Effects of selective logging, fragmentation, and dominance of bamboos on the structure and diversity of Araucaria Forest fragments

Abstract

During the colonisation of the South of Brazil, logging of tree species with high economic value was one of the main economic activities. In this process, almost all Araucaria Forest, one of the forest types of the Atlantic Forest that once covered most of this region, was severely fragmented and disturbed. One of the consequences of this disturbance was the population growth of a native bamboo species (Merostachys skvortzovii) that came out of the small patches where it occurred naturally, to dominate the understory of forest fragments. In this study, we evaluated if the fragment size, forest-edge effect, and abundance of bamboos affect forest structure and functional guilds in a region of Araucaria Forest in Parana state, Brazil. We sampled trees (DBH ≥ 4.8 cm) in five fragments (24–270 ha) in two plots (2000 m2 each) located at the edge and centre of each one. We analysed the forest structure (species composition and species richness, abundance, and basal area) and estimated the bamboo cover in each plot. We recorded 1743 individuals of 68 tree species in the five analysed patches. The fragments were very similar in floristic composition and structure (species richness, abundance, basal area). The bamboo cover was the main factor affecting forest structure and species guilds distribution, followed by distance from the fragment edge. These results show a simplification of floristic, structural, and functional attributes of Araucaria Forest remnants suggesting that the selective logging followed by fragmentation and native bamboo overabundance are important factors in the imporishment of this endangered biome.