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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.
61

The relationships between the forest fuels and vegetation of Richmond National Battlefield Park, Virginia

Helm, Amy Cimarolli 13 February 2009 (has links)
The objectives of this study were to determine the loading of dead and down forest fuels in 6 forest cover types on the upper Coastal Plain of Virginia, specifically in the Richmond National Battlefield Park, and to determine the relationships between the fuels and the vegetation. The forest fuels and vegetation were sampled in stands of the following cover types: pine, oak-pine, mixed hardwood-pine, oak, mixed hardwood, and oak-mixed hardwood. The planar intersect method was utilized to quantify the woody fuels. and the forest floor was sampled in fixed area plots. The weight. volume, depth. and species of fuel particles was determined for each stand sampled in the Park, and this information was combined for an estimate of fuel loading by cover type. The overstory trees were sampled within prism plots, and the understory was sampled in fixed area plots. Standard forestry information was collected for each sampled stand, and estimates of species dominance, density, frequency and importance were determined. In general, the fuel loading was not different between the six cover types as determined with ANOVA procedures. due to the large variation of loads within each. The loading of certain sizes of fuel particles were different between a few cover types, due to both the influence of the overstory species and the site they had occupied. For example, the 1-hr. time-lag branch fuel loading was significantly greater in the oak cover type than in the pine or mixed hardwood cover types. Another significant difference was in the forest floor loads: the mixed hardwood cover type had a lighter forest floor than the pine or oak-pine cover types. This was most likely due to the higher quality of sites upon which the mixed hardwood stand were found, and the higher palatability of litter produced by these species, which would favor the decomposition of litter more than conditions found in the pine or oak-pine cover types. To quantify relationships between the fuel loads and forest vegetation and site characteristics, Spearman's rank correlation coefficients were calculated between all the variables. Many significant relationships were found, though all but one correlation coefficient was under 0.51: total forest floor load and forest floor depth had a correlation coefficient of 0.75. Forest and site variables significantly related to fuel loadings were tested for their predictive value with multiple regression statistics. The resulting set of regressions had low coefficients of determination and varying levels of precision; their usefulness would depend on the level of sampling intensity and precision one would want to expend to get an estimate of fuel loading in a stand. If a rough estimate requiring little time in the field is desirable, then these regressions would be useful. / Master of Science
62

Monitoring the re-growth rate of alien vegetation after fire on Agulhas Plain, South Africa

Fatoki, Oluwakemi Busayo 03 1900 (has links)
Thesis (MSc (Geography and Environmental Studies))--University of Stellenbosch, 2007. / The Agulhas Plain, an area rich in fynbos, was monitored within six months after the February 2006 fire. The potential of using medium resolution imagery, specifically from the Moderate Resolution Imaging Spectroradiometer (MODIS) in determining the re-growth rates of indigenous and alien vegetation types after fire was explored. Pixels representing dense areas of each vegetation type were selected. There was a significant difference in the pixels selected for each vegetation type. A time series of Normalized Difference Vegetation Index (NDVI) data was derived and fitted to functions, such as Double Logistics and Asymmetric Gaussian as implemented in the TIMESAT software. The results show that alien vegetation grows faster after a fire occurrence than in its absence. Within the specified months of monitoring, it was observed that fynbos grew faster than the alien vegetation. Also, the re-growth rates of vegetation on the coastal soils were higher than those of vegetation on the inland soils. The determination of the re-growth rate was necessary to assist resource managers determine the appropriate time for follow-up of clearing invaded sites after fire.
63

Vegetation ecology of Drakensberg foothill moist grassland on Hlogoma Mountain, Underberg, KwaZulu-Natal

Berruti, Sharron Marion 11 1900 (has links)
Hlogoma Mountain is a small inselberg surrounded by farms and commercial forestry in the Underberg district (KwaZulu-Natal) within the Gs10 Drakensberg Foothill Moist Grassland. As little is known about the vegetation on Hlogoma, a survey was undertaken to classify, map and describe the plant communities occurring on the inselberg. A total of 100 (16 m2) randomly stratified sample plots were placed in homogeneous vegetation units within the 117 ha study area. A TWINSPAN classification, refined by Braun-Blanquet procedures, resulted in the identification of two major communities, five communities, 12 sub-communities and four variants. All communities were described and a vegetation map constructed. Ordinations identified key environmental variables that have an impact on the vegetation at the study site. A plant species checklist was created and analysed for floristic composition; rarity and threatened species; medicinal plants; endemism; phenology; flower colour and elevation range; species richness and plant community biodiversity. A total of 467 species were identified, represented by 271 genera and 87 families. Four Red Data species and a new Aspidoglossum species were discovered. Two near-endemic genera, two endemic species and 88 near-endemic species belonging to the Drakensberg Alpine Centre were found on Hlogoma. This study showed that Hlogoma Mountain is an inselberg with high plant species richness and endemism, and is a refuge of conservation importance for biodiversity. / Environmental Sciences / M. Sc.(Environmental Science)
64

A vegetation classification and management plan for the Nooitgedacht section of the Loskop Dam Nature Reserve

Nkosi, Sellina Ennie 11 1900 (has links)
The vegetation of the Nooitgedacht section of the Loskop Dam Nature Reserve resembles Bankenveld vegetation and differs from the other areas of the reserve. This study was undertaken to identify, classify, and describe the plant communities present on this section, and to determine their veld condition. The Braun-Blanquet approach was followed to classify the different plant communities. A total number of 170 sample plots (100m2) were placed in all homogeneous vegetation units in a randomly stratified basis. The Ecological Index Method (EIM) was used to determine the veld condition. Data were collected using the steppoint method and incorporated into the GRAZE model from where the veld condition was calculated. A minimum of 400 step points were surveyed in each community with more points in the larger communities. Plant community data was analysed using the JUICE software program. A total of 11 plant communities were identified. The overall veld condition score indicates the vegetation to be in a good condition, resulting in a high grazing capacity. / Environmental Sciences / M. Sc. (Nature Conservation)
65

A vegetation classification and management plan for the Nooitgedacht section of the Loskop Dam Nature Reserve

Nkosi, Sellina Ennie 11 1900 (has links)
The vegetation of the Nooitgedacht section of the Loskop Dam Nature Reserve resembles Bankenveld vegetation and differs from the other areas of the reserve. This study was undertaken to identify, classify, and describe the plant communities present on this section, and to determine their veld condition. The Braun-Blanquet approach was followed to classify the different plant communities. A total number of 170 sample plots (100m2) were placed in all homogeneous vegetation units in a randomly stratified basis. The Ecological Index Method (EIM) was used to determine the veld condition. Data were collected using the steppoint method and incorporated into the GRAZE model from where the veld condition was calculated. A minimum of 400 step points were surveyed in each community with more points in the larger communities. Plant community data was analysed using the JUICE software program. A total of 11 plant communities were identified. The overall veld condition score indicates the vegetation to be in a good condition, resulting in a high grazing capacity. / Environmental Sciences / M. Sc. (Nature Conservation)

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