Following the Chernobyl accident in 1986, sporocarps of
Suillus variegatus in Sweden showed a large amount of individual
variation
in concentration of
137Cs activity. Our aim was to determine the degrees to which
this variability in sporocarp 137Cs levels could be
explained by differences between (i) local populations, (ii) fungal genets
and
(iii) locations within genets. Five populations in a 100-yr-old Scots pine
forest, located within a 1 km2 area, and two populations in
Scots
pine/Norway spruce forest, located
40 km north-west of Uppsala, were investigated. In total, 154 sporocarps
were analysed to determine their
137Cs content. Of these, the genetic
affiliations of 86 were successfully characterized using somatic incompatibility
reactions. Twenty-six genets were found which, on
average, consisted of 6·5 sporocarps. The genets averaged 7·5
m
in size, measured as the length between the most distant
sporocarps. The mean sporocarp 137Cs level was
67·1±2·8 kBq kg−1D.W.
(range between 13·6 and 182). According to analyses of
variance, within-population variation accounted for 60% of the total variation
in
137Cs levels, while 40% was ascribed to variation
among populations. Within a population,
137Cs levels did not generally differ significantly between
genets.
Plausible reasons for
intraspecific variation in radiocaesium content in sporocarps are discussed.