The occurrence of epixylic bryophyte and lichen species in an old natural and a managed forest stand in Northeast Sweden

Abstract

An old natural spruce stand and a managed spruce stand were compared with regard to occurrence of epixylic bryophyte and lichen species and amount of decaying wood in different size classes and decay stages. Epixylic hepatics occurred more frequently in the natural stand while Cladonia species were predominant in the managed stand. This difference is explained by differences in humidity regimes, with the managed stand exposed to drought more often than the natural stand. The managed stand also had a more uneven supply of logs in different decay stages with some stages almost missing. Wood in advanced stages of decomposition was scarce and occurred mostly as stumps in the managed stand. These two factors, substrate shortage and humidity regimes, may explain why only the most drought-resistant of the epixylic species preferring well-decayed wood were found. It is concluded that drought-sensitive bryophytes growing on logs in intermediate stages of decay are among the species most threatened by modern forest management.