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Even-aged management (rotation forestry, RF) involves ditch network maintenance (DNM) operations in peatlands. Although the DNM operations contribute tree growth, they have negative environmental effects on watercources. To avoid DNM, a strip cutting (SC) management has been proposed. SC management in peatlands relies on natural regeneration by trees growing on the edge stand next to a clear-cut strip. The width of a cut strip varies, and here 20, 35 and 50 m strip width were applied in three locations in Finland: Akaa (southern), Kuopio (central), and Oulu (northern Finland). Tree growth of an edge stand and sapling stand was modeled with a stand-level model which accounted for the effect of dominant height of the edge stand and variation of shading among alternative strip widths. In southern location, RF financially outperformed SC management with interest rates 2–4%, but with a 5% interest rate and strip with of 35 or 50 m SC management was more beneficial than RF. In central and northern locations RF was better only with a 2% interest rate and with a 20 m strip width. Our results demonstrate that SC management is a financially valid option to apply in pine-dominated peatlands, particularly in northern regions. [ABSTRACT FROM AUTHOR]

In boreal-drained peatland forests, tree growth is retarded by the gradual deterioration of drainage ditch networks. In order to avoid the development of suboptimal growth conditions, ditch network maintenance (DNM) operations (ditch cleaning and/or complementary ditching) are annually conducted on an area of about 70,000 ha in Finland. The previous studies indicate that the depth of the water table prior to DNM may influence the magnitude of the growth response to DNM. Tree growth does not necessarily increase after DNM at sites with large stand volume and subsequent low water levels due to tree stand evapotranspiration. We investigated how the pre-treatment water table depth (pre-WTD) in late summer relates to the growth of Scots pine (Pinus sylvestris L.) stands after the DNM operation in 12 field experiments. The increase in mean annual volume growth caused by DNM was negatively related to the pre-WTD, with the highest growth response in stands where the pre-WTD was less than 25–30 cm. DNM did not clearly increase stand growth in sites where the pre-WTD was more than 35–40 cm below the soil surface. There was a high variation in growth response to DNM between the water levels from 20 to 35 cm below the soil surface, indicating that factors other than water table depth are also needed as decision criteria for assessing the appropriate timing of ditch network maintenance. [ABSTRACT FROM PUBLISHER]