Mc. Davey et P. Rothery, PRIMARY COLONIZATION BY MICROALGAE IN RELATION TO SPATIAL VARIATION IN EDAPHIC FACTORS ON ANTARCTIC FELLFIELD SOILS, Journal of Ecology, 81(2), 1993, pp. 335-343
1. The causes of variations in the composition of microalgal communiti
es on frost-sorted soil polygons on Signy Island, maritime Antarctica,
were investigated, based on analyses of physical and chemical conditi
ons and microalgal communities from 65 polygons. 2. Interpolygon varia
tions in all environmental factors measured were small and not much gr
eater than the intrapolygon variations. Microalgal diversity was low.
Only seven taxa occurred in sufficient numbers to be included in stati
stical analyses, two of which, Nostoc spp., were found on only one pol
ygon. The filamentous cyanobacterium Phormidium autumnale occurred on
all polygons and usually provided the largest component of the total b
iovolume. 3. Microalgal communities were qualitatively constant within
polygons, but varied markedly between polygons. Principal components
analysis indicated that each taxon varied independently of the others,
and hence it was not possible to correlate community structure with a
ny specific environmental factor. 4. Correlations between numbers of i
ndividual taxa and edaphic factors were low and accounted for a maximu
m of 18% of the observed interpolygon variation or 12% of the total va
riation. It is suggested that the observed differences in the microalg
al communities were due to the vagaries of the colonization process an
d reflect the probability of successful colonization of these ecosyste
ms by microalgae.