Productivity of bryophytes in polar regions

The productivity of various South Georgian moss species has been measured and some comparative data from Disko Island, West Greenland, are also considered. Two main aspects of growth have been assessed; crop growth-rate and net annual shoot production, using methods which included the coring of undisturbed stands and the growth of shoots in culture. It was demonstrated that methods must be selected with reference to the species to be studied as differences in growth form affect the suitability of each technique. Considerable variation in productivity was found between sites and some habitat factors were identified which might account for these

Fagaceae

The family Fagaceae is distributed world-wide although it is most characteristic of the temperate and subtropical zones of both hemispheres. The majority of species are large trees which play a dominant role in the vegetation of deciduous and evergreen forests. Many are economically important as timber trees. The family comprises seven genera with altogether about 1000 species, but of these only ten species from three genera occur in Northwest Europe. The main genus is Quercus which accounts for eight species. Two of these, Q. rubra and Q. palustris, were introduced into Europe from North America some centuries ago and are now widely cultivated. In addition, Q. pyrenaica has been included in this account because its area of distribution, in the Iberian Peninsula and southern France, borders closely on that of the Northwest European Pollen Flora