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Biomass, biomass increment and nutrient cycling were studied in (1) a Scots pine (Pinus sylvestris) stand, (2) a Norway spruce (Picea abies) stand and (3) a mixed birch (Betula pubescens)/pine stand on a drained mire at Ilomantsi, eastern Finland in 1979-85. In addition, the effect of NPK and micronutrient fertilizer treatment was studied. Above-ground and root measurements were taken. These data formed the basis of stand biomass and nutrient cycle simulations of fertilized and unfertilized stands. The increases in biomass were greater in (1) and (2) in the fertilized simulation than in the unfertilized one. For (3), the effect of fertilization on biomass increment was small. In six years only part of the applied fertilizer had been fixed in the biomass of the model stands and proportionally less micronutrients than macronutrients. The potassium stores were small compared to the nutrient amounts fixed by the stands. This supports the notion that there is a shortage of potassium on deep-peat soils.

This is the latest report in a series of publications from an on-going investigation which is concerned with the influence of different fertilization treatments and ditch spacings on the growth of Scots pine ( L.) seedlings and transplants growing on nutrient drained poor bogs in different parts of Finland. This paper concentrates on duration of the growth response to NPK-fertilization on the experimental plots. The experiment was established and the treatments performed in 1965â66.Pinus sylvestris

Data are presented from 1312 km of inventory transect, 6030 relascope sample plots and 21 700 ditches. Of the Finnish peatlands studied, more than 60% were pine mires, almost 20% were spruce mires and less than 10% each were treeless mires and paludified upland forest sites. The survey included the condition of the drainage networks, and the post-drainage development of the tree stands, their structure and silvicultural condition.