L. Beyer et al., Nutrient and thermal regime, microbial biomass, and vegetation of antarctic soils in the Windmill Islands region of East Antarctica (Wilkes Land), ARCT ANTARC, 32(1), 2000, pp. 30-39
In the antarctic summer of 1996, permafrost-affected cold soils close to th
e Australian Casey Station in the Windmill Islands region (Wilkes Land) wer
e investigated to determine in what way the thermal and nutrient regimes in
the antarctic soils an related to microbial biomass and vegetation pattern
s. The soils are characterized by a high content of coarse mineral particle
s and total organic carbon (TOC) and a low C/N ratio (mean 11). Despite the
low pH values (mean 4.0) the soils are rich in nutrients due to an input f
rom seabirds (existing or abandoned nesting sites) and an eolian distributi
on of line-grained soil material in the landscape. Vegetation influences TO
C storage and the cation exchange capacity in the uppermost soil horizons,
whereas total N and most nutrient levels are not affected by the vegetation
, but by seabird droppings. The present nutrient level does not affect plan
t adaptation, because the K, Mg, and la contents are often extraordinarily
high. This suggests that nutrient supply is not a limiting factor, whereas
microclimate effects, such as moisture availability and ground-level wind s
peed, have a primary influence on plant growth. Soil-surface temperature me
asurements indicate a strong variability in microclimate due to small-scale
variations in geomorphological surface features. Bacteria art, found in al
l soil horizons, bur not algae and yeast. Soil microbial counts are weakly
correlated to the C/N ratios and soil surface temperatures. High TOC and cl
ay contents probably improve the soil water-holding capacity and TOC contri
butes to the microbial food supply. The investigated microbial parameters a
re weakly correlated to the present vegetation carpet, the lowest counts ar
e found in the soils with scattered or no vegetation cover.