Amazonian forests host a very high biodiversity, but suffer deforestation for settling monocultures and livestock. Little is known about how different land-uses shape forest's biodiversity during further recovery. We investigated that by...
moreAmazonian forests host a very high biodiversity, but suffer deforestation for settling monocultures and livestock. Little is known about how different land-uses shape forest's biodiversity during further recovery. We investigated that by using the human-mediated community assembly-hypothesis, combined to the Unified Neutral Theory of Biodiversity and Biogeography (UNTB) as an Ockham's razor. We counted, marked, and identified all trees ≥10cm diameter at breast height on four 1-ha, secondary forest plots with already well-known land-use histories. We assessed the relative species abundances (RSA), richness, diversity, dominance, similarities, and species compositions of all plots. Plots A (12-15), B (22-25), and C (35-37y-old forests) were abandoned pastures and quasi-monocultures. Plot D (35-40y-old forest) was used for self-consumption agriculture (in Kichwa indigenous language chakra-and ushun periods) per six years (>50 planted species), then used for extracting resources-including fruits, medicine, and logs during fallow (purun period). For all plots, RSAs were lognormal (χ 2 ; p>0.24) suggesting that random-and-symmetric birth, death, and immigration from the surrounding metacommunity are enough for explaining RSAs. Species richness, Shannon-, and Fisher's-α diversities changed as follows: plotA<plotB<plotC<plotD while dominance varied in the opposite way. There was virtually no evidence of coppicing. Many species were useful for food, wood, and medicine. Dominant species are mainly wind-, animal-, and human-dispersed. Plot D's species composition was less similar to all other plots. Our results suggest that seed dispersal assembled forest communities according to UNTB, while humans mediated the secondary succession process after clear-cutting for agriculture and livestock by means of: planting, nursing, caring, and tolerating species, and opening gaps (selective logging) during fallow. For Amazonians, letting, respecting and enhancing highly diverse forests generated by natural processes guarantees a safer stock of resources so Amazonians may have no reason to make forest assembly to depart from neutral-and-symmetric birth, death, and immigration during succession.
