Content of nutrients in the biomass and nutritional efficiency in species of 'Caatinga' biome/Conteudo de nutrientes na biomassa e eficiencia nutricional em especies da Caatinga

It was aimed to know the content of mineral nutrients in the components of the biomass of the aerial part of the species of the biggest value of importance in two areas of Caatinga and to evaluate the efficiency of these plants in the use of these nutrients. The research was carried through Itapemirim farm in Floresta, Pernambuco state, where two areas of vegetation of Caatinga inside the farm were studied, presenting distinct characteristics, one in period of training of regeneration, and the other one was preserved. In the sampling, an initial inventory was made launching 40 parcels of 400[m.sup.2] in each area, having as level of inclusion CBH [greater than or equal to] 6.0 cm. For the analysis of biomass, it was used the five species of the biggest value of importance of each area, the choice of the individuals was at random and each chosen plant had measured its circumference the height of the chest and in the base. In the process of weighing and sampling the components of the aerial part, the chosen trees had been knocked down and after that, their components were all weighed and a sample was removed for the chemical analyses. In this study, it was observed that the initial survey in the two areas, bracteosa Poincianella was the species that presented greater content of nutrients in the total biomass above the ground in both the areas. The component twig was of bigger contribution in the content of nutrients in the total biomass, being N the accumulated nutrient more in the component leaf, and in timber components in both the areas, once the nutrients that presented the greatest efficiency for their use in the plants studied in both the areas, were S and P. Keywords: above ground biomass; nutrient stock; nutrient use. Objetivou-se quantificar o conteudo de nutrientes nos componentes da biomassa da parte aerea das especies de maior valor de importancia em duas areas de Caatinga e avaliar a eficiencia dessas plantas no uso desses nutrientes. A pesquisa foi realizada na fazenda Itapemirim, no municipio de Floresta--PE, onde foram estudadas duas areas de vegetacao de Caatinga em fases distintas de sucessao ecologica, apresentando caracteristicas distintas, uma em estagio de regeneracao e outra preservada. Na amostragem foi realizado um inventario inicial se lancando 40 parcelas de 400 [m.sup.2] em cada area, tendo como nivel de inclusao CAP [greater than or equal to] 6,0 cm. Para analise da biomassa foram utilizadas as cinco especies de maior valor de im