Pollution Effects on Lichen Morphology

Evernia prunastri - Antlered perfume lichen

Tolerant to air pollution.
Ubiquitous in most low elevation habitats west of the Cascade crest and some riparian forests east of the Cascades.
On trees and shrubs.
Used as a fixative in the manufacture of perfumes since the 1500's.: See image

Air pollution effects on Evernia prunastri

Note in high stress specimen:

Compact, shrubby, dwarfed growth form
Hyperproduction of soredia (reproductive propagules consisting of algal cells and fungal hyphae)
Reduced photosynthetic capacity

This specimen comes from Riverfront Park in downtown Portland. Photosynthetic yeild was measured on the tree with a portable fluorometer and compared to healthy populations in the Willamette Valley.

Hypogymnia physodes - Monk's Hood

Tolerant to sulfur dioxide and ozone but probably sensitive to fluoride.
On bark and wood throughout forested areas of the Pacific Northwest. Often in non-forested habitats (shrub thickets, farmlands, etc.).
Common name refers to the production of soralia on the undersurface of the round lobe termini-- resembling a hood with a powdery lining.
Good accumulator of elements. Used in USFS Region 6 to map deposition of S, N and metals.
: See image

Air pollution effects on Hypogymnia physodes

Note in high stress specimen:

Compact, circular, dwarfed growth form.
Hyperproduction of soredia soredia (reproductive propagules consisting of algal cells and fungal hyphae), even onto the upper surface.
Reduction in photosynthetic capacity
Color differences between this and the healthy examples are due to sun exposure. Lichens growing in shaded microhabitats are usually greener (i.e. the algal layer is closer to the surface).


This specimen comes from Riverfront Park in downtown Portland. Photosynthetic yeild was measured on the tree with a portable fluorometer and compared to healthy populations in the Willamette Valley.


Lobaria pulmonaria - Lung lichen
Sensitive to sulfur dioxide, possibly intermediate to tolerant of ozone.
On trees and shrubs. Can tolerate warmer, drier conditions than Lobaria oregana, Willamette Valley floor to mid elevations.
Nitrogen-fixing.
Survey and manage lichen.
: See image

Air pollution effects on Lobaria pulmonaria.

Note in high stress specimen:

It has a thick thallus compared to individuals from a healthy environment.
Hyper production of the powdery soredia (reproductive propagules consisting of algal cells and fungal hyphae) along the ridges
Colonization by other lichens
Slowed growth, no new individuals found in the immediate area (Finley Wildlife Refuge, Willamette Valley)


Parmelia sulcata - Shield lichen
Perhaps the most air pollution tolerant non-crustose lichen in the Pacific Northwest. Measurements of photosynthetic productivity show little difference between urban and clean air areas.
Occurring in a wide range of habitats, dropping out only at the highest elevations.
: See image

Air pollution effects on Parmelia sulcata

Note in high stress specimen:

Compact, circular growth form
Hyperproduction of soredia (reproductive propagules consisting of algal cells and fungal hyphae)
Little reduction in photosynthetic capacity


This specimen comes from Riverfront Park in downtown Portland. Photosynthetic yield was measured on the tree with a portable fluorometer and compared to healthy populations in the Willamette Valley.


Platismatia glauca - Ragbag lichen
Intermediate sensitivity to sulfur-dioxide. May be sensitive to ozone.
On conifers and shrubs throughout forested areas of North America .
Good accumulator of elements. Used in USFS Regions 6 and 10 to map deposition of S, N and metals.
: See image
Air pollution effects on Platismatia glauca

Note in high stress specimen:

Compact, circular growth form
Hyperproduction of soredia and isidia (reproductive propagules consisting of algal cells and fungal hyphae)
Bleached and reddened coloration