Bryophytes and decaying wood– a comparison between managed and natural forest

A comparative study was made of one managed forest and one natural forest regarding the supply of decaying wood on the ground and the occurrence of bryophytes on the wood, especially epixylic specialists. The total substrate surface of wood is larger in the primeval forest. The larger quantity of decaying wood increases the probability of wood occurring in ail decay stages. Logs of Populus tremula occurred only in the natural forest. An important proportion of the wood substrate in the natural forest consisted of logs of large diameter class; these logs were missing in the managed forest. Fiftyfour bryophyte species were found on decaying wood. They were separated into four different groups. Facultative epiphytes first colonized decaying wood, followed by epixylic specialists and finally by competitive epigeics. Opportunistic generalists showed a more irregular pattern of occurrence. The bryophyte flora on decaying wood was most species rich in the natural forest. Sixteen epixylic specialists occurred here, several considered to be threatened by forest management, while only 5 of these species occurred in the managed forest. The higher frequency of epixylic specialists in the natural forest is related to the greater frequency of favourable habitats, specifically: logs of large diameter, decayed wood, Populus tremula and (to a lesser extent) Picea abies.