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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.
101

The effect of burning frequency on invertebrate and indigenous flowering forb diversity in a Drakensberg grassland ecosystem.

Arnott, Wendy Lynn. January 2006 (has links)
The KwaZulu-Natal Drakensberg, South Africa, is predominantly a grassland ecosystem maintained by fire. The effect of the current burning regime on invertebrate and flowering forb diversity in this ecosystem is poorly understood. The overall aim ofthis study was to contribute towards the development of an effective burning regime for the KwaZulu-Natal Drakensberg that will conserve invertebrates and indigenous forbs, two major components of biodiversity. The objectives were to examine the effect of fire and fire frequency on flowering forb and invertebrate species diversity, to determine whether fire frequency, time since last burn or locality were influencing species composition, and to identify potential biodiversity indicators that reflect overall species richness for use in monitoring of invertebrates and forbs. Sampling took place in March, September and November of 2002 at Giants Castle Game Reserve. Invertebrates were sampled using sweep netting and targeted netting along transects, yellow pan traps and soil quadrats. Invertebrate taxa sampled were ants (Formicidae), butterflies (Lepidoptera), grasshoppers (Orthoptera), leafboppers (Cicadellidae), bees (Apoidea), bee flies (Bombyliidae), hover flies (Syrphidae), robber flies (Asilidae), spiders (Araneae), earthworms (Oligochaeta) and millipedes (Diploda). These were identified to species level with the assistance of taxon experts. Flowering forbs were sampled using five replicates of five by five metre quadrats randomly placed in each site. Overall flowering forb and invertebrate species diversity was higher in grasslands that were burnt for two consecutive years in 2001 and 2002 than in grasslands that were not burnt during those two years. Frequently (annual) and intermediately (biennial) burnt grasslands had significantly higher invertebrate and flowering forb diversity than infrequently (five years without burning) burnt grasslands. This, together with the fact that grasslands burnt during the year of sampling had higher species richness than grasslands burnt two and five years previously suggests that invertebrates and forbs are generally resilient to fire and many forb species appear to be stimulated by fire. However, each burn frequency had its own suite of unique flowering forb and invertebrate species. Invertebrate communities were influenced mostly by locality and the length of time past since the last fire and flowering forb communities were influenced mostly by the length oftime past since the last fire. Fire frequency had the least influence on both invertebrate and forb communities. Ecological succession occurred after each fire in the invertebrate communities but forb communities appear to need more than five years without fire for ecological succession to occur. The findings of this study therefore suggest that using a combination of three fire frequencies would result in patches of grassland in various stages of ecological succession, and would conserve species unique to each burning frequency, and would therefore conserve maximum diversity. Flowering forb species richness and certain invertebrate taxa (ants, leafboppers, spiders and bees) have the potential to act as indicators of overall invertebrate species richness for use in monitoring programmes. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2006.
102

The Journey of Resources : Archaeobotanical analysis of late Iron Age and medieval Sigtuna, Sweden

Pettersson, Siri January 2019 (has links)
Traditional agriculture has played an important role in shaping the landscape for thousands of years. Agriculture and interactions between humans and their surroundings have changed since the beginning of historic time in Sweden, approximately 1000 years ago. Through botanical macrofossil analysis of plant remnants found in an urban ditch in Sigtuna, Sweden, I examine which natural landscapes the town’s inhabitants may have interacted with in terms of resource collection in the beginning of the Medieval period. The results showed indications of predominantly nutritious wet grassland habitats, but also dry grassland and forests, as well as remnants of urban and cultivated species. The species indicate that the resources may have been used as winter fodder for animals, but possibly also as sustenance for humans as well as building material. The results indicated little change over time, regarding which landscape types were interacted with, but there were possible indications of a decrease in grassland resource collection in the youngest sample from 1150 A.D. Further research is needed to understand the indication. The material indicates that the Cyperaceae family will be instrumental in continuing this research.
103

The effects of dune stabilization on the spatiotemporal distribution of soil moisture resources, Northern Great Plains, Canada

Koenig, Daniel Edgar January 2012 (has links)
In dryland environments, the availability of soil moisture is the primary control on plant species’ distributions. In the sandhill regions of the northern Great Plains, vegetation establishment has transformed highly mobile, desert-like dune fields into stabilized landscapes covered by mixed-grassland prairie. This study examines how dune stabilization has modified the spatiotemporal distribution of soil moisture resources. An ergodic (space-for-time) approach was used, comparing soil moisture dynamics on active and vegetation-stabilized dunes in the Bigstick Sand Hills of southwestern Saskatchewan. Results indicate that while dune stabilization has enhanced near-surface soil moisture availability, deeper profile soil moisture recharge is reduced. Through better understanding how vegetation has modified soil moisture dynamics in stabilizing sandhill regions, better management practices may be implemented to maintain water resource availability and ecosystem health. / xii, 97 leaves : ill., maps ; 29 cm
104

Grazing management in the communal rangelands of the Upper Thukela, Kwazulu-Natal.

Tau, Mahlodi Solly. January 2005 (has links)
The grazing management project in the Okhombe ward of the Amazizi Tribal Authority formed part of the National Department of Agriculture's LandCare program to address communal natural resource management issues. Okhombe land is communal whereby every member of the community is the legal owner of the rangeland with individual ownership of stock with the chieftaincy playing a major role in land allocation. In order to avoid critics of the past and address the top-down approach of the past interventions, a participatory approach was conducted in the planning and implementation of the grazing system. The service providers held a series of visioning workshops with the community in an effort to better understand community resource use patterns, needs, constraints and opportunities as part of the participatory approach. Issues identified by the community were the need for fencing grazing camps, animal health improvement, subdivision of rangeland and crop fields and the development of a rotational grazing system. The main aims of this study were to develop a participatory grazing plan with the community, develop and support institutional structures governing range management, and build capacity of the community in range management. The effect of the current grazing system on species composition was determined. In addition to these, the project investigated the potential different fodder trees has on alleviating feed and nutritional deficit, particularly during the dry winter months of the Upper Thukela. Among the main achievements of this study was the development and strengthening of local institutional structures and effective liaison by all structures with the Inkosi and the tribal council. The community developed a rotational grazing plan, marked the camp boundaries, produced digital maps and successfully built fence boundaries (approximately 20 kms of fencing) to divide their land. The fence boundaries separated the crop fields and rangeland, closed ward boundaries in the upland to prevent access by cattle from neighbouring wards, and divided the land into three camps. Six crush pens were constructed in each subward of the Okhombe ward. A communal herders fund opened and fence construction improved crop yields due to a decrease in crop damage by cattle. Okhombe ward, located in the Highland Sourveld region of KwaZulu-Natal, experiences feed and nutrition deficits to ruminants during winter. The prevailing species composition in Okhombe was investigated as part of the grazing plan. The veld condition of the sites ranged from poor (40.7%) in the bottomland to an averaged of 47.0% in upland sites. The most distinctive feature of the rangeland in this area was the loss of highly palatable Decreaser grass species (P <0.05), such as Themeda triandra in the bottom slopes « 1300 m) when compared to the upland (> 1800 m). The proportional abundance of Decreaser species accounted for an averaged of 1.02% of the bottomland and an averaged of 11.5% of the upland compared to the values of 49% in the benchmark (grassland in optimal condition). The composition of the less palatable Increaser Il species was very high at all elevations (1200 m -80.7%, 1400 m - 75.8% and 1700 m - 55.7%) when compared to the low benchmark composition of 19%. The dominant grasses of the bottom slopes were Increaser Il species, such as Eragrostis curvula, Eragrostis plana and Sporobolus africanus and unpalatable Increaser III species such as Aristida junciformis. A significant difference (P < 0.05) in the composition of Decreaser, Increaser I and Increaser Il species was found between the bottom and slopes compared to the upland region. However, the grass cover formed by these tufted species was generally high, making it more resistant to physical degradation. The bottom slope ranged from reasonable to excellent cover (16.9%), the middle slope ranged from reasonable (15.9%) to a good cover of 18.1%, averaging 16.7% and a range of 16.1% to 17.9% for the upland plateau. In the agroforestry trial the potential of different fodder species for supplementing fodder was examined. Leucaena leucocephala had the potential of being a suitable fodder tree species for use in alley cropping (P < 0.05) compared to Morus alba and Acacia karroo. Results from the partially intercropped treatments showed that L. leucocephala yield (665 kg ha-I) varied significantly (P < 0.05) from the A. karroo (378 kg ha-I) and M alba yield (345 kg ha-I). Treatments that were fully intercropped varied, but no significant difference (P > 0.05) were recorded. Morus alba produced the least yield of 345 kg ha-I, A. karroo yielded 378 kg ha-1 and 1. leucocephala recorded the high of 664 kg ha-I. Results from the second season showed similar trend in that 1. leucocephala yielded a significant (P < 0.05) fodder production of 1715 kg ha-I in comparison to M. alba (1101 kg ha-I) and A karroo (1140 kg ha-I). M alba yielded the least dry matter production (P < 0.05) but had high potential (P < 0.05) for addressing lack of firewood in rural areas. Morus alba yielded high fuel wood production from both two seasons. There were no significant differences in fuel wood yield (P > 0.05) from the partially intercropped M alba (507.9 kg ha-I) and 1. leucocephala (455.0 kg ha-I) but the yield from both species varied significantly from the A. karroo yield (103.kg ha-I). With regard to fully intercropped plots, fuel wood yield from all tree species varied significantly, A karroo resulting in low yield (63 kg ha-I), 1. leucocephala recorded 243 kg ha-l and M alba the highest yield of 444 kg ha-I. In the second season, M. alba yielded an averaged fuel wood production of 728 kg ha-l and a low of 439 kg ha-I from 1. leucocephala. Acacia karroo, a slow growing indigenous tree, might be preferred by farmers due to its less branches resulting in minimal light competition with crops. Leucaena leucocephala tend to grow slowly in its initial establishment stage, but once roots become well established, it grows fast and produces high quantity of fodder. The effect all fodder trees had on crop yield was not negative during the trial period and further research on long term effects of alley cropping is recommended. The conclusions drawn here were based on tree growth and their likely impact in alley cropping. Leucaena leucocephala was also recommended as a preferred species for rural ruminants based on the forage quality study. The results showed high content of crude protein (19.27%), low NDF content (50.38%) and very low tannin content (1.19%) from 1. leucocephala compared to A. karroo with a high tannin content of 5.69%. Acacia karroo had a crude protein content of 13.60%, NDF percentages of 44.16 and 34.64% of ADF content. Morus alba also had a recommended chemical composition of 11.71% of CP, 42.86% of NDF, 36.96% of ADF and a low tannin content of 0.65%. L. leucocephala foliage proven is readily degradable under different diet ranging within 24 hrs of intake (P < 0.001) compared to other feeds. L. leucocephala had high dry matter loss degraded from the rumen under Eragrostis hay diet with poor nutrients to high protein concentrates diet. Under the Eragrostis hay diet for instance, L. leucocephala tend to degrade rapidly with values of dry matter loss ranging from 32.2% to 39% at 4 hrs to 16 hrs, when compared to low dry mater loss of 26% at 4 hrs to 31.33% at 16 hrs. Feeds such as M alba tend to degrade slowly within 24 hrs of intake and rapidly degrades after the stated period. The ep content of maize stover was very low ranging from 1.60% in maize stalks to 2.63% in maize leaves. The fibre content in maize stover was very high when compared to lower values in fodder samples. The NDF content ranged from 77.92% in maize leaves to 81.60% in maize stalks. Maize leaves when compared to a combination of maize leaves and maize stalks sole tend to degrade better within 24 hrs of intake. This was due to low (P < 0.05) degradability rate of maize stalks compared to a combination of maize stalks and leave and leaves sole and least NDF content in maize leaves might have attributed to these results. Due to poor chemical compositions of these roughage samples, the study recommended the establishment of fodder banks and agroforestry systems to curb the nutrients deficit during winter. In conclusion therefore, this study highlight that the sustainability of rural systems to manage communal grazing land should be further explored. Most of the challenging issues in communal range management are social in nature rather than technical concepts. These include ways of improving social contributions from cattle to the community while maintaining cultural values of the use of cattle. The interventions in communal range management by service providers should understand the institutional arrangements within a community and an attempt to strengthen such existing structures is recommended. Further interventions by service providers in Okhombe ward should bring in the planning discussions, experts from social sciences, to deal with understanding of community dynamics. Complexities in communal range management involve dealing with non-stock owners within project boundaries. Communities from neighbouring wards should not be ignored and ways of improving communications and updating project details to them should be formulated. Shortage of land and closing of ward boundaries to prevent access to land by neighbouring wards is among community complexities to be explored. Communities in rural lands do share land and in most cases boundaries are known but invisible by an outsider to identify. It is important to strengthen and maintain every success in communal lands as that may form core of the project. Successes on grazing management by locals is far from being the improvement in veld but there are rather various factors to the successes of grazing projects in rural areas. Examples of successes based on Okhombe project are reduction in stock theft, improved in relationship between community and locals institutions, a reduction in stock mortalities during winter and improved animal health. Veld improvement is among successes but there are accomplishments phases to fulfil before focusing on improvement of species composition. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2005.
105

Remote sensing of leaf area index in Savannah grass using inversion of radiative transfer model on Landsat 8 imagery : case study Mpumalanga, South Africa

Masemola, Cecilia Ramakgahlele 03 1900 (has links)
Savannahs regulate an agro-ecosystem crucial for the production of domestic livestock, one of the main sources of income worldwide as well as in South African rural communities. Nevertheless, globally these ecosystem functions are threatened by intense human exploitation, inappropriate land use and environmental changes. Leaf area index (LAI) defined as one half the total green leaf area per unit ground surface area, is an inventory of the plant green leaves that defines the actual size of the interface between the vegetation and the atmosphere. Thus, LAI spatial data could serve as an indicator of rangeland productivity. Consequently, the accurate and rapid estimation of LAI is a key requirement for farmers and policy makers to devise sustainable management strategies for rangeland resources. In this study, the main focus was to assess the utility and the accuracy of the PROSAILH radiative transfer model (RTM) to estimate LAI in the South African rangeland on the recently launched Landsat 8 sensor data. The Landsat 8 sensor has been a promising sensor for estimating grassland LAI as compared to its predecessors Landsat 5 to 7 sensors because of its increased radiometric resolution. For this purpose, two PROSAIL inversion methods and semi- empirical methods such as Normalized difference vegetation index (NDVI) were utilized to estimate LAI. The results showed that physically based approaches surpassed empirical approach with highest accuracy yielded by artificial neural network (ANN) inversion approach (RMSE=0.138), in contrast to the Look-Up Table (LUT) approach (RMSE=0.265). In conclusion, the results of this study proved that PROSAIL RTM approach on Landsat 8 data could be utilized to accurately estimate LAI at regional scale which could aid in rapid assessment and monitoring of the rangeland resources. / Environmental Sciences / M. Sc. (Environmental Science)
106

Comparison of IKONOS Derived Vegetation Index and LiDAR Derived Canopy Height Model for Grassland Management.

Parker, Gary 12 1900 (has links)
Forest encroachment is understood to be the main reason for prairie grassland decline across the United States. In Texas and Oklahoma, juniper has been highlighted as particularly opportunistic. This study assesses the usefulness of three remote sensing techniques to aid in locating the areas of juniper encroachment for the LBJ Grasslands in Decatur, Texas. An object based classification was performed in eCognition and final accuracy assessments placed the overall accuracy at 94%, a significant improvement over traditional pixel based methods. Image biomass was estimated using normalized difference vegetation index (NDVI) for 1 meter resolution IKONOS winter images. A high correlation between the sum of NDVI for tree objects and field tree biomass was determined where R = 0.72, suggesting NDVI sum of a tree area is plausible. However, issues with NDVI saturation and regression produced unrealistically high biomass estimates for large NDVI. Canopy height model (CHM) derived from 3-5m LiDAR data did not perform as well. LiDAR typically used for digital elevation model (DEM) production was acquired for the CHM and produced correlations of R = 0.26. This suggests an inability for this particular dataset to identify juniper trees. When points that registered a tree height where correlated with field values, an R = 0.5 was found, suggesting denser point spacing would be necessary for this type of LiDAR data. Further refining of the methods used in this study could yield such information as the amount of juniper tree for a given location, fuel loads for prescribed burns and better information for the best approach to remove the juniper and ultimately management juniper encroachment into grasslands.
107

Population biology and ecology of Vachellia karroo (Hayne) Banfi and Galasso in the Nylsvley Nature Reserve, Limpopo Province, South Africa

Madilonga, Mpho Given 18 September 2017 (has links)
MSc (Botany) / Department of Botany / Plant populations are determined by many elements that impose demographic filters. Following disturbance, in African savanna woodland trees regenerate both sexually and vegetatively. Vachellia karroo (Hayne) Banfi and Galasso, family Fabaceae and sub family Mimosideae, commonly known as “sweet thorn” or “soetdoring” (Afrikaans), is a leguminous shrub common throughout Southern Africa. Its distribution range is from the Southwestern Cape northwards into Namibia, Angola, Botswana, Zambia and Zimbabwe. It is a pioneer species and has the ability to encroach rapidly into grassland grazing areas. Therefore, V. karroo is considered the most important woody invader of grasslands in South Africa. This study aimed at investigating the population biology and ecology of V. karroo in the clay waterlogged site of the Nylsvley Nature Reserve. Plant height, stem circumference, canopy cover, distance between individuals were measured and disturbance levels on individuals of V. karroo were estimated during sampling. The results showed that the population of V. karroo display an adequate growth curve thus implying that the population of V. karroo in the Nylsvley Nature Reserve is healthy and viable. More mature healthy individuals were found in September and December, than during June and July; this is obviously because early summer season, and in September most of the savanna plant species were starting to actively recover from the winter dry season. This is confirmation enough that the population of V. karroo is expanding in the clay waterlogged areas of Nylsvley Nature Reserve.
108

Vegetation ecology of Egoli Granite Grassland on the farm Doornrandjie, Gauteng

Bezuidenhout, Antonia 12 1900 (has links)
A vegetation survey was conducted on the newly acquired farm portions of the farm Doornrandje 386 JR, which are being incorporated into Gauteng Department of Agriculture and Rural Development’s protected area expansion. This study provides an ecological basis for establishing an efficient management programme for the area. From a TWINSPAN classification, refined by Braun-Blanquet procedures, five plant communities were identified. A classification and description of the major plant communities is presented. Descriptions of the plant communities include characteristic species, as well as prominent and less conspicuous species of the tree, shrub, herb and grass strata. Floristic analyses of the vegetation and a biodiversity comparison of the different plant communities found on the farm are also undertaken. This study proves that the extended land incorporated into the Reserve contributes to the biological diversity of the study area. / Environmental Sciences / M. Sc. (Environmental Science)
109

Vegetation ecology of Egoli Granite Grassland on the farm Doornrandjie, Gauteng

Bezuidenhout, Antonia 12 1900 (has links)
A vegetation survey was conducted on the newly acquired farm portions of the farm Doornrandje 386 JR, which are being incorporated into Gauteng Department of Agriculture and Rural Development’s protected area expansion. This study provides an ecological basis for establishing an efficient management programme for the area. From a TWINSPAN classification, refined by Braun-Blanquet procedures, five plant communities were identified. A classification and description of the major plant communities is presented. Descriptions of the plant communities include characteristic species, as well as prominent and less conspicuous species of the tree, shrub, herb and grass strata. Floristic analyses of the vegetation and a biodiversity comparison of the different plant communities found on the farm are also undertaken. This study proves that the extended land incorporated into the Reserve contributes to the biological diversity of the study area. / Environmental Sciences / M. Sc. (Environmental Science)
110

Comparison between high-resolution aerial imagery and lidar data classification of canopy and grass in the NESCO neighborhood, Indianapolis, Indiana

Ye, Nan January 2014 (has links)
Indiana University-Purdue University Indianapolis (IUPUI) / Urban forestry is a very important element of urban structures that can improve the environment and life quality within the urban areas. Having an accurate classification of urban forests and grass areas would help improve focused urban tree planting and urban heat wave mitigation efforts. This research project will compare the use of high – resolution aerial imagery and LiDAR data when used to classify canopy and grass areas. The high – resolution image, with 1 – meter resolution, was captured by The National Agriculture Imagery Program (NAIP) on 6/6/2012. Its coordinate system is the North American Datum of 1983 (NAD83). The LiDAR data, with 1.0 – meter average post spacing, was captured by Indiana Statewide Imagery and LiDAR Program from 03/13/2011 to 04/30/2012.The study area is called the Near East Side Community Organization (NESCO) neighborhood. It is located on the east side of downtown Indianapolis, Indiana. Its boundaries are: 65 interstate, East Massachusetts Avenue, East 21st Street, North Emerson Avenue, and the rail road tracks on the south of the East Washington Street. This research will also perform the accuracy assessment based on the results of classifications using high – resolution aerial imagery and LiDAR data in order to determine and explain which method is more accurate to classify urban canopy and grass areas.

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