characterize fungal communities from
microsites differing in phosphatase activity. When examined as assemblages of
operational taxonomic units (OTUs), fungal communities were not different (Bray
Curtis, p=0.53; Jaccard p=0.52) between areas of high and low phosphatase activity
iii
across all windows, though communities did differ among the five windows (Bray
Curtis, p<0.01; Jaccard p<0.01). Furthermore, the number of sequences as OTUs
grouped by trophic status differed between microsites in some windows. Specifically,
the ratio of saprotrophic (SAP) to ectomycorrhizal (EM) fungi was higher in high
than low phosphatase sites in windows with low EM fungal richness. The results of
these experiments contribute to our understanding of fine-scale controls of P cycling
in forest soils, as well as the relative importance of various spatial scales in
structuring soil fungal communities.
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Juchheim, Julia [Verfasser]. "Quantifying the impact of forest management intensity and tree species diversity on individual tree shape and three-dimensional stand structure / Julia Juchheim." Göttingen : Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2020. http://d-nb.info/1220909416/34.
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Forshed, Olle. "Stand structure and development after selective logging with systematically aligned skid trails, directional felling and climber cutting in a dipterocarp rainforest in Sabah, Malaysia /." Umeå : Dept. of Silviculture, Swedish University of Agricultural Sciences, 2006. http://epsilon.slu.se/200630.pdf.
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Wright, David Kenyon. "Effects of Clearcutting with Whole Tree Harvesting on Woody and Herbaceous Plant Diversity After 17-Years of Regrowth in a Southern Appalachian Forest." Thesis, Virginia Tech, 1997. http://hdl.handle.net/10919/46481.
Full textAbstract:
This study examines the effects of clearcut regeneration with whole-tree harvesting on plant diversity. Three approaches were used to study changes in species composition and structure: (1) forest level, (2) stand level, and (3) diversity indices. Within each approach the forest was stratified into three horizontal vegetative regions based upon height: herb (< 1 m), shrub (between 1 and 5 m), and tree (> 5 m). Between the pre-harvest and 17-year-old forest, the relative percent cover of 3 out of 45 herbaceous and 2 out of 34 woody species were found to be significantly different (df = 3; a = 0.10) in the herb stratum; the importance value (average of relative basal area and stem density) of 2 out of 25 woody species in the shrub stratum; and 1 out of 21 woody species in the tree stratum. Within stands, the three lower quality, 17-year-old stands (SI50 = 12.2, 15.2, and 18.3 m) most resembled their pre-harvest composition; however, increases in ericaceous species were observed in the herb and shrub strata potentially inhibit the future regeneration of tree species. The SI50 = 21.3 m stand incurred the greatest changes in composition potentially due to the lack of fire as a disturbance mechanism. The major mechanism that has caused the shifts in species composition and structure is the change in the microenvironment due to the removal of the overstory, which has shifted the competitive advantages from one species to another. In all cases, diversity indices were not found to be significantly different between the 17-year-old and pre-harvest forests. Diversity indices were therefore determined to have limited use if a manager wants to know specific compositions and/or abundance of species.Master of Science
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Park, Pil Sun. "Forest stand structure characteristics for the Cispus adaptive management area, Cascade Range, U.S.A. : implications for old growth, fire hazard, silviculture, and landscape management /." Thesis, Connect to this title online; UW restricted, 2001. http://hdl.handle.net/1773/5587.
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Klinka, Karel. "Structure and regeneration of old-growth stands in the engelmann spruce - subalpine fir zone." Forest Sciences Department, University of British Columbia, 1998. http://hdl.handle.net/2429/661.
Full textAbstract:
Old-growth stands are important for management,
conservation, wildlife, recreation, and maintaining biological
diversity in forested landscapes. However, we are lacking
the information needed to adequately identify and
characterize old-growth stands. This is especially true for
high elevation, interior forests. The characterization of stand
structure and regeneration pattern will help in the
development of site-specific guidelines for identifying old growth
stands and restoring some of the old-growth
characteristics in managed stands.
This pamphlet presents a synopsis of a study investigating
stand structure and regeneration of old-growth stands in the
Moist Cold Engelmann Spruce - Subalpine Fir (ESSFmc)
Subzone near Smithers, B.C. The three stands selected for
the study were located on zonal sites, each in different
watersheds, and the stands were established after fire. The
criteria used for selection were: i) absence of lodgepole
pine, ii) presence of advanced regeneration, and iii) abundant
snags and coarse woody debris. These stands were presumed
to represent the old-growth stage of stand development or
the final (climax) stage of secondary succession.
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Ehbrecht, Martin Alexander Verfasser], Christian [Akademischer Betreuer] Ammer, Christian [Gutachter] Ammer, and Dirk [Gutachter] [Hölscher. "Quantifying three-dimensional stand structure and its relationship with forest management and microclimate / Martin Alexander Ehbrecht ; Gutachter: Christian Ammer, Dirk Hölscher ; Betreuer: Christian Ammer." Göttingen : Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2018. http://d-nb.info/1151700509/34.
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Borth, Eric B. "Drivers of Larch Forest Regeneration in Siberia." University of Dayton / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1562939303944601.
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Fleck, Stefan [Verfasser], and John D. [Akademischer Betreuer] Tenhunen. "Integrated analysis of relationships between 3D-structure, leaf photosynthesis, and branch transpiration of mature Fagus sylvatica and Quercus petraea trees in a mixed forest stand / Stefan Fleck. Betreuer: John D. Tenhunen." Bayreuth : Universitätsbibliothek Bayreuth, 2011. http://d-nb.info/1018017763/34.
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Namora, Maria Joana Afonso Matos. "Princípios e aplicabilidade da silvicultura próxima da natureza a povoamentos florestais em Portugal." Master's thesis, Universidade de Évora, 2014. http://hdl.handle.net/10174/12980.
Full textAbstract:
A silvicultura próxima da natureza é apresentada neste trabalho como uma ferramenta de gestão orientada para produções periódicas e estabelecimento simultâneo de medidas de proteção e conservação do ecossistema de povoamentos de sobreiro. Não sendo um conceito novo, com aplicações em diversas partes do mundo, tem evoluído em função das necessidades da sociedade.
De forma a maximizar este desafio, tornou-se necessário adotar um sistema de cortes e regeneração natural, com manutenção de uma cobertura contínua, baseado na irregularidade da estrutura com 2 a 4 coortes. Esta é uma abordagem holística, multifuncional e integrada, com utilização de métodos de controlo por automação biológica, que contribui para a biodiversidade.
Utiliza-se um sistema de escolha livre de cortes, justificado por interações desde o solo até às copas. A sua aplicação foi efetuada com o simulador SUBERv5.0, estimando-se o crescimento e produtividade para 2 ciclos de produção de 120 anos; Principles and applicability of close to nature silviculture to forest stands in Portugal
ABSTRACT:
The close to nature silviculture is presented in this work as a management tool focused on periodic productions and simultaneous establishment of measures to protect and conserve the ecosystem of cork oak stands. Although not a new concept, with applications in several parts of the world, it has evolved according to the needs of society.
In order to maximize this challenge it was necessary to adopt a system of cuts and natural regeneration, which maintained a continuous cover, based on the structure irregularity, with 2 to 4 cohorts. This is a holistic, multi-functional integrated approach, using control methods by biological automation that contributes to biodiversity.
It uses a system of free choice of cuts, justified by interactions from the ground to the treetops. Its application was made with the simulator SUBERv5.0, estimating growth and yield for 2 production cycles of 120 years.
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AGNOLONI, SILVIA. "Gestione pregressa e strutture attuali di faggete dell'habitat 9210* in Umbria." Doctoral thesis, Università Politecnica delle Marche, 2015. http://hdl.handle.net/11566/243031.
Full textAbstract:
In Appennino centrale le faggete sono il 13% della superficie forestale e in gran parte
classificate come habitat 9210* (Faggeti degli Appennini con Taxus e Ilex) della Rete Natura
2000. Per secoli sono state soggette a intense ceduazioni, pascolamento e attività agricole
temporanee. Da oltre un cinquantennio sono in abbandono a causa della loro marginalità e
lento accrescimento. Disturbi pregressi e/o attuali ne hanno modificato l’assetto
strutturale e le relative dinamiche fitocenotiche, ma tali condizioni non sono considerate
nella programmazione di possibili interventi, che si riducono sostanzialmente alla libera
evoluzione o conversione in fustaie coetanee. Tali opzioni sono spesso in contrasto con la
conservazione della biodiversità e dei servizi ecosistemici.
In Valnerina il 30% del territorio è nella Rete Natura 2000 e le faggete rappresentano il
70% di quelle umbre. In 32 aree permanenti sono stati rilevati i caratteri dendrometricostrutturali,
cronologici, la mortalità, la quantità di necromassa, la presenza e lo stato
vegetativo della rinnovazione gamica per ricostruirne l’assetto pregresso e i possibili
cambiamenti. Nell’analisi dei dati sono stati impiegati indici di complessità strutturale per
caratterizzare i tipi individuati e metodi di analisi multivariata per confrontare variabili
stazionali e dendrometriche e individuare relazioni tra gestione pregressa e struttura
attuale. La classificazione in tipi fisionomici eseguita con valutazioni esperte è stata in
parte confermata dalle analisi, che evidenziano la presenza di strutture forestali molto più
complesse di quelle contemplate da norme, regolamenti e protocolli operativi. Tale
condizione richiede l’applicazione di interventi selvicolturali localizzati e diversificati atti a
favorire la rinnovazione, lo sviluppo di specie obiettivo, il mantenimento o il ripristino
dello stato di conservazione dell’habitat e delle nicchie ecologiche compatibili.In central Apennines beech forests share 13% of the forest cover and a large part is classified as 9210* habitat (Apennine beech forest with Taxus and Ilex) of the Natura 2000 European network. Until the 1950’s these forests have been intensively managed with frequent coppicing, livestock grazing and temporary farming in gaps and margins. Since over 50 years these stands have been abandoned due to their marginal position and lower productivity. Past and current disturbances have changed the overall structures of these forests and altered their dynamics. These conditions are scarcely or not considered when planning management options, often limited to natural development and conversion to evenaged forests, although largely inadequate to biodiversity conservation and ecosystem services supply. In Valnerina (Umbria) 30% of the land surface is in the Natura 2000 network, where beech forests share 70% of their regional cover. We set up 32 permanent plots where we recorded structure, composition and tree growth variables on 1400 sampled trees. We also assessed tree mortality rate, presence of Coarse Woody Debris and seed regeneration to reconstruct former structure and ongoing changes. We used indexes of structural complexity to discriminate and classify the occurring forms and multivariate analysis to compare environmental and stand attributes and to detect relationships between past management and current structure. The predetermined classification, based on expert physiognomic assessment, was partly confirmed highlighting the occurrence of forest structures by far more complex than those provided by regulations and standard sylvicultural protocols. These conditions require specific and diversified forest management options aimed to favor seed regeneration, the growth of target species or individuals, the maintenance or restoration of the ecological requirements of habitat and its compatible niches.
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Edgar, Russell. "Effects of Strand Geometry on Selected Properties of Long-Stand Structural Composite Lumber Made from Northeastern Hardwoods." Fogler Library, University of Maine, 2003. http://www.library.umaine.edu/theses/pdf/EdgarRA2003.pdf.
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Bayer, Dominik [Verfasser], Hans [Akademischer Betreuer] Pretzsch, Stephan [Gutachter] Pauleit, Hans [Gutachter] Pretzsch, and Eric R. [Gutachter] Labelle. "Tree and stand structure and implications for functions and services - New evidence by novel terrestrial laser scanning (TLS) methodologies / Dominik Bayer ; Gutachter: Stephan Pauleit, Hans Pretzsch, Eric R. Labelle ; Betreuer: Hans Pretzsch." München : Universitätsbibliothek der TU München, 2018. http://d-nb.info/1160034796/34.
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McManamay, Rachel Harris. "Assessing the Impacts of Balsam Woolly Adelgid (Adelges Piceae Ratz.) and Anthropogenic Disturbance on the Stand Structure and Mortality of Fraser Fir (Abies Fraseri (Pursh) Poir.) in the Black Mountains, North Carolina." Thesis, Virginia Tech, 2009. http://hdl.handle.net/10919/42759.
Full textAbstract:
Over the past several decades, naturally occurring populations of Fraser fir (Abies fraseri) in the Black Mountains of North Carolina have been heavily impacted by both direct and indirect anthropogenic disturbances, including logging and logging- associated fires, and high mortality rates due to the introduction of the exotic insect, balsam woolly adelgid (BWA) (Adelges piceae). The decline in Fraser fir is particularly concern because it serves as a foundation species within the spruce-fir forests of the Southern Appalachian Mountains. Our objectives for this research were to 1) use current stand structure to infer whether Fraser fir trees are experiencing a cycle of regeneration-mortality that will lead to eventual decline of the population, 2) determine what role, if any, the site-specific geographic variables of slope, elevation, aspect, and land use history have on stand structure, mortality, and BWA infestation level, and 3) analyze repeat aerial photography to examine broad trends of spruce-fir forest cover change caused by anthropogenic disturbance and the BWA. In order to understand stand structure, mortality, and infestation levels, we conducted detailed field surveys of Fraser fir trees throughout the Black Mountains using 44, fixed-radius circular sampling plots. These plots were placed throughout a series of aspects, elevations, and disturbance types in order to understand geographic variability among these variables. An analysis of 4 repeat aerial photographs and corroborating ground photographs revealed broad spatio-temporal trends of spruce-fir regeneration and mortality from 1954 to 2006. Our results indicate that Fraser fir stands at higher elevations are currently in a state of recovery; whereas stands at lower elevations appear to be more susceptible to BWA-induced mortality. Changes in forest cover area from 1954 to 2006 were influenced greatly by direct and indirect anthropogenic disturbance. Our results call attention to the significant impact that direct and indirect anthropogenic disturbance has had on Fraser fir stand structure, but also provide evidence for the ability of an imperiled ecosystem to recover from high rates of insect caused mortality.Master of Science
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Pausch, Reinhard. "Ein System-Ansatz zur Untersuchung von Zusammenhängen zwischen Waldstruktur, Arbeitsvolumina und Kosten der technischen und biologischen Produktion in Forstrevieren ost- und nordbayerischer Mittelgebirge A system approach for the analysis of interrelationships between forest structure, work volume and cost of stand establishment, stand tending and harvesting operations in forest districts of Northern and Eastern Bavaria /." [S.l. : s.n.], 2002. http://deposit.ddb.de/cgi-bin/dokserv?idn=969621574.
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Gudaitis, Marius. "Nemuno kilpų regioninio parko Punios šilo sumedėjusios augalijos ekologinis vertinimas." Master's thesis, Lithuanian Academic Libraries Network (LABT), 2009. http://vddb.library.lt/obj/LT-eLABa-0001:E.02~2009~D_20090615_115419-18290.
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Magistro darbe tiriama Nemuno kilpų regioninio parko Punios šilo sumedėjusią augaliją. Darbo objektas – Punios šilas bei jame esantys gamtinis rezervatas ir botaninis – zoologinis draustinis. Dabar Punios šilas – viena svarbiausių Nemuno kilpų regioninio parko dalių. Darbo tikslas – ekologinis Nemuno kilpų regioninio parko Punios šilo sumedėjusios augalijos vertinimas. Darbo metodika – Išanalizavus literatūrinę medžiagą ir remiantis Nemuno kilpų regioniniame parke esančiame Punios šile atliktais sumedėjusios augalijos tyrimais, stebėjimais nustatytas medžių rūšių išsidėstymas, jų pasiskirstymas kvartaluose. Buvo nustatyta medynų ekologinė būklė. Tyrimai buvo vykdomi visuose 48 Punios šilo kvartaluose. Kiekvienam kvartalui sudaryta atskira lentelė, iš kurios atsispindi bendras užimamas kvartalo plotas hektarais, sklypų skaičius, medynų sudėtis, būdinga augavietė, medynų amžiaus vidurkis, skalsumas, medynų tūris. Darbo rezultatai – nustatyta esama sumedėjusios augalijos rūšinė sudėtis, medynų įvairovė, ekologinė būklė. Punios šilo gamtinių objektų būklė yra gera. Pagal medynų charakteristiką Punios šile pušynai užima didžiausią plotą, eglynai per puse mažesnį, o ąžuolynai ir beržynai beveik vienodą plotą.Post–graduate work examined the Nemunas loops regional park the forest of Punia woody vegetation. Object of the work - forest of Punia with nature reserve and botanical - zoological preserve that are in it. Now forest of Punia - one of the most important part of the Nemunas Loops Regional Park. Aim of the work - the ecological assessment of Nemunas loops regional park forest of Punia woody vegetation. Method of the work - analysis of literary material and on the basis of the Nemunas Loops Regional Park located in forest of Punia for the woody vegetation studies, the observations set out in the distribution of tree species, their distribution areas. It was found the ecological status of the woods. Studies were conducted in all 48 blocks of forest of Punia. For different block was made separate table, which is reflected in the total area in hectares occupied by block, parcel number, stand composition, characterized place of growth, average age of stands, the volume of stands. Results of the work - the existing woody vegetation species composition, stand diversity, the ecological status was set. Forest of Punia natural objects are in good condition. Under the stands testimonial pine forests occupy the largest area of the forest of Punia, fir - a half lower, and the oak woods, and birch forest takes near the same area.
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Klinka, Karel, Gordon J. Kayahara, and Christine Chourmouzis. "Regeneration, growth and productivity of trees within gaps of old-growth forests on the outer coast (CWHvh2) of British Columbia." Forest Sciences Department, University of British Columbia, 2001. http://hdl.handle.net/2429/669.
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Central to the issue of harvest feasibility on the outer BC coast (CWHvh) is the question of whether sites, once harvested, can be regenerated, and whether the time period for replacement and subsequent growth is economically and environmentally acceptable. Since low productivity sites have not been harvested in the past, there is a lack of data to answer this question. We tried to provide an answer by assessing regeneration following natural disturbances. Small scale gap disturbances are the norm within old-growth stands. If regeneration is not a problem in gaps, then we have some evidence that regeneration
should not be a problem upon implementation of our management practices. The objectives of this study were: (1) to develop baseline information on the mechanisms and the patterns of regeneration across a sequence of forest types; (2) to assess regeneration success with respect to productivity; and (3) to estimate future growth and productivity.
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Klinka, Karel. "Natural regeneration on clearcuts at the lower limit of the mountain hemlock zone." Forest Sciences Department, University of British Columbia, 1997. http://hdl.handle.net/2429/654.
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The Mountain Hemlock (MH) zone includes all subalpine forests along British Columbia’s coast. It occurs at elevations where most precipitation falls as snow and the growing season is less than 4 months long. The zone includes the continuous
forest of the forested subzones and the tree islands of the parkland subzones (Figure 1). Old-growth stands are populated by mountain hemlock, Pacific silver fir, and Alaska
yellow-cedar, and are among the least-disturbed ecosystems in the world. Canopy trees grow slowly and are commonly older than 600 years, while some Alaska yellow-cedars may be up to 2000 years old.
Early regeneration failures followed slashburning and the planting of unsuitable species. Currently, the most successful and feasible option for reforesting cutovers is natural
regeneration with a mix of the three main tree species, but uncertainties remain about the temporal and spatial pattern of regeneration, changes in species composition, and the time
required for stand establishment after cutting. Our study addressed these concerns by examining regeneration patterns on 6 sites that were clearcut 11-12 years prior to sampling and left to regenerate naturally. The sites were located at the lower
limits of the zone in the Tetrahedron Range, near Sechelt, at elevations from 1060-1100m.
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Acevedo, Callejas Michelle L. ""When He Forgets Them [Medicines]…I Can Hardly Stand to be Around Him": The Influence of Stress, Frequency of Challenges, and Coping on the Relational Quality of Partners whose Significant Other Has a Mental Health Condition." Ohio University / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1434972064.
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