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Twin Cities Household Ecosystem Project

Lawrence A. Baker, Cinzia Fissore,,Sarah Hobbie,Kristen Nelson,,

University of Minnesota

Jennifer King and Joe McFaddenUC-Santa Barbara

Support: NSF Biocomplexity Projects EAR-0322065 and CHN 0709581

Why study households?1. In post-industrial cities, large fractions of C, N, and P fluxes move through households

2. Household choices are flexible, especially over time

3. Understanding household fluxes could be used to develop environmental policies

4. Households are discrete, meaningful units, and easy to study

TCHEP Goal: “Seamless, transdisciplinary model of urban biogeochemistry that links the biophysical and social components …”

InputsCarbon- natural gas, gasoline, food, jet fuel, paper, etc.N and P - human and pet food, fertilizer, etc.

OutputsCarbon - CO2, garbage, sewageN and P - lawn runoff, sewage, garbage

2. What demographic and behavioral factors control consumption?

1. What are the “fluxes” of C, N, and P, and how does this vary among households?

3. How are environmental behavior messages processed through social networks?

Turf

InputsCompartments

OutputsTransportation(household vehicles, air, mass transit)

Fuel (Corg),Atmospheric N2

Emissions(CO2 , NOx)

Household energy (heating, cooling, appliances)

HumansFoodCorg,NorgPorg

Exported garbageCorg, Norg, Porg

Wastewater (Corg, Porg, Norg PO4

3-, NH4+)

Respiration (CO2)

Atmospheric CO2; fertilizer (Norg, NH4, NO3)

Soil (root zone)

TreesExternal compost(Corg, Norg, Porg)

Pets

Export to street (runoff + leaves)(Corg, Porg, Norg PO4

3-, NH4

+, NO3-)

Paper and plasticsPaper and plastics(Corg, Norg)

Denitrification (N2, N2O, NO2)

Export to vadose zone and aquifer(NO3

-, PO43-)

Carbon, nitrogen, and phosphorus movement through households

(Baker et al. 2007)

Individual choice: Theory of Planned BehaviorAzjen and Fishbein (many papers)

ATTITUDES TOWARD

BEHAVIOR

SUBJECTIVE SOCIAL

NORMS

PERCEIVED BEHAVIORAL

CONTROL

INTENT TO

BEHAVE

BEHAVIOR

DECISIONBEHAVIORAL

BELIEFS

(KNOWLEDGE)

NORMATIVE

BELIEFS

CONTROL BELIEFS

How this might be used:- Identify the key motivations- Identify constraints toward changing behavior- Identify method for providing information

Falcon Heights pilot study

Pilot survey of 35 households Falcon Heights, MN

Tools:- In-home survey (80 questions)- Energy bills; odometer readings- Landscape measurements

-Household Flux Calculator

Mean and variance in component C fluxes

0 1,000 2,000 3,000 4,000

Householdvehicles

Electricity*

Natural gas

Domestic flights

Internationalflights

Lawns + trees(NPP)

kg C/yr

0

2,000

4,000

6,000

8,000

10,000

12,000

14,000

Low Typical High

Hou

sehol

d C

, kg

/yr

Air travelVehiclesFoodNatural gasElectricity

Carbon consumption varies hugely within Falcon Heights homes (Baker et al., 2007)

3X!

0

1,000

2,000

3,000

4,000

5,000

6,000

7,000

8,000

9,000

Sue Leif SarahHobbie

Single male MerrittClapp-Smith

Grimes

Ca

rbo

n in

pu

t, k

g/y

rAirVehiclesFoodWoodGasElectric

Household carbon profiles for 5 volunteers

Full-scale TCHEP: Hybrid approach

Mail survey~ 80 multi-part questions22 pages30-40 minutes

Household energy records(permission from respondents)

GIS parcel data

Ground-based vegetation survey (400 homes)

UFORE model

Lawn model Household Flux Calculator

CO2 emissionsN and P fluxes

Housing Units Per Km2

6.5 - 263.7

263.8 - 618.3

618.4 - 1167.9

1168.0 - 11825.6

Returned Surveys

0 52.5 Miles´

Full-Scale TCHEP Survey

Urban

Rural

15,000 mailed surveys (May-August 2008)

- 3000 responses - 21% response rate

Vegetation survey for 400 households

New collaborator: Jeannine Cavender-Bares

28.3

15.79.6

24.6

11.4

10.4

low maintenance neat and orderly

privacy/ seclusion beautif ul yard

supports wildlif e native plants

Primary goals of household landscaping

atm. deposition

grass removal

soil

leaching, runoff,denitrification

leaves removal

fertilizers

pets

wood

Kg N

hou

seho

ld-1

yr-1

Average landscape N fluxes

INPUTS OUTPUTS ACCUMULATION

-600

-400

-200

0

200

400

600

800

1000

INPUTS OUTPUTS ACCUMULATION

grass

wood

leaves

leaf removal

leaf decomposition

heterotrophic respiration

wood

soil

Kg C

hou

seho

ld-1

yr-1

Average landscape C fluxes

0

25

50

75

100

0 25 50 75 100Cumulative % vehicles

Cum

% C

em

issi

on

1:1

Cumulative frequency for household vehicle travel

Cum. C cum. % C

Cumulative %Vehicles C emissions

25 5550 7875 93

100 100

Broader impacts: energy and GHG emissions

• Urban sustainability efforts (ICLEI, etc.)• True impact of low-impact development• Policies to encourage conservation-

targeting and tailoring

Average carbon input to Falcon Heights homes

Air travel14%

Auto28%

Electricity23%

Other12%

Natural Gas23%

Broader impacts: pollution management

Maples (all species)

y = 0.0009x2.2188

R2 = 0.9959

0

10

20

30

40

50

0 50 100 150

Diameter at breast height, cm

Lea

f P

, kg

/yr

P

Source reduction for urban stormwater

Baker et al., Storm Water Magazine, Nov. 2007

Lawn runoff

Leaf input

3 or more fertilizer applications,+ mulching

Steep slope, low infiltration soil

The Nowak disproportionality idea applied to lawn nutrient export

High nutrient export

Site characteristics

Site behaviors(TCHEP survey)

Baker et al., 2008, Cities and the Environment

TCHEP Status

• Hybrid survey approach successful: 3,000 completed surveys

• Survey tool “Our Household Choices” (Nelson et al.) is published and available

•HFC 2.0 is completed

•First overview papers this summer

•Developing practical and theoretical collaborations – vegetation, birds, urban stormwater, CO2 emissions.