Epixylic vegetation abundance, diversity and composition vary with coarse woody debris decay class and substrate species in boreal forest

Although the importance of coarse woody debris (CWD) to understorey species diversity has been recognized, the combined effects of CWD decay and substrate species on abundance and species diversity of epixylic vegetation have received little attention. We sampled a wide range of CWD substrate species and decay classes as well as forest floor in fire-origin boreal forest stands. Percent cover, species richness and evenness of epixylic vegetation differed significantly with both CWD decay class and substrate species. Trends in cover, species richness and evenness differed significantly between non-vascular and vascular taxa. Cover, species richness and species evenness of non-vascular species were higher on CWD, whereas those of vascular plants were higher on the forest floor. Epixylic species composition also varied significantly with stand ages, overstorey compositions, decay classes, substrate species and their interactions. Our findings highlight strong interactive influences of decay class and substrate species on epixylic plant communities, and suggest that conservation of epixylic diversity would require forest managers to maintain a diverse range of CWD decay classes and substrate species. Since stand development and overstorey compositions influence CWD decay classes and substrate species as well as colonization time and environmental conditions in the understorey, our results indicate that managed boreal landscapes should consist of a mosaic of different successional stages and a broad suite of overstorey types to support diverse understorey plant communities.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author