Changes in the structure of a savanna forest over a six-year period in the Amazon-Cerrado transition, Mato Grosso state, Brazil

Abstract

Vegetation changes in transition zones are still poorly studied. Changes in the vegetation structure of a savanna forest (cerradão) were assessed in the Amazon-Cerrado transition (14º42'2.3"S; 52º21'2.6"W), eastern Mato Grosso, within a period of six years (2002, 2005 and 2008). In 2002, fifty plots of 10 × 10 m were set up, where all trees with DSH30 ≥ 5 cm were measured; in 2005 and 2008 the plots were re-inventoried. In 2008, 84 species from 70 genera and 37 families were sampled; absolute density was 1,998 individuals/ha and basal area was 25.95 m2.ha-1. On the one hand, the absolute density of live individuals decreased from 2005 to 2008 (2,066 individuals/ha); on the other hand, the basal area increased in 2008 compared to 2005 (23.56 m2.ha-1) and 2002 (1,884 individuals/ha and 21.38 m2.ha-1). The species with the highest importance value in the period were Hirtella glandulosa, Tachigali vulgaris and Xylopia aromatica. Except for these three species, all other species underwent hierarchic changes in the importance value, indicating that most species frequently alternate. Community structure exhibited changes throughout the period; hence, we suggest investigations on the role of T. vulgaris in these changes, since environmental conditions caused by gap opening from the fall of senile individuals of this pioneer species with a short life cycle may contribute to community dynamics.

Post-fire dynamics of the woody vegetation of a savanna forest (Cerradão) in the Cerrado-Amazon transition zone

“…Similar results have been recorded in savannas in Brazil (Moreira 2000), Australia (Scott et al 2012), and Venezuela (San José & Fariñas 1983). The increase in species richness and diversity in the unburned plots may be related to the opening of gaps following the death of large trees, which favors the appearance of pioneer species such as Alchornea discolor and Cordiera myrciifolia, as observed by Franczak et al (2011).…”

“…An increase in tree species has also been recorded in studies of habitats unaffected by fire - Sanquetta et al (2000) recorded the addition of a species in a mixed rain forest over a period of three years, while Franczak et al (2011) subsequently recorded the recruitment of a further seven species within a seven-year period at the same site. Similar results have been recorded in savannas in Brazil (Moreira 2000), Australia (Scott et al 2012), and Venezuela (San José & Fariñas 1983).…”

Biomass hyperdynamics as a key modulator of forest self-maintenance in a dystrophic soil in the Amazonia-Cerrado transition

“…In other words, the larger biomass area of the cerradão when compared to the typical cerrado (MARIMON-JUNIOR; HARIDASAN, 2005;FRANCZAK et al, 2011) and the hyperdynamics of the vegetation may be increasing the processes tied to nutrition of the cerradão vegetation through the contribution of litter.…”

Relações espaciais entre Ananas ananassoides (Bromeliaceae) e Tachigali vulgaris (Fabaceae) influenciando a estrutura florestal na transição Amazônia/Cerrado no Brasil

“…This species controls the structural dynamics of the savanna woodland due to its pioneer characteristic, high dispersal capacity (anemochoric), quick germination, short life cycle and high annual recruitment and mortality rates (Felfili et al 1999;Franczak et al 2011;Morandi et al 2015;Reis et al 2015). Gaps caused by T. vulgaris in the savanna woodland can provide feedback to its own establishment (Franczak et al 2011).…”