Biologic Markers of Air-Pollution Stress and Damage in Forests (1989) / Chapter Skim
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Experiments and Observations on Epiphytic Lichens as Early Warning Sentinels of Forest Decline
Experiments and Observations on Epiphytic Lichens as Early Warning Sentinels of Forest Decline
Pages 205-216
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From page 205... ...
A combination of high humidity and nutrient enrichment normally allows for a prolific, species-rich epiphytic lichen flora on coniferous trees in the transition zones. In previous field studies, we have shown that boreal forest-floor lichens such as Cladina rangiferina respond to seasonal sprays of simulated, acidic rain of less than pH 3.5 by producing abnormal morphological and cytological structures.
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From page 206... ...
To determine whether specific morphological or cellular aberrations exist in species of Hypogymnia and Pseudevernia epiphytic on declining balsam fir and red spruce at these sites. Our previous research in a boreal forest ecosystem showed that branching pattern abnormalities and changes in starch and lipid content of algal cells could be induced in Claciina species by seasonal sprays of simulated rain of pH less than 3.5.
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From page 207... ...
Burt Lake, Ontario - boreal forest ecosystem Bay of Fundy, Nova Scotia - low elevation with acidic fog monitoring station Two species of lichen were present at most of the study locations. Hypogymnia physod~es, a foliose epiphyte of conifers, has a ubiquitous distribution and is semi-tolerant of gaseous pollutants such as SO2.
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From page 208... ...
The lowest percentage cover of dominant lichen species on boles of balsam fir was recorded near the summit of Whiteface Mountain, where the average crown dieback rating was 4.1, or extremely severe. On-site observations also indicated that many lichens were white or pinkish in appearance, a symptom which may be the result of membrane damage resulting in destruction of chlorophyll.
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From page 209... ...
Since the stemflow of declining trees may be both acidic and enriched with canopy leachates, altered nutritional factors may, indeed, play a role in stimulating branch production in lichens at high elevation sites. A fertilization effect from the nitrate component of the acidic fogs may also be related to the vigorous lichen growth.
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From page 210... ...
Light micrograph of growing tips of C rangiferina from a boreal forest ecosystem.
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From page 211... ...
Cytoplasm of the unicellular alga, Trebouxia, in C ran~iferina from the boreal forest simulation experiment.
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From page 212... ...
Cells are relatively normal in appearance, except that they contain numerous starch grains (St) and poly-phosphate type bodies (Pp)
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From page 213... ...
In conclusion, epiphytic lichens appear to have potential as bioindicators of forest decline. To be useful as early warning indicators, however, it is important to identify morphological and chemical markers in advance of severe tree dieback.
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From page 214... ...
890 629 92 1896 11, 100 548 650 78 1478 8,100 occur in species of Hypogymnia and Pseudevernia epiphytic on apparently healthy conifers. If, in fact, we can demonstrate that good correlations exist between atmospheric inputs and changes in lichen flora, then these studies may provide a faster, more economical way to assess ambient air quality in the absence of permanent atmospheric monitoring stations.
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From page 215... ...
1987. The effect of simulated acid rain on boreal forest floor feather moss and lichen species.
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From page 216... ...
890 629 92 1896 11, 100 548 650 78 1478 8,100 occur in species of Hypogymnia and Pseudevernia epiphytic on apparently healthy conifers. If, in fact, we can demonstrate that good correlations exist between atmospheric inputs and changes in lichen flora, then these studies may provide a faster, more economical way to assess ambient air quality in the absence of permanent atmospheric monitoring stations.
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