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Geographic distribution of isolated indigenous societies in Amazonia and the efficacy of indigenous territories.

Kesler DC, Walker RS - PLoS ONE (2015)

Bottom Line: Isolated villages were identified at mid elevations, within 20 km of the tops of watersheds and at greater distances from existing roads and trails.We further used model results, combined with boundaries of the existing indigenous territory system that is designed to protect indigenous lands, to assess the efficacy of the existing protected area network for isolated peoples.Our results are intended to help inform policies that can mitigate against future external threats to isolated peoples.

View Article: PubMed Central - PubMed

Affiliation: Fisheries and Wildlife Sciences Department, University of Missouri, Columbia, Missouri 65211, United States of America.

ABSTRACT
The headwaters of the Amazon Basin harbor most of the world's last indigenous peoples who have limited contact with encroaching colonists. Knowledge of the geographic distribution of these isolated groups is essential to assist with the development of immediate protections for vulnerable indigenous settlements. We used remote sensing to document the locations of 28 isolated villages within the four Brazilian states of Acre, Amazonas, Roraima, and Rondônia. The sites were confirmed during previous over-flights and by image evidence of thatched-roof houses; they are estimated to host over 1,700 individuals. Locational data were used to train maximum entropy models that identified landscape and anthropogenic features associated with the occurrence of isolated indigenous villages, including elevation, proximity to streams of five different orders, proximity to roads and settlements, proximity to recent deforestation, and vegetation cover type. Isolated villages were identified at mid elevations, within 20 km of the tops of watersheds and at greater distances from existing roads and trails. We further used model results, combined with boundaries of the existing indigenous territory system that is designed to protect indigenous lands, to assess the efficacy of the existing protected area network for isolated peoples. Results indicate that existing indigenous territories encompass all of the villages we identified, and 50% of the areas with high predicted probabilities of isolated village occurrence. Our results are intended to help inform policies that can mitigate against future external threats to isolated peoples.

No MeSH data available.


Related in: MedlinePlus

Marginal response curves.Marginal response curves for the top three variables included in the MaxEnt model of occurrence of isolated tribes in the Amazon Basin of Brazil. Plots reflect the dependence of predicted site suitability on each variable, and on dependencies induced by correlations between variables.
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pone.0125113.g003: Marginal response curves.Marginal response curves for the top three variables included in the MaxEnt model of occurrence of isolated tribes in the Amazon Basin of Brazil. Plots reflect the dependence of predicted site suitability on each variable, and on dependencies induced by correlations between variables.

Mentions: The village distribution model resulting from the first stage MaxEnt analysis of the 10 environmental variables identified regions of high occurrence probabilities, primarily in the southwestern portions of the study area in the states of Amazonas and Acre (Fig 2). Results further indicated strong model fit (mean AUC = 0.899; SD 0.041), so the resulting model was well above the utility threshold of 0.75. Site elevation, proximity to streams of orders 3 or higher, and proximity to roads were most influential in the model, and together the variables accounted for 72% of the model contribution (Table 1). The shape of the marginal response curves (Fig 3 and S3 Fig) for elevation indicated that village occurrence probabilities were low at the lowest elevations and that they peaked at approximately 150 m before declining again at higher elevations. Similarly, model results indicate that occurrence probabilities were low in areas close to streams of order 3 or higher, but that probabilities increased and plateaued at approximately 26 km away. Village occurrence probabilities also peaked at approximately 156 km from existing roads and trails, and then decline with greater distances. Notably, response curves for environmental variables for the village distribution model, and marginal curves created using only single variables were generally similar to the multivariate results (Fig 3).


Geographic distribution of isolated indigenous societies in Amazonia and the efficacy of indigenous territories.

Kesler DC, Walker RS - PLoS ONE (2015)

Marginal response curves.Marginal response curves for the top three variables included in the MaxEnt model of occurrence of isolated tribes in the Amazon Basin of Brazil. Plots reflect the dependence of predicted site suitability on each variable, and on dependencies induced by correlations between variables.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4430527&req=5

pone.0125113.g003: Marginal response curves.Marginal response curves for the top three variables included in the MaxEnt model of occurrence of isolated tribes in the Amazon Basin of Brazil. Plots reflect the dependence of predicted site suitability on each variable, and on dependencies induced by correlations between variables.
Mentions: The village distribution model resulting from the first stage MaxEnt analysis of the 10 environmental variables identified regions of high occurrence probabilities, primarily in the southwestern portions of the study area in the states of Amazonas and Acre (Fig 2). Results further indicated strong model fit (mean AUC = 0.899; SD 0.041), so the resulting model was well above the utility threshold of 0.75. Site elevation, proximity to streams of orders 3 or higher, and proximity to roads were most influential in the model, and together the variables accounted for 72% of the model contribution (Table 1). The shape of the marginal response curves (Fig 3 and S3 Fig) for elevation indicated that village occurrence probabilities were low at the lowest elevations and that they peaked at approximately 150 m before declining again at higher elevations. Similarly, model results indicate that occurrence probabilities were low in areas close to streams of order 3 or higher, but that probabilities increased and plateaued at approximately 26 km away. Village occurrence probabilities also peaked at approximately 156 km from existing roads and trails, and then decline with greater distances. Notably, response curves for environmental variables for the village distribution model, and marginal curves created using only single variables were generally similar to the multivariate results (Fig 3).

Bottom Line: Isolated villages were identified at mid elevations, within 20 km of the tops of watersheds and at greater distances from existing roads and trails.We further used model results, combined with boundaries of the existing indigenous territory system that is designed to protect indigenous lands, to assess the efficacy of the existing protected area network for isolated peoples.Our results are intended to help inform policies that can mitigate against future external threats to isolated peoples.

View Article: PubMed Central - PubMed

Affiliation: Fisheries and Wildlife Sciences Department, University of Missouri, Columbia, Missouri 65211, United States of America.

ABSTRACT
The headwaters of the Amazon Basin harbor most of the world's last indigenous peoples who have limited contact with encroaching colonists. Knowledge of the geographic distribution of these isolated groups is essential to assist with the development of immediate protections for vulnerable indigenous settlements. We used remote sensing to document the locations of 28 isolated villages within the four Brazilian states of Acre, Amazonas, Roraima, and Rondônia. The sites were confirmed during previous over-flights and by image evidence of thatched-roof houses; they are estimated to host over 1,700 individuals. Locational data were used to train maximum entropy models that identified landscape and anthropogenic features associated with the occurrence of isolated indigenous villages, including elevation, proximity to streams of five different orders, proximity to roads and settlements, proximity to recent deforestation, and vegetation cover type. Isolated villages were identified at mid elevations, within 20 km of the tops of watersheds and at greater distances from existing roads and trails. We further used model results, combined with boundaries of the existing indigenous territory system that is designed to protect indigenous lands, to assess the efficacy of the existing protected area network for isolated peoples. Results indicate that existing indigenous territories encompass all of the villages we identified, and 50% of the areas with high predicted probabilities of isolated village occurrence. Our results are intended to help inform policies that can mitigate against future external threats to isolated peoples.

No MeSH data available.


Related in: MedlinePlus