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Abstract
Production of perichaetia and sporophytes along environmental gradients was examined for the western Norwegian Andreaea taxa, following a previous investigation of the species-environmental relationships for the same taxa. The probability of producing perichaetia and sporophytes for each taxon, and the relative success of perichaetia in supporting sporophytes, was determined along environmental gradients. A. blyttii, the only dioecious species, had a lower proportion of perichaetial cushions supporting sporophytes (38%), compared to monoecious species of Andreaea (60 to 86%). There were four different types of sporophyte-environmental relationships: (1) rarely producing sporophytes (A. nivalis and A. obovata var. hartmannii); (2) undifferentiated response, i.e. producing sporophytes throughout the environmental range (A. rothii ssp. falcata, A. megistospora ssp. megistospora, A. frigida); (3) differentiated sporophyte production strongly correlated with the differentiated production of perichaetia (A. rupestris var. rupestris along gradients of altitude and slope); and (4) sporophyte production not corresponding with perichaetia production (A. rupestris var. rupestris along gradients of flushing and snow-cover). Both (3) and (4) are needed to explain the non-significant relationship between sporophyte production and altitude in A. rothii ssp. rothii. The assumptions behind the patch-dynamic model (sensu stricto) were scrutinized to assess whether this model fits the Andreaea data. An expansion of the model is necessary to include parameters for the sporophyte-environmental relationship and the species-environmental relationship: (1) patch distribution; (2) the environmental conditions of the patches; (3) the species-environmental relationship; (4) the sporophyte-environmental relationship; (5) the vegetative diaspore production; (6) the dispersal ability of the diaspores; and (7) the probability of both sexes appearing together within the same patch.