Conservation and Avoided Deforestation: Evidence from Protected Areas of Tanzania
Abstract
:1. Introduction
2. Methodology
2.1. Study Area
2.2. Data and Sampling
2.2.1. Spatial Data on Forests and Deforestation
2.2.2. Sampling and Sample Plots
2.2.3. Covariate Data for Propensity Score Matching (PSM)
2.2.4. Data Limitations
2.3. Data Analysis
2.3.1. Propensity Score Matching
2.3.2. Logistic Modeling, Log Odds of Avoided Deforestation, and the Odds Ratios
- (i)
- A model for an overall protection effect: To assess the overall protection effect, we fitted a binomial logit model (Equation (1)) with a binary response variable—Avoided Deforestation (AD), and a binary predictor representing Treatment (T), indicating whether a forest area was Protected or Unprotected. The purpose is to estimate the change in the odds of avoiding deforestation due to protection compared with unprotected forests.
- (ii)
- Effectiveness of the PA management regimes compared with no protection: To evaluate the effectiveness of the PA management regimes compared with unprotected forest areas, we specified a logit model (Equation (2)). In Equation (2), the response variable was Avoided Deforestation (AD), with a binary outcome, i.e., (AD = 1 if deforestation was avoided; AD = 0 deforestation occurred). The predictor variable was categorical with six levels, representing the five management regimes (NP, GR, FR, NFR, GCA) (see Table 1) and the reference category Unprotected Forests (UF).
- (iii)
- Comparing the effectiveness of the five PA management regimes: After evaluating the effectiveness of each management regime compared with the unprotected forests (UF), we further compared the effectiveness between any two management regimes, using the odds ratio. First, we fitted five additional logit models similar to Equation 1, but each with a different management regime (NP, GR, FR, NFR, and GCA) as the reference category. The resulting coefficients allowed us to calculate the odds ratio between any two management regimes to compare their effectiveness in avoiding deforestation.
- (iv)
- Assessment of Leakage: To assess evidence of leakage, we fitted a logit model (Equation (3)) with a binary response variable (D = 1 if Deforested, D = 0 if not deforested) and a binary predictor representing location (L = 1 if inside buffer areas, L = 0 if in the unprotected forest areas beyond the buffer). Equation (3) estimated the log odds of deforestation within the buffer areas compared with unprotected areas outside the buffer areas.
- (v)
- Computing and interpreting the Odds Ratios (OR). Equations (1)–(3) above estimate the coefficients corresponding to the log odds of avoided deforestation. However, for a more intuitive comparison of the effectiveness of protection against no protection, a quantitative comparison of the different management regimes, or assessing leakage, we calculated the odds ratio (OR). The OR is computed as OR = exp(βi), where βi is the slope coefficient for the predictor variable (s) in each equation. For interpretation of the OR values, for instance, an OR > 1 indicates higher odds of avoided deforestation compared with the reference category. The computation of ORs also generates a Wald Confidence Interval (WCI). The WCIs were used to assess the statistical significance of each OR. Accordingly, confidence intervals that do not include 1 were considered statistically significant.
3. Results
3.1. The Overall Effect of Protection
3.2. Effectiveness of PA Management Regimes Compared with Unprotected Areas
3.3. Differences between Pairs of Management Regimes
3.4. Evidence of Leakage
4. Discussion
4.1. Conservation Outcomes Are Positive Despite Continued Deforestation
4.2. Management Regimes Presented Variable Effectiveness
4.3. Limited Evidence of Deforestation Displacement
4.4. Implications to Climate and Biodiversity Objectives
5. Summary and Conclusions
Author Contributions
Funding
Data Availability Statement
Acknowledgments
Conflicts of Interest
References
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PA Managing Authority | PA Management Regime | Number of PAs | Area (1000 ha) |
---|---|---|---|
Tanzania Forest Services | Nature Forest Reserves (NFR) | 8 | 73 |
Forest Reserves (FR) | 657 | 14,240 | |
Forest Plantations (FP) | 23 | 5961 | |
Tanzania Wildlife Management Authority | Game Controlled Areas (GCA) | 18 | 8256 |
Game Reserves (GR) | 17 | 4848 | |
Tanzania National Parks Authority | National Parks (NP) | 17 | 330 |
Total | 740 | 33,707 |
Covariate | Description | Source |
---|---|---|
Elevation | Elevation in meters above mean sea level | ASTER GDEM V2 [24] |
Slope | Slope (%) | |
Agricultural areas | Polygons of Farmlands in Tanzania for the period near 2012 | [26] |
Water bodies | Shape-file of inland water bodies of Tanzania | [26] |
Towns | Towns from The Multipurpose Africover Database for the Environmental Resources produced by the Food and Agriculture Organization of the United Nations (FAO). | [27] |
Roads | Center line of principal roads extracted from Open Street Map. | [28] |
International boundaries | Shape polygon of Tanzania Administrative level | [29] |
Management Regime | Odds Ratio (Protected vs. Unprotected) | Lower 95% CI | Upper 95% CI |
---|---|---|---|
National Parks | 8.54 * | 7.11 | 10.32 |
Game Reserves | 9.76 * | 8.76 | 11.16 |
Nature Forest Reserves | 2.05 * | 1.53 | 2.76 |
Game Controlled Areas | 2.28 * | 2.10 | 2.53 |
Forest Reserves | 1.58 * | 1.51 | 1.66 |
Reference Management Regime | ||||||
---|---|---|---|---|---|---|
Management Regime | Game Reserves | National Parks | Game Controlled Areas | Nature Forest Reserves | Forest Reserves | |
Game Reserves | 1 | 1.14 a | 4.28 * | 4.77 * | 6.18 * | |
National Parks | 0.87 a | 1 | 3.75 * | 4.17 * | 5.40 * | |
Game Controlled Areas | 0.23 * | 0.27 * | 1 | 1.11 b | 1.44 * | |
Nature Forest Reserves | 0.21 * | 0.24 * | 0.90 b | 1 | 1.30 c | |
Forest Reserves | 0.16 * | 0.18 * | 0.69 * | 0.77 c | 1 |
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Gizachew, B.; Shirima, D.D.; Rizzi, J.; Kukunda, C.B.; Zahabu, E. Conservation and Avoided Deforestation: Evidence from Protected Areas of Tanzania. Forests 2024, 15, 1593. https://doi.org/10.3390/f15091593
Gizachew B, Shirima DD, Rizzi J, Kukunda CB, Zahabu E. Conservation and Avoided Deforestation: Evidence from Protected Areas of Tanzania. Forests. 2024; 15(9):1593. https://doi.org/10.3390/f15091593
Chicago/Turabian StyleGizachew, Belachew, Deo D. Shirima, Jonathan Rizzi, Collins B. Kukunda, and Eliakimu Zahabu. 2024. "Conservation and Avoided Deforestation: Evidence from Protected Areas of Tanzania" Forests 15, no. 9: 1593. https://doi.org/10.3390/f15091593