RESUMEN: La diversidad de especies puede contribuir a la resiliencia del ecosistema y puede evaluarse a través del banco de semillas del suelo (SSB). El SSB es un indicador del desarrollo forestal después de la ocurrencia de disturbios. Por lo tanto, este estudio tuvo como objetivo evaluar la relación de la fertilidad del suelo con el banco de semillas del suelo y la variación de la diversidad de especies en distintas etapas sucesionales después del abandono del pasto (25, 35, 45 y > 50 años). Se recogieron diez muestras de suelo por sitio, se distribuyeron en bandejas y se dispusieron en invernadero para el análisis de germinación. Los resultados indican que la diversidad de especies en el SSB es mayor en los bosques jóvenes que en los bosques maduros. Además, las características del suelo son diferentes entre las etapas sucesionales, los bosques jóvenes están asociados con una mayor disponibilidad de nutrientes. Finalmente, los bosques en etapas tempranas tienen un mayor potencial para la recuperación de áreas degradadas en relación con el banco de semillas forestales en etapas avanzadas.

SUMMARY: Species diversity can contribute to the resilience of the ecosystem and can be assessed through the soil seed bank (SSB). SSB is an indicator of forest development after the occurrence of disturbances. Thus, this study aimed at evaluating the relation of the soil fertility with the soil seed bank and the variation of seed bank species diversity at distinct successional stages after abandonment of pasture (25, 35, 45 and > 50 years). Ten samples of soil were collected per site, being distributed in trays and arranged in a greenhouse for a germination analysis. Results indicate that species diversity in SSB is higher in young forests than in mature forests. In addition, soil characteristics are different among successional stages, in which the young forests are associated with higher availability of nutrients. Finally, forests in early stages have higher potential for recovery of degraded areas in relation to the forest seed bank in advanced stages.

Resumo A regeneração natural é considerada uma das técnicas mais promissoras de restauração de áreas degradadas em função dos aspectos ecológicos, silviculturais e econômicos. O presente estudo teve como objetivo avaliar características da regeneração natural em diferentes idades de estabelecimento, em áreas de preservação permanente, após a extração de povoamentos de Eucalyptus grandis. Foi realizado o levantamento e análise florística da vegetação regenerante em áreas com idades de regeneração natural de cinco e meio, sete e nove anos, ao longo das margens de um curso de água. Foram implantadas 56 parcelas amostrais de 10 m x 20 m para o levantamento do estrato arbóreo e o mesmo número de subunidades para o levantamento do estrato regenerativo. Foi realizada a análise florística, por área e estrato da vegetação, e a comparação entre os três ambientes quanto à riqueza, diversidade, distribuição de grupos ecológicos e síndromes de dispersão. A vegetação estudada mostrou alterações na composição florística ao longo de nove anos. O número e a densidade de espécies pioneiras sofreram decréscimos, tanto no estrato arbóreo quanto no regenerativo, enquanto espécies clímax tolerantes à sombra tiveram acréscimos com o avanço das idades de regeneração. As espécies clímax exigentes em luz foram predominantes nos três ambientes, assim como a síndrome de dispersão zoocórica. A diversidade para as três áreas analisadas, e para os dois estratos, foi crescente com as idades de regeneração. Os ambientes com sete e nove anos de regeneração apresentaram maior porcentagem de espécies comuns, além de densidade e distribuição de grupos ecológicos mais semelhantes em relação ao ambiente com cinco anos e meio de regeneração.

Abstract Natural regeneration is considered one of the most promising techniques for restoration of degraded areas due to ecological, silvicultural and economic aspects. The present study aimed to evaluate the characteristics of natural regeneration at different ages of establishment, in permanent preservation areas, after Eucalyptus grandis stands extraction. A survey and floristic analysis of the regenerating vegetation was performed in areas with natural regeneration ages of five and a half, seven and nine years, along the banks of a watercourse. Fifty-six sample plots of 10m x 20m were implanted for the tree stratum survey and the same number of subunits for the regenerative stratum survey. Floristic analysis was performed by area and vegetation stratum, and the comparison between the three environments for richness, diversity, distribution of ecological groups and dispersion syndromes. The vegetation studied showed floristic composition changes along nine years. The number and density of pioneer species suffered decrease in both the arboreal and regenerative stratum, while shadow-tolerant clímax species had increase as the regeneration ages progress. Light demanding climax species were prevalent in all three environments, as was zoochoric dispersal syndrome. The diversity for the three areas analyzed, and for both strata, was increasing with the regeneration ages. Environments with seven and nine years of regeneration presented higher percentage of common species, besides density and distribution of more similar ecological groups in relation to environment with five and a half years of regeneration.

Abstract The objective of this study was to assess the potential and the alterations of the soil seed bank as a mechanism for the regeneration of tree species in disturbed forest fragments after Eucalyptus grandis harvest. Soil samples were collected in two periods, during the winter and summer, in areas with different ages after E. grandis harvest. In each environment, 20 samples of soil were collected, with 60 samples per period (winter and summer), this samples were distributed in trays and arranged in open air for germination analysis. A total of 2,002 individuals were identified, belonging to 36 species and 17 families. The highest densities occurred during the summer, which also showed higher similarity between the environments. More species and diversity in relation to the ages of regeneration was observed during this period. Therefore, this study represents a contribution for further experiments in the field of conservation and restoration.