Reforestation guidelines will consider climate change

Publicerad: 28 september 2015

Tree breeding is a long-term activity and has to be adaptive and flexible to future conditions. Future Forests supports a project that aims to develop guidelines for seedling transfer, taking future climate into account. Results have been implemented for Scots pine, in collaboration with Finland. Similar guidelines are underway for Norway spruce in a joint project involving Norway, Finland, Sweden and the Baltic states.

Sweden and Finland together use some 500 million seedlings per year for reforestation of Norway spruce and Scots pine. Three quarters of the seedlings originate from seed orchards, which are composed of genetically improved trees. These improved seedlings contribute to a significant increase in growth and CO2 uptake of the Nordic forests. Their current genetic gain is, on average, 10-15% compared to unimproved trees. In 2050, the gain is expected to be around 20-25%.

A warmer climate

Time horizons in forestry are long. Seedlings planted today will still be young trees in the middle of this century, and not ready for final harvest until several decades later. Over most of their lifespan they will probably face a climate that is warmer than today.

– The most likely scenarios forecast a temperature increase of about 2° C in southern and 4° C in northern Fennoscandia 50 years from now. We can also expect higher precipitation, especially during the winter and a longer growth period, says Johan Sonesson at Skogforsk.

Johan Sonesson is one of Future Forests’ researchers working with adaptation of reforestation material to climate change. Previous deployment guidelines are publicly available in a decision support tool (Planter’s guide). The tool shows the gain associated with reforestation material at an arbitrarily selected planting site, using transfer functions based on old provenance trials.

– These functions are already adapted to climate change, since they consider the current climate for the survival functions and the climate in around 2050 for the growth functions, says Johan Sonesson.

New climate-adapted transfer functions

Future Forests have now developed new climate-adapted transfer functions for Scots pine that are valid in both Sweden and Finland. Mats Berlin from Skogforsk has been heading this part of the project.

–Together with climate researchers at the Rossby Centre, SMHI, we have developed climate-adapted transfer functions for alternative climate scenarios, says Mats Berlin. These have been validated with almost 15 000 family mean values of survival and growth in Sweden and Finland.

The new functions have been implemented in a beta version of Planter’s guide to provide a decision support tool for selecting robust and highly productive regeneration material at an arbitrarily chosen planting site in Sweden or Finland in a changing climate.

– We are now in a process of publicly sanctioning the new deployment recommendations together with public and private forest stakeholders in Sweden and Finland, says Mats Berlin.

New project on Norway spruce

Parallel to the Scots pine project, similar work is underway for Norway spruce. Field data from a broader area in the Nordic and Baltic countries are being used together with climate data to develop new transfer functions.

– The Norway spruce project is more challenging. It covers a climatically more variable geographic area, and the performance of Norway spruce is largely dependent on its phenology. In particular, damage from late spring frost must be considered in the southern part of the region, says Mats Berlin.

So far, data have been compiled and development of the new transfer functions for Norway spruce will commence during autumn 2015.

/ Text Mats Hannerz, Silvinformation