How does microclimate affect the growth of the rare liverwort Scapania nimbosa?

Vegetative growth of bryophytes is dependent on water and will stop as soon as the plants dry out. The growth rate depends on the quality of the micro-habitat. Clonal growth and dispersal of plant fragments are important parameters to understand local distribution of bryophytes lacking spore and gemmae production. Species of the mixed northern hepatic mat mainly rely on plant fragments and vegetative growth to disperse and maintain local populations. Understanding a species' means for population maintenance and dispersal potential is important for a successful management. This study aims to investigate the micro-scale climatic requirements and growth rate of the mixed northern hepatic mat species Scapania nimbosa through measuring its growth in situ in Norway, and through comparison of micro-climate between presence localities and seemingly suitable absence localities. The results show that S. nimbosa grows approximately 4.38 ± 2.78 mm during one growing season. No difference in micro-climate was found between the presence and absence localities, suggesting that S. nimbosa is limited by dispersal, not by suitable habitats. The availability of suitable habitat, and the ability to identify these, opens up the possibility to expand its range through transplantation of plant fragments.