Growing integrated timber in a circular and sustainable bioeconomy: a new challenge

Today’s environmental challenges are multiple and far-reaching. Climate change, as a global priority, has just been revisited at #COP28, underlining, once again, the need to move towards decarbonisation by increasing renewable energy sources and improving energy efficiency. Likewise, concepts such as the bioeconomy based on the use of resources of biological origin are already part of our vocabulary, as well as the need to guarantee and promote the circularity of these resources, which to a large extent crystallises in the development of #biorefineries. Water as a limited resource is also a burning concern and is included in the United Nations Sustainable Development Goals (SDG6). Soils are also a focus of attention, with the European Environment Agency (EEA) listing a number of indicators linked to the threats they face. Similarly, the need to look further afield when addressing plant production argues for considering the valuation of ecosystem services, of which biodiversity and carbon sequestration are key issues. These are all burning issues that undoubtedly challenge everyone, but especially those of us who make it our profession.

In this landscape, the forestry sector is and will be key. Wood is an essential raw material that is being revalued in this context. Lignin, cellulose and hemicellulose are the basic components with which to generate a wide range of #bioproducts, replacing those that currently depend on fossil energy, but also to respond to challenges linked to energy generation, seeking not only the diversification of sources, but also less dependence on foreign mineral resources that are required by other renewable technologies. Forest biomass from forests and related industries should coexist in alliance with forest crops, seeking to increase the pool of this key raw material, thereby facilitating its location and seasonality, and guaranteeing a greater supply potential.

However, forest crops, especially when specifically designed for biomass production, pose uncertainties, such as those related to the occupation of certain land or the need for water to ensure satisfactory yields, sharing, in general, the same challenges faced by agriculture.

However, they also have powerful attractions, such as the capacity to capture carbon in the short term or the increase in biodiversity in the agricultural landscape. Thus, for example, carbon stocks in short rotation poplar plantations reach figures of 30 t C ha-1 in the total cultivation cycle (12 years), with 14% of this carbon remaining in the soil and the rest depending on the final use of the fraction corresponding to the aerial woody biomass. They therefore play an active role in mitigating global warming. Numerous scientific studies support the capacity of this type of forest crops to provide significantly higher levels of alpha and beta diversity than those shown by agricultural monocultures in the environments in which they are integrated, although without reaching that of natural mixed forests, thus playing an intermediate role between the two.

The selection of plant materials that are more adapted to stressful conditions and more efficient in the use of resources will be key, and this selection will also have to consider the use of new genetic editing technologies, which provide greater efficiency and precision.

Likewise, forest crop management practices will have to be adapted, not only to guarantee and maximise the ecosystem services mentioned, but also to ensure a more respectful agriculture in line with the aforementioned challenges, in line with practices that advocate the need to reverse the state of soils through so-called regenerative agriculture, with new visions regarding the management of herbaceous competition, for example, and which also seeks the circularity of resources.In this sense, water management will be key, including the need for greater technification, but also the use of second-use water from agro-industrial production processes, which can represent a tremendous opportunity to obtain biomass while reusing and regenerating a scarce resource, and at the same time providing opportunities for the use of new land.The economic viability of these crops also seems feasible, if their critical costs are addressed and even more so if the new externalities are incorporated.

For all these reasons, biomass obtained from forest crops represents an opportunity that can be economically profitable and environmentally desirable, although the challenges of how to obtain it will undoubtedly have to incorporate visions that until only a few years ago we did not take into account.The future can and must also be green.

Tribune of the BIOPLAT Newsletter – Technology and Innovation Platform “Biomass for the Bioeconomy” nº9, published in December 2023, and written by Hortensia Sixto, Senior Scientist at the Institute of Forestry Sciences of INIA – CSIC

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