Rapson et al. - Otago gully-head ribbon fens

New Zealand Journal of Botany abstracts

Subalpine gully-head ribbon fens of the Lammerlaw and Lammermoor Ranges, Otago, New Zealand

G. L. Rapson

Ecology Group
Institute of Natural Resources
Massey University
Private Bag 11222
Palmerston North 4442, New Zealand
G.Rapson@massey.ac.nz

Martin T. Sykes

Geobiosphere Science Centre
Department of Physical Geography & Ecosystems Analysis
Lund University
Sölvegatan 12
223 62 Lund, Sweden

William G. Lee

Landcare Research
Private Bag 1930
Dunedin 9054, New Zealand

Allan E. Hewitt

Landcare Research
PO Box 40
Lincoln 7640, New Zealand

A. D. Q. Agnew

Institute of Biological Sciences
University of Wales SY23 3DA
Aberystwyth, Wales

J. Bastow Wilson

Botany Department
University of Otago
PO Box 56
Dunedin 9054, New Zealand

Abstract   Vegetation patterns of subalpine gully-head mires were investigated in the flat-topped Lammerlaw and Lammermoor Ranges, South Island, New Zealand. Two intensively studied mires each consist of a series of peaty terraces and scarps. Terraces may contain pools, elongated downslope in the narrow, lower altitude mire, but across slope in the broader, upper mire. A crest occurs on some terrace lips, and marginal “spillways” (channel-like zones) occur down some scarps. Some mires have drained by subsurface pipes.
     Vegetation analysis distinguished between grassland or herbfield on gully sides, vegetation of mire margins, showing aspect differences on the steeper, lower mire, and the vegetation of gully floors, including oligotrophic mire centre vegetation and species-poor pools. The crests, though warmer, bore no special vegetation type.
     Mineral soil beneath the peat indicates a previous non-mire vegetation, which has subsequently paludified. Scarp slumps indicate downslope creep of organic material. Peat fissures, and mineral, vegetation, and erosion dams all appear to have initiated development of some pools.
     Mires are designated gully-head ribbon fens. Patterning appears to be accentuated because of the mires’ gully-head location on broad-topped ranges, and drainage of soligenous water from upslope gully sides. These apparently unique fens give insight into patterning in aapa mires, and merit special conservation.

Keywords aapa mire; bog; cushion; dam; fen; fissure; microtopography; mire; pattern; pipe; pool; string

B06003; Online publication date 19 October 2006
Received 2 February 2006; accepted 14 August 2006

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