Inland waters process large amounts of organic carbon, contributing to CO2 and CH4 emissions, as well as storing organic carbon (OC) over geological timescales. Recently, it has been shown that the magnitude of these processes is of global significance. It is therefore important to understand what regulates OC cycling in inland waters and how is that affected by climate change. This thesis investigates the constraints on microbial processing of sediment OC, as a key factor of the carbon cycling in boreal lakes. Sediment bacterial metabolism was primarily controlled by temperature but also regulated by OC quality/origin. Temperature sensitivity of sediment OC mineralization was similar in contrasting lakes and over long-term. Allochthonous OC had a strong constraining effect on sediment bacterial metabolism and biomass, with increasingly allochthonous sediments supporting decreasing bacterial metabolism and biomass. The bacterial biomass followed the same pattern as bacterial activity and was largely regulated by similar factors. The rapid turnover of bacterial biomass as well as the positive correlation between sediment mineralization and bacterial biomass suggest a limited effect of bacterial grazing. Regardless of the OC source, the sediment microbial community was more similar within season than within lakes. A comparison of data from numerous soils as well as sediments on the temperature response of OC mineralization showed higher temperature sensitivity of the sediment mineralization. Furthermore, the low rates of areal OC mineralization in sediments compared to soils suggest that lakes sediments are hotspots of OC sequestration. Increased sediment mineralization due to increase in temperature in epilimnetic sediments can significantly reduce OC burial in boreal lakes. An increase of temperature, as predicted for Northern latitudes, under different climate warming scenarios by the end of the twenty-first century, resulted in 4–27% decrease in lake sediment OC burial for the entire boreal zone.

Climate change will pose increasing challenges to forest managers working to achieve sustainable forest management in the boreal forest. A logical starting point for climate change adaptation is to proactively identify management practices and policies that have a higher likelihood of achieving management objectives across a wide range of potential climate futures. This research implemented an approach to identifying such measures by tapping into the experiential knowledge base of local forest practitioners. The assessment was organized according to a structured decision-making (SDM) approach. Northern forest practitioners consider the goals of climate change adaptation to be synonymous with those of sustainable forest management indicating that the criteria for the conservation and sustainable management of boreal forests as defined by the Montréal Process are suitable objectives against which the performance of alternative adaptation options can be assessed. The case study area for this research was the Champagne and Aishihik Traditional Territory of southwest Yukon where a climatically-driven, large-scale spruce bark beetle disturbance has been driving forest management planning yet climate change considerations have not been directly addressed in the planning process. Twenty-four adaptation options were identified as being important to implement in forest development areas to achieve regional goals and objectives of forest management across three scenarios of climate change. In addition, the performance of alternative strategies to re-establish forests was assessed. Results indicate that the applicability of alternative forest renewal adaptation strategies is strongly related to the objectives of forest management which differed across the forest management planning area. However, since none of the strategies were judged to perform highly across any of the scenarios of climate change, additional work is needed to explore whether a threshold of acceptability can be met even with the adoption of adjustments to forest management policies and practices. If not, management objectives themselves may need to be revised. An extensive list of research and monitoring needs were also identified, an indication that climate change is providing the imperative for a more comprehensive research and monitoring program to support the sustainable management of forest resources in this region. The next steps in a SDM approach are to implement adaptation options and strategies deemed appropriate and to monitor their performance in achieving management objectives within an adaptive management context.

Diss. (sammanfattning) Umeå : Sveriges lantbruksuniv. / Härtill 4 uppsatser.

Diss. (sammanfattning). Umeå : Sveriges lantbruksuniv., 2003. / Härtill 6 uppsatser.

Diss. (sammanfattning) Umeå : Umeå universitet, 2005. / Härtill 4 uppsatser.

Lic.-avh. Umeå : Sveriges lantbruksUniversity. / Härtill 2 uppsatser.

Lic.-avh. (sammanfattning) Umeå : Sveriges lantbruksuniv., 2006. / Härtill 2 uppsatser.

Diss. (sammanfattning) Umeå : Sveriges lantbruksuniv., 2006. / Härtill 4 uppsatser.

Lic.-avh. (sammanfattning) Uppsala : Sveriges lantbruksuniv., 2008. / Härtill 2 uppsatser.

Diss. (sammanfattning) Uppsala : Sveriges lantbruksuniversitet,2008. / Härtill 4 uppsatser.