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. 2012;7(3):e33373.
doi: 10.1371/journal.pone.0033373. Epub 2012 Mar 9.

Wildfires in Bamboo-Dominated Amazonian Forest: Impacts on Above-Ground Biomass and Biodiversity

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Free PMC article

Wildfires in Bamboo-Dominated Amazonian Forest: Impacts on Above-Ground Biomass and Biodiversity

Jos Barlow et al. PLoS One. .
Free PMC article

Erratum in

  • PLoS One. 2012;7(6). doi:10.1371/annotation/8013f95e-71f4-4ec0-afe9-00cea6627685

Abstract

Fire has become an increasingly important disturbance event in south-western Amazonia. We conducted the first assessment of the ecological impacts of these wildfires in 2008, sampling forest structure and biodiversity along twelve 500 m transects in the Chico Mendes Extractive Reserve, Acre, Brazil. Six transects were placed in unburned forests and six were in forests that burned during a series of forest fires that occurred from August to October 2005. Normalized Burn Ratio (NBR) calculations, based on Landsat reflectance data, indicate that all transects were similar prior to the fires. We sampled understorey and canopy vegetation, birds using both mist nets and point counts, coprophagous dung beetles and the leaf-litter ant fauna. Fire had limited influence upon either faunal or floral species richness or community structure responses, and stems <10 cm DBH were the only group to show highly significant (p = 0.001) community turnover in burned forests. Mean aboveground live biomass was statistically indistinguishable in the unburned and burned plots, although there was a significant increase in the total abundance of dead stems in burned plots. Comparisons with previous studies suggest that wildfires had much less effect upon forest structure and biodiversity in these south-western Amazonian forests than in central and eastern Amazonia, where most fire research has been undertaken to date. We discuss potential reasons for the apparent greater resilience of our study plots to wildfire, examining the role of fire intensity, bamboo dominance, background rates of disturbance, landscape and soil conditions.

Conflict of interest statement

Competing Interests: The authors have declared that no competing interests exist.

Figures

Figure 1
Figure 1. Landsat imagery of the study area (26/062006), showing fire scars (blotchy red areas) from the 2005 fires and the location of the 6 burned and 6 unburned study plots in the RESEX Chico Mendes (red and white bars, respectively).
Figure 2
Figure 2. Mean ± SD of the Normalized Burn Ratio (NBR) across the six unburned and six transects that burned in 2005 (arrow).
The NBR is widely used to detect burned forests from Landsat reflectance data. The lower NBR values in unburned forests in 2005 likely reflect smoke from ongoing fires (the image was taken on the 11th of September during the peak of the fire season) and possibly some impact of the drought. The NBR values prior to 2005 provide evidence suggesting the transects were similar before the fires; the NBR values after 2005 show the stability of the unburned plots, and the recovery of canopy cover in the burned plots, up to the time of the field sampling in 2008.
Figure 3
Figure 3. Mean (±SE) number of trees and mean (±SE) aboveground biomass per hectare, measured three years after fire.
Significant differences between unburned and burned plots are shown by *<0.05, **<0.01.
Figure 4
Figure 4. The percentage change in the number of live and dead trees recorded three years after wildfires in the RESEX Arapiuns-Tapajos (Pará) and the RESEX Chico Mendes (Acre).
Horizontal dashed lines represent the average values recorded in control plots in each region. Significant differences were tested with chi-square, using the % change in Para to calculate the expected change in Acre. Significance is shown as *<0.05, **<0.01, ***<0.001.
Figure 5
Figure 5. MDS ordination and Analysis of Similarity results comparing community structure in unburned control plots (clear symbols) and burned forest plots (grey symbols).
Figure 6
Figure 6. Individual-based species accumulation curves comparing species richness in burned forest plots with the unburned control plots.
The dotted lines represent the 95% confidence interval for the unburned forests.

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