This study examined the annual C balance and its shifting trend in Canada’s managed forests from 1991 to 2006 using the Integrated Terrestrial Ecosystem C-budget (InTEC) model. During this period, Canada’s managed forests remained a moderate C sink of 58 Mt C yr¬¬¬-1 on average, but displayed an apparent trend of shifting towards a C source. The combined risk of climate change and increased disturbances are weakening the C sink in Canada’s managed forests. This study also compared the results from InTEC with those from CBM-CFS (Carbon Budget Model of the Canadian Forest Sector) at both national and regional levels. InTEC shows larger inter-annual variability and regional difference than CBM-CFS due to its incorporation of both disturbance and non-disturbance factors. In comparison, CBM-CFS3 has likely underestimated both the true C loss and the C sink potential of Canada’s managed forests, given that it does not account for the non-disturbance factors.

This study examined the annual C balance and its shifting trend in Canada’s managed forests from 1991 to 2006 using the Integrated Terrestrial Ecosystem C-budget (InTEC) model. During this period, Canada’s managed forests remained a moderate C sink of 58 Mt C yr¬¬¬-1 on average, but displayed an apparent trend of shifting towards a C source. The combined risk of climate change and increased disturbances are weakening the C sink in Canada’s managed forests. This study also compared the results from InTEC with those from CBM-CFS (Carbon Budget Model of the Canadian Forest Sector) at both national and regional levels. InTEC shows larger inter-annual variability and regional difference than CBM-CFS due to its incorporation of both disturbance and non-disturbance factors. In comparison, CBM-CFS3 has likely underestimated both the true C loss and the C sink potential of Canada’s managed forests, given that it does not account for the non-disturbance factors.

Bird-vegetation associations are a base for bird conservation and management, as well as for predictions of the effects of resource management and climate change on wildlife populations. A recent shift in forest management priorities from timber production to native species' habitat conservation on federal lands has emphasized the need to understand the mechanisms underlying the effects of vegetation management on wildlife. The assumption of strong bird-vegetation relationships is rarely tested for forest birds, especially at large temporal extents, which are more likely to reveal instabilities in bird-vegetation relationships than short-term studies. This study aimed to quantify bird-vegetation relationships and investigate their strength in young thinned and unthinned Douglas-fir forest stands over ten to years post thinning. Additionally, this study investigated whether disturbance associated with forest thinning decoupled bird-vegetation relationships in the thinned and unthinned stands. I used abundance or occurrence data for eight bird species collected at 58 point count surveys, conducted during six breeding seasons over ten years following forest thinning. I obtained detailed local-scale vegetation characteristics associated with bird sampling points and modeled bird occurrence or abundance as a function of vegetation characteristics. Vegetation characteristics explaining individual species occurrence or abundance varied among species and among years for any given species. Six out of eight species showed responses to examined vegetation characteristics. For three out of six species, the effects of vegetation characteristics on bird occurrence or abundance remained consistently positive or negative over time. For the other three species the absolute effect of vegetation decreased over time to that of not statistically different from zero. The estimates of vegetation effects on bird response varied in size among years, though they were not statistically different among years. Magnitude of vegetation effect on bird occurrence or abundance did not increase with time, nor was it related to species prevalence or abundance. I found evidence of a response threshold for one species, Swainson's thrush. I suggest that changing abundance of resources, associated with thinning disturbance, demographic stochasticity associated with small population sizes, as well as large-scale demographic processes and possibly life history traits of examined species, mediate the strength of local-level bird-vegetation associations. Variability of vegetation effects on bird occurrence or abundance over time suggests a greater uncertainty of results of vegetation-related wildlife management efforts than has previously been suggested by short-term studies. Therefore, incorporation of the uncertainty of bird-vegetation relationships into predictive models and continued long-term monitoring of species response to management may be crucial for future successful and effective management decisions. / Graduation date: 2012

The warming of our planet is a direct consequence of anthropogenic emissions with carbon dioxide as the main driver. A need to mitigate carbon emissions is urgent and forests can be a part of the solution since they sequester and stock carbon during their lifetime This study has shown that production forests can sequester carbon to a higher degree since they consist of younger trees which are better at sequestration than older trees. But the study also show that older forests keep sequestering carbon and might not be carbon neutral as previously thought. Old growth forests contain higher carbon stocks than younger production forests since they often remain unmanaged and can continuously accumulate carbon into living and dead biomass as well as the soil. Production forests also accumulate carbon, but it is not nearly the same amount as in old growth forests. With regard to meeting the 1,5-degree goal set by the IPCC, i.e., cutting emissions with half until 2030 and having net zero carbon dioxide emissions until 2050. Harvesting with clear-cutting was found to be worse compared with harvesting at a lower frequency which causes less emissions but still supplies wood products to the industry. The result also show that we must protect more old growth and unmanaged forests that can sequester and stock carbon longer to be able to succeed with the 1,5-degree goal. The debate climate in Sweden is heated and opinions often differ. The difference may depend on the time frame or how results are interpretated.