Erkki Ahti, Soili Kojola, Mika Nieminen, Timo Penttilä and Sakari Sarkkola
After Wise Use – The Future of Peatlands, Proceedings of the 13th International Peat Congress: Peatland Forestry
ditch-cleaning, mortality, scots-pine, volume, yield
The development of drained peatland forests dominated by Scots pine (Pinus sylvestris L.) was studied by using data from eight field experiments in which ditch cleaning, complementary ditching, or both were carried out in 1982-1985. Before ditch network maintenance, the mean volume of the stands was 38 m3ha-1, and 20 years later, 104 m3ha-1. So far, no commercial cuttings have been done. In Southern Finland, both stand volume and growth were still increasing, and no clear differences between the treatments could be detected after 20 years, including the control plots having been left without ditch network maintenance. In the stands of Northern Finland with lower volumes and growth rates, tree mortality had increased more and the growth rate was lower on the untreated control plots than on the plots that hade been treated by ditch cleaning and/or complemen- tary ditching 20 years earlier.