Adaptation of Norway spruce (Picea abies (L.) Karst.) to current and future climatic conditions

Climate change urges our understanding of the capacity of Norway spruce (Picea abies (L.) Karst.) population to adapt and maintain, and even increase, their growth capacity at the level required to sustain a transition towards a biobased socioeconomic model. Climate change is already anticipated to result in an increase of temperature. Although generally an increase in the average temperature is considered favourable for growth in the boreal climates, it will also consequence in more frequent temperature backlashes and drought. Outbreaks of pests and fungi are often associated with extreme events. Altogether, this exemplifies the need to investigate how Norway spruce may respond to those predicted changes. Second generation material of eastern European origin, in relation to improved Swedish material, performs well in the current climate in southern Sweden, with later bud burst when grown in Sweden as compared to Swedish material. The second generation material is closer to Swedish material in timing of bud burst indicating a land race formation. At frost prone sites trees with late bud burst should be deployed as trees with early bud burst will increase the risk of spring frost related damages. The impact of future climate change on 18 Swedish and Eastern European provenances showed that frost days in southern Sweden are likely to decrease, but as bud burst will occur earlier this is expected to lead to an increased occurrence of spring frost events. Furthermore, above normal temperatures during the latter part of quiescence phase can induce earlier bud burst and lower cold tolerance, hence increase the risk for frost damages in spring. Drought can affect the height growth of trees both during as well as after a drought event. A higher genotype and environment interaction (G x E) was also observed to be high and significant in severely drought-damaged stands, thus drought may be the underlying factor for a stronger G x E and subsequently a change in the ranking of tree genotypes.