Made available in DSpace on 2014-07-29T15:32:05Z (GMT). No. of bitstreams: 1 DISSERTACAO_FANUEL_GEOG.pdf: 5225631 bytes, checksum: 17be1fcb54dcf706976140dca2f5dadb (MD5) Previous issue date: 2012-03-27 / Cattle ranching is extremely important for the economy of Brazil. This activity is characterized by the intensive explotation of pastures, which occupy a vast area of the Brazilian territory, i.e. approximately 150 million hectares. Currently, Brazil is the largest meat exporter in the world. Concerning its biomes, this occupation occurs mainly in the Cerrado, where the 546.251 km² of area under utilization correspond to about 37% of the total pasture area in the country. Among the states encompassed within the Cerrado limits, Goiás has the largest pasture occupation, over 38.7% of its area. In addition, it has one of the largest livestock, with about 21.3 millions of heads, producing, on average, 600.000 tons of meat a year. Within this context, arises the concern with the quality of the Goias state pastures, since several studies show that a large portion of these pastures are already degraded (i.e. low capacity), with low cattle occupation. This study, based on remote sensing data, as well as on spatial and census data, aimed at evaluating the quality of the pastures in Goias through the estimation of the net primary productivity (NPP). The distribution of pastures in relation to soil types, cattle occupation at the municipality level, infra-structure and location of the meat processing plants were considered as well. The productivity estimations were based on the MOD13Q1 vegetation index images (EVI), for the 2001 2009 period. The analysis of pasture distribution were conducted through the intersection of the derived NPP and the ancillary data mentioned above. The main conclusions of our study are: a) the highest NPP values are found in the central, southeast and extreme northeastern portions of Goias; b) the highest NPP values are related to the following soils: argissolos, cambissolos, neossolos and latossolos (Oxisols), respectively; c) the average cattle occupation in the Cerrado in Goias is usually low, around 1,07 heads per hectare; d) there are several municipalities (major cattle producers) which have the totality of their pastures severely degraded; e) there is no strict correlation between the location of meat processing plants and quality of pastures, as well as cattle occupation. Thus, the monitoring of pasture quality and the analysis of correlated factors are of great importance, as cattle ranching are responsible for the largest occupation of the Cerrado in Goias e for most of the wealth in the state. / A pecuária é uma atividade extremamente importante para a economia do Brasil. Essa atividade se caracteriza pela exploração extensiva das pastagens, ocupando vasta área do território, aproximadamente 150 milhões de hectares. Atualmente, o Brasil é o maior exportador de carne bovina no mundo. Em relação aos biomas brasileiros, essa ocupação ocorre principalmente no Cerrado, ocupando uma área de 546.251 km², o que representa cerca de 37% da área total de pastagens no país. Dentre os estados que compõem os limites do Cerrado, Goiás é o que possui maior ocupação por pastagens, com aproximadamente 38.7% de sua área. Além disso, tem um dos maiores rebanhos bovinos, com cerca de 21.3 milhões de cabeças de gado, produzindo em média, 600.000 toneladas de carne por ano. Diante desse contexto, surge a preocupação sobre a qualidade das pastagens cultivadas no estado de Goiás, uma vez que diversos estudos mostram que grandes partes dessas pastagens estão com algum nível de degradação (i.e. baixa capacidade de suporte) e baixa lotação bovina média. Esse estudo, baseado em dados de sensoriamento remoto orbital, bem como bases de dados espaciais e censitários, teve como objetivo avaliar a qualidade das pastagens em Goiás, a partir da estimativa de produtividade primária líquida da vegetação (NPP). A distribuição das pastagens em relação ao tipo de solo, lotação bovina por município, infra-estrutura e localização das plantas de processamento de carne foram considerados também. As estimativas de produtividade foram baseadas nas imagens MODIS13Q1 de índice de vegetação (EVI), para o período de 2001 - 2009. As análises da distribuição de pastagens foram conduzidas através da intersecção do NPP e os dados auxiliares mencionados acima. Os principais resultados desse trabalho são: a) os maiores valores de NPP são encontrados nas porções centrais, sudeste e extremo nordeste do estado de Goiás; b) os maiores índices de NPP estão associados aos seguintes solos: argissolos, cambissolos, neossolos e latossolos, respectivamente; c) a média de lotação bovina no Cerrado goiano em geral é baixa, gira em torno de 1,07 cabeças por hectares; d) há vários municípios (maiores produtores de gado) que estão com suas áreas de pastagens seriamente comprometidas; e) não há grandes correlações entre o local dos frigoríficos e a qualidade das pastagens, bem como a ocupação de gado. Assim, o monitoramento da qualidade das pastagens e a análise de fatores correlatos são de grande importância, pois a pecuária é responsável pela ocupação de maior parte do Cerrado goiano e geração de grandes riquezas para o estado.

Accurate simulation of energy, water, and carbon fluxes exchanging between the land surface and the atmosphere is beneficial for improving terrestrial ecohydrological and climate predictions. We systematically assessed the Noah land surface model (LSM) with mutiparameterization options (Noah-MP) in simulating these fluxes and associated variations in terrestrial water storage (TWS) and snow cover fraction (SCF) against various reference products over 18 United States Geological Survey two-digital hydrological unit code regions of the continental United States (CONUS). In general, Noah-MP captures better the observed seasonal and interregional variability of net radiation, SCF, and runoff than other variables. With a dynamic vegetation model, it overestimates gross primary productivity by 40% and evapotranspiration (ET) by 22% over the whole CONUS domain; however, with a prescribed climatology of leaf area index, it greatly improves ET simulation with relative bias dropping to 4%. It accurately simulates regional TWS dynamics in most regions except those with large lakes or severely affected by irrigation and/or impoundments. Incorporating the lake water storage variations into the modeled TWS variations largely reduces the TWS simulation bias more obviously over the Great Lakes with model efficiency increasing from 0.18 to 0.76. Noah-MP simulates runoff well in most regions except an obvious overestimation (underestimation) in the Rio Grande and Lower Colorado (New England). Compared with North American Land Data Assimilation System Phase 2 (NLDAS-2) LSMs, Noah-MP shows a better ability to simulate runoff and a comparable skill in simulating R-n but a worse skill in simulating ET over most regions. This study suggests that future model developments should focus on improving the representations of vegetation dynamics, lake water storage dynamics, and human activities including irrigation and impoundments.

The biological process of the carbon cycle in the Antarctic Ocean is controlled by the photosynthetic activity of the primary producers. The amount of fixed carbon does not only depend on the photosynthetic activity but also on the carbon losses due to respiration. Thus, the ratio photosynthesis to respiration (rP/R) is an important parameter to predict the effect of climate change on the Antarctic ecosystem. Indeed, the ongoing changes in climate change are influencing the dynamics of environmental conditions, which has tremendous effects on the phytoplankton community. Therefore, two ecologically relevant species from the Southern Ocean were here investigated: the diatom Chaetoceros sp. and the prymnesiophyte Phaeocystis antarctica, studying the changes in the rP/R under global climate change conditions. Three main parameters were examined i.e temperature, salinity and iron limitation. The P/R ratio was significantly affected by temperature, while salinity had only a secondary importance, although with species-specific differences. More specifically, the values were ranging from 12.3 to 7.5 for Chaetoceros sp. and from 12.4 to 2.5 for P. antarctica. The changes in this ratio were principally due to variations in respiration, rather than in photosynthesis. Chaetoceros sp. appears to be less flexible in the regulation of the extent of photoprotective mechanisms (non-photochemical quenching and alternative electrons), but its photoprotective level was generally higher than in P. antarctica. Regarding iron limitation, data were successfully collected only for Chaetoceros sp.. The P/R ratio, equal to 2.8, did not change under iron limitation, with iron limited cells showing a very efficient acclimation to the lowered assimilatory metabolism by decreasing their respiratory losses.

Thesis (Ph. D.)--Joint Program in Chemical Oceanography (Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences; and the Woods Hole Oceanographic Institution), 2011. / Cataloged from PDF version of thesis. / Includes bibliographical references. / A combination of uptake field studies on natural phytoplankton assemblages and laboratory proteomic and physiological experiments on cyanobacterial isolates were conducted investigating the interactions of cadmium (Cd), zinc (Zn), and phosphorus (P) in marine Synechococcus. Enriched stable isotope field uptake studies of ¹¹⁰CD in the Costa Rica Upwelling dome, a Synechococcus feature, showed that uptake of Cd occurs in waters shallower than 40 m, correlates positively with chlorophyll a concentrations and is roughly equivalent to the calculated upwelling flux of cadmium inside the dome. In laboratory experiments, Synechococcus WH5701 cells exposed to low picomolar quantities of free Cd under Zn deficiency show similar growth rates to no added Cd treatments during exponential growth phase, but show differences in relative abundances of many proteins involved in carbon and sulfur metabolism suggesting a great metabolic impact. During stationary phase, chronic Cd exposure in this coastal isolate causes an increase in relative chlorophyll a fluorescence and faster mortality rates. The interactions of acute Cd exposure at low picomolar levels with Zn and phosphate (PO4³-) were investigated in Synechococcus WH8102, an open ocean isolate. The presence of Zn appears vital to the response of the organism to different PO4 ³- cocentrations. Comparisons with literature transcriptome analyses of PO4 ³- stress show similar increases in relative abundance of PO4 ³- stress response proteins including a PO4 ³- binding protein and a Zn-requiring alkaline phosphatase. A bacterial metallothionein, a Zn-associated protein, appears to be correlated with proteins present under low PO4 conditions. Together, these experiments suggest that the interactions of Cd and Zn can affect Synechococcus and play a role in the acquisition of PO4 ³-. / by Alysia Danielle Cox. / Ph.D.

Thesis (Ph. D.)--Joint Program in Chemical Oceanography (Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences; and the Woods Hole Oceanographic Institution), 2006. / Includes bibliographical references. / This thesis explores the potential of zinc, cobalt, and phosphorus to influence primary production in the subarctic North Pacific, the Bering Sea, and the North Atlantic Ocean. In the North Pacific and Bering Sea, total zinc concentrations were measured along a near-surface transect and in selected deep profiles. Zinc speciation was also measured with a novel anodic stripping voltammetry method, and the results were consistent with previous studies using different methods. The potential for zinc to impact primary production in the North Pacific was demonstrated in a shipboard incubation and by comparing two phytoplankton pigment markers to total zinc and free zinc ion concentrations. In the North Atlantic, total dissolved zinc and cobalt concentrations were measured and compared to concentrations of dissolved inorganic phosphorus and chlorophyll. In some areas of the North Atlantic the concentrations of zinc and cobalt were decoupled.The relationship between cobalt and inorganic phosphorus suggests that cobalt drawdown may be related to a high alkaline phosphatase related demand at low phosphorus concentrations. This trend compliments a shipboard incubation where alkaline phosphatase activities increased after cobalt addition. The presence of measurable alkaline phosphatase activity indicated that the phytoplankton community in the Sargasso Sea was experiencing phosphorus stress. Shipboard incubations generally confirmed this with inorganic phosphorus additions resulting in chlorophyll increases at 4 out of 5 stations. Further, the addition of dissolved organic phosphorus, as either a phosphate monoester or a phosphonate compound, resulted in a chlorophyll increase in 3 out of 3 incubations. This suggests that dissolved organic phosphorus may be an important phosphorus source for phytoplankton in low phosphorus environments and that the ability to use phosphonates may be more widespread than previously recognized. Overall, this thesis adds to our understanding of how the nutrients phosphorus, zinc, and cobalt may influence primary production. / by Rachel J. Wisniewski. / Ph.D.

Northern hardwood forests are expected to experience an increase in mean annual air temperatures, and a decrease in winter snowpack and greater frequency of soil freeze/thaw cycles (FTCs) by the end of the century. As a result of these anticipated changes, northern hardwood forests in the northeastern U.S. will also have warmer soil temperatures in the growing season and colder soils in winter. Prior studies show that warmer soils in the growing season increase net primary productivity (NPP) and C storage as a result of increased soil net N mineralization, while increases in soil freezing in winter reduces plant uptake of N and C as a result of root damage. However, the combined effects of warmer soils in the growing season and increased soil freeze/thaw cycles in winter on tree litter mass and chemistry are unknown. We report here results from the Climate Change Across Seasons Experiment (CCASE) at Hubbard Brook Experimental Forest in New Hampshire, USA to characterize the response of leaf litter mass and chemistry to growing season warming combined with soil freeze–thaw cycles in winter. Across the years 2014-2017, litterfall mass and chemistry (%C, %N, C:N) were not significantly affected by changes in soil temperature; however, there was a trend of higher total litterfall mass and litter N mass from plots where soils were warmed in the growing season, but this increase disappeared with the addition of FTCs in winter. These results indicate that while rates of NPP and the total mass of N could be increased with rising soil temperatures over the next century in northern hardwood forests, the combination of warmer soils in the growing season and colder soils in winter may ultimate have little to no impact on litter mass or chemistry. We conclude that considering the combined effects of climate changes in the growing season and in winter is vital for the accurate determination of the response of litterfall mass and chemistry in northern hardwood forests.

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The isotopic composition of the organic components of an animal's body, with respect to carbon and nitrogen, reflect the weighted average of the isotopic compositions of the animal's food sources, with a certain degree of enrichment in the heavier isotopes. Thus, by comparing the isotopic compositions of the animal and all the potential food sources, it is possible to ascertain the relative proportions of each availible food source in its diet, if the various food sources are sufficiently isotopically distinct. This approach is particularly usefull in estuarine communities where food-webs tend to be complex and where there are several sources of primary productivity. In this study it was used on two types of claw in an arctic and a temperate estuarine tidal flat in order to assess the importance of terrestrially fixed organic matter to each community. The results indicated that while marine and terrestrial organics were important food sources in the arctic tidal flat, the clams in the temperate site depended mostly on marine organics. / Thesis / Bachelor of Science (BSc)

The tropical forests on the island of Borneo are among of the richest in the world in terms of tree diversity, and their capacity to store a large reservoir of carbon. The Southeast Asian forests are fundamentally different from Neotropical and African forests, with their single-family dominance by dipterocarp trees, and with inherently greater stature and biomass. The carbon productivity and allocation in Asian tropical forests is still poorly quantified, and their responses to environmental drivers are still poorly understood. Almost all recent advances in tropical forest carbon cycling research have occurred in the Neotropics, with very few studies in Asia. The principal aim of this thesis is to quantify the carbon budget of a lowland dipterocarp forest in the Lambir Hills National Park, Miri, Sarawak, Malaysian Borneo. I examined and explored the productivity and carbon cycling processes and their responses to environmental factors across two major and contrasting soil types, in particular the clay and sandy loam soils. I recorded and analysed the Net Primary Productivity (NPP) and respiration for the above- and below-ground components, and observed the responses to seasonal variation and environmental drivers. Total soil respiration was relatively high and contributed a great deal to ecosystem respiration. Variation in soil respiration rates appeared closely related to soil moisture content. I found a strong diurnal cycle in soil respiration. On the basis of the first soil carbon dioxide (CO2) efflux partitioning study undertaken in a tropical forest, the diurnal cycle in total soil respiration appeared to be entirely driven by the diurnal cycle in litter respiration, and in turn litter is strongly controlled by moisture. There was little seasonal variation in allocation of net primary productivity (NPP), but there was evidence showing potential inter-annual variability for several components of NPP. Further, the allocation of NPP showed a strong seasonal shift between the forest plots on clay and sandy loam soils. Combining all the data measured and obtained in this D.Phil. thesis, the overall carbon budget assessed in this lowland dipterocarp forest showed a high level of agreement with other studies in Asia using micrometeorological techniques and the situation appears to be comparable to tropical forests in Amazonia. The key difference is that the aboveground NPP is higher and is the largest component contributing to the overall carbon budget, with relatively higher carbon use efficiency (CUE). The lowland dipterocarp forest in Lambir shows higher allocation in the above-ground NPP, and there were also differences in NPP and its allocation between sandy and clay-rich plots.