Thesis (Ph. D.)--Oregon State University, 2010. / Printout. Includes bibliographical references (leaves 125-136). Also available on the World Wide Web.

Thesis (M.S.)--Mississippi State University. Department of Geosciences. / Title from title screen. Includes bibliographical references.

Thesis (M.S.) -- Mississippi State University. Department of Biological Sciences. / Title from title screen. Includes bibliographical references.

Thesis (MScFor)--Stellenbosch University, 2013. / ENGLISH ABSTRACT: One of the major objectives in plantation forestry is to achieve a high level of homogeneity of distribution and dimension of trees within the stand. Precise planting geometries, intensive silviculture and genetic selection are used to achieve this homogeneity. However, a natural variability is still introduced by micro-­‐site conditions and disturbances. A substantial source of variation is caused by edge effects of neighbouring stands or other land use forms. The edge effect causes trees at the stand edge to develop differently from trees in the interior of the stand. The overarching objective of this study is to simulate the edge effect based on average stand interior variables as typically received from an enumeration and spatial information on the current and historic stand neighbourhood. With re-­‐introducing this natural variance as well as its spatial pattern, we expect to derive improved planning information. A major aim is thus separating the effect of the edge interaction from the other factors contributing to stand variance and quantifying the result in terms of stand output. A methodology is introduced for quantifying interaction at stand edges between a given stand and its neighbouring stands over its lifetime. Transferring the edge interaction value from the edges to all the trees within the stand is then done by applying inverse distance weighting interpolation from the edges to the tree position within the stand. Once an edge interaction value has been calculated for each point, the extent of the edge effect is quantified. The spatial extent of the edge effect is derived empirically from an existing fully spatially mapped stand by means of breakpoint regression. The expected variance as a result of edge influence is then quantified by producing a set of models, which can reproduce the effect of the edge interaction on tree height, diameter and volume. The edge effect is treated as a dynamic interaction for which the temporal aspect needs to be considered, because the current spatial structure of a stand is influenced by its current neighbourhood, but also by the historic development of the neighbourhood in relation to the stand in question. Each stand therefore undergoes an edge effect which is completely unique to that stand, within a given time period. For this reason the presented methodology is a spatial-­‐temporal one, aimed at providing a way in which growth and yield forest modelling can be augmented by the inclusion of the edge effect in a practical way. To explicitly quantify edge effects, the natural variance had to be separated into a component explained by edge effect and a second component introduced by other factors such as micro site conditions and disturbance. The second component is treated as an unexplained residual variance. In order to provide a realistic simulation of a stand output at a finer, tree level, this second stand variance needs nonetheless to be quantified. The variance attributable to factors other than the edge effect is mimicked by generating a random number by means of a parameterised stochastic process based on the variance of the inner stand region, which is beyond the reach of the edge effect. In this way, a realistic spatial pattern of a plantation forest stand, taking into account the edge effect and combining it with the natural stand variance is achieved. This study, within the field of plantation forest management, aspires to land use optimization both in terms of productive capacity estimation and for the provision of information for effective land use management planning. It makes use of open source software resources namely the R framework and QGIS and explores aerial stereophotogrammetry as an option for data collection. / AFRIKAANSE OPSOMMING: Een van die hoofdoelwitte in plantasie bosbou praktyk is hoё vlakke van homogeniteit met betrekking tot die verspreiding en die dimensies van die bome in die plantasie opstand. Simetriese aanplantings, intensiewe bosboupraktyk en genetiese seleksie word gebruik om hierdie homogeniteit te verkry. Natuurlike verskille word egter nog steeds gevind as gevolg van groeiplek mikro toestande en ander versteurings in die opstand. Een van die hoofbronne van hierdie variasie is die randeffekte van buurplantasies en ander gebruike van grond. Hierdie randeffekte veroorsaak dat bome aan die rand van die opstand anders ontwikkel as die bome binne in die opstand. Die oorhoofse doelwit met hierdie navorsing is om die randeffekte te simuleer. Hierdie randeffekte is gegrond op die gemiddelde binneopstand boom veranderlikes soos afgelei uit die opmeting en uit ruimtelike inligting oor die huidige en geskiedkundige toestande in die omgewing. As hierdie natuurlike variasies asook die ruimtelike patrone weer in berekening gebring word, verwag ons om beter beplanningsinligting te bekom. ’n Belangrike doelwit tydens hierdie navorsing is dus om die effek van die rand-­‐interaksie te skei van die effek van ander faktore wat bydra tot variasies binne-­‐in die opstand en om die resultaat in terme van plantasie produksie te kwantifiseer. ’n Metodiek word voorgestel vir die kwantifisering van die interaksie op die rande tussen die opstand en die buuropstande tydens die leeftyd van die opstand. Die oorplasing van die rand interaksie waarde van die rand af na al die bome in die plantasie word dan gedoen deur om geweegde inverse afstand interpolasie vanaf die rand tot by die ligging van die boom, toe te pas. As die rand interaksie waarde vir elke punt bereken is, kan die omvang van die randeffek gekwantifiseer word. Die ruimtelike omvang van die rand effek is, met die gebruik van breekpunt regressie, empiries afgelei van ’n bestaande ten volle karteerde plantasie. Die verwagte variasie as gevolg van die randeffek word dan met die gebruik van ’n stel modelle gekwantifiseer, wat dan die effek van die rand interaksie op boomhoogte, deursnit en volume kan weergee. Die randeffek word as ’n dinamiese interaksie beskou waarvan die tydsaspek in ag geneem moet word, want die huidige ruimtelike struktuur van die plantasie word beïnvloed deur die huidige omgewing asook deur die historiese ontwikkeling van die omgewing met betrekking tot die opstand onder bespreking. Elke opstand ondergaan ’n randeffek wat uniek is aan daardie plantasie op die gegewe tydstip. Die doelwit is om ’n wyse te vind waarvolgens groei-­‐en-­‐opbrengs plantasie modellering deur die insluiting van randeffek op ’n praktiese wyse, aangevul kan word. Om hierdie rede is die aanbevole metodiek ruimtelik-­‐tydelik en gerig daarop om ’n wyse te vind waarvolgens groei-­‐en-­‐opbrengs modellering deur die insluiting van die randeffek, op ’n praktiese wyse aangevul kan word. Om randeffek eksplisiet te kwantifiseer, moes die natuurlike afwyking gedeel word in die komponent wat die gevolg is van die randeffek, en ’n tweede komponent wat die gevolg is van ander faktore soos mikroligging toestande en versteurings. Die tweede komponent word behandel as ’n onverklaarde oorblywende afwyking. Hierdie tweede plantasie afwyking moet nogtans kwantifiseer word om sodoende ’n realistiese simulasie van plantasie opbrengs op ’n fyner boom vlak te verkry. Die afwyking wat toegeskryf kan word aan faktore buiten die randeffek, word nageboots deur om ’n lukrake nommer (wat gebaseer word op die afwyking van die binne-­‐plantasie gebied wat buite die strekwydte van die randeffek is) deur middel van ‘n geparameteriseerde stogastiese proses te genereer. Sodoende word ’n realistiese ruimtelike patroon van ’n plantasie opstand verkry, wat die randeffek in ag neem en dit kombineer met die natuurlike plantasie afwyking.

The mountains of Lesotho form the catchments for the Lesotho Highlands Water Project (LHWP), which is presently under construction, and their condition will determine the longevity of the LHWP. The mountain rangelands also support an extensive livestock system. However, there is concern that grazing is negatively affecting the mountain vegetation to the detriment of both livestock production and catchment function. Therefore, the impact of environment and grazing on the vegetation was investigated to aid the development of management policy for the conservation of the grazing, floristic and water resources of the mountains. Vegetation surveys were conducted in the mountains in the east (Study Area 1: 2 625 - 3 350 m a.s.l.) and in the west (Study Area 2: 2 240 - 3 125 m a.s.l.). Indirect gradient analysis (IGA) and classification were used to investigate the influence of environment on vegetation pattern. Results of the IGA indicated that variation in species composition in the mountains is related primarily to topographic variation, in particular elevation and aspect. Five vegetation communities were identified in Study Area 1 and seven in Study Area 2. These communities occurred consistently in specific topographic positions in the landscape and were arranged along a temperate/subtropical grass species continuum which was associated with a gradient in elevation and aspect. In Study Area 1, the elevation boundary between the high-lying temperate grasslands and the lower subtropical grasslands corresponded with the generally recognised boundary between the Alpine and Subalpine vegetation belts (viz. c. 2 950 m a.s.l. on northerly aspects and c. 2 750 m a.s.l. on southerly aspects). This boundary was lower in Study Area 2 (viz. c. 2 800 m a.s.l. on northerly aspects and c. 2 300 m a.s.l. on southerly aspects). Vegetation-insolation relationships were investigated in Study Area 1 using a model for simulating solar radiation, temperature and potential evaporation patterns on sloping terrain (RADSLOPE). The spatial distribution of the identified vegetation communities and the ratio of temperate (C₃) and subtropical (C₄) grasses in the sward were related to solar irradiance patterns, as influenced by topography. Results suggest that exposure, which increases with altitude, is probably also an important determinant of vegetation pattern in the mountains. The influence of grazing on the vegetation was studied by examining changes in species composition and cover that were associated with gradients in grazing intensity that exist around cattleposts in the mountains. There was little evidence of a shift in species composition and cover under grazing in the Alpine Belt but there was an identifiable grazing gradient in the Subalpine belt. There, short dense grasslands, dominated by palatable species, degrade to a dwarf karroid shrubland with sparse cover under prolonged, intense grazing. The optimum position along the grazing gradient of the more abundant species was identified. It was proposed that the relative positions, or scores, of these species along the grazing gradient can be used in a weighted scoring procedure to provide an index for monitoring the response of the mountain vegetation to grazing. However, the species’ scores still require verification. The need for monitoring temporal changes in vegetation composition and cover in order to assess the possible effects of the LHWP and other development initiatives was noted. Such monitoring should be undertaken in conjunction with an overall programme to assess the dynamics of the socio-economy in the mountains. Therefore, interdisciplinary monitoring programmes are required to achieve this. These programmes should be focused in a few key study locations rather than spread over a wide area. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg.

Indiana University-Purdue University Indianapolis (IUPUI) / Wetland habitats are characterized by periodic inundation and saturation by water creating anaerobic conditions that generate hydric soils and support hydrophytic vegetation. Wetland habitats provide important ecological functions including breeding grounds for fish, other wildlife, water purification, reduction in flooding, species diversity, recreation, food production, aesthetic value, and transformation of nutrients (Tiner, 1999). The multiple benefits of wetlands make them an important resource to monitor. A literature review suggests a combination of geospatial variables and methods should be tested for appropriateness in wetland delineation within local settings. Advancements in geospatial data technology and ease of accessing new, higher resolution geospatial data make study at local levels easier and more feasible (Barrette et al, 2000). The purpose of the current study is to evaluate new sources of geospatial data as potential variables to improve wetland identification and delineation. High resolution multispectral digital imagery, topographic data, and soils information are used to derive and evaluate independent variables. Regression analysis was used to analyze the data.

Includes bibliographical references. / xvii, 144, [89] leaves, [18] leaves of plates : ill. (some col.), maps ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Dept. of Botany, 1995?