Avaliação de aspectos da dinâmica de florestas restauradas, com diferentes idades

Abstract

The project “Evaluatio n of aspects of the dynamics in restored forests, with different ages” had as main aim to define indicators that can be used in the evaluation and monitoring of restored areas, through the reestablishment of the resilience in those areas. This task was performed in three restored areas: Ester Sugar Mill, in Cosmopolis – SP, having 9ha been submitted to native and exotic species planting between 1955 and 1960 (≅ 46 years); Experimental Area at Plantec, in Iracemapolis – SP, with 1ha of planted area, including native and exotic species, in 1992 ( 9 years); Dedini Agro ≅ industry Area, in Santa Cruz das Palmeiras – SP, with 1ha submitted to native species planting between 1995 and 1997 (≅ 6 years). These areas differ among themselves from implementing time, number of planted species and restoration methods. In each area, 10 samples of 10x20 m were selected, with 6 sub samples of 0.5x0.5 m, and three repetitions for each treatment analyzed. For evaluating the seeds rain, 3 collectors of 0.5x0.5 m were installed for each sample (30 collectors per area), with monthly samplings. For evaluating the seeds bank, 2 samplings of soil and foliage were performed (April/01 and June/01) per sample (0.25x0.25 m), at 0.05 m depth. For evaluating the regenerating young individuals, all the individuals between 0.30 – 1.30 m height were sampled, in 2 sub samples (1x1 m) per sample (May/01 and November/01). Frequency and absolute density calculations were performed through the logarithm of truthfulness test (test G). The variation analysis (Test F) were performed for verifying the height growth of the individuals sampled in different evaluations. When significant differences were found, the probability Tukey test at 5% was applied for determining between which groups the averages differed significantly. The propagation flow measured in the areas, during an 8- month period, presented highly significant differences (P = 0.001), i.e., the seeds rain occurred heterogeneously, when the arboreal species overwhelmed the herbaceous, lianas and bushy ones. The investigation of the seeds bank on the three areas revealed highly significant variations (P = 0.001) in the seeds density in both evaluations (January and June/01). It has been noted that the number of herbaceous species germinated on the seeds banks on the three areas tended to diminish, and the arboreal, to increase along the restoration phase. The young individuals shown on the study areas are mainly arboreal species. The young individuals proportion present at the evaluations presented significant variations (P = 0.32), between the evaluations, i.e., there was a recruiting of new individuals on the second evaluation. The results on this study lead us to conclude that for recovering a degraded area does not only depend on the planting of native species but depends on i) the studying of the land use, ii) the isolation grade and iii) the monitoring and evaluation of the restoration projects, thus allowing the definition of the intervening handlings that can guarantee the success of the undertaking in terms of the restored areas perpetuation.