Vegetation regeneration on blanket mire after mechanized peat-cutting

摘要

1 Blanket mire in Northern Ireland is an ecologically threatened habitat in which land use for hand peat-cutting, forestry and agriculture has had a major influence. A recent land use change is the introduction of tractor-powered peat-harvesting. Inthis paper, the effect of machine peat-cutting on ombrotrophic blanket mire vegetation is assessed from a regional sample of cut and uncut plots. 2 Principal components analysis identified watertable depth and grazing intensity as major factors influencing the species composition of uncut mire. A key variable affecting the composition of machinecut mire across the drainage gradient was the number of times cut, with multiple annual cutting causing progressive decreases in acrotelm depth, catotelm bulk density and plant cover. Ericaceous species and Sphagnum spp. were particularly sensitive to cutting, with Eriophorum angustifolium and Carnpylopus introfiexus characteristic of multiple-cut sites. 3 Redundancy analysis, with number of times cut partialled out, showed that recovery time accounted for a significant amount of variance in vegetation composition. Species that significantly increased in abundance with recovery time were Sphagnum spp., Odontoschisma sphagni, Erica tetralix and Drosera rotundifolia. 4 Sites cut frequently, or which were grazed, recovered more slowly. Recovery from cutting was partly dependent on the post-cutting structure of the mire surface and the species that survive cutting. The rate of recovery on sites cut once, then abandoned, is relatively rapid compared with multiple-cut sites where species colonization is constrained by bare compacted peat.