• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 2
  • 2
  • 1
  • Tagged with
  • 5
  • 5
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 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

Diversidade de espécies em comunidades arbóreas: aplicação de índices de distinção taxonômica em três formações florestais do Estado de São Paulo / Tree species community diversity: aplication of taxonomic distinctness indices in three forest phytophysionomies in São Paulo State

Gorenstein, Mauricio Romero 27 August 2009 (has links)
Este trabalho faz parte do projeto Biota/FAPESP, Métodos de Inventário da Biodiversidade de Espécies Arbóreas, e analisou a diferença na estrutura florística entre as áreas estudadas. Na Estação Ecológica de Assis, SP, área de Cerradão, foram amostradas 102 espécies, 72 gêneros e 43 famílias; 67% das espécies foram exclusivas desta fitofisionomia. Na Floresta Estacional Semidecidual da Estação Ecológica dos Caetetus, município de Gália-SP, foram amostradas 208 espécies, 138 gêneros e 49 famílias; sendo 65% das espécies exclusivas. Na Floresta Ombrófila Densa do Parque Estadual de Carlos Botelho, município de São Miguel Arcanjo-SP, foram encontradas 410 espécies, pertencentes a 152 gêneros e 64 famílias; 84% das espécies exclusivas desta fitofisionomia. A Floresta Estacional apresentou maior similaridade com a Floresta Ombrófila do que com o Cerradão. Apesar de apresentar maior número de espécies, a Floresta Ombrófila Densa apresenta concentração de espécies nas famílias Myrtaceae e Lauraceae. Em outra análise foram calculados os índices de distinção taxonômica nas 5 grades amostrais para os métodos de amostragem testados. O método de Bitterlich apresentou tendência nos índices de diversidade e distinção taxonômica, conforme a diversidade taxonômica do sub-bosque. Esses índices apresentaram média independente e variância decrescente com o aumento da amostra. Os índices de distinção taxonômica média e variância da distinção taxonômica média também apresentaram variância decrescente. Porém, a estabilização da média ocorreu com amostras de maior tamanho, principalmente para as parcelas de área fixa na Estação Ecológica dos Caetetus. Na Floresta Ombrófila Densa, a distinção taxonômica média foi menor e a variância da distinção taxonômica média foi maior, devido a alta concentração de espécies de Myrtales e Laurales nesta fitofisionomia. / This research is part of the project Biota / FAPESP, \"Tree Species Biodiversity Inventory Methods, and analised floristic structural differences among three areas. In Assis Ecological Station, Forest Savanna area were sampled 102 species, 72 genus and 43 families, 67% of this species were exclusive of this phytophisiognomy. Semideciduous seasonal forest in the Caetetus Ecological Station, 208 species were sampled, 138 genus and 49 families, with 65% of exclusive species. Rain Forest in the Carlos Botelho State Park, were found 410 species, belonging to 152 genus and 64 families, 84% of exclusive species. The seasonal forest showed greater similarity to the rain forest than the Savanna. In spite of the greater number of species, the Rain Forest presents concentration of species in the Myrtaceae and Lauraceae families. In another analysis were calculated the taxonomic indices in tree species data provided by sampling methods tested in five sampling grids. The Bitterlich sampling method was tendecious in estimates the taxonomic diversity and taxonomic distinctness indices because the taxonomic diversity in the understory. These indices showed average independent and variance decreasing with increasing sample. The average taxonomic distinctness and variation in taxonomic distinctness also showed decreased, but the stabilization of the average occurred with samples of greater size, mainly for fixed area plots at Caetetus Ecological Station. In the Rain Forest the average taxonomic distinctness was lower and the variation of taxonomic distinctness was higher due to high concentration of species of Myrtales and Laurales in this phytophisiognomy.
2

Monitoring serial changes in coastal grasslands invaded by Chromolaena odorata (L.) R.M. King and Robinson.

Goodall, Jeremy Marshall. 17 December 2013 (has links)
The objective of this study was to describe the impacts of the density of Chromolaena odorata (chromolaena) on species composition in coastal grasslands and to investigate serial changes in the vegetation following the implementation of a burning programme. The thesis deals with key ecological concepts and issues, so a comprehensive literature review is included. Chromolaena invades coastal grasslands that are not burnt regularly (i.e. biennially). Grasslands that were not burnt for 30 years were seral to secondary forest. The successional pathway from open grassland to closed canopy forest varied according to soil type. Coastal grasslands on Glenrosa soils were characterised by savanna at an intermediate stage between the grassland and forest states. Shading ended the persistence of savanna species (e.g. Combretum molle, Dichrostachys cinerea and Heteropyxis natalensis) in forest, whereas forest precursors (e.g. Canthium inerme, Maytenus undata and Protorhus longifolia) only established where fire was absent. Chromolaena infestations were characterised by multi-stemmed adult plants of variable height (i.e. 1-3 m), depending on soil type. Regic sands did not support stratified woody vegetation and chromolaena infestations were self-supporting, reaching a maximum height of 1.5 m. Glenrosa soils supported tree communities and chromolaena reached more than 3 m in places. The density of chromolaena affected species composition in grasslands with moderate to dense stands (> 5 adult plants m ¯² or >50000 shrubs ha ¯¹). Chromolaena stands became monospecific when the number of adult plants exceeded 7 m ¯². Succession to forest also ceased once chromolaena became thicket-forming. Fire-induced mortality of the chromolaena depended on grass fuel loads. Grass cover of 30% (c. 1 000 kg ha ¯¹) was required to achieve 80% mortality of the parent infestation after the initial burn. Dense infestations could only be killed by running head-fires from adjacent grasslands into thickets. Under conditions where head-fires could not be used, infestations were slashed and burnt at the height of the dry season (July to August) to achieve an 80% kill rate. Seedlings were killed (99%) by annual burning in sparse (≤ 10000 shrubs ha ¯¹) to moderate < 50 000 shrubs ha ¯¹) infestations. The suppression of chromolaena and other alien species, establishing on bare ground after clearing dense infestations, required chemical control until grass cover was sufficient (i.e. 1 000 kg ha ¯¹) to effect uniform burning. Certain secondary alien invaders (e.g. Lantana camara, Psidium guajava and Solanum mauritianum) persisted by coppicing profusely after fire and herbicides need to be integrated into burning programmes when these species occur. Grasslands on regic sands (e.g. Ischaemum fasciculatum, Panicum dregeanum and Themeda triandra) were more resilient to the modifying effects of woody vegetation, than grasslands on Glenrosa soils. Grasslands on Glenrosa soils did not revert to an open state but persisted as ruderal savanna grassland (e.g. Eragrostis curvula, Hyparrhenia tamba and Cymbopogon validus) once fire-resistant tree species (e.g. Combretum molle and Heteropyxis natalensis) had established. Depending the objectives for land management and the vegetation's condition, coastal grasslands can be rehabilitated and managed in multiple states, i.e. grassland, savanna or forest communities. A state-and-transition model based on the empirical data recorded in the study is presented and shows chromolaena altering vegetation states from open grassland to chromolaena dominated thicket. The model illustrates chromolaena thickets as the dominant phase of a moist coastal forest/savanna succession, irrespective of soil type, in absence of appropriate land management practices (e.g. control burning and integrated control of alien vegetation). This model should aid in planning strategies for the control of chromolaena in subtropical grasslands in South Africa. / Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 2000.
3

Dlouhodobé změny vegetace ve vápencových lomech Českého krasu / Vegetation succession on abandoned limestone quarries of Czech Karst

BARTOŠOVÁ, Alena January 2014 (has links)
Vegetation sampling was carried out to determine changes on the limestone quarries after 30 years. These semi-permanent plots are located in the Czech Karst Protected Landscape Area in the Czech Republic.
4

Diversidade de espécies em comunidades arbóreas: aplicação de índices de distinção taxonômica em três formações florestais do Estado de São Paulo / Tree species community diversity: aplication of taxonomic distinctness indices in three forest phytophysionomies in São Paulo State

Mauricio Romero Gorenstein 27 August 2009 (has links)
Este trabalho faz parte do projeto Biota/FAPESP, Métodos de Inventário da Biodiversidade de Espécies Arbóreas, e analisou a diferença na estrutura florística entre as áreas estudadas. Na Estação Ecológica de Assis, SP, área de Cerradão, foram amostradas 102 espécies, 72 gêneros e 43 famílias; 67% das espécies foram exclusivas desta fitofisionomia. Na Floresta Estacional Semidecidual da Estação Ecológica dos Caetetus, município de Gália-SP, foram amostradas 208 espécies, 138 gêneros e 49 famílias; sendo 65% das espécies exclusivas. Na Floresta Ombrófila Densa do Parque Estadual de Carlos Botelho, município de São Miguel Arcanjo-SP, foram encontradas 410 espécies, pertencentes a 152 gêneros e 64 famílias; 84% das espécies exclusivas desta fitofisionomia. A Floresta Estacional apresentou maior similaridade com a Floresta Ombrófila do que com o Cerradão. Apesar de apresentar maior número de espécies, a Floresta Ombrófila Densa apresenta concentração de espécies nas famílias Myrtaceae e Lauraceae. Em outra análise foram calculados os índices de distinção taxonômica nas 5 grades amostrais para os métodos de amostragem testados. O método de Bitterlich apresentou tendência nos índices de diversidade e distinção taxonômica, conforme a diversidade taxonômica do sub-bosque. Esses índices apresentaram média independente e variância decrescente com o aumento da amostra. Os índices de distinção taxonômica média e variância da distinção taxonômica média também apresentaram variância decrescente. Porém, a estabilização da média ocorreu com amostras de maior tamanho, principalmente para as parcelas de área fixa na Estação Ecológica dos Caetetus. Na Floresta Ombrófila Densa, a distinção taxonômica média foi menor e a variância da distinção taxonômica média foi maior, devido a alta concentração de espécies de Myrtales e Laurales nesta fitofisionomia. / This research is part of the project Biota / FAPESP, \"Tree Species Biodiversity Inventory Methods, and analised floristic structural differences among three areas. In Assis Ecological Station, Forest Savanna area were sampled 102 species, 72 genus and 43 families, 67% of this species were exclusive of this phytophisiognomy. Semideciduous seasonal forest in the Caetetus Ecological Station, 208 species were sampled, 138 genus and 49 families, with 65% of exclusive species. Rain Forest in the Carlos Botelho State Park, were found 410 species, belonging to 152 genus and 64 families, 84% of exclusive species. The seasonal forest showed greater similarity to the rain forest than the Savanna. In spite of the greater number of species, the Rain Forest presents concentration of species in the Myrtaceae and Lauraceae families. In another analysis were calculated the taxonomic indices in tree species data provided by sampling methods tested in five sampling grids. The Bitterlich sampling method was tendecious in estimates the taxonomic diversity and taxonomic distinctness indices because the taxonomic diversity in the understory. These indices showed average independent and variance decreasing with increasing sample. The average taxonomic distinctness and variation in taxonomic distinctness also showed decreased, but the stabilization of the average occurred with samples of greater size, mainly for fixed area plots at Caetetus Ecological Station. In the Rain Forest the average taxonomic distinctness was lower and the variation of taxonomic distinctness was higher due to high concentration of species of Myrtales and Laurales in this phytophisiognomy.
5

Změny ve vegetaci přechodových rašelinišť v rybničních epilitorálech / Vegetation changes in transition bogs at fishpond epilitorals

Spilka, Josef January 2010 (has links)
This study concerns in a three peatland sites: the epilitorals of Pilská reservoir and Hořejší Padrťský fishpond in Příbram region and Kamenný fishpond in Pilsen. These peat-bobg were affected by negative conseqences of human activities. The aim of this study is to find out what kind these changes was and what extent they were. The changes in vegetation were observed from two points of view. The GIS analyses of aerial photographs represent the macroscale view. Repeating of old phytosociological relevées was the microscale view. To understand the cause of vegetation changes, the species-environment analyses were used. Four transects were made for this purpose and a water table level, pH and conductivity were mesured monthly along these transects. One-shot measurements of N and P water concentration and a peat depth were also carried out. Measured data from transects were uses in multivariate vegetation analyses and also in one- way analysis, aimed to an expansion plant species. All three sites of concern came through strong changes in past. In all of them the area of biotops of great conservation importance decreased and some endangered plant species have been lost there. The changes in Pilská reservoir epilitoral were mostly anthropogenic, whereas the mires of Hořejší Padrťský fishpond and Kamenný...

Page generated in 0.0954 seconds