june 2010 gabriel sampson. introduction opportunity cost in conservation selection conservation...
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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