Banco de sementes no solo e ecologia morfofuncional de plântulas em remanescente de Floresta Tropical conectado com matriz agrícola

Abstract

Resumo O banco de sementes no solo é um dos mecanismos de regeneração natural que contribui para o surgimento de espécies em áreas florestais ou degradadas, no entanto, a composição de espécies pode ser influenciada pelo histórico de uso da terra, pela matriz em que o fragmento está inserido, entre outros. O objetivo dessa pesquisa foi avaliar a composição florística, abundância e ecologia morfofuncional de plântulas de espécies arbóreas encontradas no banco de sementes no solo em fragmento de Floresta Tropical. Foram retiradas amostras de solos e levadas para o viveiro florestal e cobertas por tela sombrite 70%. As plântulas emergidas foram contadas, identificadas e classificadas quanto à síndrome de dispersão, grupo sucessional e ecologia morfofuncional dos cotilédones. Emergiram 3.441 plântulas, em 14 famílias e 28 morfoespécies. Predominaram Miconia prasina e Cecropia pachystachya com 22,20 e 17,78%, respectivamente; a síndrome zoocórica com 64%; houve predominância de espécies secundárias iniciais, seguida de pioneiras. 78% das plântulas são do tipo PEF (fanero-epígeo-foliáceo). Embora o remanescente esteja inserido em uma matriz agrícola possui uma média riqueza de espécies arbóreas no banco de sementes, sendo a maioria das espécies classificadas como fanero-epígeo-foliáceo, demonstrando a dinâmica e capacidade de autorregeneração da área estudada.

In Site Soil Seed-Banks: Size, Composition and Persistence across Tropical Successional Stages

“…The seed-bank in primary forests and old-fields was dominated by herbaceous and EH species, whereas for secondary forests by woody species (trees, shrubs and lianas). The low relative abundance of tree species and the high relative abundance of herbs have also been observed in other studies of soil seed-banks and forest succession [11,19]. Plots were located in alluvial terraces that were sporadically flooded, damaging the understory vegetation and creating tree fall gaps.…”

“…Local climate, species composition, fecundity of local plants, seed size, seed dormancy, seed dispersal and predation, season, and growth-form may explain the variation in seed emergence and soil seed-bank size and composition among successional stages [5,6,11,16,[29][30][31][32][33]. The seed-bank in primary forests and old-fields was dominated by herbaceous and EH species, whereas for secondary forests by woody species (trees, shrubs and lianas).…”

“…Secondary forests showed long-term persistent seed banks and thus are buffered against years of poor seed production and/or seedling survival. However, seed-banks are major factors in the persistence of several woody weedy species as well [8,11,13].…”

“…Many species of plants rely on regeneration from seed-banks (dormant seeds in the soil). Seed-banks are a major factor in the persistence of certain species [3,[7][8][9][10][11] and are particularly important in plant communities that are subjected to extreme environmental events or frequent disturbances such as: fire, seasonal drought, periodically flooded areas or agricultural fields [5,6,[10][11][12][13][14]. Furthermore, seed-banks play a vital role in the regeneration of tropical rainforests by maintaining the ecological and genetic diversity of populations and communities [14][15][16].…”

“…Furthermore, seed-banks play a vital role in the regeneration of tropical rainforests by maintaining the ecological and genetic diversity of populations and communities [14][15][16]. Seeds stored in the soil of tropical forests are an important source of new recruits and can therefore influence the course of forest regeneration and secondary succession [7][8][9][10][11]. In general, the seeds of pioneer tree species tend to dominate soil seed-banks [10,13] and seeds from these species are the first to germinate following disturbances [2,10,13].…”