Continental patterns in the human-mediated diaspora of Brazil nut (Bertholletia excelsa Bonpl.) across the Amazon Basin

Brazil nut has been important for human livelihoods and regional economies ever since the peopling of the Amazon basin more than 12,000 years ago. A meta-analysis of literature data suggests that pre-Columbian humans not only influenced the distribution of the species, but also the abundance, and in some cases the demography of Brazil nut populations. However, the footprints of human influences do not seem to be distributed randomly, but respond to a continental pattern with increasing human influences from southwestern to central and eastern Amazonia. We hypothesize that in the southwestern Amazon, natural regeneration of Brazil nut is controlled predominantly by natural processes, whereas in central and eastern Amazonia, anthropogenic disturbance has been more important since pre-Columbian times. We provide support for this hypothesis by relating it to differences in (i) human occupation and livelihood strategies, (ii) disturbance regimes, and (iii) ecological processes between southwestern and central and eastern Amazonia.