• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 3
  • 3
  • 1
  • Tagged with
  • 7
  • 7
  • 5
  • 4
  • 4
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 1
  • 1
  • 1
  • 1
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

The forest and the mainframe : the dynamics of modeling and field study in the Coniferous Forest Biome, 1969-1980

Long, Tulley A. 28 July 2005 (has links)
In an initial research proposal of December 1969, the scientists of the Coniferous Forest Biome (CFB), an ecosystem study centered in the Pacific Northwest and part of the larger International Biological Programme (IBP), expressed optimism that computer simulations and systems modeling could transform empirical knowledge of the carbon, water, and nutrient flows turned into viable forest management practice. The CFB's strategy aimed to use projections of the computer simulations and data from field study to constantly check and direct each other, resulting in a flexible, refined, and accurate understanding of forest ecosystems, as well as a reliable guide to forest management. To what extent did the CFB's research program, centered on a total system model, complete its cycle of field study, modeling, and validation? Despite the innovative strategies of the CFB modelers, ecosystem modeling lost its preeminent status among the goals of the CFB, due to different interpretations of the purpose and philosophy of ecosystem modeling and the practical limitations of administering a large research program. Instead, small field-based studies during the CFB yielded a number of ground-breaking discoveries. Although they diverged from the modeling objectives, these areas of fieldwork emerged from questions the forest's functions and cycling processes that the modeling efforts of the CFB required. Focusing on the work of CFB participants from Oregon State University and the USDA Forest Service in the H. J. Andrews Experimental Forest, this thesis addresses the relationship between the marginalization of the modeling objectives and the rising centrality of field-based forest studies in the CFB from 1969 to 1980. Given the ongoing legacy of CFB research at the Andrews Long-Term Ecological Research (LTER) site and the later implications of CFB findings in debates over forest policy and management, this thesis also seeks to evaluate the Coniferous Forest Biome as a whole and discuss the role of modeling and field work within large ecological research endeavors more generally. / Graduation date: 2006
2

Effect of snow interception on the energy balance above deciduous and coniferous forests during a snowy winter

Suzuki, Kazuyoshi, Nakai, Yuichiro, Ohta, Takeshi, Nakamura, Tsutomu, Ohata, Tetsuo 07 1900 (has links)
No description available.
3

A quantitative approach on understanding emission and removal of trace gases and atmospheric oxidation chemistry in remote and suburban forest / 遠隔域ならびに都市周辺の森林における微量成分ガスの放出・消失および大気酸化過程の理解に向けた定量的なアプローチ

Sathiyamurthi, Ramasamy 23 September 2016 (has links)
京都大学 / 0048 / 新制・課程博士 / 博士(地球環境学) / 甲第20038号 / 地環博第154号 / 新制||地環||31(附属図書館) / 33134 / 京都大学大学院地球環境学舎環境マネジメント専攻 / (主査)教授 梶井 克純, 准教授 真常 仁志, 准教授 田中 周平 / 学位規則第4条第1項該当 / Doctor of Global Environmental Studies / Kyoto University / DFAM
4

Substratpreferenser hos Crossocalyx hellerianus i svenska barrskogar : är skoglig kontinuitet en viktig faktor?

Kvarnsudde, David January 2020 (has links)
In recent time, forests in Sweden have lost habitat quality in the loss of deadwood due to the practices in productions forestry. This means that substrates for epixylic species has decreased both in quality and quantity. The aim with this study was to find which preferences the epixylic liverwort, Crossocalyx hellerianus has on its substrate and environment. C. hellerianus requires coarse logs with rotten wood, which usually is more available in forests with long forest continuity. This study was performed to see if forest continuity, isolation of habitats and if the substrate was of significance for a demanding species such as C. hellerianus. The study was performed in six sites and in each site several 50x10 meter transects were surveyed for logs. Each log was measured for diameter, sun exposure, ground contact, stage of decay and if the log was colonized by C. hellerianus. The result showed that C. hellerianus preferred coarser logs and that the species only appeared on an intermediate or later stage of decay. A high forest continuity and low habitat isolation turned out to be positive factors for the abundance of C. hellerianus
5

Har signalarter störst förekomst inom eller utanför Dalarnas boreala naturreservat? : En studie om arttätheten av signalarter i Dalarnas barrskogar / Are signal species most abundant inside-or outside the boreal nature reserves? : A study about the density of indicator species in the coniferous forests in Dalarna, Sweden

Ahlgren, Caroline January 2023 (has links)
Today, it is well known that biological diversity is decreasing worldwide, and the presence of indicator species can identify areas with high biological diversity. Environments with a high presence of indicator species are important to protect and preserve in the form of, for example, nature reserves as these environments indicate high nature values. The aim of this study is to find out whether the coniferous forest's indicator species have the greatest species density and occurrence within the boundaries of the nature reserves in Dalarna, Sweden. The distribution of 10 different indicator species within the coniferous forests of Dalarna, Sweden, was mapped in the QGIS software and the total species density inside as well as outside the nature reserves of Dalarna was compared in the statistical program SPSS. The species density of five selected indicator species was compared inside versus outside of the reserves. The result for the 10 indicator species showed that there was no significant difference between inside versus outside of the reserves, although there were a higher species density per hectare outside the boundaries of the nature reserves. The result for the five selected indicator species showed no significant difference between inside versus outside of the reserves, however, the species density of both R.subpinnatus and P.grossa were higher within the boundaries of the nature reserve. More sightings of indicator species outside the boundaries of nature reserves may indicate that the public is more inclined to report sightings in unprotected areas, rather than reporting sightings in protected areas that have already been established as having high nature values. Many species observations are found just outside the boundaries of the nature reserve, which may indicate that high nature values occur there as well. Further studies about potential buffer zones and their impact on indicator species are encouraged. / Att den biologiska mångfalden minskar världen över är idag välkänt, signalarter är arter som vars närvaro kan tyda på en miljö som kan generera en bra grund för hög biologisk mångfald. Miljöer med hög närvaro av signalarter är viktiga att skydda och bevara i form av exempelvis naturreservat eftersom dessa miljöer tyder på höga naturvärden. Denna studies frågeställning är om barrskogens signalarter har störst arttäthet och förekomst inom naturreservatens gränser. Med hjälp av artobservationer från Artportalen kartlades 10 olika signalarters utbredning i Dalarnas barrskogar i programvaran QGIS. Därefter jämfördes den totala arttätheten för studiens alla arter per hektar innanför och utanför Dalarnas naturreservat i statistikprogrammet SPSS för att se om det fanns en signifikant skillnad mellan respektive område. Även arttätheten för fem utvalda signalarter jämfördes för att se om det fanns en signifikant skillnad mellan de skyddade och icke-skyddade områdena. Resultatet visade att det inte fanns en signifikant skillnad mellan områdena (p=>0,05), även om det var fler artobservationer per hektar utanför naturreservatens gränser. Resultatet för de enskilda arternas arttäthet per hektar och område visade att det inte fanns någon signifikant skillnad mellan områdena, dock var arttätheten för både R.subpinnatus och P.grossa högre inom naturreservatens gränser. Att det förekommer fler observationer av signalarter utanför naturreservatens gränser kan bero på att allmänheten kan vara mer benägna att rapportera in fynd som gjorts i oskyddade områden, i stället för att rapportera in eventuella fynd i skyddade områden som redan har konstaterat höga naturvärden. Många artobservationer återfinns precis utanför naturreservatens gränser vilket kan tyda på att höga naturvärden förekommer även där. Vidare studier kring buffertzoner och dess påverkan på signalarter uppmuntras.
6

The diversity of fungi in coniferous forests and mixed forests / Svampars diversitet i barr- och blandskog

Asplund, Ida January 2023 (has links)
The fungal domain has one of the highest biodiversities among eukaryotes and species within the domain fill important ecological roles, such as mutualistic mycorrhiza, decomposers, parasites and pathogens. The development of forest ecosystems and their related processes has not only been linked to fungal diversity but the composition and abundance of fungi benefits the abundance and diversity of other species as well. In this study three questions concerning the differences in the fungal communities between mixed forests and coniferous forests were considered. Inventories were done in coniferous forest and mixed forest areas classified as nature reserves and later statistically analyzed. The study could show that while the probability of finding ectomycorrhiza was significantly higher in mixed forests than coniferous forests, the probability of finding saprotrophs was significantly higher in coniferous forests than in mixed forests. Results in contrast to other studies were also found. The study revealed that more is needed to be done on the topic of forest fungi in mixed forest and coniferous forest areas. / Svampdomänen har en av de högsta biologiska mångfalderna bland eukaryoter och domänens arter innehar viktiga ekologiska roller, såsom mutualistisk mykorrhiza, nedbrytare, parasiter och patogener. Utvecklingen av skogsekosystem och deras relaterade processer har inte bara kopplats till svampdiversitet utan svamparnas sammansättning och förekomst gynnar också förekomst av och mångfald hos andra arter. I denna studie behandlades tre frågor om skillnaderna i svampsamhällen mellan blandskogar och barrskogar. Inventeringar gjordes i barrskogs- och blandskogsområden klassificerade som naturreservat och analyserades senare statistiskt. Studien kunde visa att även om sannolikheten för att hitta ektomykorrhiza var signifikant högre i blandskogar än barrskogar, var sannolikheten för att hitta saprotrofer signifikant högre i barrskogar än i blandskogar. Resultat i motsats till andra studier hittades också. Studien visade att det behövs mer forskning om skogssvampar i blandskog och barrskogsområden.
7

Jämförelse av observationer av naturvårdsarter mellan skyddade värdekärnor och produktionsskogar i Dalarna, Sverige / Comparing observations of conservation species between protected high conservation value forests and production forests in Dalarna, Sweden

Jansson, Linn January 2024 (has links)
Biologisk mångfald minskar kraftigt i hela världen som ett resultat av mänskliga handlingar. Den biologiska mångfalden hos svenska boreala skogar hotas av det moderna skogsbruket där trakthyggesbruk som är en vanlig skogsbruksmetod skapar en miljö som är svår att överleva i för naturvårdsarter. I denna studie är syftet att undersöka om observationer av sex stycken naturvårdsarter är högre i skyddade värdekärnor bestående av gammal barrskog än i produktionsbarrskog i Dalarnas län, Sverige. Detta genom att analysera andelen av de totala observationerna i proportion till andelen av den totala arealen för respektive skogstyp samt andelen observationer av varje naturvårdsart för sig i proportion till andelen av den totala arealen för respektive skogstyp. Då tidigare studier visat att artantalet och den biologiska mångfalden är högre i skyddade områden, inkluderat gammal skog, förväntades det att resultatet för denna studie skulle följa samma trend. Rumsliga data för skyddade värdekärnor och produktionsskog erhålls från Naturvårdsverket, Skogskarta från Sveriges lantbruksuniversitet (SLU) och rumsliga data för artobservationer från SLU Artdatabanken. Den rumsliga analysen utfördes i QGIS och en statistisk analys genom ett Pearson Chi square-test i SPSS. Resultatet i studien visade att det inte finns en signifikant skillnad i proportionen mellan andelen observationer och andelen areal för respektive skogstyp vilket är skyddade värdekärnor och produktionsskog. För varje enskild naturvårdsart var det endast för rynkskinn (Phlebia centrifuga) som det fanns en signifikant skillnad i proportionen mellan andelen observationer och andelen areal för respektive skogstyp vilket indikerar på att den arten föredrar skyddade värdekärnor över produktionsskogar. Studiens resultat överensstämmer inte med tidigare studier men trots detta är bevarandet och främjandet av gamla skogar som är skyddade en viktig del i arbetet mot att stoppa minskningen av den biologiska mångfalden. / Biodiversity is declining rapidly worldwide as a result of human actions. The biodiversity of Swedish boreal forests is threatened by modern forestry, where clearfelling, which is a common forestry practice, creates an environment that is difficult for conservation species to survive in. In this study, the aim is to investigate whether observations of six conservation species are higher in protected high conservation value forests consisting of old coniferous forest than in production coniferous forest in Dalarna County, Sweden. This by analyzing the share of total observations in proportion to the share of the total area for each forest type, and also the share of observations of each conservation species separately in proportion to the share of the total area for each forest type. As previous studies have shown that species numbers and biodiversity are higher in protected areas including old-growth forests, it was expected that the results of this study would follow the same trend. Spatial data for protected high conservation value forests and production forests were obtained from the Swedish Environmental Protection Agency, Forest Map from the Swedish University of Agricultural Sciences (SLU) and spatial data for species observations from the SLU Swedish Species Information Centre. The spatial analysis was performed in QGIS and a statistical analysis through a Pearson Chi square test in SPSS. The results of the study showed that there is no significant difference in the proportion of observations to area for each forest type that is protected high conservation value forests and production forests. For each individual conservation species, only for Phlebia centrifuga fungus was there a significant difference in the proportion between the share of observations and the share of area for each forest type which indicates that this species prefers high conservation value forests over production forests. The results of the study are not consistent with previous studies, but despite this the conservation and promotion of protected old-growth forests is an important part of efforts to halt biodiversity loss.

Page generated in 0.0694 seconds