on Sphagnum recolonization and succession in a block-cut

This study of an abandoned cutover bog aims to understand the processes controlling moisture conditions that have led to distinct spatial patterns of Sphagnum recolonization, and also how substrate conditions may have changed since abandonment and the implications for plant establishment. Two (unreplicated) symmetrical 12 ð 3Ð5 m2 quadrats either side of the centre-line of a block-cut trench were treated by removing all recolonized vegetation, including Sphagnum, from one quadrat (REMOV), examining Sphagnum-covered (SPHAG) peat in the other, and bare peat (BARE) in both. Average volumetric soil moisture contents in the peat (2 cm below the surface) of the SPHAG and REMOV substrates were similar (86%), but greater than in BARE peat (78%). In a location not manipulated for this experiment, where Sphagnum cushions have re-established on bare cutover peat, beneath the cushions was 5–14% greater than in bare cutover peat directly adjacent to it, indicating that cushions can regulate local substrate water storage, and benefit from it during periods of increased water demand. This may have assisted in the lateral expansion of Sphagnum. A loosely structured 0Ð5 to 1Ð0 cm thick organic litter layer (chiefly Ericaceae) overlying the BARE peat substrate slowed the rate of drying of bare peat in a laboratory sample. The laboratory tests found the capillary fringe to be up to 26 cm above the water table. The dry conditions and the larger pore structure of this litter layer hindered upward capillary flow and, therefore, plant water availability. In (occluded) ditches and low areas, the capillary fringe remained within 5 cm of the surface, and these locations supported the most complete Sphagnum cover. In slightl