Sistema Agroflorestal como alternativa de uso da terra: um estudo de caso na unidade denonstrativa de permacultura (UDP), Manaus-Am.

Abstract

The forests conversion into other land use systems in the Amazon, often results in large areas abandonment after the soil nutrients depletion. Natural regeneration has an important role to restore environmental quality, however, the choice for appropriate production systems and management techniques models enables necessary conditions to assign a permanent agricultural use in the deforested areas. In 1998, a multi-strata agroforestry system was introducted over an intensive land use history site, as a demonstrative project, realized in partnership between the Instituto de Permacultura da Amazônia (IPA), and the Instituto Federal de Educação, Ciência e Tecnologia do Amazonas (IFAM, 59 ° 56'00 .22 "W, 3 ° 04'47 .94" S). This study aimed to analyze the possible environmental quality contributions, provided by the agroforestry (AFS-10) interventions practices, in comparison to the natural regeneration results observed in an adjacent secondary forest area with same age (SF-10), and another secondary forest area with 55 years old (SF-55), located at the Centro de Projetos e Estudos Ambientais do Amazonas - CEPEAM (59 ° 54'23 .65 "W, 3 ° 06'51 .68" S). The treatments were compared by vegetation parameters (composition and structure), soil (macro and micronutrients, and texture), litter (mass and nutrients) and macrofauna (density, biomass, distribution and functional groups). The experiment delineation was completely randomized design, with three plots of 40x40m in each system, divided into 10m sections. The soil, litter and macrofauna samples were performed according to the Tropical Soil Biology and Fertility method (TSBF), from April beginning and June ending in 2008. The litter fisics analysis, and soil and litter chemical analysis, followed, respectively, the recommendations described by Sarruge & Haag (1974) and EMBRAPA (1997). The species, genera and families richness was two times higher in the AFS-10 vegetation in relation to SF-10; the components distribution was more uniform, and the tree diameter growth was three times higher. A principal component analysis (PCA) showed significant differences to the systems’ nutrients levels (p <0.001), where higher values of pH, Ca 2+ , Mg 2+ , P, Zn and Mn were associated to the AFS-10 soil, while higher contents of K + and Al 3+ were related to SF-10 and SF-55 soil. Significant differences (p <0.001) for litter mass and macronutrient content were also confirmed (PCA) to the systems, associating the residual mass fraction and the levels of Ca 2 + , Mg 2+ , K + and P to AFS-10. The macrofauna groups density and richness were lower in the AFS-10. The significant predominance (ACP, p <0.001) of decomposer macrofauna groups ix(Isopoda, Diplopoda, Oligochaeta) was associated with AFS-10, while social groups (Isoptera and Formicidae) stood out in the SF-10 and SF-55. The SF-55 land use history probably favored a superior qualitatively return to the system and can justify the conservation use of this area, while the contributions provided by the AFS-10 interventions, compared to the low capacity for quality feedback from the SF -10 suggest advantage to this model for the productive utilization of the area.