1,720,973 research outputs found
Epiphytic lichens as sentinels for heavy metal pollution at forest ecosystems (central Italy)
No full textThe results of a study using epiphytic lichens (Parmelia caperata) as sentinels for heavy metal deposition at six selected forest ecosystems of central Italy are reported. The woods investigated are characterized by holm oak (Quercus ilex), turkey oak (Quercus cerris) and beech (Fagus sylvatica) and represent the typical forest ecosystems of central Italy at low, medium and high elevations, respectively. The results showed that levels of heavy metals in lichens were relatively low and consequently no risk of heavy metal air pollution is expected for the six forest ecosystems investigated. However, for two of them there are indications of a potential risk: the beech forest of Vallombrosa showed signs of contamination by Pb as a consequence of vehicle traffic due to the rather high touristic pressure in the area, and the holm oak forest of Cala Violina showed transboundary pollution by Mn, Cr and Ni originating from the steel industry in Piombino. Epiphytic lichens proved to be very effective as an early warning system to detect signs of a changing environment at forest ecosystems
Lichens as bioindicators of environmental quality in dry mediterranean areas: a case study from northern Greece
No full textIn dry Mediterranean areas, the scarcity of substrates for epiphytic lichens is a serious limiting factor in biomonitoring studies. In the present study, the epiphytic lichen vegetation of Quercus coccifera bushes was investigated in northern Greece, complementary to and compared with that of Pinus brutia trees. By combining the lichen data from these two quite different phorophytes, sampling versatility was greatly improved, and much better zonal mapping of the area was obtained
Biomonitoring atmospheric pollution: the challenge of times in environmental policy on air quality
No full textEffect of dust on epiphytic lichen vegetation in the Mediterranean area (Italy and Greece).
No full textThe epiphytic lichens around limestone and sandstone quarries were investigated in northern Greece and central Italy to study the effect of alkaline and acid dust on epiphytic lichen vegetation in the Mediterranean area. The results showed that the main factor influencing the diversity of the epiphytic lichen vegetation studied is the distance from quarries, and that the chemistry of dust is not an important parameter. The fact that all but a few resistant lichen species die when subjected to high dust concentrations suggests that epiphytic lichens could be usefully employed for monitoring dust fallout and the effects of dust contamination
Polyamine production in lichens under metal pollution stress
No full textIn the present study, thalli of the lichen species Pseudevernia furfuracea Zopf. and Evernia prunastri (L.) Ach. transplanted around an oil-fired power station. Following an exposure of 4 months, trace element concentrations (Al, Cd, Cr, Cu, Fe, Ni, Pb, V and Zn) and polyamine (PA) content [putrescine (Put), spermidine (Spd) and spermine (Spm)] of thalli were measured to study the polyamines production in lichens under metal pollution stress. The polyamine production was not significantly different for the two species but two types of statistically significant relationships were revealed between polyamines production and metals concentration in lichen thalli: a positive linear relationship for the pairs total PAs-Cd (P. urfuracea), total PAs-Cu (E. prunastri), Put-Pb (E. prunastri), Spm-Pb (E. prunastri) and a second-order polynomial relationship for the pairs Put-Cd (P. furfuracea), Spm-Cr (E. prunastri) and total PA-V (E. prunastri). A possible involvement of polyamines in metal pollution stress response of lichens is discussed
Monitoring the distribution of the Gipsy Moth (Lymantria dispar) with Evernia prunastri.
No full textLichens as bioindicators of temporal variations in air quality around Thessaloniki, northern Greece
No full textThe epiphytic lichen vegetation of 20 sites around Thessaloniki (Macedonia, northern Greece)
surveyed in 1987 was sampled again in 1997 to monitor any changes in lichen communities and
consequently in air quality. A general impoverishment in lichen communities was recorded in the
10-year period, presumably chiefly due to changes in the air pollution status. A small increase in
lichen species diversity was recorded in some stations, probably as a result of the buffering capac-
ity of airborne dust
Do polyamines alter the sensitivity of lichens to nitrogen stress
No full textThe sensitivity of lichens measuring photosynthetic efficiency and polyamines as modulator of nitrogen stress tolerance was investigated. Two lichen species with a markedly different tolerance to nitrogen compounds, namely Evernia prunastri (L.) Ach. and Xanthoria parietina (L.) Th.Fr., were incubated with deionized water (control) and solutions of KNO3, NH4NO3 and (NH4)2SO4 and then exposed to different light conditions. The Fv/Fm parameter (maximum quantum efficiency of photosystem II) was used as stress indicator. The results showed that Fv/Fm values, in the produced experimental conditions, were independent from the light gradient. Photosynthetic efficiency of E. prunastri was impaired by high ammonium concentrations, while nitrate had no effect; X. parietina was hardly influenced by nitrogen compounds. External supply of polyamines reduced the sensitivity of E. prunastri, while polyamine inhibitors reduced the tolerance of X. parietina to NH4+, suggesting that polyamines play an important role in modulating the sensitivity/tolerance to nitrogen stress
Accumulation of heavy metals in epiphytic lichens near a municipal solid waste incinerator (central Italy)
No full textThe epiphytic lichen Parmelia caperata was used as biomonitor in the area of a municipal solid waste incinerator (Poggibonsi, central Italy) to investigate the levels and the spatial distribution of the heavy metals Al, Cd, Cr, Cu, Fe, Hg, Pb and Zn. Levels of Al, Cu and Hg were similar to those in unpolluted areas, whereas high values were found for Cr, Zn and especially Cd. The distribution pattern of the last three metals and the exponential relationship of their concentrations with distance from the incinerator, showed that the disposal plant is a local source of atmospheric pollution due to Cd, Cr and Zn. For these metals, long-term hazard should be seriously taken into account
Analysis of the distribution of epiphytic lichens on Quercus pubescens along an altitudinal gradient in a Mediterranean area (Tuscany, central Italy)
No full textThe distribution of epiphytic lichens on Quercus pubescens in Tuscany, central Italy, was studied by means of multivariate techniques along an altitudinal gradient from 0 to 900 m. Great differences in community structure were found and the altitude of 500 m was identified as an ecotone. Epiphytic lichen vegetation on trees below the ecotone varied significantly in relation to bark pH. Climatic parameters (temperature and rainfall) were probably related to altitude. Dust was probably responsible for the rise in bark pH. The distribution of lichen species in the sampling belts fitted the core-satellite hypothesis. The use of core and satellite species as biomonitors of air pollution and bioindicators of environmental conditions is discussed
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