The effect of ditch cleaning and complementary ditching on the development of drained Scots pine-dominated peatland forests in Finland

摘要

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 m~3ha~(-1),and 20 years later,104 m~3ha~(-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 complementary ditching 20 years earlier.