Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgico / A conversÃo de florestas em pastagens pode ter um impacto sobre as propriedades e funÃÃes do solo, especialmente em condiÃÃes irrigadas. Partindo da hipÃtese de que a conversÃo de Ãrea natural em Ãrea sob pastagem irrigada altera algumas propriedades do solo, objetivou-se avaliar propriedades quÃmicas, fÃsicas e microbiolÃgicas indicadoras da qualidade do solo, em Ãrea sob pastagem, comparando-a com sua condiÃÃo natural. Para tanto, foram analisados atributos quÃmicos (compartimentos de carbono e nitrogÃnio no solo e lipÃdeos); microbiolÃgicos (carbono e nitrogÃnio da biomassa microbiana, respirometria, populaÃÃes de fungos micorrÃzicos arbusculares e glomalina) e fÃsicos (estabilidade de agregados, curva de retenÃÃo da Ãgua no solo, Ãndice S, e IHO), em diferentes profundidades e classes de agregados, visando estabelecer ligaÃÃes que possibilitassem identificar as alteraÃÃes sofridas no solo. Observou-se de modo geral, que o manejo empregado està conseguindo manter a sustentabilidade do sistema. No entanto, deve-se ressaltar que caracterÃsticas intrÃnsecas, como a textura do solo e densidade radicular das gramÃneas, foram determinantes no comportamento de atributos selecionados, como por exemplo, estabilidade de agregados. Foram observadas alteraÃÃes nos atributos estudados, principalmente na distribuiÃÃo dos mesmos no perfil, promovendo o aumento dos compartimentos de carbono e nitrogÃnio do solo, alÃm do teor de lipÃdeos. Os atributos microbiolÃgicos nÃo sofreram alteraÃÃes significativas, indicando que a pastagem irrigada nÃo influencia negativamente tais atributos. Quanto aos atributos fÃsicos, como CRA, IHO e Ãndice S, houve interferÃncia de caracterÃsticas intrÃnsecas, como por exemplo, a textura na determinaÃÃo da qualidade do solo. / The conversion of forests into pastures may have an impact on the properties and functions of the soil, especially in irrigated conditions. Assuming that the conversion of natural area within the area under irrigated pasture alters some soil properties, aimed to evaluate the chemical, physical and microbiological indicators of soil quality in pasture area, comparing it to its natural condition. To this end, analized the chemical (carbon pools and nitrogen in the soil and lipids); microbiological (carbon and microbial biomass nitrogen, respirometry, populations of arbuscular mycorrhizal fungi and glomalin) and physical attributes (aggregate stability, water retention curve soil, S index and IHO) at different depths and aggregate classes, to establish connections that would enable to identify the changes that occurred in the soil. It was observed generally that the management employee is able to maintain the sustainability of the system. However, it should be noted that intrinsic characteristics such as soil texture and density of the grass root, were decisive in the behavior of selected attributes, such as aggregate stability. There were changes in the attributes studied, mainly in their distribution in the profile, promoting the increase of carbon pools and nitrogen from the soil, beyond the level of lipids. The microbiological attributes did not change significantly, indicating that the irrigated pasture does not adversely affect these attributes. The physical attributes, like CRA IHO and S index, the interference of characteristics, for example, in determining the texture of the soil.

InvestigaÃÃo desenvolvida em sistemas agroflorestais que estÃo sendo testados no semi-Ãrido cearense, comparativamente a um sistema de cultivo convencional da regiÃo, identificou o aumento dos teores das fraÃÃes Ãcidos fÃlvicos (FAF) e hÃmicos (FAH). Estes resultados estÃo associados Ãs condiÃÃes em que houve revolvimento do solo como acontece nos sistemas agrossilvipastoril e convencional, o que podem ser atribuÃdos a uma possÃvel conversÃo da fraÃÃo humina em Ãcidos fÃlvicos e hÃmicos. Para testar essa hipÃtese, o presente trabalho objetivou caracterizar as fraÃÃes hÃmicas do Luvissolo, dos seguintes tratamentos: Agrossilvipastoril (AGP), Silvipastoril (SILV), Cultivo Intenso em Pousio (CIP), Mata Nativa 1 (MN1) e Mata Nativa 2 (MN2), nas profundidades 0 â 6 e 6 â 12 cm. Foram realizadas caracterizaÃÃes das fraÃÃes Ãcidos fÃlvicos e hÃmicos atravÃs das anÃlises termogravimÃtricas, elementar, ultravioletavisÃvel e infravermelho. Os resultados de todos os tratamentos analisados indicaram que os Ãcidos hÃmicos mostraram-se mais resistentes que os Ãcidos fÃlvicos. Analisando os tratamentos, o SILV apresentou fraÃÃes hÃmicas menos resistente do que os outros tratamentos estudados. O tratamento AGP apresentou fraÃÃes hÃmicas mais humificadas, podendo ser mais recalcitrante. Este fato pode estar relacionado, devido o tratamento AGP sofrer impacto pelo manejo adotado, o que nÃo acontece no tratamento SILV. Confirmando a hipÃtese de que o ambiente solo em sistemas de manejo que sofrem intensa perturbaÃÃo està sendo degradado. / Investigations about agroforestry systems, which has been carried out in the arid region in Ceara, Brazil, comparatively to a conventional tillage system in the same area, showed an increase in the concentration of fulvic fraction (FAF) and humic acid (FAH) fractions. These results are related to the conditions in which soil was plowed similar to what is usually done in agrosilvopastoral and conventional systems, which might be attributed to a possible conversion of the humin fraction into FAF and FAH. To address to this hypothesis, a field experiment was carried out aiming to characterize the humic fractions of a Luvissol, over the following treatments: Agrosilvopastoral system (AGP), Silvopastoral system (SILV), Fallow conventional tillage (CIP), Native forest 1 (MN1) and Native forest 2 (MN2), at the depths of 0 to 6 and 6 to 12 cm of the soil. Termogravimetric, elemental, visible-ultraviolet and infrared analyses were utilized to characterize FAF and HAF in the soil samples. The results showed humic acids to be more resistant than fulvic acids. Silvopastoral system had its FAH less resistant in comparison to the others. The AGP had the FAH more humified, which may be more recalcitrant. This finding might be related, due to the AGP to overgo impact by the adopted management, what does not take place in the SILV, so that it might confirm the hypothesis that soil environment overgoing intense disturb might be under degradation.

O solo é um importante sumidouro de carbono (C) atmosférico, uma vez que concentrações de CO2 da atmosfera podem ser atenuadas através de mecanismos de sequestro de C no solo. Nesse contexto, solos sob clima semi-árido estão sendo atualmente avaliados como potenciais sequestradores de C, sobretudo no processo de recuperação de áreas degradadas. No entanto, ainda há carência de informações referentes aos mecanismos envolvidos no sequestro de C. Adicionalmente, há incertezas nas estimativas dos estoques de C pela falta de conhecimento sobre sua variabilidade espacial devido à complexidade dos processos físicos, químicos e biológicos que influenciam o ciclo do referido elemento. As variações espaciais do C no solo estão relacionadas a fatores naturais e induzidos pelo homem e essas variações apresentam-se em diferentes escalas espaciais. Por tais motivos a presente pesquisa teve como objetivo avaliar a variabilidade espacial do C e de outros atributos físicos, químicos e biológicos do solo numa área de 100 ha destinada ao reflorestamento na região semi-árida do Rio Grande do Norte. Para tanto, foi estabelecida uma grade regular de 644 pontos amostrais espaçados de 40 m numa área localizada no município de Angicos (RN), pertencente à Universidade Federal Rural do SemiÁrido. Foram coletadas 1932 amostras de solo nas profundidades 0-0,1; 0,1-0,2; e 0,2-0,3 m para determinações de C, areia, silte, argila, pH, Na, P, Ca, Mg e K. Para determinar o C da biomassa microbiana (Cmic) foram utilizadas 156 amostras referentes à camada 0-0,1m. Com relação à densidade do solo (Ds) foram coletadas 246 amostras nas três profundidades mencionadas anteriormente. Adicionalmente, foram efetuados os seguintes cálculos: estoques de C, saturação por bases (V %), CTC (CTC(T)), saturação por Al (m) e soma de bases (SB). Os resultados foram submetidos à análise estatística descritiva clássica, seguida de análise geoestatística. O solo da área apresenta predominância de textura muito arenosa, baixa CTC e teores de C e Cmic; altos valores de Ds, acidez elevada e médios teores P e bases disponíveis. Estes resultados são comuns em solos de região semi-árida sob Caatinga em decorrência das condições climáticas desfavoráveis. Na análise descritiva a maioria dos atributos avaliados apresentou normalidade na sua distribuição. Os coeficientes de variação (CV) foram classificados como médios para a maioria dos atributos, a dependência espacial foi moderada com média geral dos alcances de 135 m. A maioria dos atributos ajustou-se ao modelo esférico. Na avaliação da eficiência dos modelos ajustados, tanto a validação interna como a externa apresentaram comportamentos semelhantes. A modelagem aplicada permitiu estimar o alcance e a magnitude das dependências espaciais. Por meio da krigagem foi efetuada a interpolação dos dados e gerados os mapas de variabilidade espacial para os atributos físicos, químicos e biológicos estudados. Os resultados obtidos nesta pesquisa ressaltam a importância do entendimento da variabilidade espacial do C e outras propriedades do solo, informações que servem como ponto de referência inicial (linha de base) e tem implicações importantes para futuras avaliações do impacto no sequestro de C e do potencial produtivo de Jatrofa na região semi-árida do Nordeste Brasileiro. / Soil is an important carbon (C) sink, since atmospheric CO2 concentrations can be attenuated by soil C sequestration. In this context, soils under semi-arid conditions are being evaluated as potential soil C sinks, mainly considering the process of rehabilitation of degraded areas. However, little information is available on the mechanisms associated with soil C sequestration. Moreover, there are uncertainties on soil C stocks estimates because of the lack of knowledge about its spatial variability due to the complexity of physical, chemical and biological processes that directly influence soil C cycle. Soil C spatial variability is associated with a series of natural and human-induced factors and those variations can be expressed in different spatial scales. Therefore, the main objective of the present study was to evaluate the spatial variability of C and soil physical, chemical and biological attributes in a 100 ha area destined to reforestation in the semi-arid region of Rio Grande do Norte (RN), Brazil. In order to do that, a regular grid (40 x 40 m) of 644 sampling points was defined in an area located in the city of Angicos (RN) that belongs to the Universidade Federal Rural do Semi-Árido. Samples from the 0-0,1; 0,1-0,2; e 0,2- 0,3 m soil layers were collected in each sampling point totalizing 1932 soil cores that were used for the following analyses: C, sand, silt, clay, pH, Na, P, Ca, Mg and K. For microbial biomass C, 156 samples were used from the 0-0,1 m soil depth. Samples for soil bulk density (total of 246 samples) were collected in the three mentioned soil layers. Additionally, the following calculations were performed: soil C stocks, base saturations, cation exchange capacity and aluminum saturation. The results were analyzed using classical descriptive statistics and geostatistics. The soil at the studied area is very sandy and presented low values of cation exchange capacity, C content and microbial biomass; high values of bulk density and soil acidity and medium values of P content and available bases. Those results are typical for soils under native vegetation at the semi-arid region due to unfavorable climatic conditions. From the descriptive analyses, the majority of the studied attributes presented normal distribution. The coefficients of variation (CV) for the majority of the studied attributes presented medium values; the spatial dependence was moderated with mean range value of 135 m. The majority of the attributes were fitted by the spherical model. Assessment of model adjustment efficiency was performed through internal and external validations and both presented similar trends. The application of modeling technique provides estimations of the range and the spatial dependence magnitude of the evaluated soil attributes. Using kriging techniques, analytical results were interpolated and maps were generated to show the spatial variability of the soil physical, chemical and biological properties. The results from the present study stressed the importance of adequately understand C and other soil properties spatial variability. Such information has important implications for future assessments of soil C sequestration and is useful for potential production of Jatropha in the semi-arid condition of the Brazilian northeast region.

Made available in DSpace on 2016-04-28T20:13:54Z (GMT). No. of bitstreams: 1 2009 - Thiago Rodrigo de Paula Assis.pdf: 1156521 bytes, checksum: 8bf7d83864fbb02b06a33a93314f323d (MD5) Previous issue date: 2009-12-13 / This thesis analyzes the relation between civil society and State in the execution of public policies, on the basis of the Program One Milion of Rural Watering Holes (P1MC) in Minas Gerais. Begin of 3 axles. The first, focuses the process undertaken for the ASA to institutionalize the program. After institutionalized, the second axle analyze the interactions between ASA and federal public actors, state and municipal, and its consequences for articulation and P1MC. Finally, are argued the contributions of the program for the involved organizations, the ASA and the public policies thinks. It is observed that the P1MC is born of the canalization of the subject of the human coexistence with the Semi-?rid of the world of the life for the public sphere, acquiring legitimacy, having access the sphere politics and the public agenda. This in a State Reform context. Its institutionalization occurs for the joint with a lot of actors, politicians and technician, in different governments. The interaction with public agents for its execution indicates a process of bureaucratic hardening and politics differences. But the execution provides benefits for the involved ones, with the profit of prestige, the construction of public spaces to argue the human coexistence with de Semi-?rid and the reinforcement of the articulation. It brings, however, risks of dependence of the public resources and reduction of the ASA s autonomy. / Esta tese analisa a rela??o entre sociedade civil e Estado na execu??o de pol?ticas p?blicas, com base no Programa Um Milh?o de Cisternas (P1MC) em Minas Gerais. Parte de 3 eixos. Um, enfoca o processo empreendido pela ASA para institucionalizar o programa. Uma vez institucionalizado, o segundo eixo analisa as intera??es entre a ASA e atores p?blicos federais, estaduais e municipais, e suas consequ?ncias para a Articula??o e P1MC. Por fim, s?o discutidas as contribui??es do programa para as organiza??es envolvidas, para a ASA e para pensar as pol?ticas p?blicas. Observa-se que o P1MC nasce da canaliza??o do tema da conviv?ncia com o semi-?rido do mundo da vida para a esfera p?blica, adquirindo legitimidade, acessando a esfera pol?tica e a agenda p?blica. Isso num contexto de Reforma do Estado. Sua institucionaliza??o se d? pela articula??o com diversos atores, pol?ticos e t?cnicos, em diferentes governos. A intera??o com agentes p?blicos para sua execu??o indica um processo de endurecimento burocr?tico e diferen?as pol?ticas. Mas, a execu??o proporciona benef?cios aos envolvidos, com o ganho de prest?gio, a constru??o de espa?os p?blicos para discutir a conviv?ncia com o semi-?rido e o fortalecimento da articula??o. Traz, por?m, riscos de depend?ncia dos recursos p?blicos e diminui??o da autonomia da ASA.

This research aims to develop the present knowledge of arid zone rehabilitation by scientifically testing topsoiling and seeding treatments on the Eyre Peninsula, South Australia, in a way that enables the widest application and comparison to other mining leases throughout the arid lands.

Riverine landscapes are complex. More than just a single channel, they comprise a shifting mosaic of hydrogeomorphic patches with varying physical and biological characteristics. These patches are connected by water during flows of varying magnitude and frequency, at a range of spatial and temporal scales. Combined, landscape complexity and hydrological connectivity create biological diversity that in turn maintains the productivity, ecological function, and resilience of these systems. This thesis investigates the ecological importance of spatial heterogeneity and temporal hydrological connectivity in a dryland floodplain river landscape. It focuses on anabranch channels, and uses major carbon sources in these and adjacent landscape patches as indicators of ecological pattern and process. A conceptual model was proposed, describing the potential effects upon the distribution and availability of major carbon sources of: a) a spatial mosaic of hydrogeomorphic patches in the landscape (e.g. anabranches, river channel, and wider floodplain); and b) four primary temporal phases of hydrological connection during flow pulses (disconnection, partial connection, complete connection, and draining). This was then tested by data collected over a three year period from a 16 km reach of the lower Macintyre River (NSW/QLD Australia). Results were examined at multiple spatial scales (patch scale � river channel vs. anabranches vs. floodplain; between individual anabranches; and within anabranches � entry, middle and exit sites). The data indicate that spatial heterogeneity in the lower Macintyre River landscape significantly influences ecological pattern. Carbon quantity was greater in anabranch channels compared to adjacent river channel patches, but not compared to the floodplain; while carbon quality was greater in anabranch channels compared to both adjacent river channel and floodplain patches. Stable isotope analysis indicated that carbon sources that were predominantly found in anabranch channels supported both anabranch and river organisms during a winter disconnection phase. Other carbon sources found in the main river channel and the wider floodplain appeared to play a comparatively minimal role in the food web. Different phases of hydrological connection between anabranch channels and the main river channel were associated with differences in the availability of carbon sources. In the river channel, draining of water from anabranches (the draining phase) was associated with relatively high concentrations of dissolved organic carbon (DOC) and low concentrations of phytoplankton. Conversely, the disconnection phase was associated with relatively low concentrations of DOC and high concentrations of phytoplankton in the river channel. In anabranch channels and their waterbodies, the disconnection and draining phases were associated with high concentrations of both DOC and phytoplankton. Concentrations of these carbon sources were lowest in anabranches during the partial and complete connection phases. Different hydrological connection phases were also associated with changes in trophic status in the aquatic components of the landscape. On the riverbanks, relatively low rates of benthic production and respiration during the complete connection phase were associated with heterotrophy. The remaining phases appeared to be autotrophic. Benthic production on riverbanks was greatest during the disconnection phase, and respiration was greatest during the partial connection phase. In the anabranch channels, rates of production and respiration were similar during the disconnection phase, and were associated with heterotrophy in the anabranch waterbodies. The remaining phases appeared to be autotrophic. Respiration was greatest in anabranches during the disconnection phase, and production was greatest during the draining phase. Both production and respiration were lowest during complete connection. These differences and changes varied according to the landscape patch examined. At a landscape scale, anabranch channels act as both sinks and suppliers of carbon. High rates of sediment deposition facilitate their role as sinks for sediment-associated carbon and other particulate, refractory carbon sources. Simultaneously, anabranch channels supply aquatic carbon sources from their waterbodies, as well as via processes such as inundation-stimulated release of DOC from surface sediments. Modelled data indicated that water resource development reduces the frequency and duration of connection between anabranch channels and the main river channel. This loss of landscape complexity via loss of connectivity with anabranches has the potential to reduce the total availability of carbon sources to the ecosystem, as demonstrated by a modelled 13% reduction in potential dissolved organic carbon release from anabranch sediments. This thesis has demonstrated the importance of spatial heterogeneity in riverine landscapes, by documenting its association with variability in the distribution and quality of primary energy sources for the ecosystem. It has shown that this variability is augmented by different phases of hydrological connectivity over time. Spatial heterogeneity and hydrological connectivity interact to increase the diversity and availability of ecological energy sources across the riverine landscape, at multiple spatial and temporal scales. This has positive implications for the resilience and sustainability of the system. Anabranch channels are particularly important facilitators of these effects in this dryland floodplain river system. Anabranch channels are �intermediate� in terms of spatial placement, temporal hydrological connection, and availability of carbon sources; of high value in terms of high-quality carbon sources; and relatively easy to target for management because of their defined commence-to-flow levels. Further research should be directed toward evaluating other ecological roles of anabranch channels in dryland rivers, thereby providing a more complete understanding of the importance of connectivity between these features and other patches. This knowledge would assist management of floodplain river landscapes at larger regional scales, including amelioration of the effects of water resource development.

<p>The objectives of this thesis are to assess: to what degree have natural resources deteriorated in a grazing area in northern Namibia, how do perceptions of environmental change held by local stakeholders there, correspond to scientific assessments, and how do these relate to national estimates? Analysis of the process of developing national indicators for monitoring of land degradation concluded that specific indicators should be developed on national level, and in some instances even on local level as there are no universal causes of land degradation. According to farmers overgrazing and low rainfall since the early 1990s cause negative environmental changes in the study area, partly confirming findings from national monitoring. Results also suggest that: less grazing outside the study area, improved access, permanent water supply, and fencing of large areas, also contributed. Results show that improved water supply was the most important factor. Investigation of the influence of permanent water points on grazing resources showed that perennial grasses are replaced by less palatable annual grasses as far as 6 km from water points along a water pipeline. No significant grazing induced changes in grass composition were observed around privately owned wells. Private ownership seems to be a key factor preventing over-utilization of grazing resources around the latter. A remote sensing study using Landsat TM imagery identified bare ground, saltpans and grassland with a fair accuracy. Separation of woodland from shrubland and shrubland from grassland was less accurate using supervised classification. The results show that the soil adjusted vegetation index provides valuable information about variations of green biomass over time in semi-arid environments. However, it is suggested that satellite based investigations should be supported by thorough ground based assessment due to the influence of underlying soil in this environment.</p>

The objectives of this thesis are to assess: to what degree have natural resources deteriorated in a grazing area in northern Namibia, how do perceptions of environmental change held by local stakeholders there, correspond to scientific assessments, and how do these relate to national estimates? Analysis of the process of developing national indicators for monitoring of land degradation concluded that specific indicators should be developed on national level, and in some instances even on local level as there are no universal causes of land degradation. According to farmers overgrazing and low rainfall since the early 1990s cause negative environmental changes in the study area, partly confirming findings from national monitoring. Results also suggest that: less grazing outside the study area, improved access, permanent water supply, and fencing of large areas, also contributed. Results show that improved water supply was the most important factor. Investigation of the influence of permanent water points on grazing resources showed that perennial grasses are replaced by less palatable annual grasses as far as 6 km from water points along a water pipeline. No significant grazing induced changes in grass composition were observed around privately owned wells. Private ownership seems to be a key factor preventing over-utilization of grazing resources around the latter. A remote sensing study using Landsat TM imagery identified bare ground, saltpans and grassland with a fair accuracy. Separation of woodland from shrubland and shrubland from grassland was less accurate using supervised classification. The results show that the soil adjusted vegetation index provides valuable information about variations of green biomass over time in semi-arid environments. However, it is suggested that satellite based investigations should be supported by thorough ground based assessment due to the influence of underlying soil in this environment.

<p>The rationale of this study is to apply light stable isotope chemistry towards investigations that require temporally high-resolution data. High-resolution (or high sampling frequency) data sets, are critical for testing environmental and/or paleoenvironmental hypotheses that seek to explain processes occurring over rapid or short time intervals. The investigation of climate variation (e.g., seasonality, El Niño, deglaciation), animal migration and physiology, and disturbance ecology (e.g., fire, flooding) benefits from the recovery of proxy information at decadal to subannual resolutions. The type of material used also dictates a spatial scale. Herein are presented four studies that utilize high-resolution light stable isotope profiles with contrasting temporal and spatial scales. The first study employs advances in three-dimensional computer-controlled micromilling to recover ~daily to weekly deposited carbonate from small (~1 cm) mollusc shells. Stable oxygen isotope values from freshwater mollusc shells are predictably related to the local environment of growth using previously published temperature-fractionation relationships, providing a paleoclimate record of temperature and precipitation. The second study investigates variation in stable carbon isotope values from Aplodinotus grunniens otoliths, for which high-resolution patterns were critical in assessing metabolic rate as the governing control. The third study employs high-resolution stable oxygen and carbon isotope values to determine chinook salmon (Oncorhynchus tshawytscha) seasonal and ontogenetic migration in Lake Ontario and its tributaries. Lastly, high-resolution stable hydrogen and carbon isotope values of chitin derived from Mexican free-tailed bat (Tadarida brasiliensis) guano are presented, providing a record of abrupt climate change. Thus, this thesis reports on promising new research avenues for paleoclimatology, paleoecology, and modern ecology.

<p>The rationale of this study is to apply light stable isotope chemistry towards investigations that require temporally high-resolution data. High-resolution (or high sampling frequency) data sets, are critical for testing environmental and/or paleoenvironmental hypotheses that seek to explain processes occurring over rapid or short time intervals. The investigation of climate variation (e.g., seasonality, El Niño, deglaciation), animal migration and physiology, and disturbance ecology (e.g., fire, flooding) benefits from the recovery of proxy information at decadal to subannual resolutions. The type of material used also dictates a spatial scale. Herein are presented four studies that utilize high-resolution light stable isotope profiles with contrasting temporal and spatial scales. The first study employs advances in three-dimensional computer-controlled micromilling to recover ~daily to weekly deposited carbonate from small (~1 cm) mollusc shells. Stable oxygen isotope values from freshwater mollusc shells are predictably related to the local environment of growth using previously published temperature-fractionation relationships, providing a paleoclimate record of temperature and precipitation. The second study investigates variation in stable carbon isotope values from Aplodinotus grunniens otoliths, for which high-resolution patterns were critical in assessing metabolic rate as the governing control. The third study employs high-resolution stable oxygen and carbon isotope values to determine chinook salmon (Oncorhynchus tshawytscha) seasonal and ontogenetic migration in Lake Ontario and its tributaries. Lastly, high-resolution stable hydrogen and carbon isotope values of chitin derived from Mexican free-tailed bat (Tadarida brasiliensis) guano are presented, providing a record of abrupt climate change. Thus, this thesis reports on promising new research avenues for paleoclimatology, paleoecology, and modern ecology.