Does bioenergy improve forest management?
Policies in the European Union, the United States, and Canada support the use of forest biomass in heating, power generation, and transportation as a climate mitigation strategy. However, research conflicts on whether forest bioenergy results in greenhouse gas (GHG) savings in the long-term. This study investigates if there is evidence that bioenergy demand is likely to spur substantial changes in forestry management to cause greenhouse gas savings compared to fossil fuels in a reasonable time period of 20–30 years. The analysis tests or linkages between the recent ramp-up in bioenergy production and prices, and changes in forest management, residues harvest, and forest area, focusing on Canada, Sweden, and the United States. Specifically, this study looks at evidence of changes in the removal of logging residues, such as small branches and treetops; stand management, including site preparation, thinning, and fertilization; forest species composition; and total forest area in the three countries.
The analysis shows:
- Available evidence doesn’t support assumptions that bioenergy demand will improve forest management and encourage new planting. We find no evidence that the rise in bioenergy demand over the past one to two decades has increased forest area in any of the three countries studied. For other improvements to forest management, we find some evidence of a link to bioenergy demand but not in all three countries.
- Where there is evidence of a forest management response to bioenergy demand, it is weaker than assumed in previous research. In the United States, for example, there is strong evidence that bioenergy demand has led to a 12% increase in pine plantation productivity, most likely through more intensive stand management. However, that is far less than the doubling of yields assumed in some studies.
- Policymakers should not assume that forest bioenergy will significantly mitigate climate change. Historical evidence does not support estimates of short carbon payback times for forest bioenergy. Long carbon payback times and poor climate performance are more realistic. Policies promoting energy from existing forests are unlikely to achieve climate mitigation in the near or medium term. Ancillary policy tools to promote improved forest productivity and sustainable forest management are needed to achieve any mitigation in the medium and long term.
- Forest bioenergy policy should support only additional biomass. There are two circumstances under which forest bioenergy would deliver meaningful climate benefits: (1) when tops, branches, small wood from thinning, and salvage wood are harvested sustainably, and (2) when biomass is grown on land with low-carbon stocks that would otherwise remain unused. These pathways should be explicit requirements for forest bioenergy policies to ensure climate benefits. We find that bioenergy using only trunks and limbs from existing forests is not likely to be an effective climate mitigation strategy.