Thesis (Ph.D.)--University of Adelaide, Dept. of Geographical and Environmental Studies, 2001. / Includes bibliographical references (p. 301-319).

Autumn-olive (Elaeagnus umbellata Thunb.) is an exotic species that was introduced in the U. S. in the 1800's and widely promoted as an ideal plant for erosion control, wildlife habitat and soil remediation. N-fixation by autumn-olive through a symbiotic relationship with actinomycete Frankia, can alter nitrogen cycling and potentially impair water quality through nitrate leaching. Furthermore, legacy effects of accumulated N following vegetative management and restoration efforts are unknown in areas invaded by autumn-olive. The first objective of this research was to determine if there was a relationship between autumn-olive cover and stream nitrate-N (NO3--N) concentration in twelve forested headwater watersheds in southern Illinois. Secondly, changes in autumn-olive cover and stream nitrogen concentrations were assessed by comparing current results to data collected 6 years prior. Nine of the study watersheds had significantly greater autumn-olive percent cover in 2012 compared to 2006 and mean stream NO3--N concentration significantly increased from 2006 to 2012 in all watersheds. Also, a significant exponential relationship was found between stream NO3--N concentration and autumn-olive percent cover. The long term effects of autumn-olive management on N cycling were also investigated by implementing three different vegetation treatments on invaded areas: cutting of autumn-olive trees (CU), cutting and stump herbicide application (CH) and a no treatment application or control (CO). Treated plots showed that soil NO3--N increased temporarily due to the disturbance. However, after the initial post treatment period of one year, soil water NO3--N concentrations on treated plots shifted, so that CH plots had significantly lower levels of NO3--N than in CO plots. Soil water NO3--N in CU plots also decreased, but it was not significantly different from CH plots. Subsequently, soil water NO3--N declined on CH plots, reaching the lowest levels in the third and fourth year after treatment. Reduction in soil water NO3--N in CH plots was not accompanied by differences among treatments in soil N mineralization rates or soil C:N ratios indicating persistent high nitrification rates contributing to mineralization under treated and control plots. These results demonstrate that encroachment of autumn-olive can transform N cycles in natural areas and affect water quality by saturating the soil with mobile forms of N that are leached out of the system. Significant rates of soil N cycling can persist for years after removal of autumn-olive due to the cycling of legacy N in soils and litter. Nevertheless, the cut and stump herbicide application treatment produced positive vegetation management results by halting N-fixation, controlling autumn-olive re-sprouting and by gradually decreasing N availability and NO3--N flushing in treated areas. Treatment of autumn-olive should have an impact on stream water quality in headwater watersheds, given the significant observed relationship between autumn-olive cover and stream nitrogen levels.

A vegetation survey of natural woodland and grassland was undertaken in the urban areas of the Gauteng Province, where 7,3 million of the 38,5 million people of South Africa live. Relevés were compiled in 132 stratified random sample plots in selected open spaces in the study area. A TWINSPAN classification, refined by Braun-Blanquet procedures, indicated six woodland communities represented by 72 relevés, and eight grassland communities represented by 59 relevés. The identification, classification and description of these plant communities are important for the continued conservation of open spaces in the urban environment in order to integrate landscape ecological mapping and urban spatial planning processes. The study further recorded a high number of species. It indicated that the natural areas in the urban environment have a high conservation status and maintain a high species richness. This information could in future be used for further biodiversity studies in the Province. Species with low occurrence were specifically listed and can be used to inform "red data" status research initiatives. / Dissertation (MSc (Botany))--University of Pretoria, 2006. / Plant Science / unrestricted

Forests perform many important ecological functions and provide numerous environmental services to humanity. Currently forests are under ever increasing pressures from humans through deforestation, changes in land use, and anthropogenic climate change. Managed forests play an important role in supplying forest products to the global population, necessitating the need to predict how forests will respond to climate change and how this will influence future wood product supplies. In this dissertation I used loblolly pine (Pinus taeda), the most extensively cultivated tree species in the United States, as a study system to simulate how climate change and forest management could alter the dynamics of managed forests in the future. Using the land component (the Community Land Model) of the widely used Community Earth System Model (CESM), I developed and validated a set of tools necessary to simulate the loblolly pine plantation system using the vegetation demography model embedded in CESM (FATES). This included developing a representation of loblolly pine using data from the literature, which was better able to capture forest growth and development observed in field studies than FATES's existing conifer tree representation. I added the ability to simulate several aspects of forest management not previously supported in FATES by creating the Vegetation Management Module, which I showed was able to realistically reproduce the common management practice of stand thinning. I used these new tools to perform simulations of how loblolly pine will grow across the Southeastern United States until the end of the 21st century, under the high and low climate change scenarios developed by the scientific community in the Coupled Model Intercomparison Project Phase 6 (CMIP6). Our experiments show that loblolly pine productivity may as much as double by the end of the century, with total wood harvest over that period increasing by almost half. I also showed that different management activities had significant effects on loblolly plantation yields, with mid-rotation stand thinning having an effect under both climate scenarios on par with increases due to the extreme climate change scenario SSP5 RCP8.5. I showed that these changes in wood yields could decrease the forest area in the Southeast required to meet the wood product demands over the rest of the century. These changes in plantation productivity could interact with socioeconomic factors to drive changes in land use and carbon storage in the Southeastern U.S. This work increases our understanding of how managed forests in the U.S.\ will be affected by climate change and how our management choices modulate that response. The techniques and tools developed here open up new areas of research into the role of forest management in the climate system. / Doctor of Philosophy / Forests benefit humans by regulating Earth's climate and by providing natural resources such as wood. In the Southeastern United States forestry is an important industry. Tree farms of southern pine trees produce a large percentage of the region's wood. Predicting how forests will grow in the future is important for planning and making investments. However, the burning of fossil fuels has increased carbon dioxide in the atmosphere and is changing Earth's climate. This is affecting how fast trees grow and how much wood can be harvested from forests. The methods that foresters have traditionally used to predict how trees will grow in the future do not account for climate change, and thus may not be as accurate in the future. An alternative is to use the computer models that scientists have developed to predict both how global climate will change in the future and how forests are influenced by climate. These computer programs can be used to predict how natural forests will grow in the future, but aren't set up to predict managed forests well. I made changes to one of these programs to make it possible to simulate the managed loblolly pine forests of the Southeastern United States. First, I tested these changes to make sure that simulated forests grew like real forests do today. Then I simulated how pine forests in Southeastern United States could grow over the next century with climate change. I found that pine forests will grow faster and allow more wood to be harvested as carbon dioxide in the atmosphere increases. If climate changes are extreme, loblolly forests could produce 70\% more wood than today by the end of the 21st century. I also showed that the manner in which forests were managed in simulations changes the amount of wood they produced, with some management practices increasing wood harvested by 50\% over the rest of the century. Because climate change could increase the amount of wood that can be produced from a fixed area of forest, I investigated how this might change the area of forest plantation in the Southeastern United States. Based on projections of demand for wood for the rest of the century I calculated how much loblolly pine forest would be needed to produce this wood over the next century. I found that increases in forest productivity due to climate change and forest management could decrease the forest area required to grow the wood we need. This could change how we use forests in the Southeastern United States, which in turn could have impacts on the climate.

Please read the abstract in the section 00front of this document / Thesis (PhD (Botany))--University of Pretoria, 2006. / Plant Science / unrestricted

dissertation submitted to the faculty of Science, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Master of Science. Johannesburg, 2015. / Global environmental change due to anthropogenic activity results in alterations to the Earth’s biogeochemical cycles. This study focused on nitrogen and sulphur deposition, which results in the acidification of ecosystems. Alterations to these processes will have an effect on the diversity and ecophysiology of the vegetation; moreover, little is known about the long-term impacts on the vegetation structure and composition. Increased development, mining and industrialization, within the Waterberg area, particularly with the construction of the Medupi power station, have resulted in this area coming under study. The impacts of additional air pollution to the vegetation in this area are currently unknown. The aim of this research was to determine whether increased ambient levels of atmospheric nitrogen and sulphur, resulting from the power stations, will impact the structure, functional type and the composition of the vegetation, and the resultant impacts on vegetation structure and growth as a result of the added nitrogen and sulphur to the system and increased acidity. A baseline of quantitative data was needed in order for future comparisons to be made to assess whether biodiversity is changing and at what rate. One part of the study involved the collection of baseline vegetation data along a pre-determined transect in the Waterberg area. A transect was identified which could serve as a vehicle for monitoring changes over time, with areas downwind of the Matimba and Medupi power stations assumed to be more impacted than areas upwind. The two downwind sites and the two sites closest to the power stations were found to have the highest beta diversities, with the two downwind sites having a value of 0.60 and the downwind Landelani site and upwind Withoutpan site having a value of 0.53. The high species variation between these sites may already be an indication of pollution impacts within the area. The downwind site closest to the power stations, Landelani, is particularly vulnerable as it has a high Shannon diversity index, with a value of 2.84, and high tree biomass, 46.64 tonnes/ha, with low tree density, 625 trees per hectare. iii Functional groups are assumed to react similarly under changing environmental conditions. The second part of this research focussed on photosynthetic pathways, by using two C3 woody species and two C4 grasses. The experiment was conducted in the greenhouse at the University of the Witwatersrand and showed that both tree and both grass species selected were sensitive to sulphur additions to varying degrees. Additionally Acacia sieberiana was found to be sensitive to nitrogen addition, however Combretum erythrophyllum responded to nitrogen when it was added alone. A positive response to nitrogen was seen in both grass species; however the positive response was negated by the addition of any sulphur in Eragrostis curvula. In Panicum maximum the positive response in growth to nitrogen addition exceeded any negative effects from the sulphur addition. The results of plant growth to increasing soil acidity were different between functional groups and within functional groups. A relationship between the increase in the average above and below ground mass was found to exist with a decrease in soil acidity in Acacia sieberiana (R2 = 0.45). A relationship between an increase in the average above and below ground mass with a decrease in soil acidity in Eragrostis curvula was also seen (R2 = 0.31). Changes to the structure and composition of vegetation in this area will impact land use and the management thereof, impacting land users and owners ability to generate an income and therefore their livelihoods. Changes to vegetation structure and composition will also have a greater overall effect by impacting ecosystem functioning and resilience to future disturbances.

Thesis (MTech (Applied Sciences))--Cape Peninsula University of Technology, 2007 / Changes in plant specIes richness and diversity were investigated in Rocherpan Nature Reserve across a fence (or old fence line) separating 34 years of conservation management, conservation management for 11 years south and north, natural veld grazed by cattle and goats, natural veld grazed by sheep, and strip-ploughed veld grazed by sheep. Vegetation surveys were conducted in September 2001. The modified 20 m x 50 m Whittaker plot design with its attractive features of long-thin plots and the original Whittaker plot design were used. Number of species (as richness data) and the numbers of individual recordings per species per land use (as abundance data) were used in calculations in the 20 m x 50 m (1000 m2 ) plots. The species richness index showed significantly smaller numbers of species in the conservation management 11 years south land. The results also showed an increase in species numbers under the grazing land use systems. The data from the comparative study of the five different species diversity indices showed no significant differences. As a result, the Shannon-Wiener index was selected for further assessing the species diversity index and the species diversity significance of different land uses in the West Coast Strandveld. In this particular study, the species that showed an increase in vegetation cover in response to grazing land use regimes were Hemimeris racemosa (annual herb) and Ehrharta brevifolia (annual grass).

Thesis (Ph.D.)--University of Wollongong, School of Biological Sciences. / Typescript. Includes bibliographical references: leaf 161-203.

Savanna degradation is an environmental problem occurring in most countries around the world and it poses threats to biodiversity conservation, the food industry, and other economic sectors. According to FAO, South Africa’s rangelands exhibit the highest rate of fragmentation in comparison to range ecosystems in neighbouring countries including Lesotho and Swaziland, and consensus among researchers is that communal rangelands are more degraded than commercial rangelands. Although researchers and communities have identified the occurrence of land degradation in communal savannas at a local scale, land degradation has been poorly estimated because little has been done to quantify the extent and dynamics of perceived and observed changes associated with land degradation. The main goal of this study is to provide empirical insights on the direction of changes in the communal savannas of Nkonkobe Local Municipality in order to inform policy formulation and implementation. Additional to the communal sites is a private farm included for comparative analysis of trends in communal and commercial savannas. Landsat imagery was used to map, assess, and quantify the extent of land degradation in Nkonkobe Local Municipality, over a period of 30 years between 1984 and 2014. Field investigations were undertaken in June 2015 to acquire reference data to guide supervised classification of Landsat images. Three algorithms (Mahalanobis-distance, Minimum-distance, and Maximum likelihood classification) were compared to identify a classifier that produced the best results. The maximum likelihood classifier produced the best results with classification accuracy levels of 95.24 percent, 89.66 percent, and 95.65 percent for Honeydale Farm, Thyume, and Sheshegu respectively. Regression analysis revealed that both communal and private lands have experienced statistically significant increases in bush encroachment and decreases in surface water. Communal savannas have been confronted more by expansion of built-up area, decrease in open grassland, abandonment of arable land, soil erosion, and a steady invasion by Acacia Karroo compared to the privately owned commercial farm. The land cover changes measured through this investigation suggest an environmental shift that threatens biodiversity and agricultural activity. The study provides empirically informed insights about the direction to which these savannas are changing with the hope that the findings will prompt formulation and implementation of effective policies.

This Master’s Professional Project is focused on the development of a draft Vegetation Management Plan for the City of San Luis Obispo Open Space properties. The purpose of the plan is to provide a comprehensive document which identifies how the city is addressing wildfire preparedness in city-owned open space properties. Methods used in plan development include a literature review, content analysis, geographic information systems (GIS), a course audit, and consultation with city staff and other stakeholders. Each open space property is identified in the plan, describing its location, vegetation, topography, assets, access points, water supply, evacuation routes, historical fire data, predominant risk exposure, current wildfire preparedness plan, priority ranking, and a proposed implementation plan.