Carbon Storage by Urban Soils in the USA

1
Carbon Storage by Urban Soils in the USA
Workshop on Soil Carbon Dynamics in Northern U.S.
Forests
R. Pouyat, I. Yesilonis, T. Trammell D. Nowak
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INITIAL SITE DISTURBANCE
?
2600 m2
TOP SOIL?
DISTURBED SOIL
SUB SOIL
2.7 x 104 kg SOC
McGuire (2004)
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MANAGEMENT?
Supplements
Clipping
Pesticides
4
MARYLAND, USA TURFGRASS MAINTENANCE COSTS
(MANAGEMENT EFFORT VARIES!)
COST PER ACRE (IN U.S. DOLLARS)
LAND-USE TYPE
GOLF COURSES 2,727 LAWN CARE
FIRMS 1,969 ATHLETIC FIELDS 1,155 PARKS
450 DETACHED HOMES 369 CHURCHES 166
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TRAJECTORY? RECOVERY? FACTORS?
?
PUTTING GREENS
FAIRWAYS
50
0
0
50
YEARS
From Qian and Follett (2002)
Soil factors climate, texture, litter quality,
relief Anthropogenic factors Override? Direction
of ??
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IMPORTANCE TIME, INITIAL STATE
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NET CHANGE?
10
8
Woody Vegetation C
Carbon (kg m-2)
Lawn Stubble C
6
SOC 0-10 cm
4
SOC 10-20 cm
SOC 20-30 cm
2
0
Grass- land
1990s
AGRIC.
1950s
1960s
1970s
1980s
Land Use or Decade of Development
Golubiewski and Wessman, in press
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• URBAN LAND USE CHANGE?
• Disturbance (initial, post-develop.)-
• SOC
• Introduction of impervious surfaces
• SOC- low, very slow change
• Introduction of horticultural management
  (supplements)- SOC
• Environmental change (biophysical)- SOC

8
n 2
n 2
n 4
n 6
n 2
n 8
9

• SAMPLED 126 OF 200 UFORE PLOTS
• STRATIFIED BY LAND USE
• AVOIDED ATYPICAL SOIL CONDITIONS
• MEASURED 23 SOIL VARIABLES
• VEGETATION STRUCTURE

CITY SCALE
10
1 m DEPTH SOIL CORES
11
UFORE PLOTS SOIL C STOCKS
n plots (3 cores/plot)
Pouyat, Yesilonis, Golubiewsky, Russell-Anelli
(in prep.)
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Questions Total system organic C in
Baltimore? Spatial distribution of organic
C? Potential for C sequestration?
Century model?
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• CENTURY MODEL (Residential)
• Data inputs
• 1. Plot specific (B.D., texture, rock fraction,
  pH)
• 2. Plot specific calculated for input (CN,
  mineral N)
• 3. Site specific (lat./long, prec./temp., N dep.)
• Assumptions
• 1. Site specific
• SWC lost to base flow-50
• Flow into storm flow-90
• Monthly rainfall lost via runoff-30
• 2. Crop (lawn) files (short grass and turf grass)
• 3. Tree files (depending on plot with or without
  trees)
• 4. Fertilization and irrigation (65.7 kg N ha-1
  yr-1 2.5 cm wk-1)

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• CENTURY MODEL (Preliminary run)
• Simulations
• 1. Base run (1st yr. is yr. built)
• 2. Fertilizer/Irrigation
• Fertilize during growing season (May-Aug.)
• Irrigate driest months (July-Aug.)
• Future Simulations
• 1. Higher temporal resolution weather data
• 2. Soil moisture (wilting point, field capacity)
• 3. Additional land uses
• 4. Simulate CO2 increases (350-500 ppm)
• 5. Soil warming (heat island effect)
• 6. Initial soil conditions post disturbance

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CENTURY RUNS UFORE PLOTS
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CENTURY RUNS UNDERESTIMATE SOC 1 M DEPTH
)
15
-2
n14
n4
n4
n2
10
Carbon Density (kg m
5
0
Park
Forest
Med Density Resd
High Density Resd
Land Use
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9000
8000
7000
6000
(1 m depth)
5000
-2
4000
g C m
3000
2000
no fert
fert/irrig
1000
0
20
25
30
35
40
45
50
55
60
65
70
sand ()
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URBAN SOC STORAGE FOR USA?
Dwyer et al., 2000 Nowak and Crane, 2002
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URBAN SOC DENSITIES
)
20
-2
14.4

1.2
15

7.1
2.9
Carbon Density (kg m
10

3.3
0.93
5
(n22)
(n10)
(n7)
0
Clean fill
Park use/grass
Residential grass
Land Use
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BEST ESTIMATE BASED ON FOLLOWING ASSUMPTIONS 1.
Represent all urban soils (no variation among
regions except remnant soils) 2. Soils reached
steady-state equilibrium between C accumulation
and decay post-urbanization regardless of region
(climate, native soil type) 3. SOC pools
negligible below 1 m depth
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ESTIMATED SOC DENSITIES BY LAND USE/COVER FOR USA
REGIONS
Agriculture, Forest, and Shrubland SOC estimates
from Birdsey (1992) Wetland estimate 30
reduction of 45 kg m-2 estimate for wetland soils
of N. America by Trettin and Jergensen (2003)
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Estimated urban SOC densities and SOC by Region
TOTAL
25.2 7.7 19.4 3.4
7.5 to 7.9 kg m-2 (range of data) belowabove
ratio 2.8 (compared to 2.7 for world) 7.7,
8.1, and 9.0 kg m-2 (35.0, 45.0, and 72.3 kg
m-2) (Trettin and Jergensen, 2003 Post et
al., 1982)
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LIFE ZONE
AREA C Density Soil
C
LIFE ZONE
AREA C Density Soil
C
(x10
10
m2)
(kg m
-
2
)
(x10
14
g)
(x10
10
(kg m
-
2
)
(x10
14
g)
Northeast Forest
Northeast Forest
20.81
16.2
16.2
33.7
Northeast Cropland
Northeast Cropland
-
-
6.0
6.0
-
-
Mid
Mid
-
-
Atlantic Forest
Atlantic Forest
20.29
20.29
11.2
11.2
22.7
Mid
Mid
-
-
Atlantic
Atlantic
Cropland
Cropland
-
-
4.2
4.2
-
-
Southeast
Forest
34.22
7.7
26.3
-
-
Southeast
Cropland
2.6
8.2
20.7?
USA Urban (total)
25.2
7.7
19.4?
25.2
USA (total)
915.9
619.15
USA (total)
915.9
6.8 (?)
Pouyat et al. (2003) Pouyat et al. (in
press)


Birdsey
Birdsey
(1992)
(1992)
Nowak Crane (2002)
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UNCERTAINTIES IN URBAN ECOSYSTEMS
1. C pools and fluxes (need more data!). 2.
Amount and quality of C inputs (exotics, stress
effects, C deposition). 3. Longterm effects of
soil physical disturbances (recovery?). 4.
Fluxes and pools of covered soils. 5.
Measurement of soil C density (Db). 6. Need to
go deeper fill soils, sanitary landfills
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HOMOGENIZED LANDSCAPE?

• SCALE?
• GLOBAL
• REGIONAL
• LOCAL
• WITHIN PATCH?
• BETWEEN PATCH?

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Boreal Cool Temperate Steppe Cool Tropical
Forest Moist Tropical Forest Warm Temperate
Forest Warm Desert
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Agricultural Conversion Urban
Conversion
Cd
Urban Range at Equilibrium
Global Range at Equilibrium
1.4
Time Edaphic
Cultivation Urban
Pouyat et al. (2001) Pouyat et al. (2003)
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9.5
6.3
2.1
4.4
Aboveground data from Nowak and Crane (2002)
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SOIL DISTURBANCE?
- MIXING AND COMPACTION - DISRUPTION OF
SOIL AGGREGATES - BURIAL OF NATIVE SOIL (LAND
FILL) - LOSS SURFACE HORIZONS
NET LOSS OF SOC
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IMPERVIOUS SURFACES?
- DECREASED H2O ORGANIC INPUTS - BLOCKS
GAS EXCHANGE (MULCH?) - CHANGE IN ENERGY
FLUXES - DECAY?
VERY SLOW CHANGE
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HORTICULTURE MANAGEMENT?
- OVERCOME SITE LIMITATIONS - SITE
DEPENDENT? - 1 PRODUCTIVITY VS. DECAY?
- INITIAL CONDITIONS (SITE HISTORY?) -
RECOVERY? TRAJECTORY?
NET GAIN OF SOC
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URBAN ENVIRONMENTAL ?

• 1. Altered temperature regimes
• 2. Introduction of pollutants
• - Toxic and sub lethal effects
• - Fertilization (CO2, N deposition)
• 3. Introduction of non-natives
• - Litter quality
• - Keystone species (earthworms)
• 4. Altered hydrology (riparian, wetlands)

NET LOSS OR GAIN OF SOC
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15
g)
m
)
2
LIFE ZONE
AREA (x10
2
C Density (kg m
) Soil C (x10
12
2
Tropical forest
Tropical forest
-
-
moist
moist
5.3
5.3
11.4
11.4
60.4
60.4
Temperate forest
Temperate forest
-
-
warm
warm
8.6
8.6
7.1
7.1
61.1
61.1
Temperate forest
-
cool
3.4
12.7
43.2
Temperate forest
-
cool
3.4
12.7
43.2
Boreal forest
-
wet
6.9
19.3
133.2
Boreal forest
-
wet
6.9
19.3
133.2
Cool temperate steppe
9.0
13.3
119.7
Cool temperate steppe
9.0
13.3
119.7
Warm desert
14.0
1.4
19.6
Cultivated land
21.2
7.9
167.5
Cultivated land
21.2
7.9
167.5
?
?
1.3
Urban land
Wetlands
Wetlands
2.8
2.8
72.3
72.3
202.4
202.4
TOTAL WORLD
1500(20)
Adapted from Post et al. (1982) Schlesinger and
Andrews (2000)
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