Complex Patterns in Climate and
Atmospheric Nitrogen Deposition
Influence Rocky Mountain
Ecosystems
J.S.Baron, T.A.Schmidt, M.D. Hartman,
S.A. Enders, M Pagani,
A.P. Wolfe, A.Krcmarik
Western Mountain
Initiative
Loch Vale Watershed
Rocky Mountain National Park
Loch Vale is 660 ha
•80% rock/talus
•1% permanent ice
•11% alpine
•6% old growth forest
•1% wetlands
•1% lakes
Excess N in Surface Water
LOCH OUTLET NO3
• Nitrogen in
LVWS surface
waters elevated
since ~1950
4.5
4
3.5
3
Stream NO3
mg/L
2.5
2
1.5
1
0.5
Average annual stream
NO3 mg/l and flux kgN/yr
0
• [NO3] and N flux
increase post2001
82
86
90
94
98
02
4
3
Flux, kg N
2
1
0
Conc, mg NO3
90 92 94 96 98 00 02 04 06
06
Loch Outlet N Dynamics 1991-2006
2006
2004
2004
2002
mg/L
2000
0.5
1.0
1.5
2.0
2.5
3.0
3.5
1998
1996
1994
1992
Water years
Water years
Stream NO3
2006
Stream N Flux
2002
2000
kg/ha
1998
1996
0.00
0.25
0.50
0.75
1994
1992
Se
p
ay
l
Ju
M
ec
ct
p
b
Fe
D
O
Se
ay
l
Ju
M
ec
ct
b
Fe
D
O
•Stream NO3 concentrations increase after 2001
•NO3 elevated nearly year-round
•N flux increasing over time, strong losses 2003-2005
•N flux elevated late May-August
Precipitation: Wet and Dry Cycles
L o c h O u tle t W Y P r e c ip ita tio n (c m )
160
140
120
100
80
60
40
1980
1985
1990
1995
2000
2005
2010
160
Precipitation
cm/yr
140
120
100
80
60
Discharge
40
10
05
00
95
90
85
80
Temperature is also Changing
3.0
2.5
Mean Temp.
˚C
1985
2006 Trend
Annual
1.25
1.60 +0.3
Summer (JJA)
10.75
11.95 +1.0
Winter (DJF)
-7.00
-7.45 -0.5
Annual ˚C
2.0
1.5
1.0
0.5
0.0
80 85 90 95 00 05 10
14.0
13.5
13.0
12.5
12.0
11.5
11.0
10.5
10.0
9.5
9.0
JJA ˚C
80 85 90 95 00 05 10
-5.0
-5.5
-6.0
-6.5
-7.0
-7.5
-8.0
-8.5
-9.0
DJF ˚C
80 85 90 95 00 05 10
Proxies in Sky Pond sediments record post-1950
ecological and biogeochemical change
Enders et al., in review
Poster B31A-0062
Wednesday AM (now!)
Proxies in Sky Pond sediments record post-1950
ecological and biogeochemical change
15N
trend in algal chlorins
supports change in
N deposition/N cycling
beginning ~1950
Proxies in Sky Pond sediments record post-1950
ecological and biogeochemical change
δD and δ13CnC21 trends infer
changes in hydrology of
of glaciers/permafrost
and the biology/abundance
of lichens or cyanobacteria
Weekly NPP, kg C/ha
DayCent-Chem model output
Loch Vale Forest
2005
2005
2000
2000
1995
0
100
200
300
400
1990
Water years
Water years
Loch Vale Alpine
1995
0
100
200
300
400
1990
1985
1985
3
p2
Se
4
l1
Ju
6
ay
M
5
b2
Fe
16
ec
D
7
ct
O
3
p2
Se
4
l1
Ju
6
ay
M
5
b2
Fe
16
ec
D
7
ct
O
Weekly Mineralization, kg N/ha
DayCent-Chem model output
Loch Vale Forest
2005
2005
2000
2000
1995
0
1
2
3
4
5
1990
1985
Water years
Water years
Loch Vale Alpine
1995
0
1
2
3
4
5
1990
1985
3
p2
Se
4
l1
Ju
6
ay
M
5
b2
Fe
16
ec
D
7
ct
O
3
p2
Se
4
l1
Ju
6
ay
M
5
b2
Fe
6
c1
De
7
ct
O
What’s Changing/What’s Not
Stream [NO3]
Stream N Flux
Temperature (mean, summer)
Flow:Precipitation
Lichen, Cyanobacteria Activity
Alpine/Forest Mineralization
N Deposition
Alpine/Forest NPP
Loch Vale Hypothesis
Climate
and Deposition
Drivers
Terrestrial
Controls
Nitrogen
Deposition
Temperature
Cryosphere
Alpine NPP
Mineralization
Forest NPP
Mineralization
Discharge
Aquatic controls
and
responses
Loch Vale
NO3
NO3 load
to Loch Outlet
Conclusions
While elevated atmospheric deposition has
affected high elevation ecosystems in Rocky
Mountain National Park for many years, we
now see additional influence of climate,
especially warming, on both stream hydrology
and stream nitrogen flux.
Our hypothesis is that warming has enhanced
melting in the cryosphere, and stimulated
microbial, and possibly lichen, activity in the
alpine, talus, and permafrost.
Q cm/wk
Water years
2005
2000
1995
0
2
4
6
8
10
1990
1985
3
p2
Se
4
6
l1
ay
Ju
M
16
7
ec
ct
5
b2
Fe
D
O
Loch Vale Weekly Temperature,°C, 1985-2006
Average Temperature
Water years
2005
2000
-15
-10
-5
0
5
10
15
1995
1990
1985
Se
l
Ju
p
ay
M
b
ec
Fe
D
ct
O