jill baron u.s. geological survey colorado state university fort collins co ecosystem responses to...

Jill BaronU.S. Geological Survey

Colorado State UniversityFort Collins CO

Ecosystem Responses to

Nitrogen Depositionin the

Western United States

Conversion to NO3 and NH4

NOx

NH3

Against Prevailing Winds

Fertilizers

NITRATE

AMMONIUM SULFATE

TRENDS IN WET PRECIPITATION

CONCENTRATION1983-1994

(LYNCH et al. 1996)

Change is in concentrationNilles and Conley 2001

Nilles, M.A. and B.E. Conley 2001,Wat. Air Soil Pollut. 130:409-414.

Trends of NH4-N Concentration in Precipitation

1.00

1.40

1.80

2.20

2.60

3.00(l

og

) u

eq

/l

19841985

1986

1987

1988

1989

1990

1991

1992

1993

1994

1995

1996

1997

1998

Loch Vale (p=0.003)

Niwot Saddle (p=0.001)Sunlight Peak (p=0.89)

Brooklyn Lake (p=0.04)Snowy Range (p=0.02)

+++o

-

Trends of NO3-N Concentration in Precipitation

(log

) u

eq

/l

1.00

1.40

1.80

2.20

2.60

3.00

19841985

19861987

1988

19891990

1991

1992

1993

1994

1995

19961997

1998

Loch Vale (p=0.68)



+

oooo

Trends of H Concentration in Precipitation

0

0.5

1

1.5

2

2.5

1984

1985

19861987

19881989

1990

1991

1992

1993

1994

1995

1996

1997

1998

(log

) u

eq

/l

Loch Vale (p=0.0005)


Brooklyn Lake (p=0.20)Snowy Range (p<0.001)

+++o+

Trends of SO4 Concentration in Precipitation

1

1.5

2

2.5

3

19841985

1986

1987

1988

1989

1990

1991

1992

1993

1994

1995

1996

1997

1998

Loch Vale (p<0.0001)

Niwot Saddle (p=0.47)Sunlight Peak (p<0.0001)


o

--

(log

) u

eq

/l

--

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TOTAL NITROGEN (kg/ha) at NADP SITES - 1998

Western StatesNADP SitesÑ

TOTAL NITROGEN (KG/HA)

4.652 - 4.956

4.043 - 4.652

3.739 - 4.043

3.13 - 3.739

2.825 - 3.13

2.521 - 2.825

1.912 - 2.521

1.303 - 1.912

0.39 - 1.303

Ñ

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NITRATE (kg/ha) at NADP SITES - 1998

Western StatesNADP SitesÑ

NITRATE (kg/ha)

12.84 - 13.692

11.136 - 12.84

10.284 - 11.136

8.579 - 10.284

7.727 - 8.579

6.875 - 7.727

5.171 - 6.875

2.615 - 5.171

0.91 - 2.615

(a) (b)

(c)

NHx-N NOy-N

Total N

Simulated annual N deposition for 1996 using

Models-3/Community Multiscale Air Quality Model

(CMAQ)(36 km resolution)(from Fenn et al. 2003)

Housing density 2000

WELD

JEFFERSON

DENVER

ADAMS

MORGAN

Total South Platte N emissions, Mg

0

5,000

10,000

15,000

20,000

25,000

30,000

1985

1995

NOxElect.+Ind

NOxHighway

NOxOff Road

NOxAgriculture NH3

Crops

NH3

Livestock

WHAT ARE THE ECOSYSTEMEFFECTS OF NITROGEN DEPOSITION?

N Deposition

FertilizationLoss of Soil Base Cations

Changes in Aquatic Species

LakeEutrophication

Loss of Lake ANC(acidification)

Pathways and Effects of Excess Nitrogen Pathways and Effects of Excess Nitrogen DepositionDeposition

N SaturationChanges in

Plant Communities

Figure 1

Coastal Sage Scrub Communities of Southern California

Nitrogen Deposition linked to:

-Decrease in symbiotic soil fungi (mycorrhizae) that enable native shrubs to get nutrients-Endangerment of native butterflies and up to 200 sensitive plant species-Increase in non-native annual grasses-Increase in fire frequency

(work by Edith Allen and colleagues,UC Riverside)

San Bernardino Mountains, California

-Up to 90 kg N/ha/yr at some sites-Ozone and N interact: a) cancel each other out for aboveground processes, b) combine to dramatically reduce root biomass and growth c) increased risk of severe fire d) nitrate in some streams exceed drinking water standards

Fenn, Bytnerowicz,et al., USDA Forest Service

Weedy, nitrogen-lovingpollution indicators

Xanthoria polycaropa

Physcia adscendensPollution sensitive species

Alectoria sarmentosa

Lobaria oregana

Loss of sensitivelichen species in Columbia River Gorge,Willamette Valley, San Bernardinos.

Replacement species show high tissue N

Described in Fenn et al. 2003

0

1

2

3

4

5

6

Min

eralizati

on

Rate

(u

g N

/g/d

)

0.8 0.9 1 1.1 1.2 1.3 1.4 1.5 1.6Organic Soil %N

FC-W

BR-WBC-WWR-W

WA-W

LL-E

BP-E

MP-E

ER-E

GF-W

LV-EML-E

%N min

R2=0.62

Mineralization Rate vs. Organic Horizon %N

0

0.4

0.8

1.2

1.6

1 1.5 2 2.5

%N Forest Floor

Nit

rifi

ca

tio

n u

gN

/g/d

New England, USAMcNulty et al. 1991

Colorado Front Range Baron et al. 2000Rueth & Baron 2001

Sites with measurablenitrification

Fertilization studies in low and high N dep’n standssuggest a trajectory for future change

• Between 100-160 kg N ha-1 initiates biogeochemical changes

• Within the 2nd year of fertilization we observed significant changes at Loch Vale

Soil waters in fertilized plots show high NO3, NH4,also high levels of Ca, Mg, K.

Leaching of cations is a step toward acidification.

N deposition:increased soil %N, lowered C:N ratios,

increased microbial N cycling

N Deposition



LakeEutrophication




Plant Communities

EVW NO3

$T$T

$T

$T

$T

$T

$T

$T

$T

$T

$T

$T

$T

$T$T

$T

$T

$T$T

$T

$T

$T$T

$T

$T

$T

$T

$T

$T

$T

$T

$T$T

$T

$T

$T

$T

$T

$T

$T

$T

$T

$T$T

$T

$T

$T

$TNO3 (ueq / l)$T 0 - 3.99$T 4 - 6.99$T 7 - 9.99$T 10 - 15.99$T 16 - 21

Rocky Mtn Nat Park

Indian Peaks Wilderness

Means: East 10.5 (5.0) West 6.6 (4.3)

p = 0.02

Continental Divide

Loch Outlet NO3

0

0.5

1

1.5

2

2.5

10/2

/90

10/2

/91

10/2

/92

10/2

/93

10/2

/94

10/2

/95

10/2

/96

10/2

/97

10/2

/98

10/2

/99

10/2

/00

mg

/L

Loch Outlet Alkalinity

0

20

40

60

80

100

120

140

16010

/2/9

0

10/2

/91

10/2

/92

10/2

/93

10/2

/94

10/2

/95

10/2

/96

10/2

/97

10/2

/98

10/2

/99

10/2

/00

ueq

/L

Annual dynamics,but no long-term trends are evidentfor alkalinity (ANC)

Nitrate dynamicsare biannual, but

do not show long-term trends

Asterionella formosa

Fragilaria crotonensis

Sky Pond

Lake Louise

0

4

8

12

16

20

8/22 8/29 9/5

mg/m

3

0

200

400

600

800

1000

8/21 8/29 9/5

mg

C/m

3/h

Chl-a

Productivity

Analyzing Taxonomic Data…

-0.5

0

0.5

1

1.5

2

2.5

1 2 3Week of Experiment

Cdt

La C N P NP

Gre

en A

lgae

Ch

ryso

ph

ytes

Phytoplankton Results(PRC)

WLS NO3

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NO3 (ueq / l)$ 0 - 3.99$ 4 - 6.99$ 7 - 9.99$ 10 - 15.99$ 16 - 44

Mean = 1.66 Std dev = 3.59 Range = 0 - 43.05

WLS NO3 hotspotsNO3 (ueq / l)

$ 4 - 6.99$ 7 - 9.99$ 10 - 15.99$ 16 - 44

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Salt Lake City

Los Angeles

San Francisco

Seattle

N&P lim

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Nutrient Limitation$ N$ P

17%22%

(N&P 61%)

Nutrient limitationpredicted by DIN:TP ratio

+ PEutrophication, not acidification

• Low NO3

• N limitation (17%)

• In-lake ANC production from algal NO3 assimilation

• High NO3

• P limitation

• In-lake ANC production from denitrification (less efficient)

Eutrophication Acidification

Increased N and acid deposition

Summary for Aquatic Ecosystems

-High N deposition => high [NO3] lakes-Primary productivity in high N lakes

not limited by N-Substantial species change with N deposition-Increased N deposition => acidification?

N Deposition



LakeEutrophication




Plant Communities

jill baron u.s. geological survey colorado state university fort collins co ecosystem responses to...

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