Many natural areas and systems within urban landscapes are small or narrow. Landscape ecology studies within forested and agricultural landscapes have found that small natural areas that are protected from development or resource extraction through land use planning are significantly affected by adjacent land use changes. Some eventually lose the values for which they were protected. Studies also indicate that natural area boundary structures and functions are important determinants of the extent to which external threats affect adjacent natural areas. Few studies have empirically tested whether small or narrow urban natural areas that are protected from development through municipal land use planning are significantly affected by adjacent land use changes. However, municipal planners and forest managers are concerned that activities of residents living adjacent to the forest edge, commonly referred to as residential encroachment, may be degrading the social values, and ecological forms and functions of their woodlands. Studies have recorded evidence of human impacts within suburban forest edges, indicating that both recreation and yard-related activities are occurring and that these activities occur at significantly higher frequencies in the forest edge than in the interiors of these forests. However, no study has differentiated residential encroachment activities from those of other recreationists. In addition, although a number of municipalities have developed policies to address these activities, little is known about these policies, the extent to which they are implemented, or their effectiveness in protecting their small or narrow forested natural areas from residential encroachment activities. The principal research questions answered in this research are: 1) Do municipalities within Southern Ontario have policies for protecting natural areas from the activities of residents living adjacent to suburban forest edges? 2) To what extent are they implementing these policies? 3) What encroachment activities, if any, are occurring in Southern Ontario municipal forest edges? and 4) Are municipal boundary-related policies effective in limiting edge-resident encroachment activities? Using a mixed method approach, the research incorporates qualitative and quantitative data collection to answer these questions. The content analysis of official and secondary plans and social surveys of key informants within six Southern Ontario municipalities identify boundary-related policies for protecting municipal natural areas from residential encroachment activities. They also determine the extent to which the study municipalities implement these policies. Field studies in 40 forests within these municipalities used unobtrusive measurements of encroachment behaviour to describe encroachment activities under two implemented municipal boundary demarcation policies, and other boundary treatments The three research methods, together with a literature review, were used to determine whether Ontario municipal policies are effective in limiting edge-resident encroachment activities within municipal forest edges. The content analysis and interviews indicated that, in general, municipal policies were insufficient to address the edge-resident encroachment issue. Policies had been established, but not at a sufficiently authoritative policy level (i.e. the official plan level) to support their implementation by staff. In addition, policies were missing explicit goals, objectives and strategies to direct their implementation, and the municipalities had not integrated their disparate policy components into an integrated course of action through time and space. The municipalities were successful in implementing policies to prevent edge resident encroachment within natural areas adjacent to newly developing subdivisions. However, they had infrequently implemented their policies for preventing encroachment within natural areas adjacent to established subdivisions. Furthermore, all the municipalities were not frequently implementing their policies to remediate existing encroachments within natural areas adjacent to newly developing or established subdivisions. The unobtrusive measurement of encroachment behaviour confirmed that residential encroachment activities generated a housing effect zone of impact within municipal forest edges. The distribution of the evidence of encroachment was significantly biased to the forest border. Encroachment traces were highly prevalent within study forests, occurring in over 94% of sites and covering 26 to 50% of the sampled area. Encroachment traces were particularly intense in the first 8 metres from the forest border; but extended a mean maximum extent of 16 metres from the forest border, with 95% of the evidence of encroachment lying within 34 metres. Boundary type significantly affected the mean frequency, intensity and maximum extent of encroachment. Mean frequencies, intensities and extents of all encroachment, and of most encroachment categories, were generally higher in sites with boundary types that allowed edge residents ready access to the forest edge. Conversely, sites with boundary treatments that had barriers to entry, such as fences or grass strips, tended to have lower encroachment levels. Sites with multiple barriers, such as those with fences, grass strips and paths, tended to have the lowest mean frequencies, intensities and mean maximum extents of encroachment. While sites with implemented municipal post and fence policies had significantly lower mean frequencies, intensities and, in the case of fences extents of encroachment, they were not significantly different from those of sites under some of the boundary types not subject to municipal policies. They were also significantly higher than those of sites with fences and grass strips (with or without pathways). Sites with municipal posts had significantly lower mean intensities of encroachment than sites with other boundaries that enabled residents to enter the forest edge, and had significantly lower mean frequencies of waste disposal traces than fenced sites. Sites with fences also had significantly lower mean intensities of encroachment than sites with no boundary demarcation, or sites with fences and gates, and were particularly effective in reducing the incidence of yard extension encroachments, and mean maximum extents of encroachment. Despite the effectiveness of these boundary demarcation policies, and that of some of the other boundary treatments evaluated, none of the boundary treatments was effective in eliminating encroachment traces. A buffer of between 10 and 20 metres in width would be required to segregate the mean maximum extent of encroachment activities from sensitive forest edges, depending on the boundary demarcation policy, or type. The research concludes that current municipal policies are insufficient to meet the complexity and scope of the encroachment activities occurring. Some preventative policies have been developed and are regularly implemented within natural areas adjacent to new subdivisions. However, implemented boundary demarcation policies are insufficient to eliminate, or minimize residential encroachment. Wider more complex boundary policies that limit different types of encroachment and include elements that reduce access, spatially separate, and encourage informal residential surveillance (such as fences, grass strips and pathways) can further reduce encroachment levels. Few municipalities have established boundary demarcation policies to prevent encroachment within natural areas adjacent to established subdivisions, and study municipalities infrequently implement policies and bylaws to mitigate existing encroachments within these areas. Yet interviewees, and the results of the unobtrusive measurement of encroachment in study forest edges, indicate that encroachment activities are highly prevalent within these municipal forests. Policies at all levels, and particularly at the official plan level, are required to protect natural areas from edge resident encroachment, and other forms of post development impacts on natural areas. These policies are required to support the more rigorous enforcement of encroachment bylaws, and the negotiation, and implementation of effective buffers and boundary demarcation treatments. In consideration of these results and conclusions, the dissertation describes the implications for municipal planning policy and urban and regional planning theory, and provides recommendations for future research.

Utilizing the analytical solution of the steady state sharp interface saltwater intrusion model in coastal aquifers, a multi-objective optimization formulation of pumping rates and well locations in a coastal aquifer is formulated to solve problems in water management practice. The proposed optimization problem uses progressive genetic algorithm technique and the method developed is applied to the previous work of Cheng et al. [2000]. Through this analysis, several other applications are provided to demonstrate the use of the model in practical applications. This work is the first to optimize pumping rates as well as well locations simultaneously in coastal aquifer management. Known the limitation of the analytical solution, the work is expanded to cover the physics of saltwater intrusion in a more realistic way. This is variable density flow in a variably saturated porous medium. In this method, mixing between two fluids such as saltwater and freshwater can be described and the porous medium is also expanded to cover saturated and unsaturated zones together. One of the objectives is to develop a three dimensional physical model, verify the model, and apply to various applications in coastal aquifers. The developed model, TechFlow, is used to investigate instability issues associated with the numerical solution of the Elder problem in the perspective that includes physical instability issues associated with density differences used in numerical solutions, sensitivity of the solution to idealization irregularity, and the importance of accurate estimation of the velocity field and its association to the grid density levels that is necessary to solve the problem accurately. Saltwater intrusion hydrodynamics in a beach under the influence of tidal effects is also investigated using TechFlow. Based on the results of TechFlow with the use of various boundary conditions for the transport equation, the saltwater intrusion hydrodynamics in a beach under the influence of tidal effects shows unique dynamics. These solutions are primarily affected by density differences, tidal effects on a mild slope, variably saturated porous medium and finite domain solution condition. TechFlow is also used to investigate saltwater upconing beneath pumping wells both two- and three-dimensional applications.

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Woody plant encroachment is one of the major problems worldwide because it affects negatively the herbaceous layer, which provide forage for livestock production. However, the role of ruminants particularly browsers in the dispersal of woody plant seeds still remains a concern for farmers interested in grass production. Seedpods of various woody plant species constitute a crucial part of the diet of herbivores during the dry season because of their high nutritional quality compared to herbaceous material. The interaction of associated diet quality, seed characteristics and animal species among other factors play a pivotal part in the success of livestock faecal seeds dispersion. Furthermore, dispersed seeds that successfully grow into mature woody plants become an important source of protein for herbivores. The use of woody plants as a source forage is known to be limited by plant secondary metabolites (PSMs) such as condensed tannins. The objectives of this study were to determine 1) the effects of condensed tannins and crude protein of Vachellia tortilis and Dichrostachys cinerea pods in seed recovery and germination fed to goats, and 2) the effects of diet mixing on the feed intake of plant species by goats. In the first experiment, a total of 12 female indigenous goats and 12 female Pedi sheep were utilised in this study, with the average body weights of 29.50 kg ± 1.60 (S.E) and 28.70 kg ± 1.60, respectively. Twelve goats were grouped into two groups of six goats per group, one group was fed D. cinerea pods and the other group was fed V. tortilis pods. The group of 12 sheep were divided similarly, the one group was fed D. cinerea pods and the other group was fed V. tortilis pods. Each animal was given V. tortilis and D. cinerea pods at 2.50% of their body weight. All animals were allowed to consume D. cinerea or V. tortilis pods within 24 h, after which the remaining pods were collected and weighed. Faecal collection commenced immediately after the 24 h pods feeding and was carried on until no seeds were discovered in faeces. All faeces extracted from sheep and goats were collected daily in the morning from the faecal bags. In the second experiment, a total of 24 indigenous goats with average body weight of 26.6 kg ± 0.51 were utilised. Goats were arbitrarily selected and grouped into four groups of six goats per group (goats were placed individually in 2 m2 pens). Each group was fed one of the following diets: diet one - Searsia lancea, diet two - S. pyroides, diet three - Euclea crispa and diet four - was a combination of the three plant species (Searsia lancea, S. pyroides and Euclea crispa). Searsia lancea, S. pyroides and E. crispa branches were collected every morning prior to feeding, and were weighed before offering the animals. Refusals were gathered and weighed, and intake was calculated as distinction between weight in and refusals. Plant species foliage were analysed for crude protein, condensed tannin, acid detergent lignin, acid detergent fibre and neutral detergent fibre. During the first experiment, the cumulative percentage seed recovery of V. tortilis from goats (46.00 % ± 1.90) and sheep (52.00 % ± 2.93) was significantly higher than D. cinerea from goats (13 % ± 1.47) and sheep (24.00 % ± 1.16). Germination percentage of D. cinerea seeds that passed through the gastro-intestinal tract of goats (33.12 % ± 2.94) and sheep (36.00 % ± 2.68) was significantly higher than V. tortilis seeds that passed through the gastro-intestinal tract of goats (28.98 % ± 2.68) and sheep (23.04 % ± 2.81). Average D. cinerea (34.56 % ± 1.99) and V. tortilis (26.02 %± 2.10) seeds that went through the gastro-intestinal of goats and sheep had a significantly higher germination rate than the control (i.e. no passage through the gut; D. cinerea = 2.31 % ± 1.55, V. tortilis = 5.07 % ± 2.68). The high mean cumulative percentage seed recovery of V. tortilis (18.80 %) may be attributed to the relatively higher crude protein than D. cinerea (12.20 %). This may encourage animal seed dispersal and germination of woody plant species with relatively high crude protein content. In the second experiment, Searsia lancea contained 8.50 % CP, 21.46 % acid detergent fibre (ADF), 12.50 % ADL and 39.37 % NDF. Searsia pyroides had 9.03 % CP, 27.07 % ADF, 10.89 % ADL and 40.30 % NDF. Euclea crispa had 6.19 % CP, 26.20 % ADF, 16.63 % ADL and 30.02 % NDF. Mixed diet (combination of the three plant species) had 8.96 % CP, 23.72 % ADF, 11.13 % ADL and 38.28 % NDF. Searsia lancea had 2.70 % of CTs while S. pyroides had 5.20 % CT, E. crispa had 6.44 % CT and mixed diet had 7.20 % CT. The mean dry matter intake varied significantly among dietary groups (P < 0.001). Similarly, goats offered a mixed diet consumed more CTs (P < 0.01) than those offered individual forage species. The high mean cumulative percentage seed recovery of V. tortilis may be attributed to the higher crude protein of V. tortilis (18.80 %) than D. cinerea (12.20 %). Higher passage rate may encourage animal seed dispersal and germination of plant species. The results from experiment two support the postulation that animals foraging in mixed diet systems consume more PSMs and achieve higher dry matter intake than animals confined to monocultures or single species feeding systems. Given that woody plant encroachment is already reducing farm-grazing capacities in African savannas and this problem is predicted to double by 2050, strategies that improve herbivore ability to consume woody plants will increase forage availability and inform bush control programmes and policies. Moreover, the concomitant increase in CTs by goats exposed to diets with diverse species also has positive implications for animal / Agriculture, Animal Health and Human Ecology / M. Sc. (Agriculture)

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The influence of soil water repellency (WR) on vegetation recovery after a fire is poorly understood. This dissertation presents strategies to broaden opportunities for enhanced post-fire rangeland restoration and monitoring of burned piñon and juniper (P-J) woodlands by: 1) mapping the extent and severity of critical and subcritical WR, 2) determining the influence of WR on soil ecohydrologic properties and revegetation success, and 3) evaluating the suitability of a wetting agent composed of alkylpolyglycoside-ethylene oxide/propylene oxide block copolymers as a post-fire restoration tool for ameliorating the effects of soil WR and increasing seedling establishment. Results indicate that: • Post-fire patterns of soil WR were highly correlated to pre-fire P-J woodland canopy structure. Critical soil WR levels occurred under burned tree canopies while sub-critical WR extended out to approximately two times the canopy radius. At sites where critical soil WR was present, infiltration rate, soil moisture, and vegetation cover were significantly less than at non-hydrophobic sites. These parameters were also reduced in soils with subcritical WR relative to non-hydrophobic soils (albeit to a lesser extent). Aerial photography coupled with feature extraction software and geographic information systems (GIS) proved to be an effective tool for mapping P-J cover and density, and for scaling-up field surveys of soil WR to the fire boundary scale. • Soil WR impairs seed germination and seedling establishment by decreasing soil moisture availability by reducing infiltration, decreasing soil moisture storage capacity, and disconnecting soil surface layers from underlying moisture reserves. Consequently, soil WR appears to be acting as a temporal ecological threshold by impairing establishment of desired species within the first few years after a fire. • Wetting agents can significantly improve ecohydrologic properties required for plant growth by overcoming soil WR; thus, increasing the amount and duration of available water for seed germination and seedling establishment. Success of this technology appears to be the result of the wetting agent increasing soil moisture amount and availability by 1) improving soil infiltration and water holding capacity; and 2) allowing seedling roots to connect to underling soil moisture reserves.

Wetlands are fragile ecosystems that deliver a wide range of environmental and ecosystem services that contribute to human well-being. This fragility has seen a number of wetlands succumb to degradations and loss arising from different causes. The positive contribution of wetlands to various ecosystems and the increasing rate of their degradation and loss has been a cause for concern to different stakeholders for a long time. One of the landmark indications of this concern is the constitution of the Ramsar Convention that was held in Iran in 1971 with the objective of addressing concerns regarding to wetland degradation and loss. Among the competing land uses resulting in wetlands loss and degradation could be listed urban agriculture, industrial development and housing. The research sought to assess the extent of wetland degradation with respect to housing developments in Harare, Zimbabwe. The dilemma as to why and how wetlands were being degraded was an issue of concern. The research sought to determine whether abatement or mitigation measures were in place to address the challenges Associated with wetlands loss and degradation. The subsequent growth of developments, their associated activities and possible intervention measures had to be thoroughly assessed. The administration of questionnaires and conducting of interviews was done to solicit data from the respondents. Collected data was analyzed through the Statistical Package for Social Scientists. Further to this, Google satellite imagery was used in the mapping of the Belvedere North and Epworth suburbs. Disturbed and undisturbed portions of the wetlands were analyzed by Geographical Information System software. Direct observation of the wetland area was used to examine existing natural features. To determine extent of pollution, water samples were collected in the wetlands and submitted to the laboratory for analysis. Analysis of selected chemical and physical parameters was carried out in the laboratory using selected methods. The research made two important and broad findings. First, both the Belvedere North and Epworth wetlands have been severely degraded by anthropogenic activities with housing developments and urban agriculture as the major contributors of this degradation. The development of residential properties in the wetlands is a result of a high demand for residential space in Harare. Whereas housing developments in Belvedere are formal and planned, developments in Epworth were informal and haphazard. With no formal planning, the Epworth wetlands have been severely impacted by water and sand extraction as well as contamination of underground water by pit-latrines that are common in these informal settlements. Second, the research also found that wetland degradation was closely associated with the lack of clear wetland policies both at national and local levels. The laboratory results showed that the water in Epworth was more polluted than the water in Belvedere. The measure of pollutants in Epworth was higher due to the activities being carried out as compared to Belvedere. Measures of Dissolved Oxygen, Total Dissolved Substances and conductivity increased from October to March in Epworth. Of note is the measure of Dissolved Oxygen that increased between October and March with a mean of 7.9 and 2.5 respectively. Total nitrogen and total phosphate also increased significantly in midstream and downstream sections. In essence, averages of 0.01 in October and 0.04 in March were recorded respectively for total nitrogen. The study concludes that an integrated land use approach has the potential of minimizing wetland loss and degradation. This is possible through the formulation and implementation of a comprehensive policy involving all relevant stakeholders. This will ensure a coherent decision making process. In as much as integrated land use planning and policy formulation are potential approaches to wetland sustainability, the drive to implement policy by policy makers concerning wetlands has to be explored. As ignorance concerning the ecological importance of wetlands exists in some cases, it is critical to consider wetland benefits above other competing developments such as housing and urban agriculture. This can be achieved through merging interrelated disciplines with the idea of integrating wetland information. For instance, deriving engineering solutions could promote development yet preserving wetlands. It is also suggested that environmental impact assessments, as planning tools should be carried out simultaneously with the town planning aspect. If given to proper planning, wetlands have a huge chance of survival. / Environmental Sciences / M.Sc. (Environmental Management)

Thesis (MScAgric)--Stellenbosch University, 2002. / ENGLISH ABSTRACT: African Acacia species are often major contributors to the progressive increase in the woody component of savannas, a phenomenon commonly referred to as bush encroachment. In Hluhluwe- Umfolozi Park, the numbers of adult Acacia nilotica (L.) Willd. Ex Del. trees per hectare far exceed (by III) that of A. karroo Hayne adults. The relative dominance is reversed in the juvenile stage with A. karroo (725 ha') outnumbering A. nilotica (225 ha-I) threefold outside closed woodlands. African acacias produce large quantities of seed and may have large soil-stored seed banks. They suffer pre-dispersal predation by bruchid beetles and may be either wind or animal dispersed. Once dispersed they are vulnerable to post-dispersal attack. This study tested several hypotheses regarding various aspects of seed ecology of A. karroo and A. nilotica. The null hypothesis that seed ecology does not contribute to the success of A. karroo over A. nilotica, was tested. Acacia karroo trees were smaller (mean basal diameter: 7.8 cm) than A. ni/otica trees (mean basal diameter: 18.5 cm) on average, but produced more seeds (A. karroo mean: 1628; A. nilotica mean: 992) for a given basal diameter size class. It was found that A. karroo showed less bruchid infestation (mean: 1.36-3.81%) than A. nilotica (mean: 14.67-86.70%) at all stages of pod development with a proportion of A. karroo seeds (7.1 %) being able to germinate after bruchid attack. Bruchid attack rendered A. ni/otica seeds unviable. There was no difference between the two species with regards to the soil-stored seed bank and the viability of seeds found in the soil. Acacia karroo showed higher germination levels (5.1%) and better establishment (4.9%) than A. nilotica (1.5% and 0.4% respectively). On average, there was no difference in germination levels between burnt and unbumt seeds, but there was a significant difference in germination of burnt seeds in both burnt (4.5%) and unbumt (2.5%) sites and unbumt seeds in both burnt (2.8%) and unbumt (4.9%) sites when considered separately. Post-dispersal predation of A. karroo seeds (21.8%) was higher than that of A. nilotica (12.7%). There was more rodent predation in tall grass areas (26.0%) than short grass (10.7%) or canopy areas (15.2%), and most seeds were lost from unprotected control groups. Rodent presence was a significant factor in unexplained seed disappearance. The ability of A. karroo to germinate easily and the low levels of beetle predation experienced by this species seemed to be its main advantage over A. nilotica as an encroaching species in Hluhluwe-Umfolozi Park. / AFRIKAANSE OPSOMMING: Die Acacia spesies van Afrika is dikwels belangrike bydraers tot die progressiewe toename in die houtkomponent van savannas. Hierdie verskynsel word algemeen na verwys as bosindringing. In die Hluhluwe-Umfolozi Park is die aantal volwasse Acacia nilotica (L.) Willd. Ex Del. bome per hektaar aansienlik meer (l l l meer) as die aantal volwasse A. karroo Hayne bome. In die jong stadium is die oorheersing omgekeerd, met driekeer soveel A. karroo (725 ha-I) as A. nilotica (225 ha-I) bome buite beboste gedeeltes. Afrika se Acacia spesies produseer groot hoeveelhede saad en kan oor aansienlike grond-gebergde saadbanke beskik. Voor verspreiding word die saad aan predasie deur bruchid-kewers blootgestel. Die saad kan óf deur wind óf diere versprei word en na verspreiding word dit ook aan predasie blootgestel. Hierdie studie het verskillende hipoteses rakende verskeie aspekte van die saadekologie van A. karroo en A. nilotica getoets. Die nulhipotese dat saadekologie nie tot die groter sukses van A. karroo teenoor A. nilotica bydrae nie, is getoets. Acacia karroo bome was oor die algemeen kleiner (gemid. basale omtrek: 7.8 cm) as A. nilotica (gemid. basale omtrek: 18.5 cm) bome maar het meer saad (A. karroo gemid.: 1628; A. nilotica gemid.: 992) per gegewe basale diameter grootte klas gelewer. Daar is geen verskil tussen die twee spesies rakende grondgebergde saadbanke en die lewensvatbaarheid van hierdie saad gevind nie. Acacia karroo het hoër vlakke van ontkieming (5.1%) en beter vestiging (4.9%) as A. nilotica (l.5% en .4% respektiewelik) getoon. Daar was oor die algemeen geen verskil in die ontkiemingsvlakke van gebrande en ongebrande sade nie, maar wel 'n beduidende verskil in die ontkieming van gebrande sade in beide gebrande (4.5%) en ongebrande (2.5%) areas en ongebrande sade in gebrande (2.8%) en ongebrande (4.9%) areas as dit afsonderlik geëvalueer is. Die predasie van A. karroo saad na verspreiding (21.8%) was hoër as dié van A. nilotica (12.7%). Daar was meer knaagdier-predasie in gebiede met lang gras (26.0%) as dié met kort gras (10.7%) of boomryke gedeeltes (15.2%). Die meeste saad is in onbeskermde kontrolegroepe verloor. Die teenwoordigheid van knaagdiere het 'n belangrike rol in die onverklaarde verdwyning van saad gespeel. Dit is gevind dat A. karroo se vermoë om maklik te ontkiem, asook die lae vlakke van insek skade aan die saad, die belangrikste voorsprong is wat dié spesie oor A. nilotica as 'n indringer in Hluhluwe-Umfolozi Park het.