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African mahoganies can be an alternative for wood production in agroforestry systems and/or mixed-species plantations. In this study, we aimed to evaluate the growth, yield and stem form of Khaya grandifoliola C. DC. and Khaya ivorensis A. Chev. established in successional agroforestry systems and in mixed plantations of both species. A randomized...
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... The results suggest that part of such nutrients was quickly mineralized and uptaken by African mahogany trees. This fact can be evidenced by the high growth index of both species in treatment T1, right after the regenerating plants desiccation (Santos et al., 2020). However, the absence of statistical differences in the stocks of all macronutrients in the biomass of regenerating plants (level I) also indicates that another part of these nutrients may be reuptaken by the regenerating plants that colonized the areas of this treatment. ...
... The highest biomass production and the greatest enrichment of N, P, K, Ca and Mg in the aboveground biomass of the natural regeneration of T4, in relation to those of T2, suggest that they may be benefiting from the residual nutrients applied to the agroforestry species through fertilization, as it was observed for African mahogany trees (mainly for K. ivorensis - (Santos et al., 2020)). This fact allows greater efficiency in the conservation of nutrients in organic structures of regenerating species, especially for those nutrients with higher mobility in the soil (N and K, for example) and more subject to leaching losses. ...
Our aims were to describe the role of the selective management of regenerating community (RC) on the recovery of ecosystem functions in production areas of African mahoganies under mixed stands and agroforestry systems, established on abandoned farmland. A randomized block experiment was set up with the following treatments: (T1) mixed-plantation of African mahogany under conventional system (including herbicide application); (T2) mixed-plantation of African mahogany with selective conduction of RC; (T3) agroforestry system with African mahogany; (T4) agroforestry system with African mahogany with selective conduction of RC. The parameters of horizontal structure, diversity and ecological attributes of species of the regenerating community were studied. In addition, the production of aboveground biomass and nutrient stocks, soil fertility, and soil microbial activity were assessed. In T1, herbicide application (glyphosate) affected the floristic composition of the regenerating community by reducing the dominance of monocots and Pteridium arachnoideum, allowing the regeneration of other taxonomic groups of herbaceous species. In response, there was a reduction in the litter biomass stock comparing to the other treatments. The treatments with selective management of the RC (T2 and T4) produced more biomass and accumulated higher amounts of C and nutrients than the conventional treatments (T1 and T3). These treatments also allowed other shrub and tree species to overcome the ecological filter imposed by grasses and colonize the experimental area. Baccharis dracunculifolia, Vismia guianensis, Cecropia pachystachya and Inga sp. were the most important regenerating species that contributed most to the stocks of all nutrients in living aboveground biomass. Pruning and selective management in T4 increased the soil effective cation exchange, while in the T1 treatment there was a lower activity of the β-glucosidase enzyme. The selective management of RC in agroforestry systems through the manipulation of competitive relationships allowed the colonization of native tree and shrubby species that provide several additional ecosystem services, including pollination, fauna attraction, food production, pest control and environmental regulation for the agroecosystem.
Agroforestry systems such as Taungya are sustainable alternatives for the recovery of degraded areas and profitability with commercial plantations, providing improvements in soil physical, chemical, and biological properties. In this context, African mahogany (Khaya ivorensis A. Chev) emerges as an important forest species in Brazil, with the potential for intercropping. The objective of this study was to evaluate the growth and economic return from the Taungya system compared to K. ivorensis monoculture in a degraded area in the humid tropics. Three planting systems were studied: T1, monoculture (K. ivorensis); T2, K. ivorensis + 1st cycle with Zea mays + 2nd cycle with Manihot esculenta; T3, K. ivorensis + 1st cycle with Vigna unguiculata + 2nd cycle with Zea mays. The survival, growth, and relative increments in plant height and stem diameter were determined for the three management systems. Productivity of the agricultural crops was quantified, and bacteriological analyses of the soil and economic systems were performed. The Taungya system with bean and corn crops provided greater growth of K. ivorensis, in addition to a greater density of total bacteria in the soil and provided a higher level of soil conditioning. In these systems, the cultivation and sale of agricultural crops can amortize the total cost of planting and maintenance of plantations with forest species, especially if family labor is considered. However, the completion of additional agricultural cycles may further amortize these investments.
