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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

Riparian-zone rehabilitation in pine plantations: Grassland woodland for plants and birds?

Malan, G, Meyer, E, Panagos, MD 27 July 2007 (has links)
The study compared plant and avian diversity and species composition between four habitats to review the potential implications of two distinct management practices on a forestry estate, namely to rehabilitate riparian zones to grasslands or woodlands as the two habitats that historically occurred on the property.The study habitats were Plantation (Pinus trees in riparian zone), Bushland (recently harvested), Grassland (cleared of broadleaf plants), and Woodland (control). At seven sampling sites per habitat, a vegetation assessment was conducted, while birds were caught with mist nests. Plant species richness increased from Plantation to Woodland, whereas most bird species and individuals were found in Bushland. Plant and bird species composition differed significantly between habitats. Bushland and Grassland birds were closely associated with exotic forbs. Grassland attracted birds with diverse habitat and nesting-site associations, and Woodland birds associated with woody plants. It is recommended that the majority of riparian zones be managed as grasslands, although the exact affect of the biennial summer burning and presence of exotic plants on birds needs to be investigated. To attract cavity-nesting birds to the Estate, some suitable riparian zones should be rehabilitated to Woodland by planting Ficus andAcacia trees, as these trees are the most abundant and frequently occurring in this habitat. Rather than manage avian diversity per se, the African stonechat in Grassland and lesser honeyguide in Woodland can be employed as indicators of the rehabilitation state of the riparian zones.
2

Žirgelių įvairovė ir pasiskirstymas nenuotakiuose Gražutės regioninio parko ežeruose / Diversity and distribution of dragonflies in closed lakes of gražutė regional park

Barčkutė, Dovilė 25 June 2014 (has links)
Tyrimo medžiaga (žirgelių lervos, išnaros ir suaugėliai) buvo rinkta 2008 – 2009 metais Nemuno ir Dauguvos takoskyroje esančiuose nenuotakiuose ežeriukuose Gražutės regioninio parko bei Smalvų-Smalvykščio kraštovaizdžio draustinio administracinėse teritorijose. Šiame darbe siekiama įvertinti žirgelių rūšių įvairovę ir jų pasiskirstymo ypatumus nenuotakiuose ežeruose. Tyrimams pasirinkta 31 nenuotakus ežeras, kurie pagal dydį, savo apyežerių plotus, hidrologinę būklę buvo suskirstyti į tris atskiras grupes. Juose buvo užregistruotos 35 žirgelių rūšys, iš kurių 6 įrašytos į LRK ir 3 į ES buveinių direktyvos (92/43/EEC) II priedą. Tarp ištirtų ežerų, remiantis rūšinės sudėties stabilumo skaičiuokle (Nestedness temperature calculator (NTC)), patvariausias žirgelių rūšių rinkinys nustatytas tik antros grupės ežeruose T = 31,75° (p = 0,06). Būdingos trijų ežerų grupėse rūšys nesutapo (W > 51%). Nenuotakių nedidelių ežerų kaip žirgelių buveinių svarbą patvirtina indikatorinės rūšys (sutinkamumas nuo 15% iki 40% ežerų), kurios yra skirtingos visoms ežerų grupėms (išskyrus vieną – Leucorrhinia albifrons), kuri sutapo pirmai ir antrai ežerų grupėms). Tarp indikatorinių rūšių patenka net 5 Lietuvos raudonosios knygos rūšys. / Material (dragonfly larvae, exuviae and imagos) for the study were gathered in 2008 - 2009 in closed lakes of Nemunas and Daugava basins watershed, which are located in Gražutė regional park and Smalvas-Smalvykštis landscape reserve. This work aims to evaluate the dragonfly species diversity and distribution characteristics in closed lakes. 31 closed lakes were selected for research, which according to hydrological conditions and shore size were divided into three groups. 35 species of dragonfly were recorded, of which 6 are enrolled in the Red list of Lithuania and 3 to EU Habitats Directive (92/43/EEC) Annex II. According to Nestedness temperature calculator the most durable species complex of dragon-fly among investigated lakes occurred in second group of lakes, only T = 31.75 ° (p = 0.06). Characteristic dragonfly species for all three of groups lakes were differed (W> 51%). The importance of small closed lake as a dragonfly habitat as well confirms the fact that all indicator species (abundant from 15% to 40% of lakes) were different for all groups of lakes(except one Leucorrhinia albifrons which coincided to first and second groups of lakes). Among indicator species there were five species of the Red list of Lithuania.
3

The comparative ecology of Minuartia verna (L.) Hiern and Thlaspi alpestre L. in the southern pennines, with special reference to heavy metal tolerance

Hajar, Abdulrahman Said Muhammad January 1987 (has links)
Minuartia verna (L.) Hiern and Thiaspi alpestre L. are recognized as relict elements of a preglacial montane flora in the British Isles and, as such, display a markedly disjunct distribution pattern. Their present-day distribution shows a close association with metalliferous mine workings, particularly in the Pennines, where both species have become prominent components of the flora of calcareous lead mine wastes. By comparison with M. verna, T. alpestre is more restricted in its distribution and is a rarer species. The work reported in this thesis attempted to provide an explanation for this pattern of distribution in the southern Pennines on the basis of comparative studies of the autecology and genecology of the species, their population biology and dynamics in the field and their responses to competition from other species. Both field and laboratory studies confirmed that the two species were highly tolerant of the heavy metals lead, zinc and cadmium. Short- and long-term solution culture experiments on tolerance and uptake of these heavy metals by a range of populations of both species are reported. Tolerance to other toxic metals was also investigated. T. alpestre showed superior tolerance to M. verna in these experiments, and emerged as a metal-accumulating species. M. verna by contrast, operated some degree of metal exclusion, but metal uptake and distribution differed for the various metals in both species and seasonally. Differences in metal tolerance and uptake characteristics alone could not explain the different local distribution patterns in the field, as sites of similar metal status are colonized by both the two species together and by M. verna alone. A study of inter-population variation in morphological characters showed considerable genetically-based variation in both species. M. verna was however more variable. Some of the variation detected was interpreted as being ecotypic in origin. The contrasting breeding of the two species and their seed biology are considered to be major factors in explaining the present-day distributions of the two species. The tendency for inbreeding in T. alpestre has severely limited its genetic variability within populations and potential for spread. Seedling mortality of both species in their natural habitats is very high, and survival can be related to early shelter effects of neighbouring plants. Both species, however, emerge as weak competitors as predicted from their preference for open habitats with much more bare ground. The relevance of these studies to the interpretation of the present-day global distribution of the two species and their evolutionary biology is discussed.
4

If we build it, will they come? Insect communities as indicators of restoration in an urban prairie network

Finke, Amanda Nicole January 2019 (has links)
No description available.
5

Caracterização das assembléias de peixes da bacia do rio Corumbataí (SP) / The fish assemblage characterization of the Corumbataí river basin

Cetra, Mauricio 27 May 2003 (has links)
A bacia do rio Piracicaba tem recebido atenção especial das autoridades municipais, pois possui grandes problemas de aproveitamento de seus recursos hídricos. A bacia do rio Corumbataí, um dos principais afluentes da margem direita do rio Piracicaba, é regionalmente importante, não só porque ainda possui águas de boa qualidade, mas também por apresentar elementos raros na paisagem do interior do estado. Esta tese teve o objetivo de caracterizar as assembléias de peixes na bacia do rio Corumbataí e fornecer ferramentas para avaliação de seu status ambiental. Foram escolhidos 4 rios principais com 3 pontos de coleta em cada um. Foram realizadas coletas no período de março a junho e setembro a dezembro de 2001, totalizando 24 coletas. Os dados bióticos foram avaliados através de medidas de diversidade. Para testar a hipótese de variação espaço-temporal da assembléia de peixes foi aplicado o modelo linear ANCOVA onde a variável resposta foi a riqueza de espécies; o fator foi ordem do rio; sendo utilizadas 2 covariáveis ambientais: temperatura e número de indivíduos, revelando uma variação espaço-temporal e padrões reconhecidos no meio acadêmico: relação espécie-área e conceito de rio contínuo. Técnicas multivariadas foram aplicadas para determinar a correlação entre a riqueza e a paisagem no entorno do ponto de coleta, revelando que existem mais espécies em locais com maior cobertura vegetal e mata ciliar preservada. Algumas espécies de peixes se mostraram bons indicadores ambientais: Hypostomus strigaticeps, Hoplosternum littorale e Salminus hilarii; por outro lado o Astyanax altiparanae não se mostrou um bom indicador / The Piracicaba river basin has received special attention from local authorities because it has presented a lot of problems about the misutilization of its hydric resources. The Corumbataí river basin, one of the major streams of the right side of the Piracicaba river, is regionally important, not only because it still has good water quality but also because it has unique elements inside the landscape of São Paulo state. This thesis aims to characterize the fish assemblage of the Corumbataí river basin and provide tools to assess the present environmental status of the basin. It has been chosen 4 major streams with 3 unit samples in each one of the streams. The samples were carried out from March to June and from September to December in the year of 2001, making up a total of 24 samples. The biotic data were assessed using diversity measurement. An ANCOVA was used to test the hypothesis of time-space variation of the fish assemblage, where the dependent variable was the species richness; the factor was the stream order and 2 environmental co-variates were used: temperature and number of individuals, thus revealing both time-space variation and some patterns which are recognized academically: species-area relationship and river continuum concept (RCC). Multivariate techniques were used to determine the correlation between richness and the landscape characteristics in the sampling unit, revealing that there is a greater number of species along the sites with a larger riparian zone. Some fish species have showed to be a good indicator: Hypostomus strigaticeps, Hoplosternum littorale and Salminus hilarii; on the other hand Astyanax altiparanae has not showed to be a good indicator species
6

Composition of the Community of Small Mammals in the Great Basin Desert

Phillips, Samantha Elizabeth 01 August 2018 (has links)
Small mammals are a keystone guild in arid ecosystems; often exhibiting top-down control of the diversity and structure of plant communities. However, changing climate, shifting fire regimes, and the invasion of exotic plants are modifying the structure of arid systems. Environmental changes in these arid systems are likely altering small mammal communities, and therefore, their ecological role. We examined two aspects of the community composition of small mammals in the Great Basin: changes in community composition since large scale sampling of the region began in 1930, and the current population of a sensitive species of small mammal, the dark kangaroo mouse (Microdipodops megacephalus). In Chapter 1, we compared diversity and composition of present day small mammal communities to communities sampled between the years of 1930 and 1980. We sampled 234 historical locations across the eastern Great Basin region during the summers of 2014 and 2015. Our results indicated that diversity, richness, and evenness of small mammals in the Great Basin have declined significantly over the last century (P=0.002, P=0.03, P=0.002). The relative abundance of generalist species has increased, while specialist species have declined (P<0.001, P<0.001). Also, community composition at each site has changed significantly over the past century. Alterations in the community structure of small mammals may have cascading implications for the future of the Great Basin ecoregion. In Chapter 2, we conducted a region-wide survey for the dark kangaroo mouse in western Utah. Four teams sampled 232 locations across western Utah during the summers of 2014-2015. Of the 232 sites sampled, only 5 sites resulted in dark kangaroo mouse captures, totaling 15 individuals. These results could indicate a state-wide population decline for this species, both compared to historic population levels and to the populations surveyed less than ten years ago. The rapid decline may be a result of habitat degradation associated with invasive plant species and increasing fire frequency, the effects of which are exacerbated by the dark kangaroo mouse's life history as an ecological specialist. Unless large-scale habitat restoration and preservation is conducted for remaining populations, it is likely the dark kangaroo mouse will continue to decline within the state.
7

Didaktiska arter

Hylin, Anna January 2012 (has links)
The study intends to find easily recognizable indicator species for water quality in the constructed wetland of Flemingsbergsviken. The study is relevant since indicator species can be difficult to determine for common people. Easily recognizable indicator species could improve dialogue between the scientific community, administrative authorities and the general public. Such species could be used in education systems, associations or in information campaigns. Therefore, I have chosen to refer to these species as didactical species. Water quality was examined by measuring conductivity, pH and oxygen content in relation to distance from the wetland inlet. The results demonstrate a significant correlation between conductivity and distance. Species occupy different ecological niches and distribution patterns of species in the wetland can be expected to follow changes in abiotic factors, such as water quality. Potential indicator species were investigated by inventorying twelve species of plants and animals. The results show significant linear or curvilinear correlations between one or several water quality factors and the species reedmace, common reed, yellow iris, freshwater woodlouse, twisted ramshorn, damsel- and dragonfly larvae. By carrying out a questionnaire aimed at a group of adults and by talking to a group of children, conclusions could be made regarding indicator species that were easy to recognize and associate to. The results demonstrate that adults found common reed and reedmace most easy to recognize while children found the freshwater woodlouse most interesting. Thus, these indicator species for water quality can be included in the concept didactical species. / Studien syftar till att finna indikatorarter för vattenkvalitet i Flemingsbergsvikens våtmarksanläggning som är lätta att känna igen och associera till. Studien är relevant då indikatorarter kan vara svårbestämda för gemene man. Arter som är lättigenkännbara skulle kunna förbättra dialog mellan forskarsamhället, allmänheten och myndigheter och kan användas i utbildningssyfte inom skolor, föreningar eller i informationskampanjer. Jag har därför valt att kalla arterna för didaktiska arter. Vattenkvalitet undersöktes genom att mäta konduktivitet, pH och syrgashalt i förhållande till avstånd från inlopp. Resultaten visade att det finns ett signifikant samband mellan konduktivitet och avstånd. Eftersom arter upptar olika ekologiska nischer kan artutbredningsmönstret i våtmarken förväntas följa förändringar i abiotiska faktorer, såsom vattenkvalitet. Potentiella indikatorarter undersöktes genom att inventera tolv växt- och djurarter i anläggningen. Resultaten visar signifikanta linjära eller kurvlinjära samband med en eller flera utav vattenkvalitetsfaktorerna och arterna bredkaveldun, vass, gul svärdslilja, sötvattengråsugga, remskivsnäcka samt trollsländelarver. Genom en enkätundersökning för en grupp vuxna samt samtal med en grupp förskolebarn kunde det dras slutsatser om vilka av indikatorarterna för vattenkvalitet som var lättast att känna igen och associera till. Resultaten visar att de vuxna upplevde vass och bredkaveldun som lättast att känna igen medan barnen upplevde att sötvattengråsugga var mest intressant. Dessa indikatorarter för vattenkvalitet kan således inkluderas i begreppet didaktiska arter.
8

A Classification of the Weed Vegetation in Mituo County, Kaohsiung

Lin, Chun-yi 07 February 2010 (has links)
This study surveyed floristic composition and distribution of weed vegetation in Mituo County. 206 relevés were surveyed according to relevé method. A total of 140 species belonging to 32 families of the vascular plants were recorded. The weed communities were classified with nonmetric multidimentional scaling, two-way indicator species analysis, tabular comparison method, fidelity and synoptic table analysis. Discriminate analysis was used to evaluate the distinctness of classification unitsal vegetation classification system was made using Braun-Blanquet approach of floristic-sociological classification in lower levels and physiognomic-sociological classification in higher levels. In floristic-sociological classification, assication is the basic unit, and it should be grouped into higher units (alliance) by floristic composition. The results showed 1 formation class, 2 formations in phsiogonomic units, and 4 alliances, 6 associations in floristic units: I. Lower montane-lowland weed vegetation formation A. Echinochloa colona alliance a. Echinochloa colona association b. Trianthemum portulacastrum association c. Panicum maximum association B. Dichanthium aristatum alliance d. Dichanthium aristatum association C. Eriochloa procera alliance e. Eriochloa procera association II. Sand dune vegetation formation D. Ipomoea pescaprae subsp. brasiliensis alliance f. Ipomoea pescaprae subsp. brasiliensis association
9

Transektový monitoring motýlů České republiky: Výsledky z prvních sedmi let

KOLLROSS, Jan January 2017 (has links)
The thesis presents data from butterfly transects monitoring, carried out for 7 years on 36 transects established both within nature reserves and unprotected landscapes throughout the Czech Republic and walked three times a month between April and September. Only seven transects were monitored for the whole monitoring period. There were 192 771 individual butterfly records on 127 species of butterflies and burnet moths, i.e. 76.5% of the Czech fauna of the targeted groups). Data on their abundances are for the first time available for the Czech Republic. The distribution of individual species abundances approximated a lognormal model. The abundant species were generalists of non-wooded habitats, which prosper in the intensively managed landscapes of the Czech Republic. Trends of abundance, determined by the TRIM program, were estimable for 92 species. Over the monitored period, the relative abundance of nine species significantly decreased, while those of of seven species significantly increases. The remaining 76 did not display unequivocal trends, but still, 17 are likely increasing and 29 likely decreasing. Comparing the trends with the life history and bioclimatic traits of the butterflies showed that species whose abundance did not change possess traits typical for generalist butterflies (mobile species, overwintering in later life stages, longer flight period etc.), while decreases were more common among thermophilic species. Splitting the analyses for data originating from reserve vs. unprotected areas suggested that mesophilic species and species of more advanced successional stages prosper outside of reserves, whereas thermophilic species tend to decline there, and that an opposite pattern applies to reserves. I discuss recommendations for future of the monitoring Czech butterfly monitoring scheme.
10

Especificidade de espécies arbóreas no sudeste da Mata Atlântica e padrões de diversidade em florestas com Araucária

Bergamin, Rodrigo Scarton January 2010 (has links)
Distintos padrões de composição e diversidade de espécies podem ser observados ao longo de comunidades que variam em relação ao ambiente e à posição geográfica, sendo possível a identificação de potenciais espécies indicadoras destas mudanças. Diversos estudos sobre a variação na diversidade de espécies têm demonstrado a influência de condições ambientais (teoria de nicho) e/ou da limitação na dispersão (teoria neutra), com diferentes proporções de explicação. Esta dissertação aborda a especificidade de espécies arbóreas no sudeste da Mata Atlântica e alguns padrões de variação da diversidade beta em Florestas com Araucária, na região nordeste do Rio Grande do Sul. Na abordagem de especificidade de espécies, analisamos um gradiente ambiental e espacial a partir de 21 trabalhos abrangendo diferentes tipologias florestais: Floresta de Restinga (3), Floresta Ombrófila Densa (7), Floresta Ombrófila Mista (8) e Floresta Nebular (3). Foram observados diferentes níveis de riqueza e de espécies indicadoras para cada tipo florestal. Além disso, a altitude foi a principal variável ambiental associada aos padrões florísticos observados neste estudo, que formam um continuum de substituição de espécies ao longo do gradiente. Para a abordagem da diversidade beta, foram realizados levantamentos quantitativos do estrato inferior e superior em três áreas de conservação de Floresta com Araucária, onde foram explorados a partição aditiva da diversidade em diferentes escalas espaciais e o papel do ambiente e do espaço na substituição de espécies. Ao todo foram registradas 86 espécies, contemplando 22% do pool de espécies da região sul para esta formação. A partição aditiva da diversidade revelou que a diversidade beta é significativa apenas na maior escala para ambos os estratos. Pela Análise de Redundância parcial, o espaço foi responsável pela maior fração de explicação (21%) para o estrato inferior, enquanto para o superior, o ambiente estruturado pelo espaço obteve a maior fração de explicação (36%). Sugere-se que para o estrato inferior algumas espécies da encosta apresentam limitação de dispersão em relação à distância das áreas da encosta ou mesmo pelo padrão de deposição de diásporos pelos dispersores. Para o estrato superior, a relação do ambiente com o espaço está na distância entre as áreas e como ela atua na variação do ambiente, sendo a distância destas em relação ao mar provavelmente a variável mais correlacionada, pois esta influencia a temperatura e o regime de chuvas. / Distinct patterns of species composition and diversity can be observed throughout communities that change in relation to environment and geographic position, making possible to identify potential indicator species of these changes. Several studies on species diversity variation have demonstrated the influence of environmental conditions (niche theory) and / or dispersal limitation (neutral theory), with different proportions of explanation. This thesis emphasizes tree specificity in southern Atlantic forest and some patterns of beta diversity variation in Araucaria forests in northeastern Rio Grande do Sul. In the approach of species specificity, we analyzed environmental and spacial gradients from 21 studies covering different forest types: Restinga forest (3), Tropical Rainforest (7), Araucaria forest (8) and Cloud forest (3). We observed different richness levels and different indicator species for each forest type. Furthermore, altitude was the main environmental variable associated to the floristic patterns observed in this study, which form a continuum of species turnover along the gradient. For the approach of beta diversity, quantitative surveys of the inferior and superior strata were taken out in three conservation units of Araucaria forest, where additive diversity partitioning were exploited in different spatial scales, as well as the role of environment variables and the space in species turnover. Altogether, 86 species were recorded, comprising 22% of the southern region species pool for this forest type. The additive partitioning revealed that beta diversity is significant only in larger scale for both strata. Through partial Redundancy Analyses, the space was responsible for the largest fraction of explanation (20.70%) for the inferior stratum, while the environment structured by space had the most fraction of explanation (36.43%) for the superior one. It is suggested that some colonizing species from the inferior stratum show dispersal limitation in relation to distance from the slope or even due to seeds deposition patterns. For the superior stratum, the presented relationship between environment and space seems to indicate that the distance between areas acts on the environmental variation, where the sea distance is probably the most correlated variable, since it affects temperature and rainfall.

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