The Role of Lichens in Air Quality Monitoring on Federal Lands

What information can lichen monitoring provide to air resource managers?

Linda Geiser, US Dept. of Agriculture-Forest Service, Pacific Northwest Region Air Resource Management, PO Box 1148, Corvallis OR 97330

What are lichens?

British soldiers Button lichen

Lichens are symbiotic organisms consisting of a fungus and an alga and/or a cyanobacterium.

Lung lichen

What physiological properties make lichens useful indicators of air quality?



Range of air pollution sensitivities across species.

Lichens exhibit a range of sensitivities to S- & N compounds in acid rain, sulfur dioxide, ammonia, and fluoride. Changes in distribution or populations of the most sensitive lichens provide an early warning that air pollution is beginning to adversely affect the ecosystem.

The mix of species and abundances at any one site can be used to position the site along an air quality gradient.



High surface area and no roots.

Lichens on trees and shrubs obtain nutrients from the air, precipitation, and substrate run-off.

Tissue levels of many pollutants are correlated with ambient atmospheric levels.



Readily absorb water and lack specialized barriers to prevent vapor loss

concentration and leaching of pollutants

. As pollution concentrations

. Daily cycles of wetting and drying produce a dynamic equilibrium between

change, so do concentrations in lichens.

Mobile elements: S, N, K, Ca, Mg, Na. – can change significantly over a few months. Less mobile elements: Pb, Cd, Ni—change more slowly.

What kinds of data are collected?



Lichen communities and floristics



Tissue analyses



Transplants



Laboratory

#1. Documenting deposition of pollutants in a Class 1 Area and tracing their source.

Mt. Zirkel Wilderness, Routt NF, Colorado

Yellow lines circle lichen monitoring plots (black triangles) REFERENCE: Jackson, LL, L Geiser, T Blett, C Gries, D Haddow. 1996:

Biogeochemistry of lichens and mosses in and near Mt. Zirkel wilderness, Routt National Forest, Colorado: influences of coal-fired power plant emissions

. Open-File Report, 96-295, U.S. Department of the Interior, U.S. Geological Survey. 162 pp.

Mt. Zirkel Wilderness, Routt NF, Colorado

Stable S isotope ratios in lichens were significantly heavier in the MZW and Routt NF than at regional sites. This was consistent with a local sulfur source with a heavy isotopic signature resulting from the combustion of marine-influenced coals from the Yampa Valley.

#2. Check a site within an area with established background ranges.

Lichen monitoring sites indicated by yellow triangles

Klondike Gold Rush National Historic Park, Skagway, Alaska

REFERENCE : Furbish, C.E., L.H. Geiser and C. Rector. 2000. Lichen-air quality pilot study for Klondike Gold Rush National Historical Park and the City of Skqaway, Alaska. Klondike Gold Rush National Historical Park Natural Resources Management Program. Report released December 2000.

Klondike Gold Rush National Historic Park, Skagway, Alaska

Mean concentrations of Al, Cd, Cr, Cu, Fe, Pb, Ni, P, K, S, Zn in the lichen,

Hypogymnia enteromorpha

, were higher in Klondike Gold Rush NHP samples than Tongass National Forest samples.

Lichen tissue was collected along a transect from the APC mill, through the town of Sitka to the Ferry Terminal ( red dots ).

#3.

Mapping deposition patterns from a point source.

Tongass National Forest, Sitka, Alaska

REFERENCE: Geiser, LH/ Derr, CC/ Dillman, KL 1994:

Air Quality Monitoring on the Tongass National Forest. Methods and Baselines Using Lichens

. - USDA-Forest Service, Alaska Region Technical Bulletin 46. 85 pp.

Tongass National Forest, Sitka, Alaska

Typical cover of lichens on alder in the Sitka area Lichens were absent from alder <0 .25 mi from the pulp mill, an SO 2 source.

Tongass National Forest, Sitka, Alaska

3-D view of lichen tissue concentrations in # of sd from Tongass clean sites mean (vertical axis) vs sampling site location (horizontal axes). Far right is < 1km from the pulp mill, center is Sitka city center, far left is the ferry terminal, 14 mi distant.

#4. Estimating deposition from calibrated lichen data.

Pacific Northwest National Forests

Lichen tissue collections were made within 1 km of 8 NADP monitors in Oregon and Washington (

black dots on national map above

).

Pacific Northwest National Forests

Lichen sulfur concentrations, weighted by precipitation, accurately predicted wet deposition of sulfur to within about 0.3 kg/ha/yr. 8 Hoh RS 6 4 Alsea Pack For Bull Run NC HJA Hyslop 2 0 0 Starkey Silver L 5 10 Lichen % S (pptn weighted) 15 20

Pacific Northwest National Forests

A map of wet deposition of sulfur in Pacific NW national forests constructed using calibrated lichen data. Values ranged from < 0.7 (dark blue) to > 4.0 (red) kg/ha/year.

A map of wet deposition of nitrogen was similar.

#5. Combining lichen community and tissue data to indicate patterns of anthropogenic influence and its effects on vegetation.

Alaska and Pacific Northwest Regions

Red dots indicate monitoring locations where lichen community surveys and tissue analysis have been completed by the USFS Air program. In PNW forests, monitoring is co-located with the CVS (= USFS national Forest Inventory Assessment) 3.4 mi grid.

Sensitive, ecologically important lichens, many endemic, are sparse to absent in areas where acid rain is high.

Growth of pollution-loving, weedy species is enhanced where nitrogen pollution is high.

MILES 80 Area Willamette N.F.

Lichen communities

Siuslaw N.F.

Gifford Pinchot N.F.

Mt. Hood N.F.

Willamette Valley CRGNSA Urban Parks DECMINT SMRTMP AirQual 40 0 0 Elev Easting KMocean 40 Axis 1 Ordination of sites by lichen communities. Plots (represented by triangles) with smiliar communities are close together in space. Environmental variables are overlaid on the ordination Axis 1 is correlated with increasing sulfur and nitrogen pollution. Axis 2 is 80 temperatures. In this analysis, urban parks and the Columbia River Gorge National Scenic plots receive the highest pollution scores.

#7. Determining whether instrumented monitoring is warranted

Hell’s Canyon National Recreation Area

Could ancient rock art be threatened by air pollution?

2.0

1.9

1.8

1.7

1.6

1.5

1.4

1.3

1.2

1.1

0

0.4

1.6

>1 .6

Xanthoria Cover (% ) By Distance (km)

Distance (km) 70 Wi th Con trol Dunn ett's 0 .05

60

Means Comparisons 0 0.4

>1 .6

1.6

40

0

0.0000 00 -0.3280 7 -0.3311 9 -0.3411 9

0.4

0.3280 68 0.0000 00 -0.0031 2 -0.0131 2

>1 .6

0.3311 93 0.0031 25 0.0000 00 -0.0 1

1.6

0.3411 93 0.0131 25 0.0100 00 0.0000 00 Al pha= 30 0.05

Comparisons with a control using Dunnett's Method 0 0.4

>1 .6

1.6

20

|d|

2 .484 75

Abs (Dif)-LSD

0

0 0

-0.1661 9 0.1469 65 0.1500 90 0.1600 90

1.6

> 1.6

Wi th Con trol Dunn ett's 0 .05

Pos itive va lues sho w pairs of mean s th at a re si gnifica ntly d iffe rent.

Nitrogen concentrations in lichen tissue and abundance of the nitrogen-loving lichen,

Xanthoria

, were highest at sites closest to the Snake River.

Means Comparisons Dif=Mea n[i]-Mean[j] 0 0.4

1.6

> 1.6

0

0.00 00 -36 .458 3 -39 .583 3 -42 .708 3

0.4

3 6.45 83 0.00 00 -3 .125 0 -6 .250 0

1.6

3 9.58 33 3.12 50 0.00 00 -3 .125 0

> 1.6

4 2.70 83 6.25 00 3.12 50 0.00 00 Al pha= 0.05

Comparisons with a control using Dunnett's Method |d|

2 .653 53

Abs (Dif)-LSD 0 0.4

1.6

> 1.6

0

-19 .309 1 1 4.87 00 1 7.99 50 2 1.12 00 Pos itive va lues sho w pairs of mean s th at a re si gnifica ntly d iffe rent.

Hell’s Canyon National Recreation Area

log (% N in Xanthoparmelia) By Comparison Areas

0.35

0.30

0.25

0.20

0.15

0.10

0.05

0.00

-0.05

-0.10

CRGNSA

HCNRA: 0 km

HCNRA:>.3 k m R2 Elev a R2/6 Back g

With Control Dunnett's 0.05

Comp arison Areas Average tissue concentrations of nitrogen at all sites in Hell’s Canyon were elevated relative to background sites in the western US

Means and Std Deviations Le vel

CRGNSA HCNRA: 0 km

Conclusion: Instrumented monitoring is warranted.

HCNRA:>.3 km R2 Eleva R2/6 Backg 40 12 24 29 20

Mean

0.141080

0.219858

0.123167

0.109714

0.032774

Std Dev

0.092587

0.053052

0.039872

0.054535

0.043244

Std Err Mea n

0.01464

0.01531

0.00814

0.01013

0.00967

Means Comparisons Dif=Mea n[i]-Mean[j] HCNRA: 0 km CRGNSA HCNRA:>.3 k m R2 Eleva R2/6 Bac kg HCNRA: 0 km

0.000000

-0.07878

-0.09669

-0.11014

-0.18708

CRGNSA

0.078779

0.000000

-0.01791

-0.03137

-0.10831

HCNRA:>.3 k m

0.096691

0.017912

0.000000

-0.01345

-0.09039

Alpha= 0.05

Comparisons with a control using Dunnett's Method |d|

2.41029

Abs (Dif)-LSD HCNRA: 0 km CRGNSA HCNRA:>.3 k m R2 Eleva R2/6 Bac kg HCNRA: 0 km

-0.06482

0.026523

0.040560

0.055649

0.129112

Positive values show pairs of means that are significantly different.

R2 Eleva

0.110144

0.031365

0.013453

0.000000

-0.07694

R2/6 Bac kg

0.187085

0.108306

0.090394

0.076941

0.000000

Summary: Advantages of lichen monitoring



Good indicators of deposition

containing sulfur, nitrogen, metals, other elements, radionuclides and some hydrocarbons/organochlorines.

 

Demonstrates presence of contaminants in the ecosystem Lichen communities are good summarizers of air quality

the synergistic mix of pollutants in the air.

. —respond to  

Lichen communities

(species richness, composition and abundance) can be used to

indicate whether anthropogenic activities are affecting the ecosystem Relatively fast and inexpensive

—many measuring points can be made in a short time that summarizing air quality over past months or years.



Useful in areas of rugged topography

where modeling is inadequate.



Useful in remote areas

—does not require electric power.



Can be used to map relative differences in air quality

over a geographical area of interest and to track changes over time. If air pollution tolerant species are used, can map polluted areas.



Source apportionment

isotope ratios. is possible using multi-element analysis and

Summary: Advantages of lichen monitoring

 

Plentiful existing data

for the PNW and Alaska and Canada for metals, and in arctic for POPs, some data for radionuclides from Canada. Preliminary thresholds for metals.



Can link to existing programs

: FHM (lichen communities) and USFS PNW (communities and tissue analysis).

  

Not mobile,

concentrations reflect local conditions.

Easy to collect

, lichens are widespread and easy to recognize.

Deposition can be estimated from lichen tissue levels

are available for calibration.

if instrumented sites 

Compliments instrument measurements and other monitoring information

. Element analyses, community analyses used in combination with direct measurements or other bioindicatorscan corroborate each other, making a more convincing argument for decision-makers.

Multi-element analysis can evaluate multiple stressors simultaneously

, good idea to measure effects of sulfur and nitrogen deposition together with other pollutants.

Summary: Limitations of lichen monitoring



Lichens are relatively insensitive to many air toxics

(metals, radionuclides, organics)– lichen communities affected more by acid rain, SO2, N deposition and fluorine. I.e. may be able to show presence of enhanced tissue levels but not adverse effects to ecosystem.

   

Cannot separate wet from dry deposition

or different forms of sulfur or nitrogen containing pollutants using lichens—measure total N, total S and total deposition.

Some metals

are not easily leached from lichen thalli and may

remain concentrated for 10+ years

. Can use transplants, select species with annual growth (

Hylacomium splendens

) or collect from substrate of known age (last five terminal bud scars). Or, because epiphytic lichens grow rather quickly, can monitor changes over time of the population mean.

Interference from local dust

: use enrichment factor from local soils (Al).

Tissue analysis

cannot differentiate wet from dry deposition

. May not be able to distinguish different forms of a single element.

Summary: Limitations of lichen monitoring

    

Multivariate analysis is often required to separate the pollution signal from other environmental variables

(elevation, precip, forest continuity, relative humidity, available substrates) OR restrict the range of these variables within the study area.

To obtain accurate and repeatable readings of metals,

tissue concentrations of metals should be in the 0.1 ppm range or higher

. Check detection limits of laboratory before analysis.

Lichen analysis for POPs is analytically challenging

because concentrations are usually low and natural lichen substance interfere with analyses. But much base work has been completed for the arctic.

Must have sufficient material

– lichens may be difficult to find where acid rain, SO2 or N deposition is a problem. Can use transplants. Must compare different sites using the same species.

Regulatory personnel are often unfamiliar

with lichen monitoring methods. Can establish LACs, develop an MOU, or calibrate data to units used by regulatory agencies.