The effect of land use on aboveground biomass and soil quality indicators in spontaneous forests and agroforests of eastern Amazonia

This study unites physicochemical indicators of aboveground vegetation, litter layer and topsoil (0–20 cm) in contrasting vegetation types commonly found in the eastern Amazonia. We compare three agroforestry systems (enriched fallows, homegardens and commercial plantations) with three spontaneous forest types (young and old secondary forests and mature rainforests) via one-way ANOVA, linear and non-linear regressions and multivariate analyses. Agroforests had significantly lower understory biomass when compared with young secondary forest. Commercial plantation agroforests had higher topsoil pH and Ca-contents and homegardens had higher K-contents and P-availability hotspots, as revealed by their higher variance and single very high values. Agroforests and spontaneous forests were similar in their litter biomass (both leaves and twigs) and C:N ratio, and in soil organic matter and P contents. The overstory negatively impacted the understory ( r 2 = 0.20, p