Apoyo técnico en la investigación del efecto de la hojarasca sobre la respiración del suelo y su función en la recuperación de áreas verdes en Bogotá. (Jardín Botánico José Celestino Mutis y Predio las Mercedes - Reserva Forestal Thomas van der Hammen)

Abstract

This document describes the technical accompaniment carried out during an internship aimed at evaluating the influence of leaf litter on soil respiration and the recovery of green areas in two sites in Bogota: the José Celestino Mutis Botanical Garden (JBB) and the Las Mercedes property of the Thomas van der Hammen Forest Reserve. For this purpose, 30 plots (15 per site) were established with buried PVC collars that allowed, after a minimum rest of 24 h, biweekly measurements of edaphic CO₂ flux during the months of September to November 2024, using an IRGA EGM-5 analyzer and simultaneously recording soil temperature and humidity (STP-2 probe and EXTECH MO-750 meter) and air temperature and humidity (Kestrel). In parallel, 288 nylon bags with 5 mm mesh and 5 g of leaf litter of four representative species were prepared to estimate monthly decomposition rates; after monthly collection, the samples were cleaned, dried at 60 °C to constant weight and weighed with a 0.01 g precision balance. In addition, leaf material was separated by species in the leaf litter traps to determine taxon-specific contributions. Preliminary results show higher litter production and increased soil respiration at JBB compared to Las Mercedes, attributable to the higher biomass and tree structure of JBB; Likewise, soil respiration responded positively to increases in temperature, litter removal reduced CO₂ flux in tree cover and increased it in restored grasslands, and the species with the greatest contribution were Quercus humboldtii and Retrophyllum rospigliosii in JBB, and Retrophyllum rospigliosii and Alnus acuminata in Las Mercedes. Since no clear correlation was observed between the amount of leaf litter and soil organic carbon, it is suggested to extend monitoring to an annual cycle, improve the calibration of humidity sensors and prioritize in urban restoration plans those species that contribute more leaf litter, in order to optimize carbon sequestration, microclimatic regulation and soil structural quality.