Contrasting pathways to ombrotrophy in three raised bogs from Ireland and Cumbria, England

The plant macrofossil records from three raised bogs from western and central Ireland and from Cumbria were compared to investigate variations in the character and timing of the fen-bog transition (FBT). Two modes of raised or ombrotrophic peat formation were recognized. In the first mode the transition develops through a sedge-fen stage directly to raised-bog lawn, maintaining a near surface water table throughout the FBT (Abbeyknockmoy Bog). The second mode is characterized by a switch from fen or reedswamp to a dry Eriophorum-dominated mire type, suggestive of low or unstable water tables (Mongan Bog and Bolton Fell Moss). Comparisons with the Holocene effective precipitation record suggest that the type of transition and its timing may be affected by the prevailing climate regime. All that is required for ombrotrophy is a separation of the growing peat surface from the influence of ground and surface waters. This separation may be achieved by rapid peat accumulation in a moist climate, the accumulation of decay-resistant Eriophorum vaginatum hummocks or by a lowering of the water table, leading to a 'perched peat bed'. In the latter two cases, a 'pseudo-raised bog' community often persists, laying down highly humified peat, until increased oceanicity enables Sphagnum to dominate

Utilización de compost agotado de champiñón como capa de coberturas en nuevos ciclos de producción Using spent mushroom substrate as casing layers in new growing cycles

El objetivo de este trabajo fue evaluar el comportamiento agronómico de seis mezclas de cobertura, elaboradas a partir de sustrato postcultivo del champiñón Agaricus bisporus, en nuevos ciclos de cultivo. Los resultados obtenidos mostraron la viabilidad de la reintroducción del sustrato en nuevos ciclos de cultivo, ya sea como material de base único, si se somete a un proceso de lavado para eliminar sales solubles, o bien mezclado con otros materiales de baja conductividad, como es el caso de la turba rubia o la fibra de coco. Se destacan los altos valores de eficiencia biológica registrados, que llegaron hasta los 100 kg kg-1 de compost, similares a los proporcionados por los testigos, y los altos valores relativos observados (con respecto a los testigos) en el contenido en materia seca de los carpóforos cosechados con algunas de las nuevas coberturas elaboradas. Esta reutilización del compost constituye una alternativa interesante, con vistas a reemplazar a las tierras y a los sustratos orgánicos utilizados habitualmente como cobertura, con la doble ventaja de disminuir los costos de elaboración y el impacto ambiental.<br>The objective of this work was to evaluate the agronomic behaviour of six mixtures of casing, prepared from spent mushroom substrate (SMS), in new production cycles of Agaricus bisporus. The results obtained showed the feasibility of reuse of the SMS in new cultivation cycles when used alone by submitting it to a washing process to remove soluble salts, or mixed with other materials of low conductivity, such as Sphagnum peat or coconut fiber pith. The high values of biological efficiency recorded up to 100 kg kg-1 compost, similar to that of the controls, and the same high values observed in the dry matter content of the mushrooms harvested with some of the new casing layers prepared must be highlighted. The suggested use for SMS is an important alternative to consider, in order to replace soils and other organic substrates typically used as casing, with the added advantages of lowering the production costs and decreasing the environmental impact