1 - Ecologia Mediterranea

ecologia mediterranea 23 (314),53-561997
Lichens as bioindicators of recent changes in air quality
(Montecatini Terme, Italy)
Stefano LOPPI 1 , Luciano GlOVANNEW 2 , Stergios A. PIRINTSOS 3 , Ettore PUTORTl:l & Adelmo CORSINI 4
lDepartment of Environmental Biology, University of Siena, Via PA Mattioli 4, 1-53100 Siena, Italy
2S.M.PA, U.S.L. 4, V.le Vittorio Veneto 9,1-50047 Prato, Italy
Jnepartment of Ecology, School of Biology, Faculty of Sciences, Aristotle University, GR-54006 Thessaloniki, Greece
4S.M.P.A., U.S.L. 3, Via dei Baroni 18,1-51100 Pistoia, Italy
ABSTRACT
A lichen mapping survey was repeated after three years in the town of Montecatini Terme (centralltaly). From 1993 lichens have
recovered, especially in the southem part of the study area, where new thalli of different lichen species were found and the lichen
desert does not exist anymore. In the studyarea, over the last three years the levels of S02 remained constantly low (about 15-20
...g1m\ while NOx, showed a marked decline (from about 150 ... g1m 3 in 1993 to about 100 ...g1m 3 in 1996), suggesting that their
reduction was responsible for the observed improvement in lichen frequencies.
Key-words: air quality, Italy, lichens, recolonization
RESUME
Afin de mettre en évidence de récents changements dans la qualité de l'air, une cartographie de lichens a été effectuée à Montecatini
Terme (Italie centrale), et répétée après trois ans. Depuis 1993, les lichens se sont à nouveau développés. surtout au sud de
l'endroit étudié, là où les nouveaux thalles de différentes espèces ont été trouvés, et le « désert de lichens» n'existe plus. Pendant
les trois dernières années, le niveau de S02 dans la zone de recherche est resté constamment bas (environ 15-20 ...glm 3
) alors que
le NOx a connu un net déclin (environ 150 ...glm 3 en 1993 jusqu'à 100 ...glm 3 en 1996). Ceci suggère que la réduction de NOx est
responsable de l'augmentation de fréquence des lichens.
Mots-elés : qualité de l'air, Italie, lichens, recolonisation
INTRODUCTION
Biological monitoring involves the examination of
biological variables to detect environmental changes,
based on the assumption that any changes taking place
in the environment have a significant effect on the bi·
ota (Kovacs, 1992). Lichens are a well-known tool for
biomonitoring air quality, and lichen mapping is be­
coming routine in several countries (Sigal, 1988). The
mapping of lichen diversity provides an estimate of
the biological impact of air pollution and gives an in­
tegrated picture of air quality by supplying informa­
tion on the effects of aIl pollutants present in the at­
mosphere and of their reaction products (Showman,
1988).
During the late 1960s, in Britain, zones of lichen
impoverishment have been shown to correlate closely
with mean winter levels of S02 (Hawksworth & Rose,
1970). Now that S02 levels have declined considerably,
it is becoming apparent that one form of pollution
has been replaced by another (Gilbert, 1992). Ac-
ecologia mediterranea 23 (3/4) - 1997
cording to recent investigations in central Italy (Loppi
& Corsini, 1995; Loppi et al., 1996a, 1996b, 1996c),
sulphur dioxide is no longer the main air pollutant af­
fecting lichen presence, and other gaseous contami­
nants, such as carbon monoxide and especially nitro­
gen oxides, seem to be largely responsible for lichen
decline.
In May 1993, epiphytic lichens were used as
bioindicators of air quality in the town of Montecatini
Terme and a zone·map was produced (Loppi &
Corsini, 1995). The main source of air pollution was
found to be from motorized traffic, with the worst air
quality occurring in areas with heavy vehicular traffic
and along a highway. Similar conclusions were
reached by Loppi et al. (1995) who used the epiphytic
lichen Parmelia caperata as bioaccumulator of heavy
metals in the same area.
The present study was designed to repeat the li·
chen mapping survey in the same area after three
years, and to search for recent changes in air quality.
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