Secondary forests on anthropogenic soils in Brazilian Amazonia conserve agrobiodiversity

Abstract

Throughout Brazilian Amazonia anthropogenic soils that are the product of pre-Columbian settlements are called Terra Preta de Índio (Indian Dark Earths, TPI). These soils are dramatically different from surrounding soils due to long-term human activity, but there is little information about how secondary forest succession is affected by these differences. We tested if community structure (density, richness and basal area), floristic composition and domesticated species' richness and density were similar between TPI and non-anthropogenic soils (NAS) in 52 25 9 10 m secondary forest plots in different successional stages near three traditional communities along the middle Madeira River, Central Amazonia. We sampled 858 woody individuals on TPI (77 domesticated) and 1095 on NAS (27 domesticated); 550 understory palms on TPI (169 domesticated) and 778 on NAS (123 domesticated). We found 179 species on TPI (10 domesticated), 190 on NAS (8 domesticated), and 74 (25%) in both environments. Although community structure on TPI and NAS was fairly similar, they showed significantly distinctive floristic compositions, both for woody individuals and understory palms. The density and richness of domesticated species was significantly higher on TPI than on NAS for woody individuals, but not for palms. The intimate long-term association of TPI with human activity has lead to the formation of distinct secondary forests and has favored the concentration of domesticated populations of crop species. Hence, secondary forests on anthropogenic soils concentrate agrobiodiversity, offering advantages for in situ conservation of genetic resources, and are unique ecosystems that should be considered in conservation efforts.

Natural forest regeneration in abandoned sugarcane fields in northeastern Brazil: floristic changes

“…12,no. 4 did not encounter any significant correlation between the forest ages and their floristic compositions -with each locality following a distinct and idiosyncratic path of species accumulation driven by edaphic factors (Guariguata & Ostertag 2001), colonizing species (Chazdon 2003, Junqueira et al 2010, and the landscape matrix (Bierregaard et al 1992, Nascimento & Laurance 2006. Together these results indicate that the preservation of conserved forest fragments near areas undergoing regeneration permits genetic flux and the continuity of successional processes.…”

The role of Amazonian anthropogenic soils in shifting cultivation: learning from farmers’ rationales

“…When abandoned, they form the "capoeira" (fallow), which lasts for 3-15 years before being opened again for cultivation. The swiddens are mainly cultivated with annual or biannual crops, although fruit trees and palms are planted and/or favored in some swiddens, which results in secondary forests with a high abundance of useful plants (Junqueira et al 2010(Junqueira et al , 2011. Manioc is, by far, the most cultivated crop; it is the most important component of the local diet and also the most important crop economically and culturally (Fraser 2010a, Fraser et al 2012, Junqueira et al 2016.…”

“…Amazonian dark earths contrast strongly with adjacent nonanthropogenic soils, which in most of Amazonia are infertile and acidic (Chauvel et al 1987). The differences in soils are reflected in differences in weed community composition and growth (Major et al 2003(Major et al , 2005, in the assemblage of cultivated crops and landraces (Fraser et al 2011a, Kawa et al 2011, and in the composition and usefulness of fallow vegetation (Junqueira et al 2010(Junqueira et al , 2011. Shifting cultivation systems on ADE are very heterogeneous and often more intensified when compared to other upland soils, with shorter fallow periods (German 2003a, Fraser et al 2012) and/or focused on nutrient-demanding crops (Kawa et al 2011).…”

Mundos de roças e florestas

“…Ao contrário do que a visão comum aponta, boa parte da Amazônia não seria um berço de natureza intocada, mas sim florestas antropizadas. Do mesmo modo, a Terra Preta de Índio Shepard;Clement, 2010) -solo rico em matéria orgânica e amplamente procurado por populações locais por sua fertilidade -seria resultado da dinâmica de ocupações pré-colombianas. As florestas e solos antropizados, em um processo que que Clement (2006) juntamente com outros autores denomina de "domesticação da paisagem", são altamente valorados devido ao alto potencial produtivo (maior quantidade de frutas, alta biodiversidade e espaços propícios para os roçados).…”