TOWARD A HEDONIC MODEL FOR LAND CONSERVATION IN SONOMA

COUNTY

June 2010Gabriel Sampson

Introduction Opportunity cost in conservation selection

Conservation program costs reduced considerably when land costs considered (Ando et al., 1998)

Feasibility of land-valuation models in conservation planning

GoalsHedonic model for

Sonoma County

Arrive at planning unit costs that reflect the land

marketOptimize

conservation targets subject to realistic economic

costs

Compare to results using the old cost

Methods – hedonic modelObserved market transactions for Sonoma

County parcels1991-2001

Discarded observations: industrial, commercial, condominium, restaurant, hotels, etc.

348 observations used

Hedonic modelSelected independent variables (Newburn et al.,

2006)AcresPersons per acreDistance to roadsFarmland (binary)Grazing (binary)Easement (binary)Fee, mixed, transfer (binary)High risk (binary)

Regression modelDependent Variable: LOGPRICE Included observations: 343 Excluded observations: 5 Weighting series: 1/SQRLOGACRES White Heteroskedasticity-Consistent Standard Errors & Covariance

Variable Coefficient Std. Error t-Statistic Prob.

ACREXFARM* -0.001737 0.000562 -3.094143 0.0021 ACREXGRAZING 0.000161 0.000664 0.243376 0.8079

EASEMENT 0.142708 0.127564 1.118717 0.2641 FARMLAND* 0.551931 0.130492 4.229615 0.0000

FEE_M_T 0.128560 0.116497 1.103553 0.2706 GRAZING -0.050555 0.182511 -0.276997 0.7820

HIGHRISK* -1.375266 0.064358 -21.36883 0.0000 LOGACRES -0.221061 0.408683 -0.540910 0.5889

LOGPERSONACRE* -0.095036 0.055157 -1.723011 0.0858 LOGROADS* -0.290770 0.108414 -2.682023 0.0077

C* 4.530750 0.948358 4.777471 0.0000

Unweighted Statistics

R-squared 0.090875 Mean dependent var 3.594225 Adjusted R-squared 0.063491 S.D. dependent var 0.669321 S.E. of regression 0.647724 Sum squared resid 139.2895 Durbin-Watson stat 0.174283 White Heteroskedasticity Test:

F-statistic 1.320943 Probability 0.087415 Obs*R-squared 60.84970 Probability 0.100873

Predicted planning unit costs

Predicted planning unit costs

$150

,000

$500

,000

$1,0

00,0

00

$2,5

00,0

00

$5,0

00,0

00

$7,5

00,0

00

$10,

000,

000

Mor

e0

500

1000

1500

2000

2500

0.00%

20.00%

40.00%

60.00%

80.00%

100.00%

120.00%

Frequency of planning unit hedonic costs

FrequencyCumulative %

Price per planning unit

Fre

quency

Scaled planning unit cost

100 200 300 500 700 1000 More0

200

400

600

800

1000

1200

1400

1600

1800

0.00%

20.00%

40.00%

60.00%

80.00%

100.00%

120.00%

New planning unit cost scale

FrequencyCumulative %

Cost per planning unit

Fre

quency

Old planning unit costs

100 200 300 500 700 1000 More0

200

400

600

800

1000

1200

1400

1600

1800

0.00%

20.00%

40.00%

60.00%

80.00%

100.00%

120.00%

Old planning unit cost scale

FrequencyCumulative %

cost per planning unit

Fre

quency

Using Marxan

Optimize conservation targets with

Marxan

• Modeled planning unit cost

• Modeled average cost/acre transformed to a scale of 100-1000

• The old cost scale of 100-1000

Modeled planning unit cost

Absolute costs vs. old costs

freq_polygoncost

Total 0 1 2 3 4 5 6 7 8 9 10 Frequency_old 0 82.6% 45.9% 25.4% 20.8% 17.6% 7.6% 4.2% 4.3% 3.1% .6% 23.5%

1 8.6% 18.0% 19.6% 17.6% 14.3% 5.3% 2.5% 1.4% 2.8% .5% .4% 5.0% 2 4.1% 13.9% 17.4% 18.4% 9.2% 6.1% 5.0% 5.0% 3.4% 1.5% .2% 3.8% 3 2.5% 7.4% 7.2% 10.4% 8.4% 14.4% 6.7% 7.8% 2.8% 4.6% .2% 3.0% 4 1.3% 4.9% 10.9% 12.0% 10.1% 13.6% 12.6% 8.5% 3.4% 2.1% .3% 2.9% 5 .5% 3.3% 5.8% 3.2% 10.1% 10.6% 7.6% 7.1% 3.4% 3.1% .3% 2.0% 6 .4% 4.5% 2.2% 4.0% 10.1% 10.6% 11.8% 12.8% 11.0% 5.7% .5% 2.7% 7 .8% 7.2% 4.8% 10.1% 8.3% 8.4% 9.9% 13.1% 5.7% 1.0% 2.7% 8 .4% 1.4% 4.0% 5.0% 10.6% 12.6% 11.3% 13.1% 10.8% 1.1% 2.8% 9 .8% 2.2% 4.0% 1.7% 7.6% 16.8% 16.3% 18.6% 22.2% 3.2% 4.6% 10 .7% .8% 3.4% 5.3% 11.8% 15.6% 28.3% 40.7% 92.5% 46.9%

Total 100.0% 100.0% 100.0% 100.0% 100.0% 100.0% 100.0% 100.0% 100.0% 100.0% 100.0% 100.0%

0 1 2 3 4 5 6 7 8 9 10

Frequency_old

0

500

1,000

1,500

2,000

Co

un

t

freq_polygoncost0

1

2

3

4

5

6

7

8

9

10

Bar Chart

Re-scaled costs vs. old costs

Frequency_newscore

Total 0 1 2 3 4 5 6 7 8 9 10 Frequency_old 0 86.5% 45.7% 20.8% 16.9% 5.0% 3.9% 1.6% 23.5%

1 8.5% 23.3% 18.2% 9.2% 13.3% 4.9% 4.8% 3.9% .5% 5.0% 2 3.1% 14.7% 25.2% 15.4% 13.3% 5.8% 4.0% 1.6% 3.9% 3.8% 3 .6% 8.5% 15.1% 16.2% 20.8% 8.7% 5.6% 5.5% 2.0% 1.4% .1% 3.0% 4 .7% 3.5% 10.1% 20.0% 9.2% 24.3% 11.9% 3.9% 5.3% .9% .1% 2.9% 5 .5% 1.6% 5.7% 5.4% 8.3% 8.7% 13.5% 8.7% 6.6% .5% .2% 2.0% 6 2.3% 3.8% 10.8% 13.3% 15.5% 14.3% 10.2% 10.5% 4.3% .2% 2.7% 7 .4% .6% 2.3% 5.8% 9.7% 18.3% 18.9% 15.1% 7.1% .4% 2.7% 8 .8% 5.0% 8.7% 9.5% 18.1% 14.5% 14.7% .8% 2.8% 9 .8% 2.5% 7.8% 11.1% 15.7% 23.0% 30.8% 2.7% 4.6% 10 .6% 2.3% 3.3% 1.9% 5.6% 13.4% 19.1% 39.8% 95.6% 46.9%

Total 100.0% 100.0% 100.0% 100.0% 100.0% 100.0% 100.0% 100.0% 100.0% 100.0% 100.0% 100.0%

0 1 2 3 4 5 6 7 8 9 10

Frequency_old

0

500

1,000

1,500

2,000

Co

un

t

Frequency_newscore0

1

2

3

4

5

6

7

8

9

10

Bar Chart

Site selection correlationCorrelations

freq_polygonc

ost Frequency_ne

wscore Frequency_old Spearman's rho freq_polygoncost Correlation

Coefficient 1.000 .937(**) .915(**)

Sig. (2-tailed) . .000 .000 N 4288 4288 4288

Frequency_newscore Correlation Coefficient

.937(**) 1.000 .949(**)

Sig. (2-tailed) .000 . .000 N 4288 4288 4288

Frequency_old Correlation Coefficient

.915(**) .949(**) 1.000

Sig. (2-tailed) .000 .000 . N 4288 4288 4288

** Correlation is significant at the 0.01 level (2-tailed).

Model limitationsPlanning unit prices extrapolated from

limited APN dataNeed to address land use change jointly with

purchase cost (Newburn et al, 2005)Management costs not capturedHow would conservation influence future

development patterns?10 iterations in Marxan runs

Concluding remarks

Strong correlation between site

selections

Variance in mid selection

frequencies

Irreplaceability may supersede

site cost

ReferencesAndo, A.J., Camm, J., Polasky, S., Solow, A. (1998).

Species Distributions, Land Values, and Efficient Conservation. Science 279:2126-28.

Newburn, D., Berck, P., Merenlender, A. (2006) Habitat and Open Space at Risk of Land-Use Conversion: Targeting Strategies for Land Conservation. American Journal of Agricultural Economics 88(1):28-42.

Newburn, D., Reed, S., Berck, P., Merenlender, A. (2005). Economics and Land Use Change in Prioritizing Land Conservation. Conservation Biology 1411-1420.

Re-scaled selection

Old cost selection