Juhani Päivänen , Sakari Sarkkola

The effect of thinning and ditch network maintenance on the water table level in a Scots pine stand on peat soil

Päivänen J., Sarkkola S. The effect of thinning and ditch network maintenance on the water table level in a Scots pine stand on peat soil.

Tiivistelmä

The effect of tree stand thinning and ditch network maintenance on the water table level was studied in an uneven-aged Scots pine (Pinus sylvestris L.) stand growing on a drained dwarf shrub pine bog in southern Finland. The water table level was monitored once a week during the growing seasons (May–September) of 1991–1999. This time span is divided into the following treatment periods: calibration (1991–1992), thinning (1993–1994), ditch cleaning (1995), and proper ditch network maintenance (1996–1999). The growing season of 1995 was not included in the calculations because the ditch cleaning treatment failed. The layout included three thinning intensities (9.5, 15.0, and 28.1% removal of the initial stand volume) and an unthinned control. For the ditch maintenance treatment there was an additional control sample plot. The effect of the treatments on the water table level was evaluated both by a graphical approach and linear regression analysis. Only a slight, ecologically insignificant rise in the water table level was caused by the thinning cuttings. Ditch maintenance seemed to eliminate this change. It was concluded that in the planning stage, a careful evaluation of the real need of maintaining the ditch network (ditch cleaning or complementary ditching) should be done in connection with the first commercial thinning in order to avoid unnecessary costs.

Avainsanat
forest drainage; peatland; hydrology; ditch cleaning; complementary ditching; tree harvesting

Vastaanotettu 31.10.2017 Julkaistu 1.1.2000

Katselukerrat 566

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