Niche breadth and niche overlap in three epixylic hepatics in a boreal old-growth forest, southern Finland

We investigated substratum preference, niche breadth and niche overlap in relation to selected substratum variables in three epixylic hepatics: Anastrophyllum hellerianum, Lophozia silvicola and L. longiflora. The species studied inhabit coarse woody debris, which is a patchily distributed substratum with varying qualities as determined by tree species, patch size, bark cover and stage of wood decay. The three hepatic species differ in substratum specificity and reproductive mode, being either prevailingly sexual or asexual. Although the species possessed differences in substratum preference, between-species niche overlap values were high. All three species showed wide ecological amplitude in relation to coarse woody debris quality. Our results suggest that the epixylic hepatics A. hellerianum, L. silvicola and L. longiflora exhibit opportunistic strategies in relation to substratum quality, thus maximizing survival on a temporally and patchily distributed substratum.