Tropical Timber Species Grow Faster in Full Sun Than in the Understory of Restoration Plantings

Abstract

Abstract Tropical timber species are generally shade tolerant, but preliminary studies have indicated that greater light availability can accelerate their growth. In this study, we hypothesized that native timber species can grow faster initially when planted in full sun alongside the pioneer species in high-diversity restoration plantings compared with being planted in the understory of an established forest restoration. We assessed the mortality, relative growth in height (RGH) and stem diameter (RGDGL) of eight native timber species from the Brazilian Atlantic Forest 19 months after planting. Overall seedling mortality was similar across planting conditions, and only Handroanthus heptaphyllus exhibited higher mortality in the shaded planting. The RGH and RGDGL of most species was higher in full sun planting. Therefore, our findings indicate that those tropical timber species grow faster and have higher survival rates when planted in open areas. Study Implications: We evaluated the initial growth and mortality of eight timber species native to the Atlantic Forest, focusing on their performance in forest restoration across two distinct conditions: full sun alongside pioneer species, and natural shade beneath an established canopy. Late successional timber species exhibit accelerated initial growth rates when planted in full sunlight compared with under an established forest canopy due to the greater light intensity. Our findings strongly support the practice of planting native timber species in full sun alongside pioneer species. This approach also provides logistical advantages, potentially reducing costs compared with staggered planting methods.