NordGen Forest annual conference 2013
Northern forests in a changing climate
This was the theme of NordGen Forestâ€™s annual conference held at Hallormsstadur in eastern Iceland on 17-18 September. More than 30 participants from all Nordic countries attained the conference which contained 11 high-quality presentations addressing the expected nature of climatic change, consequences for forest ecosystems and forestry and measures to meet these changes.
Although the uncertainties are substantial, climate change at high latitudes include at least 2Â° C increase in summer temperatures and 3-4Â° C increase in winter temperatures before 2100. In addition, a general large increase in precipitation is expected, whereas less change is generally expected in wind speed.
Several speakers noted the obvious positive effect of higher biomass production as a direct effect of increased temperature, but also due to increased availability of nutrients as mineralisation of the soil is facilitated. More favourable growth conditions also provide option value with respect to new forest tree species with generally higher temperature requirements.
But rapid increase in temperature implies that the growth rhythm of trees gets out of phase with the annual temperature cycle of their growing site, leading to climatic damages. Thus, climate warming particularly implies higher risk of spring frost damages, but also higher risk of wind throw when frozen soil is replaced by waterlogged soil in winter and salt spray damages in coastal areas.
How can forestry meet these changes? It was emphasised that breeding is an important tool, e.g. by selecting reproductive material with late onset of growth in spring. In addition, use of southern provenances, and also other well adapted species such as larch, sitka spruce, lodgepole pine and Douglas fir should be considered. Use of exotic species is, however, restricted in several Nordic countries.
Along with climate change species change their natural ranges, and pathogens are no exception. One presentation showed the great increase in number of pathogens and other species arriving in Iceland over the last decades. For example, it appears that milder winters pave the way for higher populations of the green spruce aphid attacking sitka spruce, and that higher summer temperatures lead to more extensive leaf rust attacks on poplar which appeared in 1999. It is quite obvious, that the arrival of new pathogens and their effects are far beyond predictability, even if the Icelandic phytosanitarian regulations for import of forest reproductive material are strict. Garden plants can, however, be imported much more freely.
Agriculture and food security are challenged by climate change and continuing human population growth. The final presentation highlighted the need taking advantage of the opportunities, e.g. securing large gene pools, developing new technologies and breeding methods and securing greater interaction between countries. Numerous questions followed each presentation, fuelling fruitful discussions.
The conference was concluded with a field trip in Hallormsstadur. The founders of the 50 year Icelandic afforestation program were openminded, and it is now clear that a number of North American (e.g. white spruce, sitka spruce, Engelman spruce) and European species (e.g. Norway spruce, Siberian larch, silver birch) are able to survive and thrive under the climatic conditions of Iceland, provided that the provenances are well suited.