17.5. Effects of forest management and climate change on energy biomass and timber production with implications for carbon stocks and net CO2 exchange in boreal forest ecosystems

Public examination of a doctoral dissertation in the field of forest sciences 

Doctoral candidate: M.Sc. Ashraful Alam 

Date and venue: 17.5.2011 at 12 noon, BOR100, Joensuu campus 

ABSTRACT 

The aim of this work was to investigate the effects of forest management and climate change on energy biomass (wood) and timber production with implications for carbon stocks and net CO2 exchange in boreal forest ecosystems in Finland. First, the impacts of thinning on growth, timber production and carbon stocks under the current and changing climate were analysed by employing an ecosystem model for the whole of Finland over a 90-year period. Concurrently, the potential of energy biomass production with implications for timber production and carbon stocks under varying thinning and climate scenarios was studied. Thereafter, a life cycle assessment (LCA) tool for estimating net CO2 exchange of forest production was developed, and it was applied in interaction with ecosystem model based simulations to study the impacts of different management regimes (initial stand density and thinning regimes) on energy biomass production and related CO2 emissions at a stand level with a rotation length of 80 years. 

The results showed that the climate change increased the production potential of energy biomass and timber, and carbon sequestration and stocks over the whole of Finland, but, in a relative sense more in northern than southern Finland. Decreasing basal area based thinning thresholds compared to the currently recommended ones, increased the harvesting of the annual average amount of timber compared to the annual average growth of stem wood, and reduced carbon stocks in the forest ecosystems. On the other hand, the use of increased basal area thinning thresholds concurrently increased energy biomass and timber production, and carbon stocks in the forest ecosystem regardless of climate applied. 

The development of the LCA tool made it also possible to estimate the net carbon exchange of the forest production. Based on the use of the LCA tool with the ecosystem model simulations, it was found that probable increased biomass growth obtained under the climate change could not compensate for decomposition and biomass combustion related carbon loss in southern Finland. It was also found that the magnitude of management related emissions on net carbon exchange were small compared to the total ecosystem fluxes, decomposition being the largest emission contributor. In addition, the increase in initial stand density compared to the conventional practice of 2000 seedlings ha-1, not only increased the energy biomass production at energy biomass thinning, but also reduced management related CO2 emissions of energy biomass production. 

To conclude, the applied management substantially affects the net atmospheric impacts of production potential of forest ecosystems. The combined use of ecosystem model simulations and the LCA tool will together provide new insights for the analysis of ecologically sustainable energy biomass and timber production systems and the climate change mitigation options of forests. 

The doctoral dissertation of Ashraful Alam entitled “Effects of forest management and climate change on energy biomass and timber production with implications for carbon stocks and net CO2 exchange in boreal forest ecosystems” will be examined at the Faculty of Science and Forestry. The opponent in the public examination is Professor Tomas Lundmark, Swedish University of Agricultural Sciences and the custos is Professor Seppo Kellomäki of the University of Eastern Finland.

Photo available for download at http://www.uef.fi/vaitoskuvat

Contact: Ashraful Alam, ashraful.alam@uef.fi, p. +358 40 0392628

Publishing year: 2011

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