Influence of different agroforestry production modules on fine roots biomass in the southeastern Amazon

Abstract

AFS provide important ecosystem services associated with carbon (C) cycling and dynamics and can store C in plant biomass that is often comparable to natural forests. The aim of this study was to quantify and compare the biomass of fine roots (diameter ≤2mm) in different SAF modules (M1, M2, M3, M4, M5) in the southeast of Pará, using two adjacent areas (Urochloa sp. pasture and secondary forest) as a reference. The modules have common crops (banana, manioc, pineapple, corn, cocoa), varying according to the other species intercropped. Each module has an area of 2 ha, the same history and time of implantation, and five 5×5 m plots were randomly installed in each one, where we collected 3 soil samples (0-10 cm) with a volumetric cylinder (196 cm³). In the laboratory, the roots were washed in running water under a 0.5 mm mesh and sorted using tweezers and a caliper. Root biomass was estimated using dry mass (g.m²) and statistical comparisons were made using ANOVA and Tukey's post-test. Forest and pasture showed greater fine root biomass compared to the SAF modules, which were similar to each other (p<0.001; Forest=283.95g.m²; M1=89.01g.m²; M2=65.89g.m²; M3=56.27g.m²; M4=115.96g.m²; M5=81.44g.m²; Pasture =359.25g.m²). In the forest, the high density and diversity of species can increase biomass. The similarity between the SAF modules indicates that the time of implementation (one year) is insufficient to influence root biomass differently, and that the history of the area and soil management influence root biomass, differentiating it from the forest analyzed.