Bioindicadores de qualidade de solo em diferentes ecossistemas

AUTOR(ES)
DATA DE PUBLICAÇÃO

2009

RESUMO

Changes due to soil management and cultivated plant species may influence carbon, nitrogen and phosphorus cycling. Cycling depends on the integration of physical, chemical and mainly microbiological processes. This work assessed some microbial activity and processes related to carbon, nitrogen and phosphorus cycles in soil from six ecosystems in Guarapuava, PR. Sampling was performed at depth of 0-10 cm in the following areas: a natural remnant of Mixed Ombrophylous Forest, Araucaria angustifolia reforestation area, commercial plantation of Pinus elliottii, secondary forest, P. elliottii regeneration after a clear cut, and annual crop area. Evaluations of some microbial functional groups; dehydrogenase, amylase, cellulase, asparaginase, glutaminase, urease, acid and alkaline phosphatases activities; nitrification and ammonification rates; microbial biomass carbon and nitrogen; respirometry; qCO2, filamentous fungal hyphae; spore density and diversity of arbuscular mycorrhizal fungi were performed. In addition to microbiological and biochemical analyses, chemical and physical soil evaluations were performed, such as total organic carbon, total nitrogen, soil available phosphorus, pH, carbon stocks, organic matter C/N ratio and water dispersible clay. Litter mass and C/N ratio were also estimated. In general, microbial functional groups did not differ among the areas, showing to be inefficient for soil quality evaluation. However, microbial biomass C and N, as well as ammonification and nitrification rates, decreased with land use intensity. Highest values of microbial biomass were obtained in forest areas, mainly with native arboreous species, what characterizes higher microbial density in comparison with Pinus and agricultural areas. The highest values of microbial respiration were found in areas with lower C/N ratio of the litter. On the other hand, qCO2 and dehydrogenase presented higher values in intensely cultivated soil, such as agricultural and clear cut areas. In the case of extracellular enzymes, most of them presented higher activity in areas with native arboreous species, suggesting that the quality and quantity of deposited organic residues may influence enzymatic dynamics. The arbuscular mycorrhizal fungi species richness, measured by Shannon s index, showed that areas with A. angustifolia, even showing less spore density, present higher species richness. Multivariate analyses based on attributes related to C and N cycles indicated that areas with native arboreous species had higher similarity with the reference area (native forest). Pinus and agricultural areas presented differences in comparison to areas with native arboreous species. The agricultural area was also different from Pinus reforestation area, although it tends to be more related to the Pinus reforestation after cutting the trees.

ASSUNTO(S)

microbiologia agrícola ciclos biogeoquímicos ciclo do nitrogênio solos - qualidade agricultural microbiology soils - quality

ACESSO AO ARTIGO

Documentos Relacionados