Forest Inventory and Analysis Ozone Indicator FIA Fact Sheet Series The Ozone Indicator is one of the However, once the presence of ozone forest health variables measured by injury is established, these indicator How are Ozone Bioindicator the FIA program. It is designed to data can be considered in association Plants Measured? detect and monitor ozone stress in the with other FIA indicators and non- Field Personnel collecting ozone forest environment. Ozone-induced FIA exposure data to assess the bioindicator data are thoroughly foliar injury data is collected from field impact of ozone stress on long-tern trained and tested prior to the sites on a nation-wide grid of ozone forest condition. beginning of each field season. biomonitoring plots. Sampling Crew procedures include site intensity varies across the landscape Ozone bioindicator plant information selection, species identification, and according to differing air quality contributes to the investigation of symptom identification and scoring. regimes and perceived risk to ozone several key forest ecosystem Each plant is evaluated for amount sensitive forest types. characteristics. As an indicator of and severity of injury. At each field stress, ozone sensitive plants provide site, the field crews evaluate up to Why is the Ozone Indicator a mechanism to detect and monitor 30 individual plants of 3 or more Important? biologically significant changes in air bioindicator species. If ozone injury Air pollutants, such as ground-level quality. They also indicate forest is recorded, leaf samples are ozone, are known to interact with condition by providing a visible link collected for validation of the ozone forest ecosystems. Ozone pollution between ozone exposure and the injury symptom by an ozone has been shown to reduce tree growth, effects of that exposure on specialist. Errors are further alter species composition, and productivity, biodiversity, and minimized by audits of the field predispose trees to insect and disease aesthetics. These relationships are personnel and by complementary attack. Ozone also causes direct foliar summarized in the conceptual model quality assurance studies. injury to many plant species. Affected shown in Figure 1. leaves are often marked with Where and When are Ozone discoloration and lesions, and they age What Species are Good Bioindicator Plants Measured? more rapidly than normal leaves.. This Bioindicator Plants? Suitable sites for biomonitoring are approach is known as biomonitoring The essential characteristic of a good open areas in which the ozone- and the plant species used are known bioindicator species is that it sensitive species are found and as bioindicators. responds to ambient levels of ozone where the trained observer is Information about ozone bioindicator pollution with distinct visible foliar reasonably certain that soil and site plants can be used to answer the injury symptoms that are easy to conditions are stable and free of following questions about the effects of diagnose. The bioindicator species chemical contaminants. The best air quality on forested ecosystems: used in eastern FIA regions have been sites are easy to get to, larger than 3 used repeatedly in ozone field studies. acres, with low drought potential • Is regional air quality (specifically The list includes blackberry, black and high plant counts. A small ozone pollution) changing over cherry, common milkweed, yellow number of biomonitoring plots in time? If so, is it improving or poplar, white ash, sassafras and each FIA region are located close to deteriorating? sweetgum. Less familiar species weather and air quality monitoring • In what percentage of a region or include big-leaf aster and spreading stations to improve the forest type are ozone bioindicator dogbane. The bioindicator species list interpretation of bioindicator data. plants indicating the possibility of for western FIA regions includes air pollution impacts on forest ponderosa pine, quaking aspen, FIA field personnel select sites for health (e.g., biodiversity, growth Scouler's willow, red alder, ninebark, ozone biomonitoring during the increment, crown condition, or elderberry, and seven additional shrub normal field season. The foliar damage)? and herb species. The FIA fieldwork injury data is collected during an contributes significantly to the much abbreviated evaluation window that The ozone foliar injury response is not needed field tests of western is different for each FIA Region. intended to be used alone when bioindicator species under natural making statements about forest health. conditions of ozone exposure. Are There any Special Concerns decreases in the injury severity index. to identify where ozone effects on When Making Measurements? Figure 2 shows an example of how sensitive tree species require a The incidence and severity of ozone ozone bioindicator plant data may be more intensive evaluation of injury on vegetation increases during displayed to show the annual injury and growth response. the summer months in eastern FIA distribution of plots with ozone Results may be linked analytically regions. By late July, symptoms have symptoms on sensitive bioindicator to forest health data collected on developed distinctly, are easier to species. These results are compared to the FIA Phase 2 and Phase 3 plots. measure and are very stable. Therefore, corresponding information on ozone quantifying ozone injury by FIA field levels in the air as well as other Are Related Data Sets Used? personnel is limited to a three-week information such as rainfall amounts Yes, air quality data sets are used in period during late July to mid-August. and soil moisture conditions. This the ozone bioindicator plants The field personnel receive a refresher additional information provides the analyses. These data are obtained training course in ozone symptom context in which the ozone through the National Air Data identification and voucher handling bioindicator data are analyzed. Branch of the US EPA. Climate immediately before the evaluation data are obtained form the nearest period. A plot-level index is formulated from National Oceanic and Atmospheric injury amount and severity ratings Administration weather stations, the In western FIA regions, due to recorded for each plant and the National Trade Data Bank, and differences in growing season, numbers of plants and species published scientific literature. topography, target species, and other evaluated at each site. This, in turn, is regional factors that influence plant used to monitor yearly fluctuations in Fact Sheet Author: Gretchen response to ozone, the identification the severity of the bioindicator Smith of an optimum evaluation window for response by region or forest type. For this indicator is problematic. trend analyses, FIA intends to use For more information about the Nevertheless, to maintain national consecutive 5-year periods with ozone indicator: consistency and improve crew variable ozone levels, weather, wind • Visit our ozone indicator logistics, the western regions use a flow, and precipitation patterns to website: http://fiaozone.net mid-season, five-week window for examine regional trends in ozone air foliar injury evaluations. quality over the long-term. Kriging For more information about the techniques are applied to the 5-year FIA Program: Other physical or biological foliar biosite averages to generate a • Visit our national FIA website: injury symptoms may mimic ozone surface of biological response data http://www.fia.fs.fed.us symptoms. Since the bioindicator across the landscape. As illustrated • See our “FIA Contacts” Fact species selected for this indicator were in Figure 3, this interpolated surface Sheet selected because of their sensitivity to may be used to identify areas of ozone and their distinct ozone injury probable ozone injury to plants and symptoms, this potential problem can be adequately covered during training. How is Ozone Data Analyzed? The primary goal of this indicator in FIA is to provide a biological index of ozone stress in the forest environment using a consistent protocol on a nation- wide system of biomonitoring plots. Results are used to quantify regional trends in ozone stress in terms of significant changes in the number and distribution of biomonitoring plots with ozone injury and increases or Figure 1. Conceptual Model for the Ozone Bioindicator Indicator Forest Inventory and Analysis Ozone Indicator FIA Fact Sheet Series Figure 3: Biosite Index Estimates and Risk in Northeastern States. Probable ozone injury and risk in the Northeast FIA region as determined by plot-level injury values (biosite index) averaged over a six-year period (1994-1999) and then categorized into four levels of risk (none, low, moderate, and high) defined in terms of the relative risk of tree or ecosystem-level disturbance to the forest resource from ambient ozone exposure. Figure 2. FIA Ozone Biomonitoring Sites, 2000. .