Variety of woody debris as the factor influencing wood-inhabiting fungal richness and assemblages: Is it a question of quantity or quality?

Abstract

Conservation of saproxylic organisms requires knowledge about the effects of forest management on their habitat. To better understand such effects, 16 beech forest sites in Navarre (Northern Spain) were examined. Woody debris volume and variety of woody debris were recorded in each sampled plot. To calculate variety of woody debris, dead wood pieces were classified into nine categories according to three size and three main decay stage classes. Results showed that forest management had a negative impact on fungal diversity and woody debris variety. Likewise, a nested mixed model design performed with PERMANOVA showed that both fungal assemblages and woody debris composition were significantly dissimilar between forests with distinct management history. When fungal richness was analyzed against variety and volume of woody debris, variety of woody debris explained much more variability than woody debris volume. Similarly, canonical correlation analysis revealed that groups formed according to the forest management factor based on fungal assemblages fitted better with the variety of woody debris variable than with the woody debris volume one. Accordingly, most fungal species showed preference for the type of woody debris on which they grow, and thus, some general growing patterns were established for them. In conclusion, taking into consideration that variety of woody debris is the main factor affecting wood-inhabiting fungal diversity and forest management is the factor which most affects the presence of wood debris variety, some recommendations for wood-inhabiting fungal conservation are provided.