Long-term effect of wetland drainage on the productivity of Scots pine stands in Poland

Abstract

The aim of this study was to estimate the long-term effect of wetland drainage on the productivity of Scots pine stands in Poland. Data were obtained from the forested area of the Niepolomice Forest District, which was drained in 1964–1968. To describe the long-term changes in site productivity, a local site index model was developed. The effect of drainage depended primarily on the age of the stand at the time of drainage. A positive growth response (i.e., an increase in height) was observed in stands that were younger than 45–50years at the time of drainage, with younger stands showing stronger responses. Drainage caused an increase in the site productivity of young stands that can be expressed as a change of 5.4m in site index. For fully stocked stands, the average effect of drainage expressed as the predicted increase in total wood production at age 100years was estimated to be approximately 200m3ha−1 (25%) in those stands planted after drainage. The predicted increase in the total volume of production at total stand age 100years for stands that were 30years old at the time of drainage was estimated to be approximately 125m3ha−1 (15%). For stands that were 40years old at the time of drainage, the predicted increase in volume production was approximately 50m3ha−1 (6%). Stands older than 50years at the time of drainage were assumed to be unaffected.