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Tropical agroforestry systems are perceived to have the capacity to be resilient to future changes in climate. This study quantifies the response of two tropical agroforestry tree seedlings; Gliricidia sepium (Jacq.) Walp and Cedrela odorata L. to increases in atmospheric concentrations of carbon dioxide (CO2) (800 ppm), temperature (+2°C daytime and +3°C nighttime) and the combined conditions. As well, this study analyzes the microbial community structure and nutrient concentration in response to elevated concentrations of CO2 on tropical silvopastoral soil, conventional pastoral soil and a regenerated forest soil. Both tree species demonstrated very individual responses to the different climate scenerios. While no significant CO2 fertilizer effect was observed in either species the combined treatment demonstrated a significant increase in seedling height for both species. The response of G. sepium to the combined treatment was similar to its response to the temperature treatment which could be a result of achieving the optimal range in temperature for growth. As well, an increase in C:N ratio from G. sepium seedling leaves under the combined treatment indicates the possibility of the nutrient concentration diminishing thereby reducing the role of this species as a provider of high nutrient biomass. The soil microbial community showed very little change in response to elevated concentrations of CO2 and differences in community structure between sites were also negligible. Soil nutrient concentration maintained the best balance over the course of both twelve week incubations for the regenerated forest site followed by the silvopastoral site and lastly the conventional pasture site. The response of soil nutrient concentration to elevated concentrations of CO2 was negligible reflecting the response of the soil microbial community.

Tropical agroforestry systems are perceived to have the capacity to be resilient to future changes in climate. This study quantifies the response of two tropical agroforestry tree seedlings; Gliricidia sepium (Jacq.) Walp and Cedrela odorata L. to increases in atmospheric concentrations of carbon dioxide (CO2) (800 ppm), temperature (+2°C daytime and +3°C nighttime) and the combined conditions. As well, this study analyzes the microbial community structure and nutrient concentration in response to elevated concentrations of CO2 on tropical silvopastoral soil, conventional pastoral soil and a regenerated forest soil. Both tree species demonstrated very individual responses to the different climate scenerios. While no significant CO2 fertilizer effect was observed in either species the combined treatment demonstrated a significant increase in seedling height for both species. The response of G. sepium to the combined treatment was similar to its response to the temperature treatment which could be a result of achieving the optimal range in temperature for growth. As well, an increase in C:N ratio from G. sepium seedling leaves under the combined treatment indicates the possibility of the nutrient concentration diminishing thereby reducing the role of this species as a provider of high nutrient biomass. The soil microbial community showed very little change in response to elevated concentrations of CO2 and differences in community structure between sites were also negligible. Soil nutrient concentration maintained the best balance over the course of both twelve week incubations for the regenerated forest site followed by the silvopastoral site and lastly the conventional pasture site. The response of soil nutrient concentration to elevated concentrations of CO2 was negligible reflecting the response of the soil microbial community.

Master of Landscape Architecture / Department of Landscape Architecture/Regional and Community Planning / Timothy D. Keane / The International Ecotourism Society (TIES), the world’s first ecotourism organization, coined what has become the most succinct definition of ecotourism: “Responsible travel to natural areas that conserves the environment and improves the wellbeing of local people (Honey 2008, p. 6).” Ecolodges are accommodation facilities within ecotourism destinations which must satisfy specific principles, while reflecting the definition of ecotourism. Ecolodge principles include water conservation, preservation of flora and fauna, design to create a small footprint, and interpretive programs to educate both employees and tourists about the surrounding natural and cultural environments, to name just a few. (Mehta 2002, p. 5) Tropical locations, where ecolodges are often found, are comprised of unique ecosystems. With tropical locales, there are specific considerations that could determine the success of a proposed ecolodge development. As a designer, one must understand the biophysical characteristics on site, to inform design decisions of the ecolodge development. In addition, a designer must understand how the indigenous populations utilize the site culturally, physically and spiritually to fully understand the importance of the ecolodge development. (Mehta 2002, p. 12) When proper analysis of cultural and biophysical factors is completed, an ecolodge development is able to conform to the ecotourism definition and satisfy ecolodge principles. Within this manual, a hierarchical list of design principles, guidelines and criteria are communicated to achieve an overall design goal called fitness design. A “fit” design is intended to achieve sustainability and quality of life for the environment and the communities that have daily interaction with the development. As readers navigate through the document, they will be exposed to various considerations of a tropical ecolodge development. The intent of the manual is to provide a structural framework to guide an ecolodge design process.

Wetlands provide important ecosystem services (ES) by storing large amounts of organic carbon (OC) and being of high biological, cultural, and economical value. Uganda is covered by vast wetland areas but has with a booming population rapidly been decreasing due to pressure on lands. The aim of this report was to examine important socio-ecological dynamics of rural wetlands in relation to variations of land use in central and eastern Uganda. This by assessing above- (ABG) and belowground (BG) C stocks, soil pH, and capturing provisioning ES and related impacts on soil and vegetation. The methods involved initial spatial analysis followed by two field campaigns with collection of soil samples, biomass measurements and recordings of provisioning ES, following locally developed standardized methods. Laboratory soil analyses included bulk density, loss on ignition and pH. The results shows that the permanent wetland LUC classes store the most total ecosystem C (273.5 to 356.5 t C ha-1), with the BG pool being the largest. It further brings new insights to the much less studied seasonal wetlands that also proves to be an important C stock (331.1 t C ha-1) as well as providing essential ES. In line with previous research, the total ecosystem C and the provisioning ES of wetlands decreases with changing land use management (farmlands 185 to 209; grasslands 125; woodland 120 to 284 t C ha-1). Further knowledge of socio-ecological dynamics of wetlands is needed, especially in seasonal wetlands, to increase sustainable wetland management. This being urgently needed for many communities in Uganda that are dependent on agroecologically-based economies in close relation to wetland ES and vulnerable to climate variations.

<p>Human and natural disturbance affect the Amazon basin at several spatial and temporal scales. In this thesis, I used satellite-detected hot pixels to examine patterns of human-caused disturbance and protected areas in the Brazilian Amazon from 1996-2006. Deforestation fires, as measured by hot pixels, declined exponentially with increasing distance from roads. Fewer deforestation fires occurred within protected areas than outside and this difference was greatest near roads. However, even within reserves, more deforestation fires occurred in regions with high human impact than in those with lower impact. El Niño-related droughts affected deforestation fires most outside of reserves and near roads. There was no significant difference in fire occurrence among inhabited and uninhabited reserve types. </p><p>Within this context of disturbance in the Brazilian Amazon basin, I examined relatively undisturbed savanna-like `campina' ecosystems. I reviewed the literature on campinas and discussed their variation and their significance for beta diversity. As one of two case studies, I assessed spatio-temporal patterns of disturbance (fire and blowdowns), and vegetation change from 1987 to 2007 in campinas in the central Brazilian Amazon using Landsat imagery. In 2001 images, an increase in open areas corresponded with significantly more visible signs of disturbance, likely precipitated by the 1997-98 El Niño. Bird community data indicated a trend of more generalist/savanna species in more frequently disturbed campinas. </p><p>As the second case study, I used daily 500 m resolution MODIS reflectance data to assess seasonal and inter-annual flooding in ~33,000 km2 of campinas in the Negro river basin. Flooding cycles of these wetland campinas critically influence regional ecosystem processes. Flooded areas ranged from 15,000 km2 at the end of the rainy season (August-Oct) to little, if any, open water in the driest times (Jan-Mar). Predictable seasonal flood pulses occurred, but also displayed high inter-annual variability. This variability was weakly correlated with the Multivariate El Niño Southern Oscillation Index (MEI). </p><p>Campina ecosystems are an important, but largely overlooked, component of the biodiversity of the Amazon basin. My research shows that climate, particularly ENSO-associated droughts, strongly affects campinas even in remote areas, just as it increases fire frequencies in more populated regions of the Amazon.</p> / Dissertation

<p>Tropical ecosystems play a key role in regulating the global climate and the carbon cycle thanks to the large amounts of water and carbon exchanged with the atmosphere. These biogeochemical fluxes are largely the result of high photosynthetic rates. Photosynthetic activity is highly dependent on climate and vegetation, and therefore can be easily modified along with changes in those two factors. A better understanding of what drives or alters photosynthetic activity in the tropics will lead to more accurate predictions of climate and subsequent effects on ecosystems. The seasonal pattern of photosynthetic activity is one of the main uncertainties that we still have about tropical ecosystems. However, this seasonality of tropical vegetation and its relationship to climate change and land cover is key to understanding how these ecosystems could be affected and have an effect on climate.</p><p>In this dissertation, I present three projects to improve our understanding about tropical ecosystems and how their photosynthetic activity is affected by climate and land cover change. The lack of field-based data has been one of the main limiting factors in our study of tropical ecosystems. Therefore, in these projects I extensively use remote sensing-derived data to analyze large scale and long term patterns. In the first study, I looked at the seasonal relationship between photosynthetic activity and climate, and how model simulations represent it. Vegetation in most of the tropics is either positively correlated with both water and light, or positively correlated with one of them and negatively with the other. Ecosystem models largely underestimate positive correlations with light and overestimate positive correlations with water. In the second study, I focus on the effect of land cover change in photosynthetic activity and transpiration in a highly deforested region in the Amazon. I find that land cover change decreases tropical forests photosynthetic activity and transpiration during the dry season. Also, land cover change increases the range of photosynthetic activity and transpiration in forests and shrublands. These effects are intensified with increasing land cover change. In the last project, I quantify the amount of change in evapotranspiration due to land cover change in the entire Amazon basin. Our remote sensing-derived estimates are well aligned with model predictions published in the past three decades. These results increase our confidence in climate models representation of evapotranspiration in the Amazon.</p><p>Findings from this dissertation highlight (1) the importance of the close relationship between climate and photosynthetic activity and (2) how land cover change is altering that relationship. We hope our results can build on our knowledge about tropical ecosystems and how they could change in the future. We also expect our analysis to be used for model benchmarking and tropical ecosystem monitoring.</p>