TEMPERATURE STRATIFICATION IN BOG PONDS

Although temperature of the bog ground and the upper layers of bog pon ds rises to values of respectable heights for some hours during a sunn y day the Sphagnum bogs were generally seen as cold environments. This could be stated in the terrestrial areas and was supposed from the aq uatic environments also. In the latter the low temperature during nigh t and the rapid and uniform decline of temperature from the upper to t he lower water layers during fine days were assumed to be the reasons for the general cold microclimate. But investigations of the embryonal and larval development of bog dwelling dragonflies demonstrated the t hermophilic character and the very different thermal demands of some o f these species, especially in the first stages. This leads to the ass umption that the bog ponds - at least in part - must be for some weeks of warm character and that the dragonfly larvae (and possibly other a quatic organisms) must be able to satisfy their high thermal demands e ven during the cold nights.