30 scientists from 13 European countries, among them two of CTFC, have discovered evidence that throws into doubt the conclusions of the study claiming abrupt changes in forest harvesting in Europe.
Forest harvest has increased by just 6% in recent years, not 69% as reported by the European Commission’s Joint Research Centre
Errors due to satellite sensitivity and natural disturbances
Is forest harvesting increasing in Europe? Yes, but not as much as reported last July in a controversial study published in Nature. The study Abrupt increase in harvested forest area over Europe after 2015, used satellite data to assess forest cover and claimed an abrupt increase of 69% in the harvested forest in Europe from 2016. The authors, from the European Commission’s Joint Research Centre (JRC), suggested that this increase resulted from expanding wood markets encouraged by EU bioeconomy and bioenergy policies. The publication triggered a heated debate, both scientific and political, as the EU Parliament and Council were discussing the Post-2020 EU Forest Strategy.
In a response published in Nature, 30 scientists from 13 European countries have discovered evidence that throws into doubt the conclusions of the JRC study. In Concerns about reported harvests in European forests, Palahí and colleagues demonstrate that the large harvest changes reported by JRC result from methodological errors.
These errors relate to satellite sensitivity improving markedly over the period of assessment, as well as to changes in forests due to natural disturbances – for example drought and storm related die-back and tree-falls – being often attributed wrongly to timber harvests.
Dr Marc Palahí, Director of the European Forest Institute (EFI), who led the response said: “In the future forest information should be more carefully assessed, considering a wide variety of methodological issues and factors, before drawing hasty conclusions. This requires enhanced collaboration as well as scientifically robust and common approaches between the European Commission and Member States to enable better informed forest-related policies in the context of the EU Green Deal.”
“Over the years, we are becoming better and better at detecting forest loss” said Dr Ruben Valbuena from Bangor University who co-led the study. One of the errors in the JRC study was to underestimate how satellite images, and the methods used to analyse them, have improved over the periods they compared. “Satellite products can only be employed under strict protocols assessing errors, and with better distinction between deforestation and other causes of forest loss”, he said.
Professor Gert-Jan Nabuurs from Wageningen University, an IPCC lead author who participated in the study, commented that “the harvest across Europe’s forests has increased in recent years, but by just 6%, not the 69% claimed by the JRC study. This is due primarily to a moderate economic recovery after the 2008–2012 recession. What is really striking is the unprecedented levels of natural disturbances affecting our forests in many parts of the continent in recent years.”
Attribution of deforestation due to natural causes to the timber industry.
A major error found was the attribution of deforestation to the demand of the forestry industry when it was related to natural reasons. Thanks to the collaboration of administrations such as the Government’s Ministry of Agriculture, Fisheries and Food, it was found that many of these areas which were attributed to logging were areas affected by tree falls caused by wind, fire, and mainly due to insect damage.
A good example is the large areas affected by the pine processionary that were identified in Catalonia and in Aragon (Spain) and that were corroborated by Dr Antoni Trasobares and Dr. Jose Ramon Gonzalez, from the CTFC, by contrasting the results of the article published in Nature with the General Directorate of Forest Ecosystems and Environmental Management of the Department of Agriculture of the Government of Catalonia.
Authors state that “these results confirm that these natural disasters accelerated by climate change that are affecting the health of our forests are playing an unprecedented role in Europe, since in recent years their incidence has increased enormously throughout the continent”.
“We need a collective effort, involving different data sources from various countries and disparate disciplines, to better understand the effects of climate change, natural disasters, and forest management-induced effects on forests”, they add.
This information and its proper use are crucial to develop a holistic analysis with forestry strategies based on scientific evidence.” Only in this way can we ensure European forests will continue being an important sink for carbon absorption and providing many other ecosystem services, maintaining biodiversity, and helping to develop an emerging circular bioeconomy that is no longer dependent on fossil fuels”, they emphasize.
The implications of the errors found by Palahí and colleagues are of global relevance, as many studies to inform policy-makers and society at large on the state of the world forests are nowadays based on remote sensing. The analysis of products based on satellite imagery is becoming key for instance to understand the extent of global deforestation, and thus we need scientifically robust remote sensing methods for sound policy-making.
Palahí M. & Valbuena R. (shared first authorship), Senf C., Acil N., Pugh T.A.M., Sadler J., Seidl R., Potapov P., Gardiner B., Hetemäki L., Chirici G., Francini S., Hlásny T., Lerink B.J.W., Olsson H., González-Olabarria J.R., Ascoli D., Asikainen A., Bauhus J., Berndes G., Donis J., Fridman J., Hanewinkel M., Jactel H., Lindner M., Marchetti M., Marušák R., Sheil D., Tomé M., Trasobares A., Verkerk P.J., Korhonen M. & Nabuurs G.J. Concerns about reported harvests in European forests. Nature 592, E15–E17 (2021). https://doi.org/10.1038/s41586-021-03292-x
Ceccherini, G., Duveiller, G., Grassi, G. et al. Abrupt increase in harvested forest area over Europe after 2015. Nature 583, 72–77 (2020). https://doi.org/10.1038/s41586-020-2438-y
Last modified: 1 May 2021