Article Figures & Data
Figures
- FIGURE 1
Zones and Concessions in the Maya Biosphere Reserve
- FIGURE 2
Deforestation in the Maya Biosphere Reserve: 1990–2008
Tables
Concession Category Concession Name Year Formed Number of Members Concession Area (ha) Resident, long-inhabited Carmelita 1997 122 53,797 Uaxactún 2000 244 83,558 Resident, recently settled San Miguel 1994 30 7,039 La Pasadita 1997 110 18,817 La Colorada 2001 39 27,067 Cruce a la Colorada 2001 65 20,469 Nonresident Suchitecos (RíoChanchich) 1998 27 4,607 Laborantes (Chosquitán) 2000 78 19,390 San Andrés (AFISAP) 2000 174 51,940 Arbol Verde (Las Ventanas) 2001 364 64,973 El Esfuerzo (Yaloch) 2002 39 25,386 Custosel (La Unión) 2002 96 21,176 Source: Data from Gómez and Méndez 2007.
Variable Nonresident Long-Inhabited Recently Settled Age of head 49.6 47.8 51.0 Education of head (years) 5.0** 4.1** 2.5*** Born in Petén (percent) 52*** 76*** 29*** Daily food expendituresa (dollars) 11.87** 8.77 7.41 Annual incomea (dollars) 7,928* 3,867* 2,413** Own land (percent) 47*** 76.8** 82** Personal landholdings (ha) 13.8** 7.6** 48.8*** Dividend payment (2011 dollars) 350*** 48*** 0*** Farmer (percent) 34.2 37.1 86*** Forest job (percent) 7.9** 25.8*** 1.7** Other job (percent) 52.6** 35.5** 10.5*** Observations 152 62 57 Note: Concession membership ranged from 20 members to more than 300. Twenty to twenty-five percent of members were randomly selected for interviews.
↵a Income and food expenditures are converted from quetzales to dollars based on October 2012 exchange rates (when the survey was conducted), Q1.00 = $0.1253 (source: www.freecurrencyrates.com/exchange-rate-history/GTQ-USD/2012). Significant difference from the other two groups based on independent sample t-tests.
↵* Significant at 10%;
↵** significant at 5%;
↵*** significant at 1%.
Variable Nonresident Long-Inhabited Recently Settled Road distance (km) 21.4 8.8 6.6 Slope (degrees) 3.7 3.5 5.0 Elevation (meters) 194 226 230 Cleared distancea (kilometers) 9.4 5.7 1.6 City distance (kilometers) 49.5 69.5 51.6 pH 6.8 7.1 7.3 Archeo distanceb (kilometers) 21.4 16.4 22.7 Aspect (degrees) 175 159 185 Village distance (kilometers) 25.3 13.1 5.1 Note: Data are from remote sensing satellite images. Observations are based on 30 m × 30 m parcels of land. See Data section for more details. All of the variables for each concession group are significantly different from the other groups at the 99% level for all covariates.
↵a Cleared distance is the distance to the nearest pixel of land cleared prior to 1990.
↵b Archeo distance is the distance to the nearest Mayan archeological site in the reserve.
Unmatched (1) Matcheda (2) Matched without 2 km Buffer (3) Model Coeff. Clustered Std. Err. Coeff. Clustered Std. Err. Coeff. Clustered Std. Err. All Groups DID −0.02 0.024 −0.042 0.038 −0.046 0.037 Probit ME 0.022** 0.011 0.004 0.008 0.0098 0.009 Observations 295,001 169,666 134,192 R-squared 0.12 0.15 0.14 Nonresident DID −0.04** 0.02 −0.033 0.02 −0.043** 0.02 Probit ME 0.003 0.02 −0.014** 0.007 −0.014* 0.007 Observations 293,248 90,190 73,159 R-squared 0.13 0.47 0.098 Long-inhabited DID −0.043** 0.02 −0.050* 0.028 −0.064* 0.033 Probit ME −0.018 0.013 −0.022** 0.011 −0.024** 0.012 Observations 294,679 94,204 84,471 R-squared 0.13 0.11 0.12 Recently settled DID 0.026 0.022 −0.078* 0.047 −0.077*** 0.019 Probit ME −0.001 0.013 −0.040** 0.016 −0.015 0.014 Observations 296,262 43,116 25,682 R-squared 0.08 0.25 0.065 Note: Standard errors are clustered at the “concession” region level with 25 clusters for “all groups” and 17 clusters in the subgroups.
↵a Matched samples are based on nearest-neighbor propensity score matching with Mahalanobis distance metric with calipers set to 0.25 standard deviations taken from the sample with 300,000 observations. Results based on a linear probability model where the dependent variable equals 1 if pixel is deforested, 0 otherwise.
↵* Significant at 10%;
↵** significant at 5%;
↵*** significant at 1%.
- TABLE 5
Average Treatment Effect on the Treated (ATT) Results for Kernel and Bias-Corrected Matching Estimators
Unmatched Kernel Bias-Corrected Concession Group Time Period ATT Std. Err. ATT Std. Err. ATT Std. Err. Nonresident Pre −0.036 0.002 −0.0028 0.004 −0.013 0.0006 Post −0.070 0.003 −0.025 0.009 −0.015 0.004 Difference −0.034*** 0.004 −0.022** 0.010 −0.0015 0.004 Long-inhabited Pre −0.036 0.002 −0.041 0.009 0.0080 0.004 Post −0.068 0.003 −0.144 0.011 −0.077 0.009 Difference −0.032*** 0.004 −0.103** 0.014 −0.085*** 0.010 Recently settled Pre −0.019 0.002 0.013 0.02 0.038 0.002 Post 0.068 0.004 −0.065 0.034 −0.046 0.020 Difference 0.087*** 0.004 −0.078** 0.039 −0.084*** 0.020 Note: Kernel matching performed in Stata Version 12 with “psmatch2” using clustered standard errors. Bias-corrected performed in Stata using the “nnmatch” command. The number of observations for each sample varies but is based on 50,000 total observations in the unmatched sample, then split up into 25,000 each for pre and post samples. The standard errors for kernel results do not take into account estimated propensity scores, but we choose not to bootstrap given the potential for errors (see Abadie et al. 2004; Abadie and Imbens 2006), since these are robustness checks. The bias-corrected ATT estimates do not include clustered standard errors.
* Significant at 10%;
↵** significant at 5%;
↵*** significant at 1%.
2 km Buffer 5 km Buffer 10 km Buffer Model Unmatched Matched Unmatched Matched Unmatched Matched OLS 0.089 0.145 0.078 −0.057 0.057 0.039 Robust Std. Err. (0.004)*** (0.008)*** (0.003)*** (0.009)*** (0.004)*** (0.014)*** Clustered Std. Err. (0.031)*** (0.003)*** (0.027)*** (0.005)*** (−0.054) (0.055) Kernel — 0.068*** — −0.13*** — −0.0004 Std. Err. — (0.018) — (0.013) — (0.036) Observations 96,899 7,230 97,756 5,582 98,014 5,004 R-squared 0.19 0.28 0.16 0.29 0.15 0.17 Note: Matched results are based on nearest-neighbor matching without replacement with Malahanobis distance metrics. Matching was done in R using “MatchIt” (Ho et al. 2011). Kernel results are from Stata Version 12 using “psmatch2.” Standard errors are in parentheses. Dependent variable is binary, equal to 1 if observation is within the designated buffer zone. OLS, ordinary least squares.
* Significant at 10%;
** significant at 5%;
↵*** significant at 1%. Significance designations based on clustered standard errors.
Nonresident Long-Inhabited Recently Inhabited Variable Odds Ratio Clustered Std. Err. Odds Ratio Clustered Std. Err. Odds Ratio Clustered Std. Err. Distance to road 1.41 0.209** 0.83 0.13 2.13 0.56*** Distance to road2 1.00 0.005 0.99 0.005 0.97 0.008*** Distance to major city 0.91 0.076 4.74 1.44*** 2.34 0.745*** Distance to major city2 1.00 0.0006 0.99 0.002*** 1.00 0.004 Elevation 1.00 0.0045 1.03 0.009*** 1.02 0.008*** Slope (degrees) 1.05 0.02*** 1.04 0.016** 1.06 0.015*** Distance to cleared parcel 2.08 0.28*** 1.62 0.314 ** 0.40 0.13*** Distance to cleared parcel2 0.97 0.97*** 0.97 0.009*** 0.93 0.07 Distance to nearest village 1.35 0.106*** 0.62 0.106*** 0.33 0.22* Distance to nearest village2 1.00 0.0016** 1.00 0.003 1.04 0.04 Distance to archeo site 0.97 0.024 1.16 0.083** 0.47 0.04*** pH 2.32 0.40*** 0.63 0.102*** 0.95 0.61 Aspect 1.00 0.002 1.00 0.0002*** 1.00 0.0002 West (dummy) 424.5 642*** 0.25 0.25 — — Constant 2.2e–6 5.2e–6*** 2.6e–23 2.7e–22*** 8.2e–7 8.9e–6 Observations 293,248 294,208 232,984 Pseudo R2 0.5828 0.7794 0.8384 Log likelihood −78,344.1 −41,589.9 −25,643 NonResident Long-Inhabited Recently Inhabited Unmatched Matched Unmatched Matched Unmatched Matched Variable Mean Diff. eQQ Med.a Mean Diff. eQQ Med.a Mean Diff. eQQ Med.a Mean Diff. eQQ Med.a Mean Diff. eQQ Med.a Mean Diff. eQQ Med.a Distance to road 6.86 6.75 1.81 1.72 −5.71 6.82 −0.03 0.67 −8.93 8.13 1.06 1.45 Distance to city −23.48 24.92 −0.96 6.60 −3.48 23.16 5.96 19.98 −14.98 21.95 5.20 6.86 Distance to village 6.62 6.52 0.88 2.65 −5.60 6.60 −0.99 0.90 −9.66 10.11 0.48 0.81 Distance to village2 305.9 217.7 32.06 71.17 −231.9 262.1 −40.10 21.99 −240.3 200.0 12.31 5.74 Distance to clearing 1.90 2.10 −0.59 1.36 −1.80 1.34 −0.14 0.56 −8.68 10.67 0.86 0.19 Distance to clearing2 18.69 19.14 −19.24 27.82 −46.52 13.78 −5.32 3.91 −152.4 133.1 7.37 0.38 Distance to archeo site −0.86 5.22 −1.89 2.01 −5.85 3.27 −0.97 2.94 3.64 5.53 −3.19 2.87 Aspect 12.88 10.01 1.01 4.40 −2.60 6.34 −0.36 1.30 20.27 14.04 −4.02 4.07 pH 0.34 0.36 0.10 0.05 0.55 0.50 −0.09 0.00 0.51 0.36 −0.13 0 Elevation 29.90 48.25 12.22 11.00 62.14 69.00 −4.29 36.00 29.93 35.00 14.7 16 Slope (degrees) 0.57 0.87 −0.36 0.00 0.38 0.46 −0.11 0.00 2.20 1.90 −1.86 1.97 West (location dummy) −0.29 0.29 0.00 0.00 −0.16 0.16 0.00 0.00 0.32 0.00 0.00 0.00 Observations 293,248 90,190 294,208 94,204 296,262 43,116 Note: Matching methods for all three data sets are nearest neighbor without replacement, with Mahalanobis distance metric for select variables.
↵a Median values for the quantile-quantile (QQ) plot differences are used for all ordinal covariates and the mean is used for categorical covariates (west). Matching is conducted in R using “Matchit” (Ho et al. 2011).
Recently Settled Long-Inhabited Nonresident Variable Coeff. Std. Err. Coeff. Std. Err. Coeff. Std. Err. Control 0.004 0.007 0.013 0.008 0.007 0.005 Year 90_93 −0.003** 0.001 −0.0008* 0.0004 −0.00002** 0.00001 Year 93_95 −0.002** 0.001 −0.0008* 0.0004 0.00000 0.00000 Control*90_93 −0.004 0.005 −0.010 0.007 −0.005 0.003 Control*93_95 −0.003 0.004 −0.003 0.002 −0.004 0.003 Constant 0.007** 0.003 0.0008* 0.0004 0.00007** 0.00003 Observations 129,099 282,537 270,564 Groups 43,033 94,179 90,188 Note: Results based on a random effects linear probability model with panel data from three preconcession periods: 1990–1993, 1993–1995, and 1995–1997. Each pixel was coded as 1 if it experienced deforestation during that period, and then remained 1 for all subsequent periods. Results based on a linear probability model where the dependent variable equals 1 if pixel is deforested, 0 otherwise.
↵* Significant at 10%;
↵** significant at 5%;
*** significant at 1%.
Nonresident Long-Inhabited Recently Inhabited Γ Pre Post Pre Post Pre Post 1 12.2 21.5 10.3 15.1 6.2 4.4 2 17.4 30.3 14.8 21.6 11.1 13.1 3 21.3 36.9 18.3 26.5 14.6 18.8 4 24.6 42.4 21.2 30.6 17.4 23.2 5 27.5 47.2 23.8 34.2 19.8 26.9 Note: Results were obtained using “mhbounds” in Stata Version 12 used for testing unobserved bias with binary dependent variables (see Becker and Caliendo 2007). Reported values are for the Mantel-Haenszel statistic Q + mh (assumption: overestimation of treatment effect). p-Values for all test statistics are less than 0.001 and thus are not displayed in the table. Pre indicates the prepolicy period from 1990 to 1996, post indicates the postpolicy period from 2000 to 2008. Γ is a measure of the degree of hidden bias required to change results of the estimated treatment effect from the kernel matching results (TABLE 5).
Variable (Dependent deforest = 1) Recently Settled Long-Inhabited Nonresident With 2 km Buffer Without 2 km Buffer With 2 km Buffer Without 2 km Buffer With 2 km Buffer Without 2 km Buffer Coef. Coef. Coef. Coef. Coef. Coef. Treat −0.003
(0.006)−0.013***
(0.002)−0.011*
(0.006)−0.014*
(0.007)−0.005
(0.004)−0.008
(0.005)Post 0.018
(0.035)0.085***
(0.024)0.015
(0.015)0.023
(0.019)0.007
(0.010)0.016
(0.013)Treat × Post −0.081
(0.059)−0.134***
(0.013)−0.041**
(0.021)−0.052**
(0.023)−0.024
(0.015)−0.034**
(0.017)Time Trend 0.026***
(0.008)0.023***
(0.006)0.007*
(0.004)0.008
(0.005)0.004*
(0.003)0.005
(0.003)Constant −0.057***
(0.016)−0.038***
(0.015)−0.006
(0.008)−0.005
(0.010)−0.005
(0.005)−0.003
(0.006)Observations 344,264 204,832 753,432 675,576 721,504 585,256 Groups 43,033 25,604 94,179 84,447 90,188 73,157 Note: Data are from remote sensing satellite images. Observations are based on 30 m × 30 m parcels of land. Panel format is based on periods where deforestation was observed. There are eight periods from 1990 to 2009. Each pixel was coded as 1 if it experience deforestation during that period and then remained 1 for all subsequent periods. Results based on a linear probability model where the dependent variable equals 1 if pixel is deforested, 0 otherwise.
↵* Significant at 10%;
↵** significant at 5%;
↵*** significant at 1%.
2 km Buffer 5 km Buffer 10 km Buffer Model Unmatched Matched Unmatched Matched Unmatched Matched Resident Indigenous OLS −0.0411 −0.037 −0.027 −0.028 0.0008 −0.010 Clustered Std. Err. (0.012)*** (0.014)*** (0.012)** (0.013)** (0.019) (0.015) Observations 96041 47246 95480 42136 94648 26932 Pseudo R2 0.181 0.1474 0.1757 0.119 0.167 0.0896 Nonresident OLS 0.0115 0.0056 0.015 −0.0014 0.015 −0.010 Clustered Std. Err. (0.011) (0.009) (0.013) (0.008) (0.034) (0.032) Observations 95,007 38,176 94,723 29,674 94,602 24,568 Pseudo R2 0.168 0.239 0.164 0.236 0.164 0.242
