The composition and concentration of airborne fungal propagules
are
probably determined by many interrelated environmental
factors, such as temperature, relative humidity, atmospheric pressure,
wind
speed, rainfall and gas pollutants. The importance of these
variables was assessed in an outdoor sampling survey conducted at regular
intervals for 12 months at a single site in Turin. Samples
were collected with a single-stage volumetric sieve sampler on potato dextrose
agar supplemented with 15 mg l−1 streptomycin and
50 mg l−1 chloramphenicol.
Canonical Correspondence Analysis showed that the four ordination axes
accounted for 93·5% of the variance in relationships
between fungal entities present in more than 20% of samples and the
environmental variables. The Monte Carlo permutation test
demonstrated that the ordination was highly significant (P=0·01).
The community's qualitative and quantitative composition mainly
depended on the factors that have the greatest influence on Turin's
climate, i.e., in descending order, temperature, relative
humidity and rainfall. The relative importance of these environmental
variables on different groups of fungi was assessed. Wind
speed positively correlated with the fungi producing conidia of larger
sizes.