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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.
1

Butterfly monitoring in Sweden reveals changes in occurrences over a five-year period

Gunneng, Vibeke January 2015 (has links)
Many of the European butterfly species have declined rapidly over the past decades. The cause is thought to be habitat loss due to factors such as increased tree cover, afforestation and intensified agriculture. I analyzed nation-wide data on butterfly occurrences in Sweden, to explore whether occurrences of individual species, grassland dependent species, grassland specialists, red-listed species, and moths, have increased or declined over a period of five years. I found that four species had significantly declined and eight had increased. The results were in accordance with other finds from Sweden, as well as from the UK, regarding the declining species. In contrast, the results regarding the increasing species only partly confirmed previous studies. I also found that grassland specialists and red-listed species had increased, possibly reflecting the fact that Sweden has a relatively large amount of boreal landscapes containing patches of clear-cuts and semi-natural grasslands.
2

Conservation ecology of endangered species in semi-natural ecosystems based on genetic analysis of extant and specimen samples / 現生個体と標本サンプルの遺伝解析を用いた半自然生態系における絶滅危惧種の保全生態学的研究

Nakahama, Naoyuki 23 March 2017 (has links)
京都大学 / 0048 / 新制・課程博士 / 博士(農学) / 甲第20428号 / 農博第2213号 / 新制||農||1048(附属図書館) / 学位論文||H29||N5049(農学部図書室) / 京都大学大学院農学研究科森林科学専攻 / (主査)教授 井鷺 裕司, 教授 柴田 昌三, 教授 神﨑 護 / 学位規則第4条第1項該当 / Doctor of Agricultural Science / Kyoto University / DFAM
3

Estimativas de variáveis biofísicas de vegetação campestre sob manejo pastoril por meio de sensoriamento remoto

Guerini Filho, Marildo January 2018 (has links)
O Bioma Pampa representa aproximadamente 63% do território do Estado do Rio Grande do Sul - Brasil caracteriza-se pela alta biodiversidade de espécies vegetais e por sua formação predominantemente campestre. Em função da contínua incorporação de espécies exóticas, monoculturas e a práticas por vezes inadequadas de manejo pastoril para produção pecuária, os campos do Bioma Pampa estão rapidamente sendo degradados, fragmentados e descaracterizados. A Biomassa é uma das variáveis biofísicas estratégicas de interesse em estudos de controle, monitoramento e estimativas da vegetação campestre. O objetivo principal deste estudo é contribuir no desenvolvimento de novas estratégias de manejo e monitoramento adequados da vegetação campestre e inferir regressão linear multivariada para estimar a biomassa dos campos nativos a partir de dados remotos e dados de campo. As avaliações foram realizadas em área pertencente à Universidade Federal de Santa Maria, localizada na região central do Rio Grande do Sul. Os manejos pastoris correspondem a duas somas térmicas acumuladas, em dias, de 375 e 750 graus-dias (GD), que determinaram os intervalos entre pastoreio. Os dados remotos utilizados foram oriundos de imagem MSI do Satélite Sentinel-2 e dados de espectrorradiômetro com amplitude de 350-2500 nm. Verificou-se que as duas técnicas apresentaram resultados satisfatórios, em que inferiu-se regressões com r²ajustado = 0.65 para estimar biomassa verde e regressões com r²ajustado = 0.61 para biomassa total e biomassa senescente. Desta forma, o estudo verificou que é possível minimizar os esforços de campo para auxiliar no monitoramento, organização e conservação dos campos nativos do Bioma Pampa utilizando dados de sensoriamento remoto como ferramenta de manejo buscando a sustentabilidade destes complexos ambientes naturais. / The Pampa Biome represents approximately 63% of the territory in the State of Rio Grande do Sul - Brazil, characterized by the high biodiversity of plant species and its predominantly rural formation. As a result of the continuous incorporation of exotic species, monocultures and excessive cattle production, the Pampa Biome fields are rapidly being degraded, fragmented and decharacterized. Biomass is one of the strategic biophysical variables of interest in studies of prevention, monitoring and estimates of the country vegetation. The main objective of this study is to contribute to the development of new strategies for the proper management and monitoring of the country vegetation and to infer multivariate linear regression to estimate the biomass of the natural grassland in native fields from remote data and field data. The evaluations were carried out in an area belonging to the Federal University of Santa Maria, located in the central region of Rio Grande do Sul. Pastoral management correspond to two accumulated thermal sums in days of 375 and 750 degrees-days (GD), which determined the intervals between grazing. The remote data used came from MSI image of Sentinel-2 Satellite and spectroradiometer data with amplitude of 350-2500 nm. It was verified that the two techniques presented satisfactory results, in which regressions with adjusted r² of 0.65 were estimated to estimate green biomass and regressions with adjusted r²> 0.61 for total biomass and dry biomass. In this way, the study verified that it is possible to minimize the field efforts to assist in the monitoring, organization and conservation of the natural grassland in native fields of the Pampa Biome using remote sensing data as a management tool seeking the sustainability of these complex natural environments.
4

Management of semi-natural grassland vegetation : long-term effects of grazing, mowing and different mowing techniques

Tälle, Malin January 2013 (has links)
Semi-natural grasslands are species-rich and one of the most threatened habitats in Europe, since land-use changes have led to reduced area of grassland. Appropriate management practices like grazing or mowing is needed to maintain the conservation values and species-richness of semi-natural grasslands. However, few studies have investigated which of grazing or mowing is most appropriate. Furthermore, almost no studies have investigated which mowing technique is best for the conservation value of grassland flora. The aim of this study was to determine which management practice of grazing and mowing, and which mowing technique, has the most positive effect on grassland flora. Data from two long-term trials were evaluated: one compared the effect of grazing and mowing in eleven sites in southern Sweden during at least twelve years; the other compared the effect of the knife mower and grass trimmer at different cutting heights in one site during twelve years. Meta-analysis was used, based on the odds for a plant record being an indicator species, using eight different indicator systems of classification of grassland plants. Over time, results show increasing odds of finding indicators of good management and no change in odds of finding indicators of lack of management in mowed compared to grazed plots. There were no differences in the odds of finding any indicator species for any of the mowing techniques. Hence, to maintain the conservation values of semi-natural grasslands, mowing is the better management practice compared to grazing. Mowing using a knife mower or grass trimmer has similar effects, and can both be recommended.
5

The importance of vegetation height and flower abundance for Swedish butterfly species in semi-natural grasslands

Löfqvist, Zandra January 2014 (has links)
Changed management of semi-natural grasslands is thought to be one important factor for explaining the decline of butterfly populations in Sweden and the rest of Europe. This study explores how vegetation height, variation in vegetation height and flower abundance can help predict the occurrence of butterfly species in semi-natural grasslands in southern Sweden. My study is based on data collected by a national environmental monitoring programme (NILS) during 2006-2010. Generalized linear models showed that all three explanatory variables significantly affected 26 of the 41 species of butterflies studied. The study also investigated preferences for three different systems for grouping species but did not find differences among groups. Several of the species would most likely benefit from variation in grazing pressure or rotational grazing as well as flower-rich grasslands. The results may also help when aiming management at the preservation of individual species.
6

Distribuição espacial de touceiras em ambientes pastoris heterogêneos : padrões de exploração e ingestão de forragem por novilhas de corte / Spatial distribution of tussocks in heterogeneous pastoral environments : explotation patterns and forage intake by beef heifers

Oliveira Neto, Renato Alves de January 2015 (has links)
O desempenho de animais em pastejo depende, em grande parte, da interação entre os mecanismos do comportamento ingestivo nas menores escalas (bocado, estação alimentar e patch) e das características estruturais da vegetação disponível. Ambientes pastoris naturais podem ser formados por espécies prostradas, geralmente de maior valor nutritivo, e espécies cespitosas, as quais apresentam maior rejeição potencial pelos animais por formarem touceiras. A presença desse tipo de estrutura no ambiente pastoril pode ser um complicador do processo de busca e seleção de forragem pelo herbívoro. Nesse contexto, foi conduzido este trabalho baseado na hipótese da existência de uma distribuição de estrato superior formado por touceiras de capim-annoni (Eragrostis plana Ness) que modifica os padrões de exploração das estações alimentares e altera a taxa de ingestão de forragem por novilhas de corte em pastejo. O trabalho foi conduzido em área experimental pertencente à EEA-UFRGS no período de junho de 2012 a dezembro de 2013. Os tratamentos consistiram de diferentes arranjos espaciais de touceiras, denominados ‘Aleatório’, Uniforme’, ‘Manchas’, ‘Faixa’ e ‘Concentrado’. A proporção de touceiras nas unidades experimentais foi em média 20,1% e o estrato inferior foi formado por Pensacola (Paspalum notatum Flugge var saurae Parodi cultivar Pensacola) e espécies nativas. Foram avaliados parâmetros em nível de patch (e.g. taxa de ingestão), de estação alimentar (e.g. taxa de bocados, bocados por estação, proporção de componentes pastejados) e de bocado (e.g. massa do bocado, taxa de manipulação dos bocados). De acordo com os resultados obtidos, a distribuição das touceiras não afeta a taxa de ingestão de forragem (0,076±0,017g de MS/kg de PV/min), devido a capacidade dos animais ajustarem seu comportamento ingestivo a curto prazo. As distribuições implicam em variação na massa do bocado, tempo e troca de sequência de bocados em estrato inferior e touceira. Além disso, a disposição das touceiras modifica o uso e exploração das estações alimentares disponíveis e a seleção de bocados dentro das mesmas. Os animais colhem maior proporção de estrato inferior quando as touceiras estão agrupadas e menor proporção quando ocorrem de maneira aleatória. Desse modo, tratamentos como ‘Manchas’ e ‘Concentrado’ podem ser considerados aqueles que oportunizam aos animais maior eficiência na ingestão. / Performance of grazing animals depends, largely, the interaction between feeding behavior mechanisms in smaller scales (bite, feeding station and patch) and structural characteristics of the available vegetation. Natural pastoral environments can be formed by prostrate species, usually presents higher nutritional value, and tussock species, which have a potential rejection by the animals because the structure formed. The presence of this type of structure in pastoral environment can be a complicating factor in the search and selection process fodder for herbivorous. In this context, we conducted a work with the hypothesis that exists a spatial distribution formed by tussocks of lovegrass (Eragrostis plana Ness) that modifies the search patterns of feeding stations and change the forage intake of beef heifers. The work was conducted in EEA- UFRGS belonging experimental area from June 2012 to December 2013. The treatments was following spatial arrangements of tussocks, called 'Random', ‘Uniform', 'Spots', 'Belt’ and 'Concentrate'. The proportion of tussocks in the experimental units was around 20.1% and the lower strata were formed by pensacola (Paspalum notatum Flugge var saurae Parodi cultivar Pensacola) and native species. There were evaluated parameters at patch level (e.g. intake rate), feeding station (e.g. bite rate, bites per feeding station, proportion of grazed component) and bite level (e. g. bite mass, handling rate). According to the results obtained, the distribution of tussocks do not affect the intake rate (0.076±0,017g DM/ kg BW/min), due to the ability of animals to adjust their short-term intake behavior. The spatial arrangements imply changes in bite mass, time and exchange sequence between lower stratum and tussocks. Furthermore, the distribution of tussocks modifies the use of feeding stations and the selection of bites. Animals consume higher proportion of lower strata when the tussocks are spots and less when they occur randomly. Thus, treatments ‘Spots’ and ‘Concentrate’, due to the similar natural environment, may be considered those which allow a better ingestive efficiency to the animals.
7

Distribuição espacial de touceiras em ambientes pastoris heterogêneos : padrões de exploração e ingestão de forragem por novilhas de corte / Spatial distribution of tussocks in heterogeneous pastoral environments : explotation patterns and forage intake by beef heifers

Oliveira Neto, Renato Alves de January 2015 (has links)
O desempenho de animais em pastejo depende, em grande parte, da interação entre os mecanismos do comportamento ingestivo nas menores escalas (bocado, estação alimentar e patch) e das características estruturais da vegetação disponível. Ambientes pastoris naturais podem ser formados por espécies prostradas, geralmente de maior valor nutritivo, e espécies cespitosas, as quais apresentam maior rejeição potencial pelos animais por formarem touceiras. A presença desse tipo de estrutura no ambiente pastoril pode ser um complicador do processo de busca e seleção de forragem pelo herbívoro. Nesse contexto, foi conduzido este trabalho baseado na hipótese da existência de uma distribuição de estrato superior formado por touceiras de capim-annoni (Eragrostis plana Ness) que modifica os padrões de exploração das estações alimentares e altera a taxa de ingestão de forragem por novilhas de corte em pastejo. O trabalho foi conduzido em área experimental pertencente à EEA-UFRGS no período de junho de 2012 a dezembro de 2013. Os tratamentos consistiram de diferentes arranjos espaciais de touceiras, denominados ‘Aleatório’, Uniforme’, ‘Manchas’, ‘Faixa’ e ‘Concentrado’. A proporção de touceiras nas unidades experimentais foi em média 20,1% e o estrato inferior foi formado por Pensacola (Paspalum notatum Flugge var saurae Parodi cultivar Pensacola) e espécies nativas. Foram avaliados parâmetros em nível de patch (e.g. taxa de ingestão), de estação alimentar (e.g. taxa de bocados, bocados por estação, proporção de componentes pastejados) e de bocado (e.g. massa do bocado, taxa de manipulação dos bocados). De acordo com os resultados obtidos, a distribuição das touceiras não afeta a taxa de ingestão de forragem (0,076±0,017g de MS/kg de PV/min), devido a capacidade dos animais ajustarem seu comportamento ingestivo a curto prazo. As distribuições implicam em variação na massa do bocado, tempo e troca de sequência de bocados em estrato inferior e touceira. Além disso, a disposição das touceiras modifica o uso e exploração das estações alimentares disponíveis e a seleção de bocados dentro das mesmas. Os animais colhem maior proporção de estrato inferior quando as touceiras estão agrupadas e menor proporção quando ocorrem de maneira aleatória. Desse modo, tratamentos como ‘Manchas’ e ‘Concentrado’ podem ser considerados aqueles que oportunizam aos animais maior eficiência na ingestão. / Performance of grazing animals depends, largely, the interaction between feeding behavior mechanisms in smaller scales (bite, feeding station and patch) and structural characteristics of the available vegetation. Natural pastoral environments can be formed by prostrate species, usually presents higher nutritional value, and tussock species, which have a potential rejection by the animals because the structure formed. The presence of this type of structure in pastoral environment can be a complicating factor in the search and selection process fodder for herbivorous. In this context, we conducted a work with the hypothesis that exists a spatial distribution formed by tussocks of lovegrass (Eragrostis plana Ness) that modifies the search patterns of feeding stations and change the forage intake of beef heifers. The work was conducted in EEA- UFRGS belonging experimental area from June 2012 to December 2013. The treatments was following spatial arrangements of tussocks, called 'Random', ‘Uniform', 'Spots', 'Belt’ and 'Concentrate'. The proportion of tussocks in the experimental units was around 20.1% and the lower strata were formed by pensacola (Paspalum notatum Flugge var saurae Parodi cultivar Pensacola) and native species. There were evaluated parameters at patch level (e.g. intake rate), feeding station (e.g. bite rate, bites per feeding station, proportion of grazed component) and bite level (e. g. bite mass, handling rate). According to the results obtained, the distribution of tussocks do not affect the intake rate (0.076±0,017g DM/ kg BW/min), due to the ability of animals to adjust their short-term intake behavior. The spatial arrangements imply changes in bite mass, time and exchange sequence between lower stratum and tussocks. Furthermore, the distribution of tussocks modifies the use of feeding stations and the selection of bites. Animals consume higher proportion of lower strata when the tussocks are spots and less when they occur randomly. Thus, treatments ‘Spots’ and ‘Concentrate’, due to the similar natural environment, may be considered those which allow a better ingestive efficiency to the animals.
8

Distribuição espacial de touceiras em ambientes pastoris heterogêneos : padrões de exploração e ingestão de forragem por novilhas de corte / Spatial distribution of tussocks in heterogeneous pastoral environments : explotation patterns and forage intake by beef heifers

Oliveira Neto, Renato Alves de January 2015 (has links)
O desempenho de animais em pastejo depende, em grande parte, da interação entre os mecanismos do comportamento ingestivo nas menores escalas (bocado, estação alimentar e patch) e das características estruturais da vegetação disponível. Ambientes pastoris naturais podem ser formados por espécies prostradas, geralmente de maior valor nutritivo, e espécies cespitosas, as quais apresentam maior rejeição potencial pelos animais por formarem touceiras. A presença desse tipo de estrutura no ambiente pastoril pode ser um complicador do processo de busca e seleção de forragem pelo herbívoro. Nesse contexto, foi conduzido este trabalho baseado na hipótese da existência de uma distribuição de estrato superior formado por touceiras de capim-annoni (Eragrostis plana Ness) que modifica os padrões de exploração das estações alimentares e altera a taxa de ingestão de forragem por novilhas de corte em pastejo. O trabalho foi conduzido em área experimental pertencente à EEA-UFRGS no período de junho de 2012 a dezembro de 2013. Os tratamentos consistiram de diferentes arranjos espaciais de touceiras, denominados ‘Aleatório’, Uniforme’, ‘Manchas’, ‘Faixa’ e ‘Concentrado’. A proporção de touceiras nas unidades experimentais foi em média 20,1% e o estrato inferior foi formado por Pensacola (Paspalum notatum Flugge var saurae Parodi cultivar Pensacola) e espécies nativas. Foram avaliados parâmetros em nível de patch (e.g. taxa de ingestão), de estação alimentar (e.g. taxa de bocados, bocados por estação, proporção de componentes pastejados) e de bocado (e.g. massa do bocado, taxa de manipulação dos bocados). De acordo com os resultados obtidos, a distribuição das touceiras não afeta a taxa de ingestão de forragem (0,076±0,017g de MS/kg de PV/min), devido a capacidade dos animais ajustarem seu comportamento ingestivo a curto prazo. As distribuições implicam em variação na massa do bocado, tempo e troca de sequência de bocados em estrato inferior e touceira. Além disso, a disposição das touceiras modifica o uso e exploração das estações alimentares disponíveis e a seleção de bocados dentro das mesmas. Os animais colhem maior proporção de estrato inferior quando as touceiras estão agrupadas e menor proporção quando ocorrem de maneira aleatória. Desse modo, tratamentos como ‘Manchas’ e ‘Concentrado’ podem ser considerados aqueles que oportunizam aos animais maior eficiência na ingestão. / Performance of grazing animals depends, largely, the interaction between feeding behavior mechanisms in smaller scales (bite, feeding station and patch) and structural characteristics of the available vegetation. Natural pastoral environments can be formed by prostrate species, usually presents higher nutritional value, and tussock species, which have a potential rejection by the animals because the structure formed. The presence of this type of structure in pastoral environment can be a complicating factor in the search and selection process fodder for herbivorous. In this context, we conducted a work with the hypothesis that exists a spatial distribution formed by tussocks of lovegrass (Eragrostis plana Ness) that modifies the search patterns of feeding stations and change the forage intake of beef heifers. The work was conducted in EEA- UFRGS belonging experimental area from June 2012 to December 2013. The treatments was following spatial arrangements of tussocks, called 'Random', ‘Uniform', 'Spots', 'Belt’ and 'Concentrate'. The proportion of tussocks in the experimental units was around 20.1% and the lower strata were formed by pensacola (Paspalum notatum Flugge var saurae Parodi cultivar Pensacola) and native species. There were evaluated parameters at patch level (e.g. intake rate), feeding station (e.g. bite rate, bites per feeding station, proportion of grazed component) and bite level (e. g. bite mass, handling rate). According to the results obtained, the distribution of tussocks do not affect the intake rate (0.076±0,017g DM/ kg BW/min), due to the ability of animals to adjust their short-term intake behavior. The spatial arrangements imply changes in bite mass, time and exchange sequence between lower stratum and tussocks. Furthermore, the distribution of tussocks modifies the use of feeding stations and the selection of bites. Animals consume higher proportion of lower strata when the tussocks are spots and less when they occur randomly. Thus, treatments ‘Spots’ and ‘Concentrate’, due to the similar natural environment, may be considered those which allow a better ingestive efficiency to the animals.
9

Differences in plant trait distribution in semi-natural grassland habitats of Sweden

Vepsäläinen, Viivi January 2020 (has links)
Habitat type has been suggested to be a major factor contributing to differencesin plant trait distribution of grassland habitats. Land use changes in agricultural landscapes have affected the available habitats and the dispersal ability of plants, which may effect plant trait diversity of agricultural landscapes. Little is also known about the effects of landscape openness on plant trait diversity. This study analysed differences in plant traits between different semi-natural grassland habitats in agricultural landscapes in four different regions in Sweden: Skåne, Södermanland, Gävleborg, and Norrbotten. The following research questions were used: (1) How does landscape openness (the amount of open andarable land found in a landscape) affect plant trait values collected from a new database in semi-natural grassland habitats in agricultural landscapes? (2) How does the type of habitat affect plant trait values in semi-natural grassland habitats in agricultural landscapes? (3) How does geographical location in Sweden affect plant trait values in semi-natural grassland habitats in agricultural landscapes? Overall 12 landscapes in each region were surveyed for plant data using 20 sample plots in each landscape. Trait values for biodiversity relevance, nectar production, nitrogen, phosphorus, grazing/mowing, soil disturbance, longevity, pollinator dependence, and seed dispenser were assigned for each plant species based on an external database, and average trait values were calculated for each of the studied traits in each sample. Kruskal-Wallis test andANOVA were performed on average trait values to identify differences between each habitat types and regions. Besides the effect of habitat type, the effect of openness in the landscape on the chosen traits was analysed with Spearman’s and Pearson’s correlations. The results revealed differences between habitat types in almost all studied traits: grazed habitats had plants with higher biodiversity relevance but lower nectar production. Differences were also found between the southern and northern regions. More open landscapes had plants with higher biodiversity relevance as well as higher tolerance for both nitrogen and phosphorus. Less open landscapes had higher tolerance for grazing/mowing and higher nectar production. The results of this study therefore support earlier findings of the importance of habitat in plant trait distribution of grassland habitats.
10

Phytosociology of northwestern KwaZulu-Natal

Robbeson, Riaan Andries Jacobus 11 April 2013 (has links)
In depth studies of the vegetation of large parts of southern Africa, including detailed maps and descriptions of vegetation units are mainly limited to small areas. Meanwhile, various agricultural practises have led to destruction or deterioration of the quality of natural grassland ecosystems. The agricultural sector in developed and rapidly developing areas of southern Africa is confronted with problems like veld deterioration and the loss of natural areas that effectively contribute to the depopulation of rural areas. The necessity to identify, classify and describe the vegetation types and communities within the Grassland Biome was stressed by Mentis and Huntley (1982). The aim of the Grassland Biome Project is to integrate knowledge. comprehension and expertise, which will enable scientists to forecast the results of the available options of grassland management programmes. The phytosociological classification of northwestern KwaZulu-Natal forms part of this project. Known previous vegetation studies of this area were conducted on a large scale and a considerable time ago, which underlines the necessity for a more comprehensive and phytosociologically refined investigation of this area. The study area lies in the northern part of KwaZulu-Natal and comprises the Drakensberg mountains and slopes in the west and undulating plains and bushveld valleys in the east and south. Relevés were compiled in 526 stratified random sample plots over an area of 9300 km2, comprising the northwestern part of KwaZulu-Natal. The vegetation was classified by means of TWINSP AN and Braun-Blanquet procedures. A phytosociological investigation of this vegetation revealed great variation in floristic composition. Further refinement of the data disclosed five major vegetation types containing nine plant communities. The topography and geology of the study area contributes greatly to the diversity of the vegetation, but poor agricultural practises have caused deterioration of the vegetation. / Dissertation (MSc)--University of Pretoria, 1998. / Plant Science / unrestricted

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