Occurrence and berry production of Rubus chamaemorus L., Vaccinium oxycoccus L. & Vaccinium microcarpum Turcz. and Vaccinium vitis‐idaea L. on Swedish peatlands

During three consecutive years, 1978–1980, cloudberries (Rubus chamaemorus L.), cranberries (Vaccinium oxycoccus L. & Vaccinium microcarpum Turcz.) and lingonberries Vaccinium vitis‐idaea L.) growing wild in Swedish forests and mires were inventoried in the annual National Forest Survey. Both the coverage and fertility of these were estimated. Observations from 42 000 test sites (314 m² each) were processed according to geographical region, composition of tree and field layer, altitude and occurrence of draining ditches. Cloudberries cover 425 000 hectares or 1.5 % of the total investigated area (28.6 million hectares). The corresponding values for cranberries and lingonberries are 136000 hectares (0.5 %) and 1362000 ha (4.8%) respectively. Open mires have a greater degree of coverage by cloudberry and cranberry than wet forests on peat. The reverse situation is true for lingonberry. The total berry yield on peatland was estimated to 116.6 million kg (freshweight), distributed as 75.7 million kg cloudberries, 20.8 million kg cranberries and 20.1 million kg lingonberries. The corresponding production of lingonberries on mineral soils was 188.8 million kg. Both in wet forests and on mires, drained areas show lower berry production for the three species, with one exception. Lingonberries yielded better on drained mires. Productive stands of cloudberries and cranberries ought not to be drained for economic reasons.     

The formation of tephra layers in peatlands: An experimental approach

Tephrochronology provides a valuable method of dating peat deposits but results may be compromised if tephra undergoes significant post-depositional movement. This study takes an experimental approach to investigate the processes of tephra taphonomy. Tephra was applied to peats and movement monitored over periods of up to 6 years. Experiments combined field studies on six British peatlands with rainfall simulation experiments in the laboratory. Tephra moved up to 15 cm down through the peat but the vast majority remained at the surface at time of deposition, forming a layer which accurately recorded the palaeo-surface. Tephra moved both down, by shards sinking through the peat, and up, with shards probably being moved by plant growth or with water table variability. The extent of tephra movement most likely depends on the density and porosity of the surface peat; there is no simple relationship with wetness. There is some indication that the extent of tephra movement depends on the tephra particle size but this will require further work to confirm. The taphonomy of tephra is an important issue which should be considered in all tephrochronology studies in peatlands.     

Investigating thickness and internal structure of alpine mires using conventional and geophysical techniques

We investigated the thickness and composition of five small alpine mires in Tyrol (Austria), performing a combination of conventional techniques (telescope rods, drilling) and geophysical methods. GPR surveys were carried out using 100 and 200 MHz antennas. Geoelectrical profiles supplemented the GPR at two sites; the 2D-surveys were enhanced by additional 1D-profiling. The aim was to achieve data on mire thickness, to cross-check the methods and to find reasons for different performance at the five sites. The investigations contribute to establishing a future protection concept.