ESTRUTURA POPULACIONAL E REGENERAÇÃO DE ESPÉCIES ARBÓREAS NA FLORESTA NACIONAL DE SÃO FRANCISCO DE PAULA, RIO GRANDE DO SUL

• Main Authors: Angela Luciana de Avila, Maristela Machado Araujo, Solon Jonas Longhi, Paulo Renato Schneider, João Olegário Pereira de Carvalho
• Format: Article
• Language: Portuguese
• Published: Universidade Federal de Santa Maria 2016-01-01
• Series: Ciência Florestal
• Online Access: http://www.redalyc.org/articulo.oa?id=53447685012

ABSTRACT The aim of this study was to characterize the population structure and aspects of regeneration of Araucaria angustifolia (Bertol.) Kuntze, Blepharocalyx salicifolius (Kunth) O. Berg and Ilex paraguariensis A. St.- Hil. in different environmental and disturbance conditions in the National Forest of São Francisco de Paula, RS state. Six conglomerates of one hectare were used, with 16 plots (20 x 20 m) each, where the species were sampled in three size classes. The size class II (SC II – diameter at breast height (DBH) ≥ 9.55 cm) was sampled in 96 plots, the SC I (4.8 ≤ DBH < 9.55 cm) in 36 subplots of 10 x 10 m, and the established natural regeneration (ENR) (1 ≤ DBH < 4.8 cm) in 36 cells of 3.16 x 3.16 m. The seedling bank (SB - height ≥ 30 cm and DBH < 1 cm), the seed rain (SR) and the soil seed bank (SSB) were sampled in all plots of 20 x 20 m. The data were analysed by taking into account all the different vegetation groups together and separately for each cluster identified in a previous study. For SC II, the frequency distribution of DBH was analysed combined with the analysis of absolute density and frequency for all life stages (SR, SSB, SB, ENR, SC I and SC II). The results indicated high variability in density of these species among the different life stages and environmental conditions. Araucaria angustifolia presented gaps in the regeneration process in areas that had low past disturbance, not showing the “reverse-J” distribution (SC II) and with lower regeneration capacity in relation to the other species (SR, SSB and SB). Ilex paraguariensis and Blepharocalyx salicifolius showed higher population stability in environment with low level of human interference (SC II). The first species demonstrated preference for soils with good drainage, while the second species for humid soils. Moreover, gaps in the regeneration process of different populations were detected, which changed according to environmental conditions and disturbance levels. Therefore, the results suggest the importance of taking into account the different vegetation groups, the species autecology and to apply possible interventions that aim to improve regeneration and balance the population dynamics of these species.