Current issue: 52(4)
Under compilation: 52(5)
This investigation is part of series of studies aiming at defining the present condition and growing stock of drained peatlands. The studies were conducted in 1955–1957. The first part concentrates on the state of the areas, and second part the growth and volume of the stands.
Condition of the drained peatlands, a total of 45,224 ha, in Southern and Northern Finland, was studied occularly as surveys by stands. The stands to be studied were chosen randomly. Drainage effect of the areas proved to be relatively good especially in Southern Finland in private lands. In Northern Finland in the State forests, however, were many drained areas with poor drainage effect. Many of these were preliminary drainages that had not been continued. Others had too sparse drainage system, the planning was insufficient or the ditches had deteriorated. The need for supplementary draining should be considered. The condition of the ditches in old draining areas was relatively weak. This can be problematic especially in private lands. Therefore, the ditches should be planned in a way that minimizes the need for repair. The silvicultural state of the forests was poor, mostly because forest management, and sometimes regeneration had been neglected.
A total of 1,368 sample plots were measured to determine the growing stock of the studied stands. The country was divided in five climatic zones to determine local variations in the growth. The material covered large variation of peatland types. The growth of different spruce swamp types had increased close to the mineral soil sites, but especially in originally treeless or sparcely wooded stands the growth was still poor. In addition to fertility of the peatland type, the climate zone had strong effect on the volume of the stands when similar peatland types were compared. Tree species composition seemed to be strongly determined by the peatland type. Against previous understanding thickness of the peat layer had little effect on the growth of the trees, and shallow peat layer proved not to improve the drainability of a peatland.
The PDF includes a summary in German.