ATRIBUTOS MICROBIOLÓGICOS E ESTRUTURA DE COMUNIDADES BACTERIANAS COMO INDICADORES DA QUALIDADE DO SOLO EM PLANTIOS FLORESTAIS NA MATA ATLÂNTICA

In Brazil, in order to minimize the impact of native forest exploitation for commercial purposes, forest plantations have been implemented mainly with exotic species. The evaluation of these crops as to the environmental impact on attributes that can guarantee their productivity has received more attention in the last years, and in this context, the study of microbiological attributes. This paper assesses the impact of Pinus sp. (pinus) and Araucaria angustifolia (araucária) forest plantations on the microbiological soil attributes and the structure of bacterial communities, which can act as indicators of soil quality. Soil samples have been collected on three areas of the National Forest of Três Barras, in Santa Catarina (SC) state: one area of native forest (F), one area of reforestation with araucária (A) and one area of reforestation with pinus (P). Later on, the soil was chemically and physically characterized and the microbiological analyses were performed, as basal respiration, β-glucosidase and fosfatase enzymatic activity and analysis of bacterial community structure by PCR-DGGE. Low fertility was presented on all three soils collected, highlighting the importance of microorganisms in order to maintain this environment. The β-glucosidase and fosfatase enzymatic activity were higher on the areas F and A, suggesting a higher presence of important microorganisms for nutrients cycling. The analysis of the bacteria community structure resulted in low distinction between the pinus and the araucária areas. This paper presents that based on the microbiological attributes and structure of bacterial communities of soil, in forest plantations of the Atlantic Forest, it is possible to conclude that araucária is the best alternative for reforestation, aiming the maintenance of soil quality

The genetics and conservation of Araucaria angustifolia: I. Genetic structure and diversity of natural populations by means of non-adaptive variation in the state of Santa Catarina, Brazil

The objective of this study was to generate information relative to the allele distribution and dynamics within and among populations of Araucaria angustifolia, a naturally-occurring conifer in the south of Brazil, being known popularly as "pinheiro-do-Paraná", "araucaria" or pine tree. In order to elucidate the levels and the distribution of the genetic variability, the population's genetic structure and the genetic distance among natural populations of this species with different levels of disturbance in different geographical areas were studied in detail. For this, samples of leaf tissue were collected from 328 adult individuals in nine natural populations in Santa Catarina State. To analyze the samples, the allozyme technique was applied in starch gel electrophoresis (penetrose 13%), with citrate/morfholine buffer. Nine enzymatic systems (PGM, PGI MDH, PRX, SKDH, 6PGDH, ACP, IDH and G6PDH) revealed 15 loci. The analysis provided values for He and Ho of 0.084 and 0.072, respectively. The general average of polymorphic loci was 73% in the species and 26.6% in the studied populations and the allele number per locus was 1.6. Wright's F-statistical estimates indicated the existence of inbreeding in populations (F IS= 0.148) and a low divergence among populations (F ST = 0.044). However, the inbreeding values were variable in different populations. Taken together, the results indicated that the greater part of the genetic variability is contained within populations. The working hypothesis that originally there was greater genetic diversity can be supported by these results which indicate that in the degraded populations the diversity indexes are lower in the degraded populations than those found in better-conserved populations. Thus the fragmentation of the forest followed by "araucaria" exploitation could have contributed to the genetic differentiation expressed through the allele frequency of the studied population