Data dearly show 



t/iot ozone can 



adversely affect 



plant growth. 



Medium exposure 



is typical of ozone 



concentrations west 



of file Cascades. 



Source: Mavity et al. 1 995. 



Small Blackberry 



(Rubus parviflorus) 



1.2 



which protects life on Earth from the Sun's ul- 

 traviolet rays, ozone in the troposphere — cre- 

 ated from nitrogen oxides and volatile organic 

 compounds by sunlight — is known to be un- 

 healthy for people as well as plant life. 



Ozone is generally a problem to forest veg- 

 etation only in the summer when plumes of 

 pollutants flow downwind from major urban 

 centers. Possible effects to vegetation include 

 visible leaf injury, reduced photosynthetic ca- 

 pacity, increased respiration, premature leaf 

 death, reduced growth, and mortality. 



Ozone damages the most sensitive plants at 

 concentrations lower than those that are harm- 

 ful to people. The federal human-health stan- 

 dard is 120 parts per billion (ppb). Lichens, a 

 group of ozone-sensitive organisms, can be 

 adversely affected at concentrations between 

 15 and 70 ppb. Effects on lichens are subtle 

 but can ultimately be fatal. Entire lichen spe- 

 cies can disappear from the landscape before 



Low Med High 



Ozone Exposure Level 



Passive 



ozone 



samples 



are taken 



on Mount 



Baker- 



Snoqualmie 



National 



Forest 



anyone notices. Recent studies of native her- 

 baceous seedlings and ozone profiles com- 

 monly found in the Pacific Northwest showed 

 that typical ozone concentrations could cause 

 damage and increase mortality of certain com- 

 mon species. 



The Forest Service air program in Oregon 

 and Washington and the Washington Depart- 

 ment of Ecology currently measure ozone elec- 

 tronically at Darrington, for the Glacier Peak 

 Wilderness; Packwood Lake, for the Goat Rocks 

 Wilderness; and Wishram in the Columbia 

 River Gorge. Ozone is also being measured in 

 wilderness areas by passive sampling, which 

 uses inexpensive coated filters that chemically 

 react at a known rate when exposed to differ- 

 ent ozone concentrations. The next step is to 

 establish plots of ozone-sensitive species in the 

 highest ozone-exposure areas downwind of the 

 Puget Sound and Portland urban areas as an- 

 other monitoring method. 



Table I -I — Effects of declining air quality on lichen communities in the Pacific Northwest 



Air quality 



Effect on lichens 



pood 



Decline beginning 

 becllne clearly visible 



The most sensitive lichens are present and healthy. Diversity and biomass of lichens is high. 

 The most sensitive lichens are overgrown by other lichens or algae.Young individuals are absent. 

 The most sensitive lichens are missing on conifers; other lichens are still abundant.The remaining 



lichens show high diversity and biomass. 

 The most sensitive lichens are missing on hardwoods and conifers. Some of the remaining lichens 



show pollution effects. Diversity and biomass are intermediate to high. 

 The most sensitive lichens are missing. All of the remaining lichens show pollution effects; 



diversity and biomass are intermediate. 

 All lichens show strong pollution effects (high frequency of dwarfed, shrubby, compact growth 



forms; discoloration; fungal parasitism; and overproduction of dispersal propagules). Diversity 



and biomass are low to nonexistent. 



Overview — 20 



