Terricolous lichens are relevant associates of biological soil crusts in arid and
semiarid environments. Dunes are ecosystems of high conservation interest, because
of their unique, vulnerable and threatened features. The function of lichens is affected
by the changing seasons and different microhabitat conditions. At the same time, inland
dunes are less investigated areas from the terricolous lichens point of view. We explored
the effect of seasonal variation and different micro-environmental conditions (aspect)
on the metabolic activity of five terricolous lichen species, representing various
growth forms, in temperate semiarid grasslands. Populations of Cladonia
foliacea, C. furcata, C. pyxidata
group, Diploschistes muscorum and Thalloidima
physaroides were investigated. Thalli sampled from the south-west and
north-east facing microhabitats were studied by chlorophyll fluorescence analysis
for 2 years. The present study aims to understand how changing climate (during the
year) and aspect affect photosynthetic activity and photoprotection. Microclimatic
data were also continuously recorded to reveal the background of the difference between
microhabitat types. As a result, the air temperature, photosynthetically active radiation,
soil temperature and vapour pressure deficit were significantly higher on south-west
than on north-east facing microsites, where relative humidity and water content of
soil proved to be considerably higher. Higher photosynthetic activity, as well as
a higher level of photoprotection, was detected in lichens from north-east-oriented
microsites compared with south-west populations. In addition, the difference between
sun and shade populations varied seasonally. Since a species-specific response to
both aspect and season was detected, we propose to investigate more than one species
of different growth forms, to reveal the response of lichens to the changing environment
in space and time.
