jill baron u.s. geological survey colorado state university fort collins co ecosystem responses to...
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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)
Niwot Saddle (p=0.01)Sunlight Peak (p=0.16)
Brooklyn Lake (p=0.21)Snowy Range (p=0.97)
+
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)
Niwot Saddle (p=0.03)Sunlight Peak (p=0.0009)
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)
Brooklyn Lake (p=0.01)Snowy Range (p=0.002)
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
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
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
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