On the afternoon and night of Saturday 8 January, a major low-pressure system that had been building over the Atlantic unleashed a ferocious storm over southern Sweden. By Sunday morning, Cyclone Gudrun, as it came to be known, had moved eastwards over the Baltic, but the devastation in the southernmost third of Sweden was clear: many million trees had been felled, 400 000 people were without electricity, and many roads and railway lines were blocked by fallen trees.
Gudrun’s consequences for the forest sector in southern Sweden were nothing short of catastrophic. Some 75 million m3 of timber was felled, more than in all storms in the 20th century in Sweden put together. In a matter of hours, timber equaling an entire year’s annual harvest in the whole of the country was brought down. Gudrun also came to be a true wake-up call for Swedish forestry when it comes to climate change adaptation.
The 2014 annual two-day Autumn Excursion organized by the Swedish Forestry Association (Föreningen Skogen) gathered 150 people – among them a veritable Who’s Who of Swedish forestry – to discuss what has been learned in the almost 10 years since the storm.
A future for Norway spruce?
More than 80% of the felled wood was Norway spruce. With their shallow roots, the Norway spruce trees were already vulnerable to high winds, and this vulnerability was multiplied by the fact that warm early winter weather had meant forest soils were not frozen. Although it is not certain that Gudrun-scale storms will become more frequent or more intense with a warmer climate, it is certainly possible; warmer winter weather is even more likely. One of the biggest questions raised by Gudrun is around the future role of Norway spruce – currently by far the favourite tree species in forestry in southern Sweden – in a changing climate.
Discussions during the excursion focused on two possible strategies: switching to another, less vulnerable, tree species, and continuing to cultivate Norway spruce, but changing management practices to reduce the risk from storms.
Neither choice is simple. To begin with, Norway spruce has become the predominant timber species in southern Sweden as it has a number of advantages. First, it is straightforward to manage; most importantly, it’s not a favourite food of deer and moose, who make it virtually impossible to plant Scots pine in large parts of southern Sweden. Secondly, there is assured and large industrial demand for Norway spruce within Sweden. Viable alternative tree species, like larch, might need to be transported abroad to find a seller willing to pay a decent price.
Thus it seems like Norway spruce is here to stay as the dominant timber species in southern Sweden. This is despite both governmental subsidies for the establishment of oaks and beech and the efforts of people like Anders Lomholt, forest manager at Sperlingsholm Estate and an enthusiastic proponent of exotic tree species like hybrid larch and Sitka spruce.
Adapting to uncertainty
That brings us to management changes. A hot topic for discussion during the excursion was if, how and when to thin out spruce plantations. Thinning boosts productive potential and quality of the remaining trees. However, it also opens up forest stands and can make them more vulnerable to high winds. This means that the timing and methods of thinning can make a huge difference to commercial forests’ vulnerability to storms.
At the same time as a warming climate alters conditions for forestry all over the country, large parts of the Swedish forest industry are having to adapt to a drop in demand, thanks in part to the shift from printed to digital media. This became evident during a study visit to Hyltebruk, where Stora Enso’s papermill, a major newsprint producer, was recently forced to halve its staff. One clear message from the discussions during the excursion is that the Swedish forestry sector is moving towards an ever more uncertain future.
Next year’s excursion will be hosted by Mistra-SWECIA – where SEI is a key partner. Following the same path, it will focus on another, more recent disastrous event: the August 2014 forest fire in Västmanland, and how to deal with risk and the unknown unknowns potentially affecting Swedish forestry.