Tree stumps as biofuel – results from eight years of research presented

Some years ago, there were quite many knowledge gaps about the environmental impact of stump harvesting. In a program financed by SLU, the Swedish Energy Agency and several forest companies, a number of economists, carbon flux researchers, hydrologists and experts on biodiversity collaborated to fill the knowledge gaps about stump harvesting.

The aim of the program was to assess the overall impact of stump harvesting on soil, water and biodiversity, and in addition determine the climatic benefit of using stumps and coarse roots as biofuel in relation to burning of fossil fuels. The first part of the program took place between the years 2008 and 2011, and the second part between 2011 and 2015.

Now, the results have been presented in a special issue of the journal Forest Ecology and Management.

– We are very happy that the researchers have filled a number of knowledge gaps and been able to provide a better basis for guidelines on where and how stump harvesting can be conducted, says Professor Tryggve Persson who has coordinated this research program.

The results show that stump harvesting is beneficial to the climate and can, if carried out correctly, limit the spread of root rot. Stump harvesting increases soil disturbance, but this disturbance does not seem to increase the emission of greenhouse gases. It does not seem to affect the production of the next tree generation. However, intense stump harvesting has negative effects on dead-wood dependent species. However, the risk of species extinction seems to be minimal if only 10 % of the clear-cuts in the forest landscape are stump harvested.