Evolving forest certification criteria seem to drive the increase in the amount of deadwood
Ecologically sufficient source of deadwood has been among the most distinct features in commercially managed forests that has been lacking. Only a limited amount of deadwood develops within one rotation period, and historically speaking we have been too eager to “clean” that up during harvesting. This has been the way of the trade despite the fact that thousands of species in Finland rely on or benefit of it. Those species include not only a whopping diversity of fungi and beetles but a myriad of other insects, mosses, lichens and birds.
The PEFC (PEFC/02-21-17) and FSC® (FSC C105876) certification criteria as well as UPM’s self-set biodiversity targets give guidelines for our management measures. We leave all deadwood intact, we leave retention trees to provide a source of new deadwood, we may even create deadwood in the form of artificial snags if the natural formation of deadwood has been slow. We aim to ensure the sufficient resources for the deadwood-dependent species over the whole rotation period.
According to a recent inventory study by Natural Resources Institute Finland, there is a significantly greater amount of deadwood in areas that were regenerated after 2011 than in areas regenerated at the beginning of the millennium. The year 2011 stands as a significant milestone for UPM-owned forests as the FSC certification criteria were adopted. The study shows that the average amount of deadwood in the areas regenerated in 2012–2018 was 13m3/ha, compared to the amount of only 3.1m3/ha for the areas regenerated in 2000–2006. Although the result is based on a sample, the amount of deadwood in the company's forests appears to be increasing. The result not only reflects a widespread attitudinal change towards deadwood, but UPM has sought to promote deadwood for its recognised biodiversity value. The result is very promising from the perspective of UPM's Forest Action and NPI (Net Positive Impact) targets: increasing the average amount of deadwood in company’s forests to 10m3/ha appears achievable.
Does increase in deadwood translate into increase in biodiversity?
UPM has committed to improve biodiversity in its forests. The certification criteria essentially aim for the same objective via promoting ecological management measures. However, in a case of a deadwood-dependent species, it may be unclear whether the absence or scarcity of a species is solely due to the lack of deadwood. The species may have further habitat requirements, e.g., for certain microclimatic conditions, which cannot be satisfied by increasing the amount of deadwood. To verify the benefits of our actions on biodiversity, it is of utmost importance to monitor if deadwood in regeneration areas actually gets accepted by deadwood-dependent species.
Researchers from the Natural Resources Institute Finland inventoried the species living on deadwood in the UPM-owned regeneration areas. The study focused mostly on polypore species but some saproxylic beetle species were also found. An average number of polypore species in the more recently regenerated areas was more than three times the number of species in the areas regenerated at the beginning of the millennium. Most of the observations were made on deadwood that was over 15cm thick. Among the species detected there were 18 red-listed species, five of which are classified as threatened.
In summary, species richness has increased with the increase in the amount of deadwood. Based on the results, we cannot know what proportion of deadwood-dependent species accepts the deadwood in the regeneration area, but we do know that many species accept it. Arguably, there is still room for better optimisation in our management measures, and not enough attention is paid to the fact that all deadwood is not of equal value for biodiversity. Thick deadwood seems to attract more biodiversity than thin deadwood, and deadwood formed from a variety of trees is followed by a wider diversity of species. In addition to the sufficiency, the continuity of the resource is equally important and should be ensured. Regardless, the results of this study excite us to continue our work towards ecologically sustainable future. Our management measures are contributing to the revival of nature, and it is happening today, which is an achievement to be proud of.
Far too often it is the negative developments that make the headlines, so I hope you found this reading cheering!