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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

Succession of an Upland Oak/Hickory Forest in the Central Hardwood Region

Hoover, Nathan 01 August 2018 (has links)
For the last 9,000-10,000 years the Central Hardwood Region (CHR) has been primarily composed of a mosaic of mesophytic communities in climax and communities of successional forest types dominated by oak (Quercus Linnaeus) and hickory (Carya Nuttall). Shade intolerant oak/hickory dominated forest types have been maintained by natural disturbance processes in synergy with anthropogenic causes, resulting in a large composition of communities which are neither at climatic nor edaphic climax. Reduction in fire events, thinning, forest grazing, and other disturbance processes over the last 80-100 years have coincided with decreased regeneration of shade intolerant species due to lack of adequate light availability and recruitment of shade tolerant species of communities dominated by American beech (Fagus grandifolia L.) and maple (Acer saccharum L.) into the overstory of forests typically dominated by oak/hickory. Forest inventory data at Trail of Tears State Forest was analyzed across two separate time events (1980 and 2014) to determine compositional and structural changes which have occurred. Density, basal area, and community patterns via ordination were compared across six Ecological Land Types (ELTs) to determine topography’s effect on composition. Community trends were analyzed via NMS Ordination and between ELTs by a Mantel Test. A Multi-Response Permutation Procedures (MRRP) was also used as a nonparametric method for assessing differences between ELTs examined in the NMS. Density and basal area between years for species, ELT, and species*ELT interactions were compared. Across all ELTs, between 1980 and 2014, overstory density decreased from 218 trees/ac in 1980 to 180 trees/ac in 2014 and basal area increased from 98 ft2/ac in 1980 to 106 ft2/ac in 2014. Maple basal area increased from 5 ft2/ac to 12 ft2/ac while beech increased from 1 ft2/ac to 8ft2/ac, signifying progression of these species from the understory up into the canopy. The component of soft masting species within the forest has also decreased sharply in the last 34 years. MRPP analysis of overstory compositional gradients reported distinct species compositions between ELTs, however the trend was weak (MRPP: p < 0.001, A = 0.038). NMDS ordination graphs confirmed MRPP showing little separation among ELTs. The final stress was 18.71146 and instability was < 0.01 after 212 iterations (Table 6). Our research at TTSF is a clear example of oak/hickory succession to beech maple on an upland site among species community types as delineated by topographic moisture gradient (ELTs) within the CHR. Expansion of beech and maple onto xeric ELTs suggests a breakdown of edaphic barriers that have previously been thought to be resistant to encroachment from mesophytic species. Currently oak decline induced by lack of management is likely the number one forest health issue resulting in loss of oak/hickory and other soft masting species.
2

The phytosiology of the natural vegetation occuring in the Cradle of Humankind World Heritage Site Gauteng, South Africa

Eloff, Gareth 08 1900 (has links)
The natural vegetation of the Cradle of Humankind World Heritage Site (COH WHS) was classified using Braun-blanquet methodology. This identified 22 distinct plant communities and 2 variants. Sampling took place over two growing seasons with a total of 91 releves being compiled. A stratified random approach to sampling used Land Types as a means of primary area stratification, with terrain position providing the means for further refinement. The grassland comprised of 12 plant communities and 2 variants and the woodland comprised of 10 plant communities. The classification of the woodland areas included some bush clumps associated with the entrances of caves which were also described independently in which seven distinct plant communities were identified A positive linear correlation exists between the size of the cave entrances and the extent to which the surrounding woody vegetation extends. This suggests the likelihood of cave entrance size influencing the surrounding vegetation. / Environmental Sciences / M. Tech. (Nature Conservation)
3

The phytosiology of the natural vegetation occuring in the Cradle of Humankind World Heritage Site Gauteng, South Africa

Eloff, Gareth 08 1900 (has links)
The natural vegetation of the Cradle of Humankind World Heritage Site (COH WHS) was classified using Braun-blanquet methodology. This identified 22 distinct plant communities and 2 variants. Sampling took place over two growing seasons with a total of 91 releves being compiled. A stratified random approach to sampling used Land Types as a means of primary area stratification, with terrain position providing the means for further refinement. The grassland comprised of 12 plant communities and 2 variants and the woodland comprised of 10 plant communities. The classification of the woodland areas included some bush clumps associated with the entrances of caves which were also described independently in which seven distinct plant communities were identified A positive linear correlation exists between the size of the cave entrances and the extent to which the surrounding woody vegetation extends. This suggests the likelihood of cave entrance size influencing the surrounding vegetation. / Environmental Sciences / M. Tech. (Nature Conservation)
4

Srovnání vybraných způsobů ocenění pro nemovitost typu stavební pozemek v lokalitě města Třinec a jeho okolí / Comparison of Selected Methods of Valuation of Building Land-type Real Estate in the Locality of Třinec and its Surroundings

Zawada, Miroslav January 2011 (has links)
The objective of my master's thesis is comparison of selected methods of valuation of building land-type real estate in the locality of Třinec and its surroundings. My thesis is focused on properties, built up with houses on each of the lots , on which the construction of a house is planned. Both groups of these properties have been estimated by the methods and historical prices have been compared and analyzed.The integral part of the master's thesis is the evaluation of the individual methods of estimation,according to the pre-determined criteria.
5

Dynamique saisonnière de la végétation forestière (arbres et sous-bois) dans le massif des Landes : application de la télédétection optique au suivi des hétérogénéités à l'échelle régionale / Seasonal dynamic of the forest vegetation (understory and tree canopy) in “les Landes” forest : usefulness of the optical satellite sensors to monitor heterogeneity at the regional scale

Yauschew-Raguenes, Nathalie 14 December 2012 (has links)
L’objectif de la thèse est d'évaluer l’apport des données satellites dans le suivi saisonnier de la végétation forestière (sous-bois et strate arborée). L'étude a été conduite sur la forêt landaise. Elle est basée sur une série de sept ans d'observations satellitaires décadaires d’un indice de végétation (PVI) et de mesures in situ de la surface foliaire (LAI) du sous-bois et des arbres. Tout d’abord, les observations in-situ ont été analysées. Elles montrent que le sous-bois est le déterminant majeur de la trajectoire saisonnière du LAI de l’ensemble du couvert végétal. Puis, ces informations ont été comparées aux données satellitaires. Il apparaît que la phénologie printanière du PVI renseigne sur celle du LAI du sous-bois. Enfin, ces résultats été exploités à l’échelle régionale et une carte régionale des types de landes a pu être produite. Cette étude ouvre des perspectives en matière d'intégration et de spatialisation des bilans d'eau et de carbone des écosystèmes forestiers à l'échelle régionale. / The aim of this thesis is to assess the potential of the remote sensing data to monitor the seasonal dynamic of the forest vegetation (understory and tree canopy). The study has been carried out on the maritime pine forest in the Southwest of France. It is based on a 7-year time-series of the 10-day vegetation index PVI composite derived from satellite and on in situ leaf area measurements (LAI) of understory and tree story.At first, the in situ observations have been analysed. It shows that the understory vegetation is the main driver of the seasonal dynamic of the whole forest LAI (understory+tree story). Then, these informations have been compared with the time-series of remote sensed PVI . It appears that the spring phenology of the PVI informs directly about the LAI understory one.Finally, these results have been used at the regional scale and a regional map of the lande types has been produced. This study opens some new prospects about integration and spatialisation of water and carbon balance of forest ecosystems at regional scale.

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