Above and belowground carbon and nutrient distribution of Samanea saman plantation in the Eastern Andes, Colombia

Abstract

In tropical soils that are poorly fertile and degraded by agriculture, native nitrogen-fixing species have the potential to recover soil fertility and carbon stock, which contribute to climate change mitigation. This study aimed to quantify the nutrients and carbon stock of a Samanea saman plantation. The aboveground biomass was estimated directly by falling nine trees 5.8 years after planting. Soil samples were collected to quantify organic carbon content and fine root biomass - FRB (Ø < 2 mm) during the rainy period. Total aboveground biomass was 51.1 Mg ha^-1, which was stored mostly in the stemwood with 41%. Leaves and branches Ø < 5 cm represented 30% of the aboveground biomass, but accumulated close to 50% of nutrients, except for Ca, Fe, and Mn, which were high in the stembark. The FRB was not affected significantly by soil depth (0-15 and 15-30 cm) and the collection distance from the crown radius projection (50 and 100%), with the average being 8.5 Mg ha^-1. The carbon stock of the forest system up to 30 cm depth of soil was 81.7 Mg ha^-1. These results suggest that Samanea saman is a potential native species for the rehabilitation of degraded areas in the humid lowlands of the Colombian Andes.