Natural regeneration in various microsites after three years of utilization in a sub-humid natural forest of Bajo Paraguá, Santa Cruz, Bolivia

Abstract

The sustainability of a forest management plan is largely contingent upon adequate natural regeneration following utilization. This study was conducted in a sub-humid natural forest in Bajo Paraguá, within the CINMA & San Martín LTDA. concession, located in the Santa Cruz Department of Bolivia. The aim was to assess the natural regeneration response three years after timber extraction across six distinct microsites (clearings, logging tracks, roads, scarified areas, areas with plantations, and untreated areas). It was observed that the utilization microsites significantly influence natural regeneration, appearing to enhance the establishment and survival of seedlings, particularly in roads and scarified areas, with the highest abundance recorded in the "Brinzal" category, alongside a notable decrease in "Latizales" and "Fustales". Regarding species abundance, in the Brinzal category, the cuta species (Apuleia leiocarpa) exhibited the highest abundance across all microsites (79 ind/ha), followed by cambará macho (Qualea paraensis) (27 ind/ha) and cambará hembra (Erisma uncinatum) (12 ind/ha). In the Latizal category, cuta (A. leiocarpa) was the most abundant species (16 ind/ha), while the paquió species (Hymenaea courbaril) was only found in this category (1 ind/ha). Additionally, the cedro species (Cedrela fissilis) also showed a low number of individuals (0.3 ind/ha). Conversely, in the Fustal category, the abundance was even lower, with cuta (A. leiocarpa) being the most prevalent (3 ind/ha), followed by tajibo (Handroanthus sp.), cambará macho (Q. paraensis) with 1 ind/ha, and cambará hembra (E. uncinatum) (0.3 ind/ha). Lastly, the species jichituriqui amarillo (Aspidosperma sp.), mara (Swietenia macrophylla), roble (Amburana cearensis), and verdolago (Terminalia amazonica) did not have any individuals recorded in the study. It is recommended to implement silvicultural treatments and management practices to ensure the development of natural regeneration, enhance enrichment for stands with plantations, particularly for absent species, especially oak (A. cearensis), paquió (H. courbaril), mara (S. macrophylla), and cedar (C. fissilis). Additionally, it is important to conduct monitoring and cleaning, scarify the stands and clearings for utilization to facilitate the recruitment of natural regeneration, and perform release treatments to promote regeneration, particularly in the sapling and pole sizes, due to the limited number of individuals in those categories.