Commercial tree regeneration 6 years after high-intensity burns in a seasonally dry forest in Bolivia

Abstract

The effects of three site-preparation treatments (high-intensity burn, low-intensity burn, and mechanical cleaning with machetes and chainsaws) on the regeneration of commercial tree species, composition and structure of competing vegetation, and soil chemical and structural properties were evaluated in a seasonally dry forest in southeast Bolivia. Six years after controlled burns, the high-intensity burn treatment had the both the highest density and the tallest individuals of shade-intolerant commercial tree species. Competing vegetation was also less dominant in the high-intensity burn treatment relative to other treatments. However, high-intensity burns were not beneficial for commercial tree species with shade-tolerant or intermediate regeneration. Soil analyses revealed that certain changes in soil texture and soil chemistry (e.g., Ca and Mg concentrations and cation exchange capacity) caused by high-intensity burns persisted 6 years after the fires. These findings confirm that this suite of shade-intolerant commercial species requires very intense disturbances for their regeneration. However, several ecological, economic, and social barriers currently preclude the management-scale application of prescribed fire in Bolivia. More research is needed on cost-effective treatments to improve regeneration.