■»!- 



-^ 



Forest Health 

 Monitoring Plots 

 Evaluated for 

 Ozone Damage 

 in 1994. 



• INJURY PRESENT 



O INJURY NOT PRESENT 



forests. A network of biomonitoring sites has been es- 

 tablished in forested areas throughout the East Each 

 year these sites are evaluated for the amount and rela- 

 tive se verity of ozone injury to bioindicator plants. The 

 results from the 1994 and 1995 field seasons are pre- 

 sented in Figures I and 2. Differences between years 

 are due to differences in air quality as well as in other 

 environmental factors. Documenting fluctuations in num- 

 ber and distribution of ozone injury sites and examining 

 associations between ozone injury and other attributes 

 of forest condition, such as growth rate, will let us an- 

 swer important questions about the long-term effects of 

 air quality on the health and stability of our regional 

 forests. 



Research showing that ozone causes significant dam 

 age to plant species comes from a variety of sources in 

 agriculture, forestry, and arborculture. Crop plants com- 

 monly affected by ozone include bean, cucumber, 

 grape, morning glory, onion, potato, soybean, spinach, 

 tobacco, and watermelon. Not all species and cultivars 

 are uniformly sensitive to ozone. For example, the 

 green bean cultivar "Tempo" is extremely sensitive to 

 ozone while "Long Tendergreen" is relatively resistant. 

 Blackberry, blueberry, clover, and some grasses impor- 

 tant in agriculture are sensitive. Native species affected 

 include bigleaf aster, common milkweed, and some al- 

 pine plants. Deciduous trees commonly affected by 

 ozone include black cherry, green ash, quaking aspen, 

 sycamore, and tulip poplar. Sensitive conifers include 

 eastern white pine, Jeffrey pine, ponderosa pine, and 

 white fir. 



There are many published reports containing long 

 lists of tree species that have been tested for ozone 

 sensitivity under controlled conditions. Most of these 

 studies were conducted with tree seedlings grown in an 

 artificial medium and the findings are not readily trans- 

 ferable to larger trees grown under field conditions. 

 Trees in general are less sensitive to ozone than 

 nonwoody plants, although those species listed above 

 are often affected, and individual trees of black cherry 

 or white pine, for example, may be almost completely 

 defoliated by ozone. 



Knowledge of plant species sensitive to ozone may 

 help growers in their selection of trees, shrubs, crops, 

 and landscape plants. Ozone damage can reduce plant 

 vigor or yield, or weaken it to invading pests. Designers 

 may wish to avoid ozone-sensitive species for aesthetic 

 reasons. Discoloring stipple, yellowing, and leaf death 

 distracts from the quality of a landscape. 



Gretchen Smitk is a Forest Health Specialist with the Viniversittj 

 of Massachusetts. Florence Peterson is a Forest Health Specialist 

 with the Forest Health Protection Staff of the USDA Fores/ 

 Service in Durham, NH. Map was produced by Thomas Luther, 

 a Geographic l«forwfl(io« Specialist also with the Forest Health 

 Protection Staff of the USDA Forest Service in Durham. For 

 further information, call 603/868-7709. 



THE PLANTSMAN 



