Message - 7th IAL Symposium

The 7 th International Association for Lichenology Symposium 2012
(5I-P2) Submission ID: IAL0120-00001
NOCTURNAL HYDRATION INCREASES LICHEN GROWTH RATES
Bidussi M. 1 , Gauslaa Y. 1 , Solhaug K. 1
1 Department of Ecology and Nature Resource Management, Norwegian University of Life Sciences, Ås, Norway
The aim of this experiment was to understand how hydration events during periods of light and darkness
influenced viability and growth in Lobaria pulmonaria and L. scrobiculata under controlled conditions. The
study was motivated by a need to develop optimal conditions for lichen growth during short-term experiments.
In total 400 thalli of each species were grown in growth chambers for 14 days at a 12 hrs photoperiod with 100
μmol photons m -1 s -2 light intensity at four diurnal temperature regimes: 25°-20°C, 21°-16°C, 13°-8°C, and 6°-1
°C during which the highest temperature in each regime was given during day, and the lowest during night. The
samples were given two different treatments: 50% of the thalli were moistened twice a day to keep them continuously
wet, whereas 50% were moistened only once early. The latter treatment kept the thalli moist during the
light periods, but dry during all dark periods. Chlorophyll a fluorescence (CaF) was assessed before and after the
experiment to quantify possible stress due to treatment, and growth rates were quantified in terms of biomass
(dry weight) and thallus area increments. In general, both species showed higher growth rates (dry mass and
area) and higher values of photosynthetic efficiency, Fv/Fm when they were permanently moist. This suggests
that nocturnal respiration may enhance the conversion rate of photosynthates into thallus extension and thus,
at least in short term, boost lichens growth. Furthermore, the growth chamber temperature strongly influenced
growth rates for both species. However, L. pulmonaria had a higher optimal temperature for growth (21-16°C)
than L. scrobiculata (13-8°C).
(5I-P3) Submission ID: IAL0161-00001
LICHENS AS BIO-INDICATORS OF AMMONIA CONCENTRATION IN FLANDERS
Van Den Broeck D. 1 , Herremans M. 2 , Meremans D. 3 , Van Avermaet P. 3
1 Bryophyta-Thallophyta, National Botanic Garden of Belgium, Brussels, Belgium
2 Studie, Natuurpunt Studie VZW, Mechelen, Belgium
3 Air, Vlaamse Milieumaatschappij, Antwerp, Belgium
Monitoring of ammonia through its effects on biodiversity using epiphytic lichens is well established in
some countries, e.g. the Netherlands. The present study investigated the feasibility of using epiphytic lichens
for bio-monitoring ammonia concentrations in Flanders (Belgium), with particular focus on the classification of
concentrations above or below the WHO-norm of 8 µg/m 3 (critical level for vegetation). Secondary aim was
to find a simple yet sufficiently accurate method that could even be applied by non-specialists of lichens. Air
concentrations of ammonia were continuously measured for 13 months by passive samplers at 100 points at
different distances to the northeast of a live stock farm. Lichens were studied on (6-) 10 oaks or poplars at the
same points. Results indicate that it is possible to develop a bio-monitoring network based on a small selection
of lichen species, particularly in order to distinguish between minimum ammonia levels below or above the
WHO-norm.
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