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  • 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.
91

Forest vegetation and fuel dynamics following stand-replacing wildfire, re-burn, and postfire management in the Siskiyou Mountains, Oregon /

Donato, Daniel C. January 1900 (has links)
Thesis (Ph. D.)--Oregon State University, 2008. / Printout. Includes bibliographical references (leaves 172-187). Also available on the World Wide Web.
92

The determination of the concentration of aqueous smoke solutions used in restoration projects

Meets, Michiel 12 1900 (has links)
Thesis (M.Sc.)--Stellenbosch University, 2000. / ENGLISH ABSTRACT: It is well known that smoke and aqueous smoke solutions promote the germination of certain seeds. This has considerable practical implications for restoration in fire prone areas like the Cape fynbos. The aqueous smoke solution (more commonly known as smoke water) can be used in restoration projects to stimulate seeds to germinate faster so that a wide diversity of plants can be established rapidly. Smoke water is made using different methods and different plant materials. This inevitably results in different concentrations of smoke water. Although made in different ways, different smoke waters may all have an enhancing effect on seed germination. In this study, the germination of Grand Rapids lettuce seed was used to determine the differences between five different types of smoke water. Germination was done in a controlled environment, using through-flow germination boxes (patent no. ZA2000/1832, registered 1114/2000) instead of traditional petri dishes. The differences in the concentrations were determined using bioassays. A very strong concentration of smoke water damaged the seed and a very weak concentration did not have any enhancing effect on germination. The concentrations of the different smoke waters were compared to a standard smoke solution (the first smoke solution ever made, that of De Lange & Boucher (1990». The different concentrations of the smoke solutions were determined by comparing them to the standard, using a best fit line on the germination graphs. Each of the smoke solutions tested is given a "delb" rating (after De Lange & Boucher), with the standard smoke water being 1 delb. The delb value is used to determine the dilution factor for each smoke solution. It is concluded that the five smoke solutions tested all differed from each other emphasizing the need for quality control in commercial and experimental applications. / AFRIKAANSE OPSOMMING: Dit is wel bekend dat rook en vloeibare rook oplossings (rookwater) die ontkieming van sekere sade bespoedig. Dit het groot praktiese implikasies vir hervestiging in gebiede met gereelde vuur, soos die Kaapse fynbos. Die rookwater kan in hervestiginsprojekte gebruik word om sade te stimuleer om vinniger te ontkiem om sodoende 'n groot diversiteit van plante vinnig te vestig. Rookwater word op verskillende maniere en met verskillende materiaal vervaardig. Dit kan lei tot verskillende konsentrasies rookwater, alhoewel al die verskillende rookwaters 'n stimulerende effek op saadontkieming kan bewerkstellig. In hierdei studie is Grand Rapids slaai saad gebruik om die verskille tussen vyf verskillende rookwaters te ondersoek. Ontkieming was in 'n beheerde atmosfeer gedoen en deurvloei ontkiemingsbakke (patent nr. ZA2000/1832, geregistreer 11/4/2000) is gebruik, i. p. v. traditionele petri bakkies. Die verskille in konsentrasies is gemeet m. b. v. biotoetse. 'n Baie serk konsentrasie het die sade beskadig en 'n baie flou konsentrasie het geen stimulerende effek op ontkieming gehad nie. Die konsentrasie van die verskillende rookwaters is vergelyk teenoor 'n standaard rookwater (die eerste rookwater ooit gemaak, die van De Lange en Boucher (1990». Die verskillende rookwater konsentrasies is bepaal deur dit met die standaard te vergelyk m. b. v. 'n regressie lyn op die ontkiemingsgrafieke. Elke rookwater getoets kry dan 'n "delb" waarde (n. a. v. De Lange & Boucher), met die standard gelyk aan 1 delb. Die delb waarde word gebruik om die optimale verdunning van elke rookwater te bepaal. Daar word opgesom dat al die rookwaters getoets wel van mekaar verskil en dit beklemtoon die waarde van kwaliteits beheer in kommersiële en eksperimentele toepassings.
93

Postfire regeneration of mountain fynbos by resprouting : a comparison of species with different life history types

Marais, Karen E. 12 1900 (has links)
Thesis (MScConEcol)--Stellenbosch University, 2012. / ENGLISH ABSTRACT: The fire-prone mediterranean-type climate regions of the world are immensely biodiverse. Changes in fire frequency due to anthropogenic ignitions and climate change are one of the factors threatening the plant diversity of these regions. Many postfire regeneration studies have focused on seedling recruitment, whereas much can still be learned about regeneration through resprouting. This project focused on resprouters after a fire and assessed if there are differences between the obligate (OS) and facultative (FS) resprouting life history types. OS species have to resprout after fire, as their seeds are not fire resistant and seedling recruitment takes place in fire-free periods, whereas FS species have the ability to resprout and recruit seedlings after a fire. My analyses found a significant difference in postfire resprout success between OS species and FS species, supporting the division of woody resprouting shrubs into these two life history types. OS species had minimal fire-related mortality and this was related to their ability to resprout early and vigorously after fire. OS species had no postfire mortality, which points to traits that enable them to endure the hot and dry summer months. The FS species varied in their response to fire and had greater fire induced mortality than the OS species. Postfire mortality (post-sprouting) was also greater compared to OS species, especially towards the end of the long dry summer suggesting a link to water stress. A postfire seedling survey of target FS, OS and non-sprouters (NS), revealed that NS species had seedling/adult ratios that were orders of magnitude higher ranging between 40-200 seedlings per adult against less than 1-10 seedlings per adults for FS, with OS species recruiting no seedlings directly postfire, as is consistent with their life history type. Although the NS species do not sprout and the FS species had some mortality, the population was at or above replacement two-year postfire on account of seedling recruitment. OS species maintained their pre-fire population by successfully resprouting and by experiencing almost no postfire mortality. These results provide strong justification for grouping woody resprouters into OS and FS species in future studies seeking to understand the underlying differences in postfire recovery. Postfire flowering phenology was also observed during the two year study period. Geophytes, mostly belonging to the Iridaceae and Orchidaceae were overrepresented within the first year postfire, many displaying fire-stimulated flowering. This suggests that some geophytes limit their reproductive cycle to the immediate postfire environment, when nutrients and light are abundant. Smaller resprouting shrubs generally flowered earlier than larger resprouting shrubs. Many non-sprouting shrubs did not reach maturity within the study period and those that did mostly belonged to the Fabaceae and Asteraceae families. This study added 71 species to the existing Paarl Mountain species list, including eight new red listed species, highlighting the importance of early postfire field surveys. / AFRIKAANSE OPSOMMING: Veldbrande is ‘n natuurlike verskynsel in die meditereense klimaatstreke van die wereld. Hierdie areas is ook bekend vir hulle ryk biodiversiteit. Veranderinge in die vuur frekwensie as gevolg van klimaatsverandering en veldbrande wat deur mense veroorsaak word, bedreig die plantdiversiteit van hierdie streke. Vorige veldbrandstudies het meestal gefokus op saailinge en daar bestaan ‘n groot leemte om regenerasie deur herspruiting beter te verstaan. Hierdie navorsingsprojek fokus op herspruiting van fynbos plante as ‘n oorlewingstrategie na ‘n veldbrand. Spesifiek word daar gekyk na verskille tussen verpligte (VH) en nie-verpligte (fakultatiewe) herspruiters (FH). VH spesies moet herspruit na vuur om hulle populasie stabiel te hou, aangesien hulle saad nie vuurbestand is nie. FH spesies het die vermoë om te herspruit sowel as saailinge te werf na ‘n brand. Die studie bevindinge dui op betekenisvolle verskille tussen hierdie twee lewensgeskiedenistipes en regverdig die groepering van houtagtige herspruiter spesies as VH of FH. VH het minimale mortaliteit getoon na die veldbrand. Bykans alle plante het vinnig en kragtig herspruit. VH besit ook eienskappe wat hulle in staat stel om die warm, droeë somers te oorleef. Die oorlewing van FH was wisselvallig, met mortaliteit as gevolg van direkte vuurskade en verdere mortaliteit gedurende die lang somermaande, moonlik as gevolg van water stress. ‘n Saailingstudie van VH, FH en ook nie-spruiters (NS) het getoon dat die saailing/volwasse verhoudings van NS ordes hoër is as die van FH. VH het geen saailinge direk na die vuur geproduseer nie. Twee jaar na die vuur was FH en NS saailing getalle steeds heelwat meer as die aantal volwasse plante wat dood is in die veldbrand. VH het hul populasie stabiliteit gehandhaaf deurdat alle volwasse plante suksesvol herspruit het. Hierdie bevindinge regverdig die verdeling van herspruitende fynbos spesies as VH of FH. Verdere studies is belangrik om die onderliggende ekofisiologiese verskille tussen die twee lewensgeskiedenistipes beter te verstaan. Die blompatrone van verskillende spesies is ook aangeteken tydens die tweejaar studieperiode. Bolplante, veral in die iris- (Iridaceae) en orgidee (Orchidaceae) families het oorheers gedurende die eerste jaar na die brand, aanduidend van ‘n vuur-gestimuleerde blompatroon. Sommige bolplante mag hul voorplantingssiklus beperk tot die periode direk na veldbrand, terwyl daar genoeg lig is en die grond verryk is met voedingsstowwe. Kleiner herspruitende struike het in die algemeen vroeër geblom as groter struike. Nieherspruitende struike het meestal nie seksuele volwassenheid bereik binne twee jaar na die veldbrand nie, buiten sommige in die ertjie- (Fabaceae) en asterfamilies (Asteraceae). Die studie het 71 nuwe spesies tot die bestaande Paarlberg spesielys gevoeg, waarvan agt rooidataspesies was, wat die waarde van plantopnames direk na ‘n veldbrand beklemtoon.
94

Living with Wildfire in Arizona

Dolan, Corrine, Rogstad, Alix January 2007 (has links)
226 pp. / UACE Firewise publications (8 total) / The Living with Wildfire in Arizona educational materials synthesize the most recent scientific and technically known information available on fire ecology for the ecosystems of Arizona, including mixed conifer forests, ponderosa pine forests, pinyon-juniper and oak woodlands, chaparral, grasslands and desert scrub, and riparian areas. The materials are meant to educate homeowners living in the wildland urban interface areas as to the natural function of fire in each ecosystem and what significant changes have impacted fire behavior over time. Information includes the natural role of fire, how and why fire behavior has changed over time, and the role that humans play in affecting that change in protecting themselves and their property.
95

Management Tools for Prescribed Burning for Tallgrass Prairie Restoration at the Lewisville Lake Environmental Learning Area

Moreno, Maria C. 12 1900 (has links)
The Lewisville Lake Environmental Learning Area (LLELA) is a wildlife management area with tallgrass prairie, an endangered ecosystem. Essential ecosystem processes, especially fire, are part of restoration. To support fire management efforts at LLELA and surrounding areas, this project evaluated and developed tools for fire restoration. The four primary prairie grasses respond favorably to burning. Fuel loads and fuel models vary by scale and survey method. One- and 10-hour fuel moisture can be predicted using a statistical model; 100- and 1,000-hour fuel moisture cannot. Historic weather data suggests that burning can occur when it is most effective. The production of ozone precursors produced by burning is comparable to those emitted every six minutes by regional automobiles.
96

Fire-mediated succession and reversion of woody vegetation in the KwaZulu-Natal Drakensburg, South Africa

De Villiers, Andrew 04 February 2013 (has links)
Long term fire exclusion has been attempted in Catchment IX (CIX) at Cathedral Peak. Baseline vegetation of CIX was sampled in 1952, with follow-up surveys in 1973, 1986 and 2010. These took place at key times in terms of changes in fire history within the catchment. Complete fire exclusion was achieved between 1973 and 1986, but eight accidental fires burnt part of CIX thereafter. The woody component was resurveyed in 2010 after the latest of thirteen unintended fires had swept through CIX in 2007. This fire burnt about 90% of the catchment. The vegetation of the area not burnt was a distinct community and size structure indicating it had not been burnt by other accidental fires. Partial exclusion of fire over 58 years resulted in vegetation transforming from grassland to a grassland-fynbos-scrub forest mosaic. Erica evansii and Leucosidea sericea, a reseeder and resprouter respectively, were the two dominant species in CIX. These displayed expected responses to a single fire, resulting in dominance shifting from E. evansii (92% mortality) to L. sericea (1.6% mortality). The decrease in E. evansii individuals resulted in a relative increase in community contribution of species not affected by fire. Leucosidea sericea’s post-fire dominance in burnt plots was not apparent in fire-protected areas. A successional trend of colonisation of woody species, predominantly E. evansii and L. sericea, into grassland was observed. Despite occasional fires since 1986 vegetation did not revert to grassland. The emergent woody community was not homogenous. This was attributed to a combination of an irregular pattern of accidental burns and environmental variability within the catchment. The mosaic of distinct grassland, woodland, ecotonal and scrub forest communities are predicted to remain as such.
97

Anthropogenic Fire and the Development of Neolithic Agricultural Landscapes: Connecting Archaeology, Paleoecology, and Fire Science to Evaluate Human Impacts on Fire Regimes

January 2019 (has links)
abstract: The recent emergence of global ‘megafires’ has made it imperative to better understand the role of humans in altering the size, distribution, and seasonality of fires. The dynamic relationship between humans and fire is not a recent phenomenon; rather, fire has deep roots in our biological and cultural evolution. Because of its long-term perspective, archaeology is uniquely positioned to investigate the social and ecological drivers behind anthropogenic fire. However, the field faces challenges in creating solution-oriented research for managing fire in the future. In this dissertation, I originate new methods and approaches to archaeological data that enable us to interpret humans’ long-term influences on fire regimes. I weave together human niche construction theory and ecological resilience, creating connections between archaeology, paleoecology, and fire ecology. Three, stand-alone studies illustrate the usefulness of these methods and theories for charting changes in land-use, fire-regimes, and vegetation communities during the Neolithic Transition (7600 - 3800 cal. BP) in eastern Spain. In the first study (Ch. II), I analyze archaeological survey data using Bayesian methods to extract land-use intensities from mixed surface assemblages from a case study in the Canal de Navarrés. The second study (Ch. III) builds on the archaeological data collected computational model of landscape fire, charcoal dispersion, and deposition to test how multiple models of natural and anthropogenic fire activity contributed to the formation a single sedimentary charcoal dataset from the Canal de Navarrés. Finally, the third study (Ch. IV) incorporates the modeling and data generated in the previous chapters into sampling and analysis of sedimentary charcoal data from alluvial contexts in three study areas throughout eastern Spain. Results indicate that anthropogenic fire played a significant role in the creation of agricultural landscapes during the Neolithic period, but sustained, low-intensity burning after the late Neolithic period maintained the human created niche for millennia beyond the arrival of agro-pastoral land-use. With global fire activity on the rise, it is vital to incorporate perspectives on the origins, development, and maintenance of human-fire relationships to effectively manage fire in today’s coupled social-ecological landscapes. / Dissertation/Thesis / Doctoral Dissertation Anthropology 2019
98

The influence of repeated prescribed burning and forest conversion on soil fungal communities

Bastias, Brigitte A., University of Western Sydney, College of Health and Science, Centre for Plant and Food Science January 2007 (has links)
Fungi are key components in forest ecosystems, being involved in decomposition of plant biomass and the cycling of nutrients in forest soils. Despite their importance little is understood about the influence forest management practices, such as long-term prescribed burning and forest conversion are having on soil fungal communities. Part of the work described in this thesis investigated the effects of long-term repeated prescribed burning on the total soil fungal community, the diversity of mycelial communities of ectomycorrhizal fungi and the influence of biennial prescribed burning on the cellulolytic soil fungal community using stable isotope probing techniques. The influence of long-term repeated prescribed burning on soil fungal communities was investigated through a series of studies conducted at Peachester State Forest, Queensland, Australia. This site has been the centre of a long-term repeated prescribed burning experiment, established since 1972, consisting of plots subjected to biennial, quadrennial or no burning. Denaturing gradient gel electrophoresis (DGGE) was used to show that long-term prescribed burning significantly altered the total fungal community structure in the top 10 cm of soil, when compared with unburned plots. Hyphal ingrowth bags, used to target ectomycorrhizal (ECM) mycelia in soil, along with DGGE analysis, indicated that profiles of the soil fungal community from 2 yr burn plots significantly differed from those of the 4 yr burn and unburned plots. Following analysis of clone assemblages from the different burn regimes, results indicated that this difference reflected an altered ECM fungal community composition. 13C stable isotope probing (SIP), following the incubation of soil with 13C labelled cellulose, and DGGE analysis was found to significantly alter the active fungal community in the upper 10cm of soil at Peachester State Forest. Fewer active fungi in the 2 yr burn plots were found to have incorporated 13C compared to the unburned plots, strongly suggesting that the activities of cellulolytic fungi were negatively affected by the 2 yr burning treatment. The thesis also incorporated work that assessed the effect of forest conversion from native eucalypt to Pinus elliottii plantation on the soil fungal community at Beerburrum State Forest, Queensland, Australia. ITS and 18S RNA and DNA were used, along with terminal restriction fragment length polymorphism (T-RFLP) and DGGE analysis, indicating that total and active fungal communities differed significantly between the native eucalypt forest and first rotation P. elliottii plantation. This suggested that the conversion from native eucalypt forest to P. elliotti plantation significantly altered the soil fungal community at the Beerburrum site. / Doctor of Philosophy (PhD)
99

Fire frequencies for Western Sydney's woodlands : indications from vegetation dynamics

Watson, Penelope J., University of Western Sydney, College of Health and Science, School of Natural Sciences January 2005 (has links)
Although the importance of fire management for biodiversity conservation is increasingly being recognised, little is known about the relationship between fire regimes and plant diversity in Australia’s temperate grassy woodland ecosystems. This project sought to address this gap in the woodlands of Western Sydney’s Cumberland Plain. Aspects of vegetation dynamics were investigated through six studies, mostly in shale-based Cumberland Plain Woodland (CPW) remnants. Results indicate that fire frequency profoundly affects both vegetation composition and structure. The influence of fire cycles was most readily apparent in the shrub layer. Findings from the six studies were synthesized into a state and transition model which allows exploration of management actions. Interfire intervals between 4 and 12 years are predicted to maintain Themeda woodland with both Bursaria thickets and open areas, and obligate seeder shrubs. Variable intervals across time and space within these thresholds should maintain much of the landscape at fuel levels compatible with property protection; fuel loads in CPW peak well below those in woodlands on sandstone. Low fire frequency remnants dominated by Bursaria retain many conservation values, but are likely to support lower abundances of obligate seeder shrubs and open patch herbs, and to be more weed-prone, than remnants burnt once or twice a decade. Experimentation with one or two short interfire intervals may be appropriate in long unburnt CPW. / Doctor of Philosophy (PhD)
100

Rhetoric and the restoration landscape forest restoration in environmental debate /

Vranizan, Gregory Matthew. January 2006 (has links)
Thesis (M.S.)--University of Montana, 2006. / Title from title screen. Description based on contents viewed Mar. 9, 2007. Includes bibliographical references (p. 64-65).

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