Comparação da estrutura e do teor de nutrientes nos solos e nas folhas de especies arboreas de duas matas mesofilas semideciduas no triangulo mineiro

AUTOR(ES)
DATA DE PUBLICAÇÃO

1992

RESUMO

The soil availability and foliar concentrations of nutrients in the tree species of two mesophytic semideciduous forests in Triângulo Mineiro, Minas Gerais, were compared to determine the influence of soil fertility on the mineral nutrition of these two communities. Phytosociological surveys of tree especies (circunference at breast height greater than or egual to 10 cm) were carried out in fifty 10 m x 10 m plots in each forest, one at Estação Ecológica do Panga and the other at Fazenda Experimental do Glória, both properties belonging to the Universidade Federal de Uberlândia. Soil samples from the A1 and A3 horizons from each plot were analyzed to determine soil texture, pH, organic matter content and the availability of plant nutrients. Leaf samples from alI tree species in the two areas were analyzed to determine their concentrations of N, P, K, Ca, Mg, Fe, Mn, Zn, Cu and AI. The soil and leaf samples were collected at the end of the rainy season. A total of 151 species belonging to 104 genera and 53 families were present in the two forests. Ninety-three species belonging to 73 genera and 42 families, with a tree density of 2202 individual ha-1 and a basal area of 23.8 m2 h-1, were encountered in the forest community at Panga and ninety-six species belonging to 78 genera and 44 families, with a tree density of 1632 individuaIs ha-1 and a basal area of 28 m2 ha-1 , in the forest community at Glória. Thirty-eight species belonging to 47 genera and 36 familias were common to both communities. The Shannon diversity index for species was 3.7 at Panga and 4.1 at Glória. The five most important species at Panga were Lithraea molleoides, Chrysophyllum marginatum, Campomanesia velutina, Alibertia sessilis and Terminalia brasiliensis, accounting for 30% of the total of the importance value index. Ocotea corymboBa, Cryptocarya moschata ta, Machaerium villosum, Copaifera langsdorfii and Casearia grandiflora, the five most important species at Glória accounted for only 20% of the total of the importance value index. The soil at Panga was sandy loam and the soil at Glória was clayey. Soil pH, available Ca and Mn, and base saturation were higher in the A~ horizon at Panga than at Glória. Organic matter content, saturation of AI and availabiity of Fe, Zn, Cu and AI were higher at Glória. There was no significant difference between the two soils in the availability of K and Mg in the A1 horizon. The only inversion in these differences at lower depths occurred in Mn availability. The soil at Glória showed significantly higher concentrations of Mn in the As horizon than the soil at Panga. Species with the highest importance values at Panga and those exclusive to Panga had higher foliar concentrations of Ca and K and lower concentrations of Mg than those at Glória. The Ca concentrations in the 42 tree species at Panga varied from 15.7 to 59.5 mg/g while most of the species at Glória had concentrations lower than 10.8 mg/g. Species common to both areas showed a better equilibrium among the foliar concentrations of the major nutrient cations K, Ca and Mg, than the exclusive ones and those with the highest importance values. There were no significant differences between the two communities in the foliar concentrations of N and P. The P/N ratio was very low in most of the species in both areas, which indicates that P was probably the most limiting major nutrient in these two ecosystems. The species exclusive to Panga and those with highest importance values showed lower Mn concentrations than those at Glória, as would be expected from the higher pH of the soil at the former site. As compared to cerrado sensu stricto and cerradão commun ities of central Brazil, a larger number of manganese-accumulating species with foliar concentrations above 300 mg!kg (31 at Glória and 11 at Panga) was detected in the two areas. On the contrary, ony a few Al-accumulating species (five at Panga e 7 at Glória) were present in the two communities

ASSUNTO(S)

ecologia vegetal

ACESSO AO ARTIGO

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