The effect of temperature on the radial growth of Scots pine in northernmost Fennoscandia

Abstract

The effect of temperature on the low-frequency variation of Scots pine growth was analyzed using tree-ring data from the northern forest limit, northern Finland. Special effort was, therefore, made to avoid loss of low-frequency variation in standardizing ring-width series. Three models representing different approaches were used for describing the climate-growth relationship. Two of them, a dynamic model based on daily maximum temperatures and a traditional linear model, emphasize mainly the effect of midsummer temperatures. In addition, a dynamic model was constructed for describing the effects of spring and autumn temperatures, based on describing the seasonal variation of the CO 2 uptake capacity of Scots pine. The results show that the very large low-frequency variation in ring-widths, typical for regions with harsh climate, is to a considerable extent due to climate. The results are in accordance with previous findings suggesting that the climatic signal in northern tree rings is dominated by the effect of July temperatures. However, the results also suggest that temperature throughout the photosynthetically active period can be useful in explaining growth variation of Scots pine.