Stem respiration is an important part of respiration coming from different dead and living stem tissues of trees, which makes an important contribution to the overall forest carbon balance. This report investigated spatial differences regarding radial diffusion of CO2 through the bark on trees across different old growth forests in Sweden. Some key environmental factors such as precipitation, wetness classes, temperature, stem diameter, distance from the coast, and latitude have been analysed to find relationships with stem respiration. Measurements were carried out on the most common tree species in Sweden, Pinus sylvestris, Picea abies and Betula pubescens. This was done by using a portable gas analyser strapped to the trees. The results show statistical differences in stem respiration for each tree species between some of the forests, while no statistical differences were found between wetness classes within or between forests. The only environmental factor that was found to have a significant relationship with stem respiration was stem diameter for P. sylvestris. Overall, these results indicate that stem respiration rate is relatively insensitive to environmental variation, which potentially simplifies the process of extrapolating this flux over space and time. Knowledge about stem respiration is important for understanding of the carbon cycle and prediction of future global change. Therefore, it is crucial to gain extensive information and understanding about the external relationships that could influence stem respiration.

Diss. (sammanfattning) Stockholm : Karolinska institutet, 2002. / Härtill 6 uppsatser.

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