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

The effect of temperature on the low-frequency variation of Scots pine grow th was analyzed using tree-ring data from the northern forest limit, northe rn Finland. Special effort was, therefore, made to avoid loss of low-freque ncy variation in standardizing ring-width series. Three models representing different approaches were used for describing the climate-growth relations hip. Two of them, a dynamic model based on daily maximum temperatures and a traditional linear model, emphasize mainly the effect of midsummer tempera tures. In addition, a dynamic model was constructed for describing the effe cts of spring and autumn temperatures, based on describing the seasonal var iation of the CO2 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 i n northern tree rings is dominated by the effect of July temperatures. Howe ver, the results also suggest that temperature throughout the photosyntheti cally active period can be useful in explaining growth variation of Scots p ine. (C) 2001 Elsevier Science B.V. All rights reserved.