Abstract
The dynamics of the natural process of recuperation of the structure and diversity of native vegetation following anthropogenic disturbance has been the subject of a great deal of controversy in restoration ecology research. The present study evaluates the natural regeneration of savanna forest ( cerradao ) 32 and 36 years after the clear-cutting of the vegetation. We compared species diversity, and the structure and dynamics of the vegetation in two communities, one representing preserved cerradao (PC), and the other, the regenerating cerradao (RC), which was clear-cut in 1976. Surveys were conducted in 2008 and 2012, 32 and 36 years after clear-cutting, respectively. In 2008, we demarcated 81 permanent 10 m x 10 m plots, 50 in the RC and 31 in the PC, and measured all live plants with a diameter at soil level > 5 cm. In 2012, the plots were resampled, including the original plants and all the recruits. The species were classified as specialists in savanna (SA) or forest habitat (FO), or as generalists (SA/FO). The RC presented the highest species richness and diversity, density, annual increment, and mortality rates. However, no significant differences were found between communities in the distribution of specialist or generalist species, or between years (2008 and 2012) in basal area or recruitment rates. While the species composition of the two communities is highly similar, the RC was characterized by a higher frequency of SA species, and was more similar to nearby savanna communities (cerrado sensu stricto ). Trees in the RC were smaller and suffered higher rates of mortality than those in the PC, but also higher annual increments. While the RC demonstrated a high degree of resilience following clear-cutting, it was still found to be at an intermediate stage of succession, even after almost four decades, indicating that regeneration is a slow process.
Highlights
The Cerrado biome (RIBEIRO; WALTER, 2008) has the highest plant biodiversity of all the world’s savannas (MENDONÇA et al, 2008), the rapid, ongoing conversion of its natural habitats into pasture and plantations, especially on the agricultural frontiers of the Brazilian states of Mato Grosso and Goiás, has resulted in a steady decline in the extent of its original vegetation cover over the past few decades (SANO et al, 2010)
The mean density of individuals per plot was higher in the regenerating cerradão (RC) than the preserved cerradão (PC) in both years (Table 1), the mean diameter of individuals was higher in the PC plots
The relative abundance of exclusive species in the RC appears to reflect its link with the savanna formations, which was reinforced by its greater similarity with the cerrado típico plots, and that 35.1% of these exclusive species were typical of savanna, whereas only 23.1% of the exclusive species in the PC were savanna species
Summary
The Cerrado biome (RIBEIRO; WALTER, 2008) has the highest plant biodiversity of all the world’s savannas (MENDONÇA et al, 2008), the rapid, ongoing conversion of its natural habitats into pasture and plantations, especially on the agricultural frontiers of the Brazilian states of Mato Grosso and Goiás, has resulted in a steady decline in the extent of its original vegetation cover over the past few decades (SANO et al, 2010). The advance of the agricultural frontier in this region has a major impact on local biodiversity (BUENO et al, 2005), especially in the so-called “arc of deforestation”, which straddles the interface between the Cerrado and Amazon biomes, reinforcing the need for the recuperation of degraded habitats. The Cerrado is characterized by a mosaic of habitats, including grasslands, savannas, and forests. This diversity of vegetation types appears to be related to the characteristics of the soil (depth, texture, fertility, and water retention), as well as the occurrence of bushfires (COUTINHO, 1990; RIBEIRO; WALTER, 2008, ASSIS et al, 2011). Most cerradão has been converted into farmland because it grows on more fertile soil than the cerrado sensu stricto, and often on relatively flat terrain (RATTER, 1971; EITEN, 1972; OLIVEIRA-FILHO et al, 1994)
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