Print PageBackground/Question/Methods
Within the Brazilian Amazon, protected areas (PAs) are effective in inhibiting rates of deforestation and fire incidence. Roughly 21% of the Brazilian Amazon is designated as terras indigenas (TIs). While populated reserves may be included in studies of conservation within PAs, TIs are not managed under uniform rules like most federally established PAs but rather as semi-autonomous territories granting indigenous people sovereign use rights. This study examined the effectiveness of 197 TIs across the Brazilian Amazon to inhibit fire. Using remotely-sensed (AVHRR) fire incidence data from 1999-2006 for TIs and surrounding areas, we integrated GIS-based spatial analyses and non-parametric statistical hypothesis testing to examine patterns in the distribution of fires within TIs and surrounding buffer regions of 20km and 60km. A ratio of fire inhibition (RFI) for each high fire pressure TI and corresponding 20 km buffer was created for every year from 1999-2006, with fire inhibition “effectiveness” ranging from highly fire resistant ( < 0.25) to fire-originating ( > 1.1). To explore the influence of confounding factors (e.g. road proximity and vegetation type), we created a spatially-explicit probabilistic model of fire incidence. Finally, expert knowledge of reserves and tribal history provided insight into the most anomalous reserves.
Results/Conclusions
Of the 197 TIs, 128 were located in regions with near-zero background fire levels, located in forest ecosystems of the central and western Amazon. Our analysis of fire inhibition was thus restricted to the 69 TIs located in regions of high fire incidence (located in the central and eastern Amazon). Using our RFI, we found that most (n=50) TIs offer some protection against fire compared to buffers. TI effectiveness ranged from highly resistant (n=20) to highly susceptible (n=7) to fire pressure. Twelve TIs had fire pressure originating within reserve boundaries, mostly in cerrado areas bordering the ‘arc of deforestation’. Proximity to paved roads, presence of cerrado and grassland ecosystems, and a long dry season were positively correlated with fire incidence, though did not explain higher fire inhibition within TIs. The reserve with the highest fire incidence, Maraiwatsede, was found to be operating effectively as cattle ranch and soy plantation despite its TI designation, and has been subject to intense conflict over land ownership. With increasing land-use demands upon the Brazilian Amazon, this study provides an example of how the secure establishment of sovereign rights may lead to positive and sustainable conservation outcomes.
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