Thesis (D. Phil.)--University of Nairobi, 1973. / Includes bibliographical references.

Thesis (Ph.D.)--University of Delaware, 2007. / Principal faculty advisor: Stephen Craig Cary, College of Earth, Ocean, & Environment. Includes bibliographical references.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1967. / Typescript. Vita. Description based on print version record. Includes bibliographical references (leaves 151-173).

Thesis (Ph. D.)--University of Oregon, 2000. / Typescript. Includes vita and abstract. Includes bibliographical references (leaves 132-150). Also available for download via the World Wide Web; free to University of Oregon users.

xvii, 141 p. A print copy of this thesis is available through the UO Libraries. Search the library catalog for the location and call number. / This study considers the role of the forest ecosystem in Trinity County, California's economy. I seek to better understand the natural resource-based economy of a national forest-proximate community by creating a framework that describes the resource flows into and out of Trinity County and guides ecosystem services valuation within the County. Thus, this study examines the monetary benefits that ecosystem functions create through delivery of goods such as water, energy, and timber and also estimates the value of services, such as recreation, carbon sequestration, and amenity value. Finally, this study examines how money is spent to maintain the ecosystem functions that create these goods and services, such as who pays to maintain water collection and filtration capacity or habitat. Ultimately, this study offers insight into opportunities and limitations for ecosystem services valuation at the county level, and considerations for future attempts to value ecosystem services. / Committee in Charge: Cassandra Moseley, Chair; John Bliss; Trudy Cameron

Doctorat en Sciences / info:eu-repo/semantics/nonPublished

This study explores two interlinked aspects of human-environment relationship—cash crop development and biodiversity conservation—by examining the situations of the Hmong people, the largest traditional pioneer swidden group in the Thai highlands. Cash crop adoption among the Hmong have occurred in two main ways. The first involves the adoption of low-input upland crops and a shift to high-input vegetable crops. This pattern is found in the Lower North and spread to the Upper North, particularly in Tak, Phrae, Nan, Payao and Chiang Rai. The adoption is closely linked to the development of roads into the uplands and the diffusion of maize cultivation in the lowlands. The second pattern is a direct shift from opium to high-input crops, particularly cabbage. Large scale cabbage growing began in the early 1980s as a response to the demand for off-season vegetables. The most important driving factors behind cash crop adoption were the government poppy eradication activities, the contacts between market agents and the Hmong and the increased accessibility of Hmong villages. Adoption was facilitated by favourable market prices at the initial period and by the Hmong clan network. Each type of cash crops has had its particular effects on the Hmong socio-economy. Cut-flowers bring small but regular income into a household while cabbages bring a lump sum, a few times a year. Cabbage production induces high level of truck ownership leading to increased mobility, rapid diffusion of innovations, changing cultural values and increased uses of lowland services (such as health care, schools, market, etc.). Flower production, on the other hand, allows women to take active parts in marketing. The study also found a type of movement not discussed in earlier literature, the temporary migration of households or parts of households to take advantage of successful cash crop cultivation in other villages for a period of 1–2 years. The examination of four cash crops: opium, maize, cabbage and carnations shows that the Hmong have gradually shifted from land extensive to land intensive cash crops. This move to economize on land is, however, recompensed by the need for high inputs in agriculture. The more land intensive the crop is, the more fertilizers and pesticides are used. Comparisons between crops on three variables: population-land ratio, income and pesticide used per unit area, suggest that cut-flowers may be a superior crop, if measures to reduce pesticide uses can be found. Cash crop adoption affect the relationships between the people and wildlife in three ways. First, the labour-intensive nature of cash crop production prevents farmers from spending as much time in the forest as in the past. Second, cash crops provide incomes which allow the people to obtain meat from the market and thus reducing the needs for wild meat. Third, cash crop economy orients people toward the lowland, resulting in weakening traditional knowledge about wildlife behaviours, hunting or trapping. Most Hmong view hunting as a leisure activity, and some, particular women, see it as a waste of time. Reduced hunting, however, has not lessen the pressure on wildlife as the population of all species are reportedly declining. Many Hmong villages have rules against hunting some species, particularly gibbons. This rule is respected by most people but not all. Since the people do not feel that their livelihood is greatly affected by the disappearance of wildlife, the direct relationships between economic improvement and conservation is not clearly apparent. / Graduate

This study explores two interlinked aspects of human-environment relationship—cash crop development and biodiversity conservation—by examining the situations of the Hmong people, the largest traditional pioneer swidden group in the Thai highlands. Cash crop adoption among the Hmong have occurred in two main ways. The first involves the adoption of low-input upland crops and a shift to high-input vegetable crops. This pattern is found in the Lower North and spread to the Upper North, particularly in Tak, Phrae, Nan, Payao and Chiang Rai. The adoption is closely linked to the development of roads into the uplands and the diffusion of maize cultivation in the lowlands. The second pattern is a direct shift from opium to high-input crops, particularly cabbage. Large scale cabbage growing began in the early 1980s as a response to the demand for off-season vegetables. The most important driving factors behind cash crop adoption were the government poppy eradication activities, the contacts between market agents and the Hmong and the increased accessibility of Hmong villages. Adoption was facilitated by favourable market prices at the initial period and by the Hmong clan network. Each type of cash crops has had its particular effects on the Hmong socio-economy. Cut-flowers bring small but regular income into a household while cabbages bring a lump sum, a few times a year. Cabbage production induces high level of truck ownership leading to increased mobility, rapid diffusion of innovations, changing cultural values and increased uses of lowland services (such as health care, schools, market, etc.). Flower production, on the other hand, allows women to take active parts in marketing. The study also found a type of movement not discussed in earlier literature, the temporary migration of households or parts of households to take advantage of successful cash crop cultivation in other villages for a period of 1–2 years. The examination of four cash crops: opium, maize, cabbage and carnations shows that the Hmong have gradually shifted from land extensive to land intensive cash crops. This move to economize on land is, however, recompensed by the need for high inputs in agriculture. The more land intensive the crop is, the more fertilizers and pesticides are used. Comparisons between crops on three variables: population-land ratio, income and pesticide used per unit area, suggest that cut-flowers may be a superior crop, if measures to reduce pesticide uses can be found. Cash crop adoption affect the relationships between the people and wildlife in three ways. First, the labour-intensive nature of cash crop production prevents farmers from spending as much time in the forest as in the past. Second, cash crops provide incomes which allow the people to obtain meat from the market and thus reducing the needs for wild meat. Third, cash crop economy orients people toward the lowland, resulting in weakening traditional knowledge about wildlife behaviours, hunting or trapping. Most Hmong view hunting as a leisure activity, and some, particular women, see it as a waste of time. Reduced hunting, however, has not lessen the pressure on wildlife as the population of all species are reportedly declining. Many Hmong villages have rules against hunting some species, particularly gibbons. This rule is respected by most people but not all. Since the people do not feel that their livelihood is greatly affected by the disappearance of wildlife, the direct relationships between economic improvement and conservation is not clearly apparent. / Graduate

Solar evaporite systems are man-managed ecosystems which are highly vulnerable to biological,physical and chemical disturbances. The problems encountered in such systems are in many cases found to be associated with the microbial ecology and the design of the system. This project focussed on investigating the nature of organic compounds contaminating soda ash produced at a solar evaporite production system located at Sua Pan in Botswana. Several years after the plant was commissioned, problems, including accumulation of total organic carbon (TOC) and discolouration of the soda ash product were encountered. The salt produced also retained high moisture content and was coloured pink. These phenomena impacted severely on the economic performance of the enterprise. This study was aimed at determining the origin and fate of these organic compounds within the system in order to elucidate the nature of the problem and also to conceptualise a remediation strategy suitable to reducing its impact. This was achieved by analysis of both dialysed and solvent extracts of the influent brine (well-brine), brine in the ponds (T-brine) and the bicarbonate filter cake. Although complete identification of the organic compounds isolated was not undertaken in this study, spectroscopic analysis of compounds isolated, by UV, IR, NMR and MS, strongly indicated that fulvic acids, a component of the influent well-brine organics, contribute to the organic contamination of the final product. Part of this component, however, is degraded during the ponding process. It was shown that an extracellular polysaccharide (EPS) produced by Dunaliella. spp., which proliferates in the evaporation ponds, contributes in a major way to the accumulation of TOC in the system. This was demonstrated by relating the sugar profile of carbohydrates isolated from the pond brine and final product, being arabinose, xylose, 2-o-methyl hexose, mannose, glucose and galactose. Studies reported show that EPS production was enhanced when algal cultures were exposed to stress conditions of high illumination, increasing salinity and temperature, and nitrogen limitation. Studies undertaken for the development of a remediation process for this system have shown that nutrient stripping and bacterial systems could be applied to deal with the dissolved TOC fraction, whereas adsorption systems could deal with the particulate fractions. Algal systems showed most potential for the removal of nutrients in the influent well-brine compared to chemical processes.Complete removal of ammonium and phosphorus removal efficiencies of pproximately 50% were achieved in an unoptimised pilot-scale Dunaliella-based HRAP. While similar effects were demonstrated for chemical processes, some economic constraints were noted. The potential of halophilic bacterial systems for the degradation of organic compounds in brine was also demonstrated. The limitations on the performance of such systems, associated with the low metabolic diversity, and poor immobilisation of physico-chemical processes were found to have a very low impact on the dissolved TOC fraction of the brine, the removal of the particulate material was found to result in a 35% TOC reduction in the final soda ash product and the production of a white final product.halobacteria, however, were noted. Although physico-chemical processes were found to have a very low impact on the dissolved TOC fraction of the brine, the removal of the particulate material was found to result in a 35% TOC reduction in the final soda ash product and the production of a white final product. Apart from a description of the microbial ecology of the ponds and the identification of major contributions to the TOC of the final product, a number of remediation strategies were evaluated and are described. These include chemical and biological stripping of nutrients sustaining microbial TOC production in the ponds, and also biological and physico-chemical processes for their removal once formed. Future studies to undertake the further development of these proposals has been described

Marine unconsolidated sediments constitute the largest ecosystems on earth in terms of spatial coverage, but there are still critical gaps in the science required to support conservation and ecosystem-based management. This is mainly due to the inaccessibility of these ecosystems in wave-exposed environments or deeper waters and the difficulty in observing biota in their three-dimensional sedimentary habitat. Currently, the physical driving processes of intertidal unconsolidated sediment ecosystems are much better understood than those of the subtidal ecosystems. However, these ecosystems are linked through water and sediment movement. This thesis, therefore, considers the continuum of unconsolidated sediment ecosystems across the entire continental shelf (i.e. intertidal to the shelf edge). The aim of this thesis was two-fold; (i) to advance the foundational understanding of biodiversity patterns and driving processes in unconsolidated sediment habitats, and (ii) to apply this knowledge in the development of a systematic conservation plan for marine unconsolidated sediment ecosystems. The South African west coast continental shelf was used as a case study in order to represent Eastern boundary upwelling regions. This study sought to investigate biodiversity patterns in macro-infaunal communities and determine their driving processes for incorporation into habitat classifications and the development of a habitat map. Systematic conservation plans require a map of biodiversity patterns and processes, and quantitative conservation targets to ensure representation of all biodiversity features including habitats.in marine protected areas. This thesis provided these key elements by classifying the unconsolidated sediment habitats and determining habitat-specific evidence-based conservation targets to support conservation of these important ecosystems. The application of these elements was then demonstrated in a systematic conservation plan for the unconsolidated sediment ecosystems of the South African west coast. Diversity patterns were examined using physical and macro-infauna data, ranging from the beach to the shelf edge (0-412 m). These data were analysed to develop two different habitat classifications, namely seascapes derived from geophysical and biophysical data, and biotopes derived from the combination of macro-infaunal and physical data. Multivariate analyses of 13 physical variables identified eight seascapes for the unconsolidated sediment samples from 48 sites on the South African west coast. These were based on depth, slope, sediment type, and upwelling-related processes (i.e. maximum chlorophyll concentration, sediment organic carbon content and austral summer bottom oxygen concentration). Latitude and bottom temperature were not considered major drivers of seascapes on the west coast because latitude closely reflected changes in upwelling-related processes and the temperature range was narrow across the shelf. This study revealed that productivity, a biophysical variable not usually included in geo-physical habitat classifications, played a significant role in the definition of seascapes on the South African west coast. It is therefore recommended that productivity be included in future seascape classifications to improve the utility of these classifications particularly in areas of variable productivity. Seascapes should, however, be tested against biological data to improve the understanding of key physical drivers of communities in unconsolidated sediment ecosystems. Macro-infaunal community distributions were determined along with their physical drivers for the unconsolidated sediments of the South African west coast. A total of 44 828 individuals from 469 taxa were identified from 48 sites representing 46.2 m2 of seafloor. Seven distinct macro-infaunal communities were defined through multivariate analyses and their key characteristic and distinguishing species were identified. These communities reflected five depth zones across the shelf, namely beach, inner shelf (10-42 m), middle shelf (60-142 m), outer shelf (150-357 m) and shelf edge (348-412 m). The processes driving the community structure of these depth zones were postulated to be tides, wave turbulence, seasonal hypoxia, habitat stability and homogeneity, and internal tides and/or shelf break upwelling, with drivers listed in order of increasing influence with depth. The middle shelf was further separated into three distinct communities based on sediment type, sediment organic carbon content and frequency of hypoxia. Variations in water turbulence, sediment grain size, upwelling-related variables and riverine sediment input were identified as the likely primary drivers of macro-infaunal community patterns. This chapter culminated in the development of a biotope classification based on the combination of macro-infaunal communities and their physical habitats (i.e. biotopes). South Africa has developed an expert-derived National Marine and Coastal Habitat (SANMC) Classification System which is used as a biodiversity surrogate in ecosystem assessment and spatial planning. This thesis tested the validity of this classification and the data derived Seascape classification against macro-infauna species abundance and biomass data in an effort to determine how well the different classifications represent macro-infaunal diversity of the west coast. These two classifications were also compared to the Biotope classification which combines macro-infaunal communities with their physical habitats. A canonical analysis of principle coordinates (CAP) was utilised to test the success with which each sample was allocated to the relevant habitat type in each classification. The total allocation success for each classification was used as a measure of effectiveness in terms of representing biodiversity patterns. Both classifications had similar allocation successes of 89-92 percent and 92-94 percent for the Seascape and National Habitat Classification respectively, but either over- or under-classified the macrofauna communities. The Biotope classification had the highest allocation success (98 percent), therefore it is the most accurate reflection of the macrofauna biodiversity patterns on the west coast. A key finding of this study was the increasing accuracy of classifications from physically- to expert- to biologically-derived habitat classifications. In this thesis, the Biotope classification was deemed the best representative of biodiversity patterns and was therefore used to produce the Biotope map for use in spatial assessment and planning. The distinct depth patterns that emerged in both the Seascape and Biotope classifications highlighted the need for further investigation of the relationship between depth and biodiversity. Despite variability in macro-infaunal communities, a general unifying pattern in biodiversity across the shelf was sought. Three relationships between depth and species richness have been described in the literature; namely a unimodal pattern, a positively linear relationship with depth, and no relationship between depth and species richness. These hypotheses were tested on the west coast. Two different species richness metrics were utilised to test the depth-diversity relationship, namely observed species density (spp.0.2m-2) and estimated species richness (spp.site-1). Observed species density increased from the beach to the shelf edge (350 m), then decreased to 412 m. The decline may have been due to difficulty in detecting species at greater depths as a result of sampling challenges. The inclusion of an innovative extrapolative method for estimating species richness (the capture-recapture heterogeneity model) within the Bayesian statistical framework mitigated the effects of species detection heterogeneity and revealed that species richness actually increased continuously across the shelf from beach to shelf edge. Thus the general relationship between depth and species richness is positively linear on the west coast of South Africa The new macro-infauna dataset and biotope map provided the opportunity to develop the first habitat-specific evidence-based conservation targets for unconsolidated sediments of the west coast. Species-Area Relationship (SAR) based conservation targets were developed for the biotopes using a modification of the generally accepted methodology. The accepted methodology has three steps (i) the estimation of total species richness for each habitat using the Bootstrap asymptotic estimator, (ii) the calculation of the slope of the species area curve (i.e. the z-value), and (iii) the calculation of targets representing 80 percent of the species. The inclusion of an innovative extrapolative species richness estimator, the Multi-species Site Occupancy Model (MSOM) provided better species richness estimation than the more conventional bootstrap species richness estimator, even though both are based on species accumulation. The MSOM, applied in the Bayesian statistical framework takes detectability of a species into account.