Tree species richness and composition 15 years after strip clear-cutting in the Peruvian Amazon

Although strip clear-cutting has a long history of use in the temperate zone, it was only recently introduced for timber extraction in tropical rain forests, where it is known as the PalcazA(o) Forest Management System. In this system heterogeneous tropical forests are managed for native gap-dependent timber species by simulating gap dynamics through clear-cutting long, narrow strips every 40 years. As part of an assessment of the sustainability of this system, we evaluated the recovery of tree basal area, species richness, and composition after 15 years of regeneration on two strips (30 x 150 m) clear-cut in 1989 in Jenaro Herrera, Peru. Timber stocking and the effects of silvicultural thinning were assessed in both strips. The strips recovered 58-73% of their original basal area and 45-68% of their original tree species richness. Although both strips recovered more than 50% of their original composition, commercial species had lower basal areas and lower densities than in the forest before the clearing. Pioneer species with high basal areas remained dominant 15 years after the cutting. Silvicultural thinning in 1996 reduced the abundance of pioneer species in both strips, and increased the abundance of commercial species in one of the strips. Half of one strip was harvested by deferment-cut (only commercial trees > 30 cm dbh and "other" species > 5 cm dbh were cut); regeneration here had greater abundance of commercial species and lower abundance of pioneer species. The low stocking of commercial trees challenges the sustainability claims for this forest management system.