NUTRIENT CONCENTRATIONS IN PEAT - NEEDLE RELATIONS AND FROST HARDINESS IN SCOTS PINE IN VARIOUS CLIMATES IN NORTHERN CENTRAL FINLAND

摘要

We studied the soil and foliar nutritional characteristics of 145 tree stands on drained mires in northern central Finland (64°N-66°N). The peat and needle samples were collected from 145 sites. The frost hardiness of Scots pine needles was tested from three stands. Humification of the peat in the depth of 5 to 10 cm increased from H 3.6 to H 4.6 and mean nitrogen concentration from 1.6 % to 2.3 % respectively with the increasing temperature sum. Soil phosphorus and iron concentrations also increased from north to south. The results suggest that in the warmer climates the peat is more decomposed and provides sufficient amounts nitrogen for tree growth through natural mineralization. The needles were nitrogen deficient (N < 1.30 %) in coldest climates. The mean phosphorus concentration in the needles was over the deficiency limit (1.39 mg g~(-1)) in coldest climatic region and decreased in the warmer climates. The mean potassium concentration in the needles decreased from 4.6 mg g~(-1) to 3.8 mg g~(-1) as the temperature sum increased from 850 dd to 1050 dd. In September the needles were most cold hardened in the 850 dd climate, compared to those of the warmer regions. In October, however, there were only minor differences in the frost hardiness of the needles in different climates. The decrease in the frost hardiness along a temperature gradient in September was attributed to the well-known temperature control of frost hardiness. Frost hardiness in nitrogen rich sites, needles having the highest foliar nitrogen concentrations, were slightly lowered in the two warmest climates where as no effect was found in the coldest climate.