Structure and dynamics of forest eco-units in a semideciduous seasonal forest fragment in Piracicaba region, São Paulo state, Brazil

Abstract

This paper describes changes in richness, diversity and floristic composition of tree species of four forest eco-units ("low capoeira", "high capoeira type 1", "high capoeira type 2" and "mature forest") identified through the Rapid Ecological Assessment procedure in a semideciduous seasonal forest fragment of9.5 ha in Piracicaba region, São Paulo State, Brazil. Two different periods were used for two different size classes to evaluate these changes: a 4-yr period (for individuals ≥ 5 cm DBH, 1991 and 1995) and 1-yr period (for individuals ≥ 50 cm of height and < 5 cm DBH, 1995 and 1996). Different patterns of floristic composition, richness and diversity were found for each eco-unit, for both times and size classes analysed. For adults, in both times, richness and diversity were higher in both "high capoeira type 2" and "mature forest" in relation to "low capoeira" and "high capoeira type 1". Pioneer species were well represented in both "low capoeira" and "high capoeira type 1", gap-opportunistic species in "high capoeira type 2", shade-tolerant canopy species and shade-tolerant understory species in "mature forest". For saplings, density, richness and diversity were lower in "low capoeira" and this eco-unit was well represented by pioneer and gap-oportunistic species. In "high capoeira type 1", in despite of the same richness and diversity of "high capoeira type 2" and "mature forest", had lower density and was well represented by pioneer and gap-opportunistic species. Unlike, shade-tolerant canopy species and shade-tolerant understory species were well represented in "mature forest". These results show that the different eco-units identified through the Rapid Ecological Assessment show different of forest structures in a fragment and thus can be used in defining conservation strategy and management of semideciduous seasonal forest fragments.