Temperature and humidity conditions affect the growth and success of
ectotherm insects. Red wood ants of the Formica
rufa group are able to regulate the temperature of their nests to be close
to the optimum, typically higher than ambient in northern latitudes and higher
elevation. The mound-shaped nests are constructed from organic particles
(needles, sticks, etc. plant material) and from soil particles. Nest mounds
typically have a relatively dry inner structure but moister surface layer which
may help the ants to insulate nests against cooling winds. Forest clear felling
exposes nest mounds to direct sunlight, drier microclimate and increased wind.
We studied whether clear felling affects the nest surface moisture and
temperature conditions. We found that i) nest surfaces were significantly drier
in clear fells than in forests, ii) a high height/diameter ratio and an
increase in the nest volume increases surface dryness in clear fells but not in
forests, iii) the nest temperatures relative to ambient temperature was higher
in forests than in clear fells, and iv) the relative temperature increased with
increasing moisture content of nest surface layer. The drying nest material and
more unstable inside temperature may have adverse effects not only on the red wood
ants themselves, but also for nest-dwelling soil organisms and myrmecophiles
that live in red wood ant nests. In addition, changes in moisture and
temperature could have effects on the rate of decomposition and nutrient
turnover.