Silviculture of Tropical Dry Forests: Bolivian Case Study

Abstract

Tropical dry forests in Bolivia are considered to be the best conserved in Latin America and provide many forest resources, particularly wood products and environmental services. The objectives of this chapter are to demonstrate the limitations of current forest management, considering the characteristics of the tree species, and to suggest the use of silvicultural treatments to improve production and sustainability. There are various problems with natural regeneration in these forests, especially with regeneration from seed origin, which is principally caused by the long dry season. However, many species do not have regeneration problems because of their ability to resprout. The overall growth rate shown (mean = 3 mm year−1) is another limitation to the recovery of stand volume after harvesting, which is exacerbated by a high rate of liana infestation. The majority of the commercial species are long-lived pioneers or partially shade-tolerant species, and the abundance of trees varies greatly by species. The majority of commercial species have wind-dispersed seeds with an annual seed production cycle. Approximately half of the species resprout from cut stems or root systems. In Bolivia, including dry forests, reduced impact logging and silvicultural treatments are employed to increase growth rates and reduce stand damage. The most effective reduced impact logging practices include directional felling, planning of skid trails, and marking of future crop trees. For silvicultural treatments, prescribed burning increases the abundance of seedlings and saplings as well as the abundance and growth rates of resprouts. Liana cutting and liberation of crop trees increases diameter growth with relatively low investment. Despite limitations to management in Bolivian dry forests, the sustainability of harvesting can be enhanced by employing reduced impact logging practices combined with silvicultural treatments that increase the regeneration and growth rate of commercial tree species.