Traços funcionais de duas leguminosas arbóreas: translocação de nutrientes e associação micorrízica

Abstract

The environmental impacts caused by trees in reforestation projects can be influenced by the nutritional requirements of the species and the quality of the litter that contributes to the soil. Species that show faster growth tend to accumulate more nutrients per unit of biomass than species that grow more slowly. The objectives of this work were: 1) to evaluate the use of nutrients through the assessment of the nutritional status, translocation and efficiency of use of N, P, K. Ca, Mg and S using the leaves; 2) to evaluate the quality of the litter using indicators of degradability such as C / N, QHL, ILC; 3) and estimate the rate of mycorrhizal infestation in thin roots of adult Schizolobium parahyba (paricá) and Anadenanthera peregrina (angico) in monoculture. Their symbiotic association with N2-fixing bacteria distinguishes the species, by the density of the wood and by their growth rates. Both species are senescent and were 96 months old during the evaluations. For the study, 9 trees per species were selected in the 3x3m spacing, distributed in 3 plots. In these trees, senescent leaves and green leaves were collected, and thin roots were used to evaluate mycorrhiza. Paricá showed higher rates of translocation of nutrients when compared to angico, with emphasis on phosphorus (63%). Paricá was more efficient in using N than Angico. Angico's leaf litter is more easily degraded than paricá leaf litter. The presence of arbuscular mycorrhizal fungi was detected in the fine roots of paricá and angico with an infestation rate of 66% and 73%, respectively. The present study indicates that the species present differences in the use of nutrients and in the quality of the litter, with angico providing 105% more of N to the soil when compared to paricá, in addition to a greater ease of degradation of its leaves. These characteristics can lead to different impacts on soil chemistry and fertility