Asexual reproduction in a population of a leafy hepatic species Lophozia silvicola Buch in central Norway

Abstract

The seasonal pattern and degree of asexual reproduction of a boreal hepatic species, Lophozia silvicola Buch, were studied in a lowland population of the species in central Norway. Asexual reproduction was quantified as numbers of 1–2 -celled gemmae produced per individual shoot, with average production ranging from 1000 to 7000 gemmae per shoot. Despite a slightly increasing trend in early spring, average numbers of gemmae present on shoots were fairly constant during the growing season. Germinability of gemmae was high in early spring, but declined rapidly towards the end of the season, suggesting an increasing proportion of gemmae in the dormant stage in the diaspore bank. Despite repeated sampling, average shoot density remained fairly constant in L. silvicola colonies during the growth season. Gemma production did not correlate with shoot density. Local colonization efficiency was estimated as frequency of occupied substrate patches and proportion of substrate area occupied by L. silvicola in a 10×20 m plot. Colonizable substrates included decaying wood, bare soil and rock surfaces. Colonies of L. silvicola were small, and differences in colony sizes between the substrate types were not significant. Colonies were found in 38% of the substrate patches, but total cover was low, less than 0.1% of all colonizable substrate.