The variations in discharge and water chemistry among and within headwater catchments are not well understood. Developing a better understanding of the processes that control these variations is crucial to determining how headwater catchments will respond to changes in climate and land use. This dissertation explores how hydrologic processes in headwater catchments may be better understood by utilizing a hydropedological framework, where similar soils are grouped together and considered to be representative of and developed by similar hydrologic and biogeochemical processes. In the first chapter, soil groups, called hydropedological units (HPUs) are found to be indicative of distinct water table regimes characterized by the interquartile range and median of shallow groundwater levels, the percent time water table exists in the soil, and the level of catchment storage at which groundwater responds. The second chapter explores the hydrological processes that may lead to the formation of HPUs in the catchment. By examining water table records and unsaturated water potential from tensiometers we found that lateral unsaturated flow regimes may be partially responsible for the patterns of lateral translocation observed in HPUs. Finally, the third chapter identifies two HPUs in the catchment as sources of streamwater dissolved organic carbon (DOC). While near-stream areas have typically been found to be DOC sources in headwater catchments, the HPUs identified as sources occur at high elevations in the catchment, near channel heads. Overall, these findings will be useful to better explain runoff generation, soil formation, and DOC export from headwater catchments. Headwater streams source water to larger bodies of water that are valuable natural resources. Therefore, explaining these processes is critical to predicting and responding to changes in climate and land use that may affect important water supplies. / Ph. D.

Experiments were conducted to monitor nutrient dynamics in the forest floor of an upland Appalachian oak forest stands following clearcutting and whole-tree removal. Samples from the L, F, H, and A₁ layers were collected during June, August, and November of 1979 and 1980. Monthly litterfall was collected from October, 1979, through October, 1980. Soil solution samples were extracted on a biweekly basis from April, 1980, through March, 1981, and concurrent soil moisture and temperature determinations were made. All samples were collected from the clearcut area and an adjacent uncut area. Nutrient analyses included total N, P, K, Ca, and Mg, and pH, NH₄-N, and NO₃-N for the soil solutions only. Comparisons were made between nutrient contents in the forest floor and mineral soil from the clearcut and uncut areas, between nutrient contents within forest floor layers within each area, and between nutrient contents collected over time within each area. Similar comparisons were made using litterfall nutrient contents and soil solution nutrient concentrations. Immediate clearcutting effects were most pronounced on the L layer of the forest floor, due to the logging slash input. Immediately after cutting the L layer in the cut area had a dry weight over 9,500 times that of the L layer in the uncut area. This logging slash rapidly became incorporated into the forest floor of the cut area, and after 15 months, the cut area had a forest floor slightly higher in dry weight and nutrient content than did the uncut area. Slash inputs accounted for these increases, since over the course of the study the cut area received only 14% of the litterfall that occurred in the uncut area. Soil temperature, moisture, and soil solution NH₄-N concentrations were all higher in the clearcut area. Soil solution NO₃-N concentrations were variable but generally the same in both areas. After 15 months following clearcutting and whole-tree removal, the forest floor in the clearcut area was slightly higher in dry weight and nutrient content than an adjacent uncut area, and no site degradation was noted. / Ph. D.

Thesis (M.S.)--Oregon State University, 2007. / Printout. Includes bibliographical references (leaves 42-54). Also available on the World Wide Web.

Thesis (M.S.)--Oregon State University, 2008. / Printout. Includes bibliographical references. Also available on the World Wide Web.

by Au Pui Sze. / Thesis submitted in: December 2000. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2001. / Includes bibliographical references (leaves 135-150). / Abstracts in English and Chinese. / Abstract --- p.i / Abstract (in Chinese) --- p.iii / Acknowledgement --- p.iv / Table of contents --- p.vi / List of tables --- p.x / List of figures --- p.xi / List of appendices --- p.xii / Chapter Chapter one --- Introduction / Chapter 1.1 --- The role of plantations in ecosystem rehabilitation --- p.1 / Chapter 1.2 --- Reforestation history in Hong Kong --- p.2 / Chapter 1.3 --- Conceptual framework of the study --- p.5 / Chapter 1.4 --- Objectives of the study --- p.15 / Chapter 1.5 --- Scope and significance of the study --- p.16 / Chapter 1.6 --- Organisation of the thesis --- p.17 / Chapter Chapter two --- The Study Area / Chapter 2.1 --- Geographical setting of Hong Kong --- p.18 / Chapter 2.1.1 --- Climate --- p.18 / Chapter 2.1.2 --- Geology --- p.20 / Chapter 2.1.3 --- Soils --- p.20 / Chapter 2.1.4 --- Vegetation --- p.21 / Chapter 2.2 --- Site selection --- p.23 / Chapter 2.3 --- Site description --- p.26 / Chapter 2.4 --- Nature and extent of disturbance prior to planting --- p.30 / Chapter 2.5 --- Planting techniques and post-planting maintenance --- p.31 / Chapter Chapter Three --- Stand Characteristics of Acacia Plantations / Chapter 3.1 --- Introduction --- p.33 / Chapter 3.2 --- Methodology --- p.37 / Chapter 3.2.1 --- Sampling plots design --- p.37 / Chapter 3.2.2 --- Tree density --- p.37 / Chapter 3.2.3 --- Tree growth parameters --- p.38 / Chapter 3.2.4 --- Data processing and statistical analysis --- p.38 / Chapter 3.3 --- Results and discussion --- p.39 / Chapter 3.3.1 --- Growth dynamics of acacias --- p.39 / Chapter 3.3.2 --- Growth characteristics of the reforested species --- p.44 / Chapter 3.3.3 --- Sustained growth and natural regeneration of acacia plantations --- p.48 / Chapter 3.3.4 --- Rehabilitation of degraded lands by exotic species plantations --- p.52 / Chapter 3.4 --- Conclusion --- p.54 / Chapter Chapter Four --- Cover Soil Characteristics of Acacia Plantations / Chapter 4.1 --- Introduction --- p.56 / Chapter 4.2 --- Methodology --- p.60 / Chapter 4.2.1 --- Soil sampling --- p.60 / Chapter 4.2.2 --- Laboratory analysis --- p.61 / Chapter 4.2.3 --- Texture --- p.61 / Chapter 4.2.4 --- Soil pH --- p.61 / Chapter 4.2.5 --- Organic carbon --- p.62 / Chapter 4.2.6 --- Total Kjeldahl nitrogen --- p.62 / Chapter 4.2.7 --- Carbon : nitrogen ratio --- p.63 / Chapter 4.2.8 --- Mineral nitrogen (NH4-N and N03-N) --- p.63 / Chapter 4.2.9 --- Available phosphorus --- p.64 / Chapter 4.2.10 --- Exchangeable cations --- p.64 / Chapter 4.3 --- Data processing and statistical analysis --- p.64 / Chapter 4.4 --- Results and discussion --- p.65 / Chapter 4.4.1 --- Effect of acacias on soil texture and pH --- p.65 / Chapter 4.4.2 --- "Effect of acacias on SOM, TKN and mineral N" --- p.69 / Chapter 4.4.3 --- Effect of acacias on the available P and exchangeable cations… --- p.77 / Chapter 4.4.4 --- Soil nutrient status of the plantations --- p.82 / Chapter 4.5 --- Conclusion --- p.90 / Chapter Chapter Five --- Understorey Vegetation of Acacia Plantations / Chapter 5.1 --- Introduction --- p.92 / Chapter 5.2 --- Methodology --- p.96 / Chapter 5.2.1 --- Understorey plant sampling --- p.96 / Chapter 5.2.2 --- Species identification and nomenclature --- p.98 / Chapter 5.2.3 --- Plant growth parameters --- p.98 / Chapter 5.2.4 --- Data processing and statistical analysis --- p.99 / Chapter 5.3 --- Results and discussion --- p.100 / Chapter 5.3.1 --- Floristic composition of the acacia plantations --- p.100 / Chapter 5.3.2 --- "Species richness, diversity and woody abundance of the understories" --- p.101 / Chapter 5.3.3 --- Species composition and structure of the understories --- p.106 / Chapter 5.3.4 --- Mechanisms and pathway of succession in the exotic plantations --- p.115 / Chapter 5.4 --- Conclusion --- p.116 / Chapter Chapter Six --- Conclusion / Chapter 6.1 --- Summary of findings --- p.118 / Chapter 6.2 --- Implications of the study --- p.122 / Chapter 6.2.1 --- Ecological value of exotic plantations in Hong Kong --- p.122 / Chapter 6.2.2 --- Restoration strategies for borrow areas --- p.125 / Chapter 6.2.3 --- Enrichment planting after fire --- p.128 / Chapter 6.3 --- Limitations of the study --- p.131 / Chapter 6.4 --- Suggestion for future study --- p.132 / References --- p.135 / Appendices --- p.151

Thesis (M.S.)--Oregon State University, 2006. / Printout. Includes bibliographical references (leaves 96-107). Also available on the World Wide Web.

Three studies were completed to investigate the influence of mineral assemblage on soil organic carbon (SOC) cycling and pedogenesis in forest soils. Two studies utilized a lithosequence of four parent materials (rhyolite, granite, basalt, limestone/volcanic cinders) under Pinus ponderosa, to explicitly quantify the contribution of parent material mineral assemblage to the character of the resulting soil. The first study explored variation in pedogenesis and elemental mass loss as a product of parent material through a combination of quantitative X-ray diffraction and elemental mass balance. Results indicated significant differences in degree of soil development, profile characteristics, and mass flux according to parent material.The second study utilized the same lithosequence of soils, but focused on organic C cycling. This study explored variation in SOC content among soils of differing mineralogy and correlations among soil physiochemical variables, SOC content, soil microbial community composition and respiration rates. Metal-humus complex and Fe-oxyhydroxide content emerged as important predictors of SOC dynamics across all parent materials, showing significant correlation with both SOC content and bacterial community composition. Results indicated that within a specific ecosystem, SOC dynamics and microbial community vary predictably with soil physicochemical variables directly related to mineralogical differences among soil parent materials.The third study focused specifically on the influence of goethite and gibbsite on dissolved organic matter characteristics and microbial communities which utilize DOM as a growth substrate. Iron and aluminum oxides were selected for this study due to their wide spread occurrence in soils and their abundance of reactive surface area, qualities which enable them to have a significant effect on SOC transported through forest soils. Results indicated that exposure to goethite and gibbsite surfaces induces significant differences in DOM quality, including changes in thermal properties, molecular structure, and concentrations of P and N. Investigation of the decomposer communities indicated that exposure to goethite and gibbsite surfaces caused significant differences in microbial community structure.These investigations emphasize the important role of mineral assemblage in shaping soil characteristics and regulating the cycling of C in soils, from the molecular scale to the pedon scale.

Orientador: José Luiz Stape / Coorientador : Iraê Amaral Guerrini / Banca: Magali Ribeiro da Silva / Banca: Kelly Cristina Tonello / Resumo: A disponibilidade de água e nutrientes são os fatores abióticos que tem maior influência no crescimento de plantações nos trópicos. O projeto BEPP estabeleceu no ano 2001 uma rede experimental instalada em oito locais do Brasil, cujo objetivo foi determinar as taxas de crescimento potencial em plantações de eucalipto quando as limitações nutricionais e hídricas são removidas. A unidade florestal da empresa Vallourec incorporou-se ao projeto no ano 2005, estabelecendo na região de Bocaiúva (MG) dois experimentos compostos por quatro clones de interesse comercial. O primeiro foi estabelecido seguindo um esquema fatorial 2x2, avaliando dois níveis de disponibilidade hídrica (controle e irrigado) e de fertilização (tradicional e extra). No segundo, avaliou-se a influência da disponibilidade hídrica no crescimento incorporando mais um tratamento: redução da água de chuva, e mantendo as doses de fertilização da empresa. Dados climáticos foram extraídos da estação meteorológica Carbonita (INMET) localizada na região. Para atingir os objetivos do trabalho, foi desenvolvida uma equação para o cálculo de matéria seca do fuste com base na cubagem rigorosa feita em 2013. Através de técnicas de sensoriamento remoto foi feito o processamento de imagens do satélite LANDSAT 5 TM+ e LANDSAT 7 ETM+ estimando o Índice de Vegetação da Diferença Normalizada (NDVI) e o Índice de Área Foliar (IAF) mensal para cada tratamento no período entre 2007 e 2008. Tratamentos com irrigação apresentaram incrementos de 62% em matéria seca quando comparados com o tratamento controle. A fertilização extra não influenciou o crescimento, indicando que as demandas nutricionais foram supridas com a fertilização da empresa. No Experimento 1, não houve diferenças significativas no IAF entre tratamentos. No Experimento 2, a diminuição de 16% do IAF do tratamento com redução da água de ... / Abstract: The availability of water and nutrients are the abiotic factors that have most influence on the growth of plantations in the tropics. The BEPP project established in 2001 an experimental network installed in eight locations in Brazil, aimed to determining the potential growth rates in eucalyptus plantations when the nutritional and water limitations are removed. The forest department of the company "Vallourec" joined the project in 2005, establishing in the region of Bocaiúva (MG) two experiments, including four clones of commercial interest. The first experiment was established following a 2x2 factorial design, evaluating two levels of water availability (control and irrigated) and fertilization (traditional and extra). The second experiment evaluated the influence of water availability incorporating one more treatment: reduction of rainwater, while kept the traditional doses of fertilizer of the company. Climatic data were obtained from the meteorological station Carbonita (INMET) located in the region. In order to achieve the objectives of this study, biomass equations were developed based on cubing. Through remote sensing techniques, we analyzed and processed de satellite images from LANDSAT 5 TM + and LANDSAT 7 ETM +; estimating the Normalized Difference Vegetation Index (NDVI) and the Leaf Area Index (LAI) for each month, during 2007 and 2008. Irrigation treatments showed increases of 62% dry matter when compared to the control treatment. Extra doses of fertilization did not influence growth, indicating that the nutritional demands were satisfied with the traditional fertilization rate of the company. Experiment 1 did not registered significant differences in LAI between treatments. In Experiment 2, a decrease of 16% of the LAI showed in the irrigated plots, generated 23% of losses in timber growing. The light use efficiency (LUE) varied between 0.72 and 0.73 g MJ-1 in the treatments without ... / Mestre

No description available.

No description available.