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CRITICAL LOADS FOR RESOURCE PROTECTION

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CLAD REFERENCES

EPA HERO REFERENCES

Open in a new window This reference list includes published articles and reports that document North American critical loads and supporting information related to the science of critical loads. References are listed by publication year. Documents from other continents are also included if they present information on methods or critical load concepts that are broadly applicable to North America.

Authors	Year	Title	Publication	Vol/pp	DOI/URL
Fenn, M.E., J.S. Baron, E.B. Allen, H.M. Rueth, K.R. Nydick, L. Geiser, W.D. Bowman, J.O. Sickman, T. Meixner, D.W. Johnson, and P. Neitlich	2003	Ecological effects of nitrogen deposition in the Western United States	BioScience	53(4): 404-420	doi:10.1641/0006-3568(2003)053[0404:EEONDI]2.0.CO;2
Dupont J., Clair, T.A., Gagnon, C., Jeffries, D.S., and Kahl, J.S.	2005	Estimation of critical loads of acidity for lakes in northeastern United States and eastern Canada	Environmental Monitoring and Assessment	109: 275-291	https://doi.org/10.1007/s10661-005-6286-x
Porter, E., T. Blett, D.U. Potter, and C. Huber	2005	Protecting resources on federal lands: Implications of critical loads for atmospheric deposition of nitrogen and sulfur	BioScience	55(7): 603-612	doi:10.1641/0006-3568
Baron, Jill S.	2006	Hindcasting nitrogen deposition to determine an ecological critical load	Ecological Applications	16(2): 433-439	(pdf)
Groffman, P.M., J.S. Baron, T. Blett, A.J. Gold, I. Goodman, L.H. Gunderson, B.M. Levinson, M.A. Palmer, H.W. Pearl, G.D. Peterson, N.L. Poff, D.W. Rejeski, J.F. Reynolds, M.G. Turner, K.C. Weathers, and J. Wiens	2006	Ecological Thresholds: The key to successful environmental management or an important concept with no practical application	Ecosystems	9: 1-13	doi:10.1007/s10021-003-0142-z
Li, H. and S.G. McNulty	2007	Uncertainty analysis on simple mass balance model to calculate critical loads for soil acidity	Environmental Pollution	149: 315-326	https://doi.org/10.1016/j.envpol.2007.05.014
McNulty, S.G., E.C. Cohen, J.A. Moore Myers, T.J. Sullivan, and H. Li.	2007	Estimates of critical acid loads and exceedances for forest soils across the conterminous United States	Environmental Pollution	149: 281-292	(link)
Porter, E., S. Johnson	2007	Translating science into policy: Using ecosystem thresholds to protect resources in Rocky Mountain Nation Park	Environmental Pollution	149: 268-280	doi:10.1016/j.envpol.2007.06.060
Burns, D.A., T. Blett, R. Haeuber, and L.H. Pardo	2008	Critical loads as a policy tool for protecting ecosystems from the effects of air pollutants	Frontiers in Ecology and the Environment	6(3): 156-159	doi:10.1890/070040
Saros, Jasmine	2009	Determining critical N loads to subalpine lakes in the Pacific Northwest.	Climate Change Institute, University of Maine	Final Report: 1-11	(pdf)
Fenn, M.E., E.B. Allen, S.B. Weiss, S. Jovan, L.H. Geiser, G.S. Tonnesen, R.F. Johnson, L.E. Rao, B.S. Gimeno, F. Yuan, T. Meixner, and A. Bytnerowicz	2010	Nitrogen critical loads and management alternative for N-impacted ecosystems in California	Journal of Environmental Management	91: 2404- 2423	doi:10.1016/j.jenvman.2010.07.034
Geiser, L.H., S.E Jovan, D.A. Glavich, and M.K. Porter	2010	Lichen-based critical loads for atmospheric nitrogen deposition in Western Oregon and Washington Forests U.S.A.	Environmental Pollution	158: 2412-2421	https://doi.org/10.1016/j.envpol.2010.04.001
McDonnell, T.C., B.J. Cosby, T.J. Sullivan, S.G. McNulty, and E.C. Cohen	2010	Comparison among model estimates of critical loads of acidic deposition using different sources and scales of input data	Environmental Pollution	158:2934-2939	doi:10.1016/j.envpol.2010.06.007
McNulty, S.G., and Boggs, J.L.	2010	A conceptual framework: Redefining forest soil’s critical acid loads under a changing climate	Environmental Pollution	158: 2053-2058	doi:10.1016/j.envpol.2009.11.028
Sullivan, T.J., B.J. Cosby, and T.C. McDonnell	2010	Aquatic critical loads and exceedances in acid-sensitive portions of Virginia and West Virginia	E&S Environmental Chemistry, Inc. Final Report	1-91	(pdf)
Fenn, M.E., K.F. Lambert, T.F. Blett, D.A. Burns, J.H. Pardo, G.M. Lovett, R.A. Haeuber, D.C. Evers, C.T. Driscoll and D. S. Jefferies	2011	Setting limits: Using air pollution thresholds to protect and Restore U.S. Ecosystems	Issues in Ecology	Report No. 14. 21 pages	(pdf)
Sullivan, T.J., B.J. Cosby, C.T. Driscoll, T.C. McDonnell, and A.T. Herlihy	2011	Target loads of atmospheric sulfur deposition protect terrestrial resources in the Adirondack Mountains, New York against biological impacts caused by soil acidification	Journal of Environmental Studies and Sciences	1(4): 301-314	doi:10.1007/s13412-011-0062-8
Baron, J.S., C.T. Driscoll, J.L. Stoddard, and E.E. Richer	2011	Empirical critical loads of atmospheric nitrogen deposition for nutrient enrichment and acidification of sensitive U.S. Lakes	BioScience	61(8): 602-613	https://doi.org/10.1525/bio.2011.61.8.6
Lampman, G., G.B. Lawrence, T.J. Sullivan, K.C. Weathers, B.J. Cosby, and T.C. McDonnell	2011	Comparison of methods for estimating critical loads of acidic deposition in the Western Adirondack region of New York. New York State Energy Research and Development Authority.			(pdf)
Pardo, L.H., M.J. Robin-Abbott, and C.T. Driscoll	2011	Assessment of nitrogen deposition effect and empirical critical loads of nitrogen for ecoregions of the Untied States	Gen.Tech. Rep. NRS-80. U.S. Department of Agriculture, Forest Service Northern Research Station.	291 pp.	(link)
Pardo, L.H. Fenn, M., Goodale, C.L., Geiser, L.H., Driscoll, C.T., Allen E., Baron, J. Bobbink, R. Bowman, W.D., Clark, C., Emmett, B., Gilliam, F.S., Greaver, T., Hall, S.J., Lilleskov, E.A., Liu, L., Lynch, J., Nadelhoffer, K., Perakis, S., Robin-Abbott, M.J., Stoddard, J., Weathers, K., Dennis, R.L	2011	Effects of nitrogen deposition and empirical critical loads for nitrogen for ecoregions of the United States	Ecological Applications	21(8): 3049-3082	(10.1890/10-2341.1)
Hessburg et al	2011	Predicting Acid Neutralizing Capacity and Base Cation Weathering in the Southern Appalachian Mountains. Final Report
Sullivan, T.J., B.J. Cosby, and W.A. Jackson	2011	Target loads of atmospheric deposition for the protection and recovery of acid-sensitive streams in the Southern Blue Ridge Province	Journal of Environmental Management	30: 1-8	https://doi.org/10.1016/j.jenvman.2011.07.014
Sullivan, T.J., B.J. Cosby, W.A. Jackson, K.U. Snyder, and A.T. Herlihy	2011	Acidification and prognosis for future recovery of acid-sensitive streams in the Southern Blue Ridge Province	Water, Air & Soil Pollution	219: 11-26	https://doi.org/10.1007/s11270-010-0680-x
W.D. Bowman, J. Murgel, T. Blett, and E. Porter	2012	Nitrogen critical loads for alpine vegetation and soils in Rocky Mountain National Park	Journal of Environmental Management	103: 165-171	doi:10.1016/j.jenvman.2012.03.002
McDonnell, T.C., Cosby, B.J., Sullivan, T.J.	2012	Regionalization of soil base cation weathering for evaluating stream water acidification in the Appalachian Mountains, USA	Environmental Pollution	162: 338-344	doi:10.1016/j.envpol.2011.11.025
Miller, E.	2012	Steady-State Critical Loads and Exceedance for Terrestrial and Aquatic Ecosystems in the Northeastern United States	Technical Report to the Mulit-Agency Critical Loads Project of CLAD, NADP		(link)
L. Nanus, D.W. Clow, J.E. Saros, V.C. Stephens, and D.H. Campbell	2012	Mapping critical loads of nitrogen deposition for aquatic ecosystems in the Rocky Mountains, USA	Environmental Pollution	166: 125-135	doi:10.1016/j.envpol.2012.03.019
Phelan, J.N	2012	Review of Models to Evaluate Interactive Impacts of Nitrogen Deposition and Climate Change on Ecosystems and Ecosystem Services	Final Report prepared by RTI International for Chris Clark, EPA Office of Research and Development, National Center for Environmental Assessment. 61pp.	Available by request from Chris Clark	clark.christopher@epa.gov
Porter, E., H. Sverdrup, and T.J. Sullivan	2012	Estimating and mitigating the impacts of climate change and air pollution on alpine plant communities in national parks	Park Science	28(2): 58-64	(link)
Reynolds K.M., Hessburg P.F., Sullivan T., Povak N.A., McDonnell T., Cosby B., Jackson W	2012	Spatial Decision Support for Assessing Impacts of Atmospheric Sulfur Deposition on Aquatic Ecosystems in the Southern Appalachian Region	Hawaii International Conference on System Sciences	45: 1-10	doi:10.1109/HICSS.2012.542
Sullivan, T.J	2012	Combining ecosystem service and critical load concepts for resource management and public policy	Water 4:905-913		doi:10.3390/w4040905
Sullivan, T.J., B.J. Cosby, C.T. Driscoll, T.C. McDonnell, A.T. Herlihy, and D.A. Burns	2012	Target loads of atmospheric sulfur and nitrogen deposition for protection of acid sensitive aquatic resources in the Adirondack Mountains, New York	Water Resource Research	48 (W01547): 1-16	doi:10.1007/s13412-011-0062-8
Sullivan, T.J., B.J. Cosby, T.C. McDonnell, E.M. Porter, T. Blett, R. Haeuber, C.M. Huber, and J. Lynch	2012	Critical loads of acidity to protect and restore acid-sensitive streams in Virginia and West Virginia	Water, Air & Soil Pollution	223:5759-5771	doi:10.1007/s11270-012-1312-4
Sullivan, T.J., ed	2012	USDA Forest Service National Protocols for sampling air pollution-sensitive waters	Gen. Tech Rep. RMRS-GTR-278WWW. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station. 334 p.		https://doi.org/10.2737/RMRS-GTR-278
Sullivan, T.J. and T.C. McDonnell	2012	Application of Critical Loads and Ecosystem Services Principles to Assessment of the Effects of Atmospheric Sulfur and Nitrogen Deposition on Acid-Sensitive Aquatic and Terrestrial Resources. Pilot Case Study: Central Appalachian Mountains	Report prepared for the U.S. Environmental Protection Agency, in association with Systems Research and Applications Corporation. E& S Environmental Chemistry, Inc., Corvallis, OR.
Sverdrup, H., T.C. McDonnell, T.J. Sullivan, B. Nihlgard, S. Belyazid, B. Rihm, E. Porter, W.D. Bowman, L. Geiser	2012	Testing the feasibility of using the ForSAFE-VEG model to map the critical load of nitrogen to protect plant biodiversity in the Rocky Mountains Region, U.S.A.	Water, Air & Soil Pollution	223: 371-387	doi:10.1007/s11270-011-0865-y
Clark, C.M., Morefield, P.E., Gilliam, F.S., and Pardon, L.H.	2013	Estimated losses of plant biodiversity in the United States from historical N deposition (1985-2010)	Ecology	94: 1441-1448	doi:10.1890/12-2016.1
Duarte, N., L. H. Pardo and M. J. Robin-Abbott.	2013	Susceptibility of Forests in the Northeastern USA to Nitrogen and Sulfur Deposition: Critical Load Exceedance and Forest Health	Water, Air & Soil Pollution	224	doi:10.1007/s11270-012-1355-6
R. A. Ellis, D. J. Jacob, M. P. Sulprizio, L. Zhang, C. D. Holmes, B. A. Schichtel, T. Blett, E. Porter, L. H. Pardo, and J. A. Lynch.	2013	Present and future nitrogen deposition to national parks in the United States: critical load exceedances	Atmos. Chem. Phys.	13, 9083-9095	doi:10.5194/acp-13-9083-2013
G.M. Lovett.	2013	Critical issues for critical loads	Proceedings of the National Academy of Sciences	110 (3): 803-809.	10.1073/pnas.1219007110
McDonnell, T.C., T.J. Sullivan, B.J. Cosby, W.A. Jackson, and K. Elliott.	2013	Effects of climate, land management, and sulfur deposition on soil base cation supply in national forests of the Southern Appalachian Mountains	Water, Air & Soil Pollution	224:1733	doi:10.1007/s11270-013-1733-8
R.J. Payne, N.B. Dise, C.J. Stevens, D.J. Gowing, and BEGIN Partners.	2013	Impact of nitrogen deposition at the species level	Proceedings of the National Academy of Sciences	110 (3): 984-987	doi:10.1073/pnas.1214299109
Povak, N.A., P.F. Hessburg, K.M. Reynolds, T.J. Sullivan, T.C. McDonnell, and R.B. Salter.	2013	Machine learning and hurdle models for improving regional predictions of stream water acid neutralizing capacity	Water Resources Research	49	doi:10.1002/wrcr.20308
Sullivan, T.J., G.B. Lawrence, S.W. Bailey, T.C. McDonnell, and G.T. McPherson.	2013	Effects of acidic deposition and soil acidification on sugar maple trees in the Adirondack Mountains, New York	NYSERDA Report No. 13-04. New York State Energy Research and Development Authority, Albany, NY.		(link)
Sullivan, T.J., G.B. Lawrence, S.W. Bailey, T.C. McDonnell, C.M. Beier, K.C. Weathers, G.T. McPherson, and D.A. Bishop.	2013	Effects of acidic deposition and soil acidification on sugar maple in the Adirondack Mountains, New York	Environmental Science & Technology		doi:10.1021/es401864w
Blett, T.F., J.A.Lynch, L.H. Pardo, C. Huber, R Haeuber, R. Pouyat	2014	FOCUS: A pilot study for national-scale critical loads development in the Unites States	Environmental Science and Policy	38:225-236	doi:10.1016/j.envsci.2013.12.005
Cox, R. D., K. L. Preston, R. F. Johnson, R. A. Minnichc, E. B. Allen	2014	Influence of landscape-scale variables on vegetation conversion to exotic annual grassland in southern California, USA	Global Ecology and Conservation	2 190–203	doi:10.1016/j.gecco.2014.09.008
Cummings, T., T. Blett, E. Porter, L. Geiser, R. Graw, J. McMurray, S. Perakis and R. Rochefort	2014	Thresholds for protecting Pacific Northwest ecosystems from atmospheric deposition of nitrogen: State of knowledge report	Natural Resource Report NPS/PWRO/NRR—2014/823. National Park Service, Fort Collins, Colorado.		(link)
McDonnell T.C., S. Belyazid, T.J. Sullivan, H. Sverdrup, W.D. Bowman, E.M. Porter	2014	Modeled subalpine plant community response to climate change and atmospheric nitrogen deposition in Rocky Mountain National Park, USA	Environmental Pollution	187	doi:10.1016/j.envpol.2013.12.021
McDonnell, T.C., and T.J. Sullivan	2014	Comparison of Regional Stream ANC Predictions for the George Washington National Forest Using Spatial and Non-Spatial Regression Modeling. Final Report USDA Forest Service, Asheville, NC.	E&S Environmental Chemistry, Inc.	pp. 37	(link)
McDonnell, T. C., and T. J. Sullivan	2014	Total Atmospheric Nitrogen and Sulfur Deposition in Forest Service Wildernesses and National Forests Throughout the Conterminous United States.	E&S Environmental Chemistry, Inc. Corvallis, OR		(link)
McDonnell, Todd C., Timothy J. Sullivan, Paul F. Hessburg, Keith M. Reynolds, Nicholas A. Povak, Bernard J. Cosby, William Jackson, and R. Brion Salter	2014	Steady-state sulfur critical loads and exceedances for protection of aquatic ecosystems in the U.S. southern Appalachian Mountains	Journal of Environmental Management	Volume 146, 15 December 2014, Pages 407–419,	doi:10.1016/j.jenvman.2014.07.019
McMurray, J. A., D. W. Roberts, L. H. Geiser	2014	Epiphytic lichen indication of nitrogen deposition and climate in the northern rocky mountains, USA	Ecological Indicators	49 154–161	doi:10.1016/j.ecolind.2014.10.015
New York State Energy Research and Development Authority (NYSERDA)	2014	Critical Loads for Air Pollution: Measuring the Risks to Ecosystems.	NYSERDA Report 14-24. Prepared by the Wildlife Conservation Society and E&S Environmental Chemistry.		(link)
Phelan, Jennifer, Salim Belyazid, Daniel Kurz, Scott Guthrie, James Cajka, Harald Sverdrup, Randall Waite	2014	Estimation of Soil Base Cation Weathering Rates with the PROFILE Model to Determine Critical Loads of Acidity for Forested Ecosystems in Pennsylvania, USA: Pilot Application of a Potential National Methodology	Water, Air, Soil & Pollution	225:2109	doi:10.1007/s11270-014-2109-4
Povak, N. A., P. F. Hessburg, T. C. McDonnell, K. M. Reynolds, T. J. Sullivan, R. B. Salter, and B. J. Cosby	2014	Machine learning and linear regression models to predict catchment-level base cation weathering rates across the southern Appalachian Mountain region, USA	Water Resour Res.	50	doi:10.1002/2013WR014203
Root, H. T., McCune, B., & Jovan, S.	2014	Lichen communities and species indicate climate thresholds in southeast and south-central Alaska, USA	The Bryologist	117(3), 241-252.	doi:10.1639/0007-2745-117.3.241
Scheffe, R. D J. A. Lynch, A. Reff, J. T. Kelly, B. Hubbell, T. L. Greaver, J. T. Smith	2014	The Aquatic Acidification Index: A New Regulatory Metric Linking Atmospheric and Biogeochemical Models to Assess Potential Aquatic Ecosystem Recovery	Water, Air, & Soil Pollution	225:1838	doi:10.1007/s11270-013-1838-0
Schirokauer, D., L. Geiser, A. Bytnerowicz, M. Fenn, and K. Dillman	2014	Monitoring air quality in Southeast Alaska’s National Parks and Forests: Linking atmospheric pollutants with ecological effects	Natural Resource Technical Report NPS/SEAN/NRTR—2014/839. National Park Service, Fort Collins, Colorado		(link)
Shaw G. D., R. Cisneros, D. Schweizer, J. O. Sickman, M. E. Fenn	2014	Critical Loads of Acid Deposition for Wilderness Lakes in the Sierra Nevada (California) Estimated by the Steady-State Water Chemistry Model	Water Air & Soil Pollution	225:1804	doi:10.1007/s11270-013-1804-x
Sheibley, R. W, M. Enache, P. W. Swarzenski, P. W. Moran, J. R. Foreman	2014	Nitrogen Deposition Effects on Diatom Communities in Lakes from Three National Parks in Washington State	Water, Air & Soil Pollution (2014)	225:1857	doi:10.1007/s11270-013-1857-x
Watmough, Shaun A., Colin J. Whitfield , Mark E. Fenn	2014	The importance of atmospheric base cation deposition for preventing soil acidification in the Athabasca Oil Sands Region of Canada	Science of the Total Environment	493 (2014) 1–11	doi:10.1016/j.scitotenv.2014.05.110
BassiriRad, H., Lussenhop, J.F., Sehtiya, H.L., and K.K. Borden	2015	Nitrogen deposition potentially contributes to oak regeneration failure in the Midwestern temperate forests of the USA	Oecologia	177: 53–63	doi:10.1007/s00442-014-3119-z
Burns, D.A., and T.J. Sullivan	2015	Critical Loads of Atmospheric Deposition to Adirondack Lake Watersheds: A Guide for Policymakers	NYSERDA Technical Report, Albany, NY	16 p.	http://dx.doi.org/10.13140/RG.2.1.4281.7366
Bytnerowicz, A., Johnson, R.F., Zhang, L., Jenerette, G.D., Fenn, M.E., Schilling, S.L., and Gonzalez-Fernandez, I.	2015	An empirical inferential method of estimating nitrogen deposition to Mediterranean-type ecosystems: The San Bernardino mountains case study	Environmental Pollution	203: 69-88	doi:10.1016/j.envpol.2015.03.028
Cleavitt, N. L., Hinds, J. W., Poirot, R. L., Geiser, L. H., Dibble, A. C., Leon, B., Perron, R., Pardo, L. H.	2015	Epiphytic macrolichen communities correspond to patterns of sulfur and nitrogen deposition in the northeastern United States	The Bryologist	118(3), 304-324	doi:10.1639/0007-2745-118.3.304
Clow, David W., Heidi A. Roop, Leora Nanus, Mark E. Fenn, Graham A. Sexstone	2015	Spatial patterns of atmospheric deposition of nitrogen and sulfur using ion-exchange resin collectors in Rocky Mountain National Park, USA	Atmospheric Environment	101 (2015) 149-157	doi:10.1016/j.atmosenv.2014.11.027
Lawrence, G.B., Sullivan, T.J., Burns, D.A., Bailey, S.A., Cosby, B.J., Dovciak, M., Ewing, H.A., McDonnell, T.C., Minocha, R., Quant, J., Rice, K.C., Siemion, J., and Weathers, K.C.	2015	Acidic deposition along the Appalachian Trail corridor and its effects on acid-sensitive terrestrial and aquatic resources: Results of the Appalachian Trail atmospheric deposition effects MEGA-transect study	Natural Resource Report NPS/NRSS/ARD/NRR—2015/996. National Park Service, Fort Collins, Colorado	241 p.	(link)
Leavitt, S. D., and Clair, L. L. S.	2015	Bio-monitoring in Western North America: What Can Lichens Tell Us About Ecological Disturbances?	In Recent Advances in Lichenology	pp. 119-138. Springer India.	(link)
Fenn, M.E., J.S. Fried, H.K. Preisler, A. Bytnerowicz, S. Schilling, S. Jovan, and O. Kuegler	2015	Remeasured FIA plots reveal tree-level diameter growth and tree mortality impacts of nitrogen deposition on California’s forests	Proceedings of the 2015 FIA Symposium. Gen. Tech. Rep. PNW-GTR-931. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station		(link)
Mast, M. Alisa, David W. Clow, Jill S. Baron, and Gregory A. Wetherbee	2015	Links between N Deposition and Nitrate Export from a High-Elevation Watershed in the Colorado Front Range	Environmental Science Technology		doi:10.1021/es502461k
McMurray, J. A., Roberts, D. W., & Geiser, L. H.	2015	Epiphytic lichen indication of nitrogen deposition and climate in the northern rocky mountains, USA	Ecological Indicators	49, 154-161	doi:10.1016/j.ecolind.2014.10.015
Pardo, L.H., Blett, T., Clark, C.M., and L.H. Geiser	2015	Impacts of nitrogen pollution on terrestrial ecosystems in the United States	EM: Air and Waste Management Association's magazine for Environmental Managers	65: 24-30	(link)
Pardo, L. H., Robin-Abbott, M. J., Fenn, M. E., Goodale, C. L., Geiser, L. H., Driscoll, C. T., ... & Dennis, R. L.	2015	Effects and Empirical Critical Loads of Nitrogen for Ecoregions of the United States	In Critical Loads and Dynamic Risk Assessments	pp. 129-169. Springer Netherlands	(link)https://doi.org/10.1007/978-94-017-9508-1_5
Root, H. T., Geiser, L. H., Jovan, S., and Neitlich, P.	2015	Epiphytic macrolichen indication of air quality and climate in interior forested mountains of the Pacific Northwest, USA	Ecological Indicators	53, 95-105	doi:10.1016/j.ecolind.2015.01.029
Will-Wolf, S., Jovan, S., Neitlich, P., Peck, J. E., & Rosentreter, R.	2015	Lichen-based indices to quantify responses to climate and air pollution across northeastern USA	The Bryologist	118(1), 59-82	doi:10.1639/0007-2745-118.1.059
Zhou, Q., Driscoll, C.T., Moore, S.E., Kulp, M.A., Renfro, J.R., Schwartz, J.S., Cai, M., and J. A. Lynch	2015	Developing critical loads of nitrate and sulfate deposition to watersheds of the Great Smoky Mountains National Park, USA	Water Air and Soil Pollution	226:255	doi:10.1007/s11270-015-2502-7
Allen, E.B., Egerton-Warburton, L.M., Hilbig, B.E., and J.M. Valliere.	2016	Interactions of arbuscular mycorrhizal fungi, critical loads of nitrogen deposition, and shifts from native to invasive species in a southern California shrubland	Botany	94: 425–433	doi:10.1139/cjb-2015-0266
Baldigo, B.P., Roy, K.M., and C.T. Driscoll.	2016	Response of fish assemblages to declining acidic deposition in Adirondack Mountain lakes, 1984-2012	Atmospheric Environment	146: 223-235	doi:10.1016/j.atmosenv.2016.06.049
Beier, C.M., Caputo, J., Lawrence, G.B., and T.J. Sullivan.	2016	Loss of ecosystem services due to chronic pollution of forests and surface waters in the Adirondack region (USA)	Journal of Environmental Management		doi:10.1016/j.jenvman.2016.12.069
Bingham, A.H. and M. F. Cotrufob.	2016	Organic nitrogen storage in mineral soil: Implications for policy and management	Science of The Total Environment	551–552: 116–126	doi:10.1016/j.scitotenv.2016.02.020
Bytnerowicz, A., Fenn, M., Allen, E.B., and Cisneros, R.	2016	Atmospheric Chemistry, pp. 107-128, In H. Mooney and E. Zavaleta (Eds.)	Ecosystems of California-A Sourcebook	University of California Press. Berkeley, California	(link)
Caporn, S., Field, C., Payne, R., Dise, N., Britton, A., Emmett, B., Jones, L. Phoenix, G., Power, S., Sheppard, L., and Stevens, C.	2016	Assessing the effects of small increments of atmospheric nitrogen deposition (above the critical load) on seminatural habitats of conservation importance	Natural England Commissioned Reports, Number 210.		(link)
Caputo, J., Beier, C.M., Sullivan, T.J., and G.B. Lawrence.	2016	Modeled effects of soil acidification on long-term ecological and economic outcomes for managed forests in the Adirondack region (USA)	Science of the Total Environment	565: 401-411	doi:10.1016/j.scitotenv.2016.04.008
Cathcart, H., Aherne, J., Jeffries, D.S., and K.A. Scott.	2016	Critical loads of acidity for 90,000 lakes in northern Saskatchewan: A novel approach for mapping regional sensitivity to acidic deposition	Atmospheric Environment	146: 290-299	doi:10.1016/j.atmosenv.2016.08.048
DeWalle, D.R., Boyer, E.W., and A.R. Buda.	2016	Exploring lag times between monthly atmospheric deposition and stream chemistry in Appalachian forest using cross-correlation	Atmospheric Environment	146: 206-214	doi:10.1016/j.atmosenv.2016.09.015
Dibble, A.C., Hinds, J.W., Perron, R., Cleavitt, N., Poirot, R.L., and L.H. Pardo.	2016	Monitoring air quality in class I wilderness areas of the northeastern United States using lichens and bryophytes	Gen. Tech. Rep. NRS-165. Newtown Square, PA: U.S. Department of Agriculture, Forest Service, Northern Research Station	44 p.	https://doi.org/10.2737/NRS-GTR-165
Engel, B.J., Schaberg, P.G., Hawley, G.J., Rayback, S.A., Pontius, J., Kosiba, A.M., and E.K. Miller.	2016	Assessing relationships between red spruce radial growth and pollution critical load exceedance values	Forest Ecology and Management	359: 83–91	doi:10.1016/j.foreco.2015.09.029
Fakhraei, H., Driscoll, C.T., Renfro, J.R., Kulp, M.A., Blett, T.F., Brewer, P.F., and J.S. Schwartz.	2016	Critical loads and exceedances for nitrogen and sulfur atmospheric deposition in Great Smoky Mountains National Park, United States	Ecosphere	7(10):e01466	doi:10.1002/ecs2.1466
Heard, A. M., and J. O. Sickman.	2016	Nitrogen assessment points: development and application to high-elevation lakes in the Sierra Nevada, California	Ecosphere	7(11):e01586. 10.1002/ecs2.1586	doi:10.1002/ecs2.1586
Hernandez, D.L., Vallano, D.M., Zavaleta, E.S., Tzankova, Z., Pasari, J.R., Weiss, S., Selmants, P.C., and C. Morozumi.	2016	Nitrogen pollution is linked to US listed species declines	BioScience	66: 213–222	doi:10.1093/biosci/biw003
Kenkel, J.A., Sisk, T.D., Hultine, K.R., Sesnie, S.E., Bowker, M.A. and N.C. Johnson	2016	Indicators of vehicular emission inputs into semi-arid roadside ecosystems	Journal of Arid Environments	134: 150-159	doi:10.1016/j.jaridenv.2016.06.007
Morrison, E.W., Frey, S.D., Sadowsky, J.J., van Diepen, L.T.A., Thomas, W.K., and A. Pringle.	2016	Chronic nitrogen additions fundamentally restructure the soil fungal community in a temperate forest	Fungal Ecology	23: 48-57	doi:10.1016/j.funeco.2016.05.011
Phelan, J., S. Belyazid, P. Jones, J. Cajka, J. Buckley, and C. Clark.	2016	Assessing the Effects of Climate Change and Air Pollution on Soil Properties and Plant Diversity in Sugar Maple–Beech–Yellow Birch Hardwood Forests in the Northeastern United States: Model Simulations from 1900 to 2100	Water, Air & Soil Pollution	227(3): 1-30	doi:10.1007/s11270-016-2762-x
Simkin, S.M., E.B. Allen, W.D. Bowman, C.M. Clark, J. Belnap, M.L. Brooks, B.S. Cade, S.L. Collins, L.H. Geiser, F.S. Gilliam, S.E. Jovan, L.H. Pardo, B.K Schulz, C.J. Stevens, K.N. Suding, H.L. Throop, and D.M. Waller.	2016	Conditional vulnerability of plant diversity to atmospheric nitrogen deposition across the United States	Proceedings of the National Academy of Sciences of the United States of America, online in advance of print		doi:10.1073/pnas.1515241113
Stevens, C.J.	2016	How long do ecosystems take to recover from atmospheric nitrogen deposition?	Biological Conservation	200: 160–167	doi:10.1016/j.biocon.2016.06.005
Valliere, J.M., and E.B. Allen.	2016	Interactive effects of nitrogen deposition and drought-stress on plant-soil feedbacks of Artemisia californica seedlings	Plant and Soil	403: 277-290	doi:10.1007/s11104-015-2776-y
Valliere, J.M., and E.B. Allen.	2016	Nitrogen enrichment contributes to positive responses to soil microbial communities in three invasive plant species	Biological Invasions: 1-16		doi:10.1007/s10530-016-1166-6
Whitfield, C.J., Mowat, A.C., Scott, K.A., and S.A. Watmough.	2016	A modified approach for estimating the aquatic critical load of acid deposition in northern Saskatchewan, Canada	Atmospheric Environment	146: 300-310	doi:10.1016/j.atmosenv.2016.05.025
Wilkins, K., Aherne, J., and A. Bleasdale.	2016	Vegetation community change points suggest that critical loads of nutrient nitrogen may be too high	Atmospheric Environment	146: 324-331	doi:10.1016/j.atmosenv.2016.07.016
Williams, J.J., M. Beutel, A. Nurse, B. Moore, S.E. Hampton, J.E. Saros.	2016	Phytoplankton responses to nitrogen enrichment in Pacific Northwest, USA Mountain Lakes	Hydrobiologia	pp. 1-16	doi:10.1007/s10750-016-2758-y
Williston, P., Aherne, J., Watmough, S., Marmorek, D., Hall, A., de la Cueva Bueno, P., Murray, C., Henolson, A., and J.A. Laurence.	2016	Critical levels and loads and the regulation of industrial emissions in northwest British Columbia, Canada	Atmospheric Environment	146: 311-323	doi:10.1016/j.atmosenv.2016.08.058
Bell, M.D., Phelan, J., Blett, T.F., Landers, D., Nahlik, A.M., Van Houtven, G., Davis, C., Clark, C.M., and J. Hewitt	2017	A framework to quantify the strength of ecological links between an environmental stressor and final ecosystem services	Ecosphere	8(5):e01806
Clark, C.M., Bell, M.D., Boyd, J.W., Compton, J.E., Davidson, E.A., Davis, C., Fenn, M.E., Geiser, L., Jones, L., and T.F. Blett	2017	Nitrogen-induced terrestrial eutrophication: cascading effects and impacts on ecosystem services	Ecosphere	8(7):e01877	doi:10.1002/ecs2.1877
Crowley, K.F., and G.M. Lovett	2017	Effects of nitrogen deposition on nitrate leaching from forests of the northeastern United States will change with tree species composition	Canadian Journal of Forest Research	47(8): 997-1009	doi:10.1139/cjfr-2016-0529
Fakhraei, H., Driscoll, C.T., Kulp, M.A., Renfro, J.R., Blett, T.F., Brewer, P.F., and J.S. Schwartz	2017	Sensitivity and uncertainty analysis of PnET-BGC to inform the development of Total Maximum Daily Loads (TMDLs) of acidity in the Great Smoky Mountains National Park	Environmental Modelling & Software	95: 156-167	doi:10.1016/j.envsoft.2017.06.013
Irvine, I.C., Greaver, T., Phelan, J., Sabo, R.D., and G. Van Houtven	2017	Terrestrial acidification and ecosystem services: effects of acid rain on bunnies, baseball, and Christmas trees.	Ecosphere	8(6):e01857	doi:10.1002/ecs2.1857
Lawrence, G.B., T.C. McDonnell, T.J. Sullivan, M. Dovciak, S.W. Bailey, M.R. Antidormi, and M.R. Zarfos	2017	Soil base saturation combines with beech bark disease to influence composition and structure of sugar maple-beech forests in an acid rain-impacted region	Ecosystems	191:19-27	10.1007/s10021-017-0186-0
Lawrence, G.B., T.J. Sullivan, T.C. McDonnell, M. Dovciak, S.W. Bailey, M.R. Antidormi, and M.R. Zarfos	2017	Soil Acidification and Beech Bark Disease: Influencing the Composition and Structure of Sugar Maple/Beech Forests	Summary Report 17-26 prepared for the New York State Energy Research and Development Authority. E&S Environmental Chemistry, Inc., Corvallis, OR		(link)
Nanus, L., McMurray, J.A., Clow, D.W., Saros, J.E., Blett, T., and J.J. Gurdak	2017	Spatial variation of atmospheric nitrogen deposition and critical loads for aquatic ecosystems in the Greater Yellowstone Area	Environmental Pollution	223: 644-656	doi:10.1016/j.envpol.2017.01.077
O'Dea, C.B., Anderson, S., Sullivan, T., Landers, D., and C.F. Casey	2017	Impacts to ecosystem services from aquatic acidification: using FEGS-CS to understand the impacts of air pollution	Ecosphere	8(5):e01807	doi:10.1002/ecs2.1807
Rhodes, C., Bingham, A., Heard, A.M., Hewitt, J., Lynch, J., Waite, R., and M.D. Bell	2017	Diatoms to human uses: linking nitrogen deposition, aquatic eutrophication, and ecosystem services	Ecosphere	8(7):e01858	doi:10.1002/ecs2.1858
Robin-Abbott, M.J., and L.H. Pardo	2017	How Climatic Conditions, Site, and Soil Characteristics Affect Tree Growth and Critical Loads of Nitrogen for Northeastern Tree Species	Gen. Tech. Rep. NRS-172. Newtown Square, PA: U.S. Department of Agriculture, Forest Service, Northern Research Station	143 p.	(link)
Sullivan, T.J	2017	Air Pollution and its Impacts on U.S. National Parks	CRC Press	680 pp.	(link)
Sullivan, T.J., T.C. McDonnell, G.B. Lawrence, M. Dovciak, and M.R. Zarfos	2017	Acidification and Forest Understory Plant Communities in the Adirondack Mountains	Summary Report. 17-27. New York State Energy Research and Development Authority, Albany, NY.		(link)
Valliere, J.M., Irvine, I.C., Santiago, L., and E.B. Allen	2017	High N, dry: experimental nitrogen deposition exacerbates native shrub loss and non native plant invasion during extreme drought	Global Change Biology		doi:10.1111/gcb.13694
Williams, J.J., Chung, S.H., Johansen, A.M., Lamb, B.K., Vaughan, J.K., and M. Beutel	2017	Evaluation of atmospheric nitrogen deposition model performance in the context of U.S. critical load assessments	Atmospheric Environment	150: 244-255	doi:10.1016/j.atmosenv.2016.11.051
Williams, J., and S.G. Labou	2017	A database of georeferenced nutrient chemistry data for mountain lakes of the Western United States	Scientific Data		doi:10.1038/sdata.2017.69
Williams, J. J., J. A. Lynch, J. E. Saros, and S. G. Labou	2017	Critical loads of atmospheric N deposition for phytoplankton nutrient limitation shifts in western U.S. mountain lakes	Ecosphere	8(10):e01955	doi:10.1002/ecs2.1955
Clark, C.M., Phelan, J., Doraiswamy, P., Buckley, J., Cajka, J.C., Dennis, R.L.,Lynch, J., Nolte, G.N., & Spero, T.L	2018	Atmospheric deposition and exceedances of critical loads from 1800-2025 for the conterminous United States	Ecological Applications	28(4), 2018, pp. 978–1002	doi:10.1002/eap.1703
Fenn, M.E, Bytnerowicz, A, Schilling, S.L., Vallanob, D.M., Zavaleta, E.S., Weiss, S.E., Morozumi, C., Geiser, H.G., and Hanks, K	2018	On-road emissions of ammonia: An underappreciated source of atmospheric nitrogen deposition	Science of the Total Environment	625 (2018) 909–919	doi:10.1016/j.scitotenv.2017.12.313
Horn, K. J., Thomas, R. Q., Clark, C. M., Pardo, L. H., Fenn, M. E., Lawrence, G. B., ... Watmough, S.	2018	Growth and survival relationships of 71 tree species with nitrogen and sulfur deposition across theconterminous U.S.	PLoS One	13(10)	10.1371/journal.pone.0205296
McDonnell, T.C., S. Belyazid, T.J. Sullivan, M. Bell, C. Clark, T. Blett, T. Evans, W. Cass, A. Hyduke, and H. Sverdrup	2018	Vegetation dynamics associated with changes in atmospheric nitrogen deposition and climate in hardwood forests of Shenandoah and Great Smoky Mountains national parks, USA	Environmental Pollution	237:662-674	doi:10.1016/j.envpol.2018.01.112
McDonnell, T.C., Reinds, G.J., Sullivan, T.J., Clark, C.M., Bonten, L.T.C., Mol-Dijkstra, J.P., Wamelink, G.W.W., and M. Dovciak	2018	Feasibility of coupled empirical and dynamic modeling to assess climate change and air pollution impacts on temperate forest vegetation of the eastern United States	Environmental Pollution	234: 902-914	doi:10.1016/j.envpol.2017.12.002
McDonnell, T.C., T.J. Sullivan, and C.M. Beier	2018	Influence of climate on long-term recovery of Adirondack Mountain lakewater chemistry from atmospheric deposition of sulfur and nitrogen. Adirondack Journal of Environmental Studies	22:20-45		(link)
McDonnell, T.C., W.A. Jackson, B.J. Cosby, and T.J. Sullivan	2018	Atmospheric Deposition Effects Modeling for Resource Management on Southern Appalachian National Forests	Report prepared for USDA Forest Service, Asheville, NC. E&S Environmental Chemistry, Inc., Corvallis, OR.		(link)
Pardo, Linda H.; Duarte, Natasha; Van Miegroet, Helga; Fisher, L. Suzanne; Robin-Abbott, Molly J	2018	Critical loads of sulfur and nitrogen and modeled effects of deposition reduction for forested ecosystems of Great Smoky Mountains National Park	Gen. Tech. Rep. NRS-180. Newtown Square, PA: U.S. Department of Agriculture, Forest Service, Northern Research Station	26 p.	doi:10.2737/NRS-GTR-180
Sullivan, T.J., M.R. Zarfos, M. Dovciak, T.C. McDonnell, and G.B. Lawrence	2018	Effects of Acid Deposition on the Biodiversity of Forest Understory Plant Communities in the Northern Hardwood Forests of the Adirondack Mountain Region	Final Technical Report 18-17. New York State Energy Research and Development Authority (NYSERDA), Albany, NY.		(link)
Whitfield, C.J., Phelan, J.N., Buckley J., Clark, C.M., Guthrie, S, & Lynch, JA	2018	Estimating Base Cation Weathering Rates in the USA: Challenges of Uncertain Soil Mineralogy and Specific Surface Area with Applications of the PROFILE Model	Water Air Soil Pollution (2018)	229:61	doi:10.1007/s11270-018-3691-7
Belyazid, S., Phelan, J., Nihlgard, B., Sverdrup, H., Driscoll, C., Fernandez, I., ... Clark, C.	2019	Assessing the effects of climate change and air pollution on soil properties and plant diversity in northeastern US hardwood forests: Model setup and evaluation	Water Air and Soil Pollution	230(5), [106]	doi:10.1007/s11270-019-4145-6
Clark, C. M., Richkus, J., Jones, P. W., Phelan, J., Burns, D. A., de Vries, W., ... Watmough, S. A.	2019	A synthesis of ecosystem management strategies for forests in the face of chronic nitrogen deposition	Environmental Pollution	248, 1046–1058	doi:10.1016/j.envpol.2019.02.006
Clark, C. M., S. M. Simkin, E. B. Allen, W. D. Bowman, J. Belnap, M. L. Brooks, S. L. Collins, L. H. Geiser, F.S. Gilliam, S. E. Jovan, L. H. Pardo, B. K. Schulz, C. J. Stevens, K. N. Suding, H. L. Throop, and D. M. Waller	2019	Potential vulnerability of 348 herbaceous species to atmospheric deposition of nitrogen and sulfur in the United States	Nature Plants	5:697-705	doi:10.1038/s41477-019-0442-8
Geiser, L. H., P. R. Nelson, S. E. Jovan, H. T. Root, and C. M. Clark	2019	Assessing Ecological Risks from Atmospheric Deposition of Nitrogen and Sulfur to US Forests Using Epiphytic Macrolichens	Diversity	0.51875	doi:10.3390/d11060087
McDonnell, T.C., J. Aherne, T.J. Sullivan, C. Barton, C. Cotton, and B. Jackson	2019	Variation in Forest Soil-Nutrient Availability: Dynamic Model Estimates of Past and Future Conditions at Two Sites in the Daniel Boone National Forest, Kentucky, USA	Report Prepared for USDA Forest Service	E&S Environmental Chemistry, Inc., Corvallis, OR.	(link)
McDonnell, T.C., T.J. Sullivan, and D.L. Moore	2019	Critical Loads of Atmospheric Nitrogen and Sulfur Deposition for Protection of Sensitive Aquatic and Terrestrial Resources in the Intermountain Region of the USDA Forest Service	Report Prepared for the USDA Forest Service. E&S Environmental Chemistry, Inc., Corvallis, OR.		(link)
Pardo, L. H., J. A. Coombs, M. J. Robin-Abbott, J. H. Pontius, and A. W. D'Amato	2019	Tree species at risk from nitrogen deposition in the northeastern United States: A geospatial analysis of effects of multiple stressors using exceedance of critical loads	Forest Ecology and Management	454:117528	doi:10.1016/j.foreco.2019.117528
Sickman, J. O., A. E. James, M. E. Fenn, A. Bytnerowicz, D. M. Lucero, and P. M. Homyak	2019	Quantifying atmospheric N deposition in dryland ecosystems: A test of the Integrated Total Nitrogen Input (ITNI) method	Science of the Total Environment 646:1253-1264		doi:10.1016/j.scitotenv.2018.07.320
Simpson, A. C., D. Zabowski, R. M. Rochefort, and R. L. Edmonds	2019	Increased microbial uptake and plant nitrogen availability in response to simulated nitrogen deposition in alpine meadows	Geoderma	336:68-80	doi:10.1016/j.geoderma.2018.08.029
Symstad, A. J., A. T. Smith, W. E. Newton, and A. K. Knapp	2019	Experimentally derived nitrogen critical loads for northern Great Plains vegetation	Ecological Applications	29:e01915	doi:10.1002/eap.1915
Templer, T. Thompson, D. Tong, G. A. Wetherbee, T. H. Whitlow, Z. Wu, Z. Yu, and L. Zhang	2019	Toward the improvement of total nitrogen deposition budgets in the United States	Science of the Total Environment	691:1328-1352	doi:10.1016/j.scitotenv.2019.07.058
Van Houtven, G., Phelan, J., Clark, C., Sabo, R., Buckley, J. J., Thomas, Q., ... LeDuc, S	2019	Nitrogen deposition and climate change effects on tree species composition and ecosystem services for a forest cohort	Ecological Monographs		doi:10.1002/ecm.1345
Walker, J. T., M. D. Bell, D. Schwede, A. Cole, G. Beachley, G. Lear, and Z. Wu	2019	Aspects of uncertainty in total reactive nitrogen deposition estimates for North American critical load applications	Science of the Total Environment	690:1005-1018	doi:10.1016/j.scitotenv.2019.06.337
Walker JT, Beachley G, Amos HM, Baron JS, Bash J, Baumgardner R, Bell MD, Benedict KB, Chen X, Clow DW, Cole A, Coughlin JG, Cruz K, Daly RW, Decina SM, Elliott EM, Fenn ME, Ganzeveld L, Gebhart K, Isil SS, Kerschner BM, Larson RS, Lavery T, Lear GG, Macy T, Mast MA, Mishoe K, Morris KH, Padgett PE, Pouyat RV, Puchalski M, Pye HOT, Rea AW, Rhodes MF, Rogers CM, Saylor R, Scheffe R, Schichtel BA, Schwede DB, Sexstone GA, Sive BC, Sosa Echeverría R, Templer PH, Thompson T, Tong D, Wetherbee GA, Whitlow TH, Wu Z, Yu Z, Zhang L.	2019	Toward the improvement of total nitrogen deposition budgets in the United States	Science of The Total Environment	2019 Nov 15;691:1328-1352	doi:10.1016/j.scitotenv.2019.07.058.
Wieder, R.K., Vitt, D.H., Vile, M.A., Graham, J.A., Hartsock, J.A., Fillingim, H., House, M., Quinn, J.C., Scott, K.D., Petix, M. and McMillen, K.J.	2019	Experimental nitrogen addition alters structure and function of a boreal bog: critical load and thresholds revealed	Ecological Monographs	89(3), p.e01371	doi:10.1002/ecm.1371
Zarfos, M.R., M. Dovciak, G.B. Lawrence, T.C. McDonnell, and T.J. Sullivan	2019	Plant richness and composition in hardwood forest understories vary along an acidic deposition and soil-chemical gradient in the northeastern United States	Plant Soil		doi:10.1007/s11104-019-04031-y
Driscoll, C.T., T.J. Sullivan, B.P. Baldigo, D.A. Burns. S. Shao. T.C. McDonnell, and G.B. Lawrence	2020	The Response of Streams to Changes in Atmospheric Deposition of Sulfur and Nitrogen in the Adirondack Mountains	Report 20-19, New York State Energy Research and Development Authority, Albany, NY		(link)
McDonnell, T.C., T.J. Sullivan, B. Knees, M. Bell, and E. Felker-Quinn	2020	Intermodel Comparison of Atmospheric Nitrogen Deposition Estimates for the Conterminous United States and Critical Load Exceedance for Selected National Parks	NPS/NRSS/ARD/NRR—2020/2125. National Park Service, Fort Collins, Colorado		(link)
McDonnell, T.C., Reinds, G.J., Wamelink, G.W.W., Goedhart, P.W., Posch, M., Sullivan, T.J., and C.M. Clark	2020	Threshold effects of air pollution and climate change on understory plant communities at forested sites in the eastern United States	Environmental Pollution	262: 114351	doi:10.1016/j.envpol.2020.114351
Shao, S., C.T. Driscoll, T.J. Sullivan, D.A. Burns, B.P. Baldigo, G.B. Lawrence, and T.C. McDonnell	2020	The response of stream ecosystems in the Adirondack region of New York to historical and future changes in atmospheric deposition of sulfur and nitrogen	Science of The Total Environment		doi:10.1016/j.scitotenv.2020.137113
Wieder, R.K., Vitt, D.H., Vile, M.A., Graham, J.A., Hartsock, J.A., Popma, J.M., Fillingim, H., House, M., Quinn, J.C., Scott, K.D. and Petix, M.	2020	Experimental nitrogen addition alters structure and function of a boreal poor fen: Implications for critical loads	Science of The Total Environment	p.138619	doi:10.1016/j.scitotenv.2020.138619
Baron, J.S., H.M Rueth, A.M. Wolfe, K.R. Nydick, E.J. Allstott, J. T. Minear, and B. Moraska	2020	Ecosystem responses to nitrogen deposition in the Colorado Front Range	Ecosystems	3: 352-368	doi:10.1007/s100210000032

Documents from other continents are also included if they present information on methods or critical load concepts that are broadly applicable to North America.

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References are listed by publication year.