Biogeochemical processes in seasonally snow covered systems Snow Distribution
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Transcript of Biogeochemical processes in seasonally snow covered systems Snow Distribution
Biogeochemical processes in seasonally snow covered systems
Snow Distribution
Vegetation Water Source
Hydrochemistry
Biosphere-Atmosphere Gas Exchange
Snow DistributionVegetation communities are strongly linked to patterns of snow accumulationand melt by their influence on mass, chemical and energy exchanges, and bytheir sensitivity to snow thermal insulation and spring time inputs of meltwater, nutrients and latent heat.
Snow Distribution
1) Interception
Snow Distribution – Vegetation Effects
2) Wind Redistribution
Snow Distribution – Vegetation Effects
3) Wind Redistribution/ Energy Balance
Vegetation Water Source
Biomass ProductionAgricultureProtected Areas
Parks and Wilderness
Habitat
Snow Biogeochemistry; Hydrochemistry
Dissolved Organic Matter
Inorganic Nitrogen
0
40
80
120
160
Sn
ow
Dep
th (
cm)
-12
-8
-4
0
So
il T
emp
erat
ure
(oC
)
JAN FEB MAR APR MAY
DEEP
DEEP
SHALLOW
SHALLOW
-6 -5 -4 -3 -2 -1 0
Soil Temperature
CO
2 F
lux
(mg
C/m
2 /d
)
Relationship between temperature and soil heterotrophic activity
0
400
200
600
0
1
2
3
4
5
6
7
8
0 50 100 150
Julian Day
Gra
ms
N m
-2
Snowmelt Began
microbial biomass
0
1
2
3
4
5
6
7
8
0 50 100 150
Julian Day
Gra
ms
N m
-2
Snowmelt Began
microbial N
soil inorganic N
y = -0.0106x + 1.3327
R2 = 0.9919
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
0 20 40 60 80 100 120
Mean Daily CO2 Flux (mg C/m2)
Nit
rate
Lea
chat
e (g
N/m
2 )
Snow Cover Duration
Ov
er-
win
ter
Het
ero
tro
ph
ic
Ac
tivi
tyFrozen SoilLimits
Activity
Freeze-Thaw Cell Lysis Increases Carbon
Substrate
Absence of Freeze-Thaw
Decreases Carbon Substrate
Snow CoverLimits Primary
Production
Conceptual Model of How Snow Cover Controls Over-winter Heterotrophic Activity
y = -0.5381Ln(x) + 2.8147
R2 = 0.9171
y = -0.3725Ln(x) + 2.1949
R2 = 0.9232
0
0.2
0.4
0.6
0.8
1
1.2
1.4
0 100 200 300 400 500
CO2 Flux (mg C/m2/d)
Nit
rate
Lea
chat
e (g
N/m
2 /yr
)
Forest Sites
Meadow Sites
y = 0.0245x - 0.2965
R2 = 0.7627
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
2
40 45 50 55 60 65 70 75 80 85
Winter precip (cm)
N r
eten
tio
n (
kg/h
a)
Discharge (Montezuma) and DOC (DC5)1980 - 1996
0
5
10
15
20
25
Water Year
Dis
char
ge
(m3/
sec)
0
1
2
3
4
5
6
7
DO
C (
pp
m)
1980 1981 1982 1984 1985 1986 1993 1994 1995 1996
y = 0.0637x + 4.2667
R2 = 0.9065
5
10
15
20
25
30
35
100.0 150.0 200.0 250.0 300.0 350.0 400.0 450.0
Mean Daily CO2 Flux (mg C m-2 d-1)
DO
C L
each
ate
(g C
m-2
)
Heterotrophic activity vs. DOC export
y = 0.3994x + 0.8987
R2 = 0.836
y = 0.3697x - 0.3526
R2 = 0.6544
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
5
0 1 2 3 4 5 6 7 8 9 10Discharge (m3/sec)
DO
C C
on
cen
trat
ion
(p
pm
)
Vegetation communities are strongly linked to patterns of snow accumulation and melt by their influence on mass, chemical and energy exchanges, and by their sensitivity to snow thermal insulation and spring time inputs of meltwater, nutrients and latent heat.
Many snow models and parameterisations presume stationary plant communities as part of their regional calibrations.
It is now felt that the complex cumulative impacts of a changing environment have created a global need for focused studies of snow-vegetation interactions at several scales: plant, plant community, landscape, biome and global.
Discharge (Montezuma) and DOC (SN2)1980 - 1996
0
5
10
15
20
25
Water Year
Dic
har
ge
(m3/
sec)
0
1
2
3
4
5
6
7
DO
C (
pp
m)
1980 1981 1982 1984 1985 1986 1993 1994 1995 1996
y = 0.0245x - 0.2965
R2 = 0.7627
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
2
40 45 50 55 60 65 70 75 80 85
winter precip (cm)
N r
ete
nti
on
(k
g/h
a)
y = 1.0342x - 32.142
R2 = 0.9948
y = 0.1265x - 0.4547
R2 = 0.7326
0
5
10
15
20
25
30
30 35 40 45 50 55 60
Water yield (cm)
DO
C E
xpo
rt (
106 g
ram
s)