Forest Recovery after Swidden Cultivation across a 40-year Chronosequence in the Atlantic Forest of Southern Bahia, Brazil

background

Secondary forest with a range of ages was compared to old growth forest in the Serra do Conduru State Park in Southern Bahia, Brazil in terms of species composition and structure.

Goals & Methods

To compare the secondary forest with the old growth forest, the authors randomly selected twelve stands selected that represented three age classes: 10, 25, and 40 year old with four replications in each class. All stands selected had been established after abandonment from swidden cultivation and were surrounded by old-growth forests. In every stand, ten 0.01-ha transects were established and all stems (≥5 cm diameter at breast height) were measured and identified.

Conclusions & Takeaways

Species diversity increased from the 10 year old plots to the 25 year old and the 40 year old, with old growth plots containing the highest diversity. The 25 and 40 year old plots, however, did not significantly differ. Basal area and height increased with increasing age. Results show that more than 40 years are required for secondary forests to attain old growth forest structure, though species richness recovery was high with younger forests. The results support the initial floristics hypothesis, i.e. that a significant portion of old growth species are present in early stages of succession. Given the high diversity of the early secondary forests, the author concludes that preservation of these young forests has high conservation value.