Abstract
Seasonally dry tropical forests (SDTFs) have high tree species richness and endemism, whose dynamics and succession depend on natural regeneration (NR). To test whether NR is influenced by the mature stratum and environmental variables, we compared structural and floristic patterns of mature trees [Mt (DBH ? 5 cm)] with the NR of a SDTF on limestone outcrops in Central Brazil. Additionally, we tested for effects of environmental variables on species abundance in these different strata. Within NR categories [JuvA (total height < 100 cm) and JuvB (total height ? 100 cm and DBH < 5 cm)], we recorded 597 individuals in 69 angiosperm species. Within NR and Mt we recorded 110 species distributed in 33 families, and 54 were common to both (~50% of total richness). Shannon diversity was 3.83, 3.13 and 3.33 for Mt, JuvA and JuvB, respectively. Besides the high number of exclusive species recorded in Mt (23), JuvA (18) and JuvB (24), comparisons indicated high floristic similarity (51%) between strata. Mt, JuvA and JuvB were influenced by different environmental variables, indicating that species requirements change along the establishment process. This highlights the importance of environmental variability for maintaining tree species diversity in SDTFs, and the importance of this remnant for the conservation of SDTFs in Central Brazil.Keywords: Cafuringa, Cerrado, dry forest, forest succession, limestone outcrops, sapling.
Highlights
The seasonally dry tropical forests (SDTFs) are one of the most endangered forest types in the world and 54% of their remaining area is located in South America (Miles et al, 2006)
The SDTF covered about 15% of the Brazilian Cerrado (Felfili, 2003), but these forests are heavily degraded by land use (Felfili, 2003; Felfili et al, 2006; Felfili et al, 2007a; Scariot and Sevilha, 2005; Silva et al, 2006)
In Central Brazil, the SDTFs predominate in the valleys and are surrounded by a savanna formation that covers the plateaus and slopes (Felfili, 2003; Nascimento et al, 2004; Silva et al, 2006; Felfili et al, 2007a). They generally occur on well-drained soils which are rich in nutrients, and may occurs on limestone outcrops where they present a different floristic composition (Rizzini, 1997; Ribeiro and Walter, 2008) and considerable endemism similar to ecological refugees (e.g. Chapada dos Veadeiros) (Pereira et al, 1996; Felfili 2003; Fernandes, 2003; Felfili et al, 2006; Vieira and Scariot, 2006; Pereira et al, 2011)
Summary
The seasonally dry tropical forests (SDTFs) are one of the most endangered forest types in the world and 54% of their remaining area is located in South America (Miles et al, 2006). In Central Brazil during the last four decades a large percentage of this forest type was converted into production areas (Felfili, 2003; Klink and Moreira, 2003; Felfili et al, 2006; Silva et al, 2006; Pereira et al, 2011), which has fragmented the natural vegetation and compromises the maintenance of ecosystems and species. Outcrops increase micro-relief variation leading to a higher variability of surfaces, canopy height and substrate characteristics (e.g. capacity of retaining moisture) This microhabitat variability favors species with different requirements, as those from the Cerrado, Caatinga, Pantanal and dry forests from Bolivia (Rizzini, 1997; Felfili et al, 2007a; Pereira et al, 1996; Pereira et al, 2011). Resprouting may consist an important regeneration-mechanism (Lieberman and Mingguang, 1992), mostly in degraded areas (Vieira and Scariot, 2006; Vieira et al, 2006), the NR is mainly developed by seeds
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