|Ten-year results of a comparison of methods for restoring afforested blanket bog||downloads: 100 | type: pdf | size: 2 MB|
Volume 19 (2017) Article 6
Ten-year results of a comparison of methods for restoring afforested blanket bog
by R. Anderson and A. Peace
Published online: 26.02.2017
There is growing interest in the restoration of blanket bogs that were afforested during the 1960s to 1980s, to avoid further loss of carbon to the atmosphere and to regain and defragment important blanket bog habitat. This paper reports the findings from a ten-year experiment in the UK to test the effectiveness of restoration treatments on water table depth, peat bulk density and water content, ground surface height and vegetation development. Treatments used were the six combinations of damming or not damming plough furrows with leaving the trees alive, felling and leaving them on the ground or felling and removing them. Combining felling with damming furrows was most successful in raising the water table, whether or not the felled trees were removed. Only where felling was combined with damming did the water table continue to recover between Years 5 and 10. Over ten years, the water level in these treatments rose to slightly below that of non-afforested reference bog at the same sites. This occurred as a rapid initial rise, following which there was only very slight further improvement. Felling caused the species composition of the vegetation to change towards that of the reference bogs. The process was slow, with the vegetation becoming more dissimilar to non-forested reference bog in the first five years and then becoming more similar to the reference bog after Year 5. Surprisingly, damming plough furrows had little effect on the vegetation except that, in combination with felling, it increased differentiation between the plough furrows and other positions on the ploughed ground. Conifer seedlings established on the restored plots, most densely where they adjoined standing forest, and had similar density and growth in all the felled treatments. The restoration treatments resulted in a decrease in bulk density and increase in water content of the upper peat, probably due to an unloading effect caused by the raised water table buoying up the drained peat layer. In some treatments this was amplified by removal of the weight of the trees. Damming the plough furrows caused a 5–7 cm rise in ground surface height, suggesting that subsidence resulting from primary consolidation and secondary compression is at least partly reversible.
Anderson, R. & Peace, A. (2017): Ten-year results of a comparison of methods for restoring afforested blanket bog. Mires and Peat, 19(6), 1-23. (Online: http://www.mires-and-peat.net/pages/volumes/map19/map1906.php); 10.19189/MaP.2015.OMB.214
IMCG and IPS acknowledge the work of the reviewers.