Journal of Biogeography
SUPPORTING INFORMATION
Uncovering spatial patterns in the natural and human history of Brazil nut (Bertholletia excelsa)
across the Amazon Basin
Evert Thomas, Carolina Alcazar Caicedo, Crystal H. McMichael, Ronald Corvera and Judy Loo
Appendix S3 Supporting maps and figures.
Figure S1 Comparison Amazonian Dark Earth (ADE) buffers (60 km) with ADE suitability map
(McMichael et al., 2014a).
Figure S2 Comparison geoglyph buffers (60 km) with geoglyph suitability map (McMichael et al.,
2014b).
Figure S3 Maxima of average Brazil nut (Bertholletia excelsa) stand diameters (stems ≥ 10 cm d.b.h.) at
resolution of 30 and 2.5 arc-minutes for the Amazon Basin and Madre de Dios, respectively, to improve
visual representation. The hatched areas represent buffer areas of 60 km radius around known ADE
(black) and geoglyph (brown) sites, respectively. The red polygons represent different regions in
Amazonia (NWA: north-western Amazonia; SWA: south-western Amazonia; CA: central Amazonia; SA:
southern Amazonia; EA: eastern Amazonia; GS: Guiana shield; after ter Steege et al., 2013)
Figure S4 Comparison of habitat suitability, stand densities and average stand diameters of Brazil nut in
and outside of ADE and geoglyph buffer areas. Significant differences between different areas are
indicated by different letters (‘abc’ and ‘ABC’ for 30 and 60 km buffers, respectively; P < 0.05;
Wilcoxon and chi-square tests for habitat suitability and density and diameter comparisons, respectively).
Figure S5 Comparison of ADE suitability scores (based on McMichael et al., 2014a) between Brazil nut
stands with at least 8 trees ha−1, or less. Numbers associated with points are sample sizes. Significance
levels are given above the x-axis (NS = not significant; * P < 0.05; ** P < 0.01; *** P < 0.001; Wilcoxon
tests). Error bars represent standard error the mean.
(a)
(b)
(c)
(d)
Figure S6 Variation across a south-western to north-eastern gradient of the proportion of high density
Brazil nut stands (≥ 5, ≥ 8, ≥ 10 and ≥ 15 stems ha−1, respectively) over all stands considered. Individual
boxplots show the distribution of proportions calculated from 1,000 bootstrap samples (with replacement)
of the minimum sample size of 15 Brazil nut stands (i.e. the total number of stands in our dataset for the
north-easternmost area of comparison). Distributions were significantly different (P << 0.001) across
areas of comparison (Kruskal–Wallis chi-square tests). Letters indicate groups of study areas with similar
distributions, based on multiple comparison post-hoc tests (threshold at P < 0.05) (Siegel & Castellan,
1988; Giraudoux, 2014).
(a)
(b)
(c)
(d)
Figure S7 Variation across a south-western to north-eastern gradient of the proportion of Brazil nut
stands with high average diameters (≥ 125, ≥ 130, ≥ 135 and ≥ 140cm d.b.h., respectively) over all stands
considered. Individual boxplots show the distribution of proportions calculated from 1,000 bootstrap
samples (with replacement) of the minimum sample size of seven Brazil nut stands (i.e. the total number
of stands in our dataset with diameter data for the north-easternmost area of comparison). Distributions
were significantly different (P << 0.001) across areas of comparison (Kruskal–Wallis chi-square tests).
Letters indicate groups of study areas with similar distributions, based on multiple comparison post-hoc
tests (threshold at P < 0.05) (Siegel & Castellan, 1988; Giraudoux, 2014).
Figure S8 Precipitation during the coldest quarter of the year (http://www.worldclim.org), compared to
the location of Brazil nut records. Most high density Brazil nut stands are located in the areas receiving
higher levels of precipitation.
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