Browsing by Author "Tuomaala, Emilia"
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Tuomaala, Emilia (2022)Permafrost peatlands have a significant role in the global carbon cycle, as they store ca. 185 Pg of carbon. Because of the slow decomposition of organic matter, they have sequestered carbon dioxide from the atmosphere and cooled the climate for thousands of years. However, in anaerobic decomposition also methane – a strong greenhouse gas – is produced. Climate change results in changes in permafrost peatland habitats; distribution and proportional share and these changes also affect the CO2 and CH4 fluxes. In this master’s thesis I compare the net ecosystem exchange and pore water methane concentrations in different microhabitats in the Stordalen palsa mire in Abisko, Sweden. In addition, I review the reported climate change-driven habitat changes in the area and its effects on the CO2 and CH4 fluxes. My results suggest that Sphagnum sp. and Sphagnum fuscum -microhabitats were net sinks of CO2 whereas lichen-, shrub- and Eriophorum-microhabitats were net sources. These results were best explained by the proportional coverage of green vegetation, which was highest in both Sphagnum-microhabitats. No discernible differences were found between pore water methane concentrations in different habitats. Permafrost thawing has increased the occurrence of wet habitats in Stordalen. These habitat changes have increased carbon sequestration in the area but at the same time methane emissions have also increased. Because of this, the radiative forcing of the peatland has changed from negative to positive and the on-going habitat changes will likely continue in future. On a longer timespan though, the radiative forcing will likely switch back to negative as carbon sequestration increases and the effects of the methane emissions decrease.
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Tuomaala, Emilia (2014)Taita Hills are situated in southeastern Kenya (03°20'S 38°15'E), only 350 km from the equator. Ecology and biodiversity of the area is one of a kind and has been subject to multiple studies of natural sciences during the last decades. Taita Hills belong to the Eastern Arc Mountains, an ancient chain of mountains in Eastern Africa and one of the 25 biodiversity hotspots of the world. To qualify as a biodiversity hotspot an area must have lost significant amounts of its original vegetation and inhabit a number of endemic plant species. Both of these criteria are met in Taita Hills where the favorable climate enables endemic species to thrive. Large areas of forest has been cut down in order get more room for agriculture, the main source of livelihood in Kenyan countryside, making the environment threatened. The diverse environment of Taita Hills produces a multitude of ecosystem services. Ecosystem services can be defined as all benefits people obtain from nature. They are often divided into four categories: provisioning services, regulating services, cultural services and supporting services. Ecosystem services link ecological knowledge and economics together by enabling monetary valuation of abstract aspects of nature (e. g. water retention). This link helps decision makers to take environmental issues into consideration by providing a possibility to compare concrete and abstract aspects of nature with each other through tangible monetary values. Research on ecosystem services has grown exponentially in the recent years and decades. However, most of this research has been conducted in developed countries and only little research has been completed in developing countries such as Kenya. It has been established that provisioning services are considered the most important services in developing countries, though. This was the case in Taita Hills, too; the majority of ecosystem services recognized by the local people were provisioning services. Services like firewood, medicinal usage of local plants and scenery were familiar to local people and the role of water was also emphasized in their perceptions of ecosystem services and biodiversity as a whole. Phoenix reclinata was one of the keystone species of ecosystem services. People's perceptions of biodiversity can vary a lot. Like ecosystem services, biodiversity is a subjective concept that can be understood differently by different people. Understanding how people see nature that surrounds them and biodiversity it beholds can help e. g. in planning nature conservation areas. When people agree on decisions made about their environment and recognize their own basic values in the decisions made they are more eager to support them. Even so, research on people's perceptions of biodiversity is currently lacking. Results that have been obtained have suggested that plants' role in people's perceptions is emphasized and people respond better to beautiful and imposing species than modest or ugly species. This was true also in Taita Hills where people linked plants and forest directly to biodiversity. They also recognized local plant species well, regardless of their nativeness, and had a close relationship with nature overall.
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