Park Air Profiles - Lassen Volcanic National Park

Air Quality at Lassen Volcanic National Park

Most visitors expect clean air and clear views in parks. Lassen Volcanic National Park (NP), California, well known for volcanic landforms and interesting geology, lies downwind of the populated Sacramento Valley and areas of agriculture and manufacturing. Air pollutants blown into the park can harm natural and scenic resources such as surface waters, plants, and visibility. The National Park Service works to address air pollution effects at Lassen Volcanic NP, and in parks across the U.S., through science, policy and planning, and by doing our part.

Nitrogen and Sulfur

Visitors come to Lassen Volcanic NP to enjoy scenic views of unique geology, lakes, and volcanic land forms.

Nitrogen (N) and sulfur (S) compounds deposited from the air may have harmful effects on ecosystem processes. Healthy ecosystems can naturally buffer a certain amount of pollution, but once a threshold is passed the ecosystem may respond negatively. This threshold is the critical load, or the amount of pollution above which harmful changes in sensitive ecosystems occur (Porter 2005). N and S deposition change ecosystems through eutrophication (N deposition) and acidification (N + S deposition). Eutrophication increases soil and water nutrients which causes some species to grow more quickly and changes community composition. Ecosystem sensitivity to nutrient N enrichment at Lassen Volcanic National Park (LAVO) relative to other national parks is high (Sullivan et al. 2016); for a full list of N sensitive ecosystem components, see: NPS ARD 2019. Acidification leaches important cations from soils, lakes, ponds, and streams which decreases habitat quality. Ecosystem sensitivity to acidification at LAVO relative to other national parks is very high (Sullivan et al. 2016); to search for acid-sensitive plant species, see: NPSpecies.

From 2017-2019 total N deposition in LAVO ranged from 3.0 to 3.7 kg-N ha^-1 yr^-1 and total S deposition ranged from 0.7 to 1.0 kg-S ha^-1 yr^-1 based on the TDep model (NADP, 2018). LAVO has been monitoring atmospheric N and S deposition since 2000, see the conditions and trends website for park-specific information.

In some areas of the country, increased N deposition has allowed weedy annual grasses to invade shrublands and grasslands, replacing native plants that evolved under N-poor conditions.

Volcanic formations at LAVO, including boiling mud pots and fumaroles, naturally emit S compounds such as sulfur dioxide and hydrogen sulfide. Concentrations of S from volcanic emissions are relatively low and are not known to cause acidification on sensitive resources like high elevation lakes.

Alpine ecosystem effects

Alpine environments are particularly vulnerable to large inputs of reactive nitrogen because of the sparse cover of vegetation, short growing seasons, large areas of exposed bedrock and talus, and snowmelt nutrient releases (Williams et al., 1996; Nanus et al., 2012). Approximately 7% of the land area in LAVO is alpine (~328 km² above 1550 m). McClung et al. (2020) compared the 2015 estimated total N deposition (TDep; NADP, 2018) to the critical load of N for an increase in alpine sedge growth (alpine plant critical load = 3 kg-N ha^-1yr^-1) and the critical load of N for alpine soil nitrate leaching (alpine soil critical load = 10 kg-N ha^-1yr^-1; Bowman et al., 2012). They found that deposition exceeded the alpine plant critical load in 88% of the park’s alpine area, but was below the alpine soil critical load throughout the park’s entire alpine area.

Epiphytic macrolichen community responses

Epiphytic macrolichens grow on tree trunks, branches, and boles. Since these lichens grow above the ground, they obtain all their nutrients directly from precipitation and the air. Many epiphytic lichen species have narrow environmental niches and are extremely sensitive to changes in air pollution. Geiser et al. (2019) used a U.S. Forest Service national survey to develop critical loads of nitrogen (N) and critical loads of sulfur (S) to prevent more than a 20% decline in four lichen community metrics: total species richness, pollution sensitive species richness, forage lichen abundance, and cyanolichen abundance.

McCoy et al. (2021) used forested area from the National Land Cover Database to estimate the impact of air pollution on epiphytic lichen communities. Forested area makes up 269 km² (61.9%) of the land area of Lassen Volcanic National Park.

• N deposition exceeded the 3.1 kg-N ha^-1 yr^-1 critical load to protect N-sensitive lichen species richness in 31.9% of the forested area.
• S deposition was below the 2.7 kg-S ha^-1 yr^-1 critical load to protect S-sensitive lichen species richness in every part of the forested area.

For exceedances of other lichen metrics and the predicted decline of lichen communities see Appendices A and B of McCoy et al. (2021).

Additional modeling was done on 459 lichen species to test the combined effects of air pollution and climate gradients (Geiser et al. 2021). A critical load indicative of initial shifts from pollution-sensitive toward pollution-tolerant species occurred at 1.5 kg-N ha^-1 yr^-1 and 2.7 kg-S ha^-1 yr^-1 even under changing climate regimes.

Plant species response

Plants vary in their tolerance of eutrophication and acidification, and some plant species respond to nitrogen (N) or sulfur (S) pollution with declines in growth, survival, or abundance on the landscape. Horn et al. (2018) used the U.S. Forest Service national forest survey to develop critical loads of N and critical loads of S to prevent declines in growth or survival of sensitive tree species. Clark et al. (2019) used a database of plant community survey to develop critical loads of N and critical loads of S to prevent a decline in abundance of sensitive herbaceous plant species. According to NPSpecies, Lassen Volcanic National Park contains:

• 5 N-sensitive tree species and 18 N-sensitive herbaceous species.
• 6 S-sensitive tree species and 15 S-sensitive herbaceous species.

Mycorrhizal fungi community response

Many plants have a symbiotic relationship with mycorrhizal fungi (MF). Through the roots, the plants supply the fungi with carbon from photosynthesis and in exchange the MF enhance nutrient availability within soils, increase drought tolerance, and provide physical resistance to soil erosion (George et al., 1995; Cheng et al., 2021; Burri et al., 2013). Anthropogenic Nitrogen (N) deposition can disrupt this symbiotic relationship resulting in a shift from N sensitive to N tolerant mycorrhizal fungi and plant communities.

With increased N deposition to the soil, MF become less important for nutrient uptake and many plants will cease the exchange of nutrients altogether making them more vulnerable to stressors such as drought (Lilleskov et al., 2019). The CL-N for the shift in mycorrhizal community is 5-6 kg-N ha^-1 yr^-1 in coniferous forests and 10-20 kg-N ha^-1 yr^-1 broadleaf forests.

Lassen Volcanic National Park has 349.5 km² of coniferous forests. Using the range in critical loads above, the minimum CL is exceeded in 0% of forested area and the maximum CL is exceeded in 0% of forested area based on 2019-2021 TDep Total N deposition.

Change in N and S deposition from 2000 to 2021

The maps below show how the spatial distribution of estimated Total N and Total S deposition in LAVO has changed from 2000-2002 to 2019-2021 (TDep MMF version 2022.02). Slide the arrows in the middle of the image up and down to compare N and S deposition between the two years (Yearly Data).

• Minimum N deposition decreased from 3.7 to 2.7 kg-N ha^-1 yr^-1 and maximum N deposition decreased from 6.0 to 3.4 kg-N ha^-1 yr^-1.
• Minimum S deposition decreased from 0.7 to 0.5 kg-S ha^-1 yr^-1 and maximum S deposition decreased from 1.4 to 0.7 kg-S ha^-1 yr^-1.

Estimated total nitrogen and sulfur deposition levels from 2000-2002 (top) compared to the 2019-2021 (bottom) average at LAVO. Estimated values were developed using the National Atmospheric Deposition Program - Total Deposition (TDep) approach that combines measured and modeled data. Estimated values are valuable for analyzing gradients of deposition and the resulting ecosystem risks where monitors are not present.

Persistent Pollutants

Pollutants like mercury and pesticides are concerning because they are persistent and toxic in the environment. These contaminants can travel in the air thousands of miles away from the source of pollution, even depositing in protected places like national parks. In addition, while some of these harmful pollutants may be banned from use, historically contaminated sites continue to endure negative environmental consequences.

When deposited, airborne mercury and other toxic air contaminants are known to harm wildlife like birds and fish, and cause human health concerns. Many of these substances enter the food chain and accumulate in the tissue of organisms causing reduced reproductive success, impaired growth and development, and decreased survival.

• Mercury concentrations in some fish sampled at Lassen Volcanic NP exceeded the toxicity thresholds for fish, birds, and/or human consumption. Fish were sampled and analyzed for mercury from three sites at the park and compared to data across 21 western parks; the average fish mercury concentration (96.4 ng/g ww) was higher than the study-wide mean (77.7 ng/g ww). Mercury concentrations exceeded the thresholds for fish toxicity, bird toxicity, and US EPA’s human consumption guidance in 2%, 40%, and 2% of fish sampled, respectively (Eagles-Smith et al. 2014). However, the data may not reflect the risk at other unsampled locations in the park. Fish consumption advisories may be in effect for mercury and other contaminants (NPS 2022).
• One out of 45 male fish sampled from the park was found to be intersex (Schreck and Kent 2013). Reproductive abnormalities such as intersex, the presence of both male and female reproductive structures in the same fish, can signify exposure to contaminants.

• Some dragonfly larvae sampled at Lassen Volcanic NP had mercury concentrations at moderate impairment levels. Dragonfly larvae have been sampled and analyzed for mercury from three sites in the park; 33% of the data fall into the moderate (100-300 ng/g dw) impairment category for potential mercury risk. An index of moderate impairment or higher suggests some fish may exceed the US EPA benchmark for protection of human health (Eagles-Smith et al. 2018, Eagles-Smith et al. 2020).

• Contaminants and pesticides have been found in park fish, air, water, and vegetation samples. Dieldrin concentrations in one out of eight fish exceeded the human health threshold for subsistence fish consumption, and current-use pesticides were elevated in the Sierra Nevada – likely due to the proximity to agricultural and industrial sources (Flanagan Pritz et al. 2014). Elevated concentrations of combustion by-products (PAHs), current-use pesticides (endosulfans, dacthal), and historic-use pesticides (DDTs, HCB) were found in park air and vegetation samples (Landers et al. 2008; Landers et al. 2010).
• Pesticides toxic to fish and bees and most likely to drift into park boundaries due to application in the counties surrounding Lassen Volcanic NP are herbicides like Glyphosate, Isopropylamine Salt, and Hexazinone (Meyer and DeMars 2018).

The NPS Air Resources Division reports on park conditions and trends for mercury. Visit the webpage to learn more.

Visibility

Clean, clear air is essential to appreciating the scenic vistas at Lassen Volcanic NP.

Visitors come to Lassen Volcanic NP to enjoy spectacular volcanic landforms and relatively undisturbed natural resources, including forests, lakes, and streams. Park vistas are sometimes obscured by haze, reducing how well and how far people can see. Visibility reducing haze is caused by tiny particles in the air, and these particles can also affect human health. Many of the same pollutants that ultimately fall out as nitrogen and sulfur deposition contribute to this haze. Organic compounds, soot, and dust reduce visibility as well. Significant improvements in park visibility on clearest days have been documented since the 1990’s. However, no significant trends have occurred on haziest days and visibility in the park still needs improvement to reach the Clean Air Act goal of no human caused impairment.

Visibility effects:

• Reduction of the average natural visual range from about 165 miles (without pollution) to about 130 miles because of pollution at the park
• Reduction of the visual range to below 70 miles on high pollution days

Explore scenic vistas through live webcams at Lassen Volcanic National Park.

Visit the NPS air quality conditions and trends website for park-specific visibility information. Lassen Volcanic National Park has been monitoring visibility since 1988. Explore air monitoring »

Ground-Level Ozone

Ponderosa Pine trees are one of the ozone sensitive species found at Lassen Volcanic NP.

At ground level, ozone is harmful to human health and the environment. Ground-level ozone does not come directly from smokestacks or vehicles, but instead is formed when other pollutants, mainly nitrogen oxides and volatile organic compounds, react in the presence of sunlight.

Over the course of a growing season, ozone can damage plant tissues making it harder for plants to grow and store carbon. Ozone causes leaf injuries like bleaching or dark spots on some sensitive plants. There are 7 plants that may display ozone leaf injury at Lassen Volcanic National Park. Search ozone-sensitive plant species found at Lassen Volcanic National Park.

US Environmental Protection Agency and NPS found in ozone exposure experiments that ozone slowed tree seedling growth. NPS uses W126 values from averaged seedling responses in those experiments to describe park condition in terms of Vegetation Health. Ozone affects actively growing plants, so the W126 metric weights a sum of ozone concentrations during daylight hours over three months in the growing season.

A recent re-analysis of the seedling experiments established critical levels of ozone protective of each tree species tested (Lee et al. 2022). The ozone critical levels are W126 values that will prevent 5% or greater deficit in tree seedling biomass. Air Quality Conditions and Trends reports a 5-year average of W126 for each park. In 2018-2022, the average W126 value for Lassen Volcanic National Park was 11.6 ppm-h. Based on this ozone level, trees present in the park (NPSpecies) are at risk of the following ozone effects:

• The tree species ponderosa pine (Pinus ponderosa), with an ozone critical level of 6 ppm-h, is at risk of 8% biomass deficit in seedlings. The tree species quaking aspen (Populous tremuloides), with an ozone critical level of 9 ppm-h, is at risk of 7% biomass deficit in seedlings.

• Tree species Douglas-fir (Pseudotsuga menziesii) is at low risk from ozone despite its known sensitivity. Recent ozone levels in the park are below critical levels that protect this tree from 5% biomass deficit.

Ozone critical levels are for tree seedlings, which represent the regenerative capacity and long-term stability of sensitive species within a forest. These tree species are also known to be sensitive to ozone as adults (Bell et al. 2020), but critical values for seedling growth do not predict ozone effects on mature trees. Air Resources Division is currently working with collaborators to establish critical levels for mature trees using data from forest monitoring plots.

Ozone causes growth deficits in non-woody plants as well as in trees. Ozone critical levels have been established to protect non-woody plants that grow in European meadows and grasslands (Van Goethem et al. 2013). Twenty herb species with ozone critical levels grow in California. A county-level assessment predicted that seven herb species in Shasta, Lassen, Plumas, and Tehama counties lost more than 10% biomass annually due to ground-level ozone pollution (Kaylor et al. 2023). Ozone effects on sensitive herbs in the counties that contain Lassen Volcanic National Park exceed European recommendations to cap growth deficits at 10% annual losses.

Visit the NPS air quality conditions and trends website for park-specific ozone information. Lassen Volcanic National Park has been monitoring ozone since 1989 View live ozone and meteorology data.

Explore Other Park Air Profiles

There are 47 other Park Air Profiles covering parks across the United States and its territories.

References

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