Climate changes - how trees survive in changing conditions

Latest weather forecasts estimate that the average annual temperature in Finland will rise by the end of the century even more than 5 - 7 degrees, and possibly a precipitation nearly 40% in comparison to the period from 1961 to 1990. Temperature rise and increase in the precipitation are concentrated to winter time. Longer dry periods and more common extreme climatic events are a threat to growing season.

A change and it ´s speed makes it difficult to forest trees to adapt to new circumstances. Responding to the change demands knowledge of future condition and breeding material´s capacity to react and together speed up a processing cycle.

Tree species will react differently to climate change

Finnish main tree species; Scots pine, Norway spruce and Silva birch are wind pollinated. Wind brings new gene material to populations also from a distance. A strong gene flow increases variety in populations and allows quick adaption to changing circumstances.

Large variations in the conditions and particularly the extreme conditions are affecting to reproductive capacity of trees. For example, a drought during a differentiation of flower primordias in June-July and early spring periods of heat in reproductive cell development stage can prevent a formation of functional germs. If conditions vary strongly either in pollination or in fertilization, the seed development is interrupted. Changes may be reflected to a different origin pollen´s capacity to pollinate and fertilize.

In some tree species such as oak and little-leaf-linden, a global warming may contribute to a seed maturation. Especially the little-leaf-linden´s weak seed maturation has limited it´s spreading in Finland. The global warming will also lead to greater a evaporation and affects in particular to growth of low shallow root system species, such as spruce.
The climate change may also affect to a relationship between generative and vegetative reproduction. In this case, for example, aspen may spread to new environments. Aspen reproduces both generative from seed and asexual from root.