Changes to blanket bog adjoining forest plots at Bad a' Cheo, Rumster Forest, Caithness

Some impacts of 28-year-old South Coastal lodgepole pine foreston adjacent open blanket bog were investigated. A general risein ground level in unplanted areas between 1966 and 1987 hadbeen cancelled out by subsidence over most of the area by 1996.The forest plots had subsided by 40–80 cm since planting,depending on the cultivation/drainage treatment used and hadan increased peat dry bulk density (0.13 Mg m^–3) and adecreased water content (7 kg kg^–1 dry matter) comparedwith points more than 50 m from the forest (0.060–11 Mgm^–3 and 9–16 kg kg^–1 dry matter). The depthto water table in July averaged 55 cm in the forest but only20 cm outside. The zone outside the forest affected by subsidence averaged30 m wide in 1996, compared with 10–20 m in 1987, suggestingthat by the end of the first rotation a 40-m wide zone willbe affected. The development of a slope outside the forest bysubsidence was considered to be a consequence of more rapidrun-off and seepage towards the forest, rather than root spreadonto the bog. Where pool systems or other vulnerable habitatsare surrounded by forest, a buffer zone at least 40 m wide isneeded between the edge of the habitat and the edge of the forestto safeguard the habitat during the first rotation. A narrowerbuffer zone may be sufficient in higher rainfall areas.