Growth and population dynamics of the moss Polytrichum alpestre. in the Maritime Antarctip. Strategies of growth and population dynamics of tundra Plants 2
The pattern of growth of Polytrichum alpestre Hoppe, a common moss in the maritime Antarctic, is described. It may form extensive communities, sometimes growing with another moss, Chorisodontium aciphyllum (Hook. f. & Wils.) Broth. Underlying the basic stability of such communities there is a persistent change in shoot composition from season to season. These changes have been followed both photographically and stratigraphically, since a complete record of past changes exists within the slowly decomposing turf. Considerable instability in the total population of shoots of P. alpestre occurs during the first few years of its establishment but as time proceeds and conditions more favourable to the growth of P. alpestre develop, the mean life expectancy of shoots increases. Variation in spatial density of shoots is discussed in relation to size and weight of the annual increments in P. alpestre. The relationship between weight of the annual increment and the spatial density approximates to the density effect law applied to higher plants, in which yield per unit area is little affected by variation in density