Bioenergy as a ‘wicked problem’
Forests are often seen as a promising solution for the two major environmental crises of our era: climate change and the rampant loss of biodiversity. They play an important role in storing and regulating carbon, fostering biodiversity, and strengthening the resilience of nearby communities. Yet, forest-based solutions, especially related to biomass bioenergy, are not a panacea. Rather, the potential of forests and bioenergy to mitigate climate change and preserve biodiversity exists in a complex interface of environmental, social and economic concerns.
The Joint Research Centre (JRC) report on´The use of woody biomass for energy production in the EU´ shows the complexity of sustainability in bioenergy. Bioenergy can be a controversial topic, and its complex nature classifies it as a ‘wicked problem’: while sometimes lauded for the opportunities it offers to harness nature-based solutions to fuel the future, the industry has also been blamed for deforestation, especially in tropical regions, and for prioritizing fuel over food production. Thus, the main question of the JRC study concerns how we can “ensure that pathways for the provision of woody biomass, following increased demand for wood, are not detrimental to climate and to biodiversity?”
The report analyses biomass sources in Europe and trends for bioenergy. The JRC scientists then give special attention to how different management practices and approaches might contribute to the sustainability and climate benefits of bioenergy schemes.
Sources of wood for bioenergy in Europe
As a first step to answering this question, JRC scientists quantified the sources of wood most commonly used for bioenergy in Europe. As shown in Figure 1 below, nearly half of the woody biomass used in the EU for energy is so-called secondary woody biomass, i.e. forest-based industry by-products, bark and recovered post-consumer wood, like furniture or salvaged construction materials. 37% of biomass for wood-based bioenergy is primary woody biomass: this is the wood extracted directly from forests. It is estimated that this primary woody biomass consists of 20% stemwood (the thick trunk of the tree) and 17% other components, such as treetops, branches, etc. The remaining 14% is uncategorised, but is more probable to be primary wood. Summarising, wood for bioenergy is likely to be equally divided between primary and secondary woody biomass.
More than half of the stemwood used for bioenergy is expected to come from coppice systems, which means that wood from coppice forests makes up at least 10% of the total woody biomass used for bioenergy in the EU. Coppice systems are those forest management systems where the trees (or shrubs) are periodically cut back to their stump to stimulate regrowth through vegetative regeneration. Coppice systems are one of the oldest forms of forest management for the supply of firewood (energy) and timber. Nowadays, coppice systems are especially important in Mediterranean Europe, where about 32% of the forest area is reported as coppice forest. In fact, nearly all of the coppice forests in the EU are located in EU Mediterranean countries.
Management pathways and trade-offs
If the EU-level push for sustainable energy leads to an increase in the demands on wood for bioenergy, management choices are essential to ensure that the extraction of additional wood is not detrimental to biodiversity and climate. The JRC scientists evaluated the impacts of three categories of management practices that could potentially increase the supply of “additional” biomass for the production of bioenergy: afforestation; removal of logging residues; and conversion of natural forests to bioenergy plantations. Furthermore, the report shows the importance of informed decision-making, as these management practices “are high on the agenda of potential climate mitigation strategies and could occur, in the EU or outside, as a direct or indirect effect of increased EU demand for forest biomass for wood products and bioenergy.” Through analysing these management practices, the report identifies different management pathways that balance trade-offs between biodiversity and carbon emissions reduction: some are “lose-lose”, some prioritize one over the other, and some are “win-win”.
The “win-win” practices are removal of fine woody debris generated by logging or natural disturbances (slash) and afforestation on abandoned agricultural land with polyculture plantation or other planted land managed with low intensity. These “win-win” management pathways were identified as having a positive impact on both biodiversity and climate change mitigation. Similarly, the report identified “lose-lose” management practices: all management practices that involve conversion of natural forests to plantations have a negative impact on both biodiversity and climate, as they “would damage forest ecosystems without providing carbon emission reductions in policy-relevant timeframes”. Also of importance, any management calling for the removal of coarse woody debris, such as fallen trees or large branches, and removal of low stumps are “lose-lose” pathways, with particularly damaging effects on biodiversity. The authors also defined pathways with trade-offs, i.e. those with a positive impact on one crisis and a negative impact on the other crisis. Afforestation (with plantations or planted forest) on natural grassland or heathland are examples of such trade-offs in management practices, as they contribute positively to climate change mitigation but have a detrimental impact on biodiversity and ecosystem conditions.
Mediterranean coppice systems: opportunities and challenges
As demand grows for wood-based bioenergy, an important opportunity for Mediterranean Europe may be in linking the outcomes of the report on the sustainability of different management practices to the large areas of coppice forests in the Mediterranean that are no longer managed. Coppice restoration was not assessed as an intervention in the JRC report, but the authors recommend other researchers to expand the research to other interventions, including coppice conversion or restoration. Whether to choose coppice restoration or conversion as a management approach must depend on local conditions. However, the results of the report suggest that restoring those large areas of abandoned coppice systems using sustainable forest management could lead to the provision of additional biomass for bioenergy production while protecting biodiversity and reducing carbon emissions.
Traditionally, coppice systems have played an important socioeconomic role for rural communities in the Mediterranean; they are also highly valued in nature conservation terms because of their distinctive combination of flora and fauna, thanks to their variety in light intensities.
With the “win-win” management pathways examined by the JRC in mind, Mediterranean policy makers and researchers have an opportunity to further explore the potential of maximising bioenergy through sustainable forest management in coppice systems. Indeed, in the face of these many pathways and an urgent need to act in the face of climate change, the report clearly maintains that the positive potential of bioenergy can only be realised if the forest biomass is produced sustainably and used efficiently.
For more information, read the full Joint Research Centre (JRC) report on ´The use of woody biomass for energy production in the EU´.