TREE STRUCTURE, SPECIES COMPOSITION, AND CARBON STORAGE IN TROPICAL SILVOPASTORAL SYSTEMS

Background: Silvopastoral systems, agroforestry with grazing livestock, have a high capacity for carbon sequestration in tree biomass and enhance biological diversity in grasslands, contributing to counteract the negative effects of deforestation led by the expansion of open pasturelands. Objective: To assess tree structure, species diversity, and carbon storage in biomass components in three different silvopastoral systems (SPS): 1) scattered trees in pasture (STP), 2) live fences (LF), 3) forest plantations (FP), and compare them with pasture monoculture (PM). Methodology: Carbon stock in biomass, relative importance value of tree species, Shannon´s biodiversity, Pileou´s evenness, and Sorenson´s similarity indices were calculated in forty sampling plots, ten for each system in Tabasco, Mexico. Results: Biomass stock varied significantly (P<0.05) between SPS and PM. FP had the highest carbon stock in the biomass pool with an average of 73.5 MgCha-1, followed by STP (45.8), LF (20.8), and PM (9.1). STP system tended to be more diverse with a relatively even distribution of tree species, while tree density per hectare was greater in FP. Species composition and their relative value indices varied between SPS but there was a medium level of similarity between them. Furthermore, we determined an optimum basal area of 14.5 m2ha-1 to harmonize the trade-offs between carbon sequestration in woody biomass and forage production in grass (herbaceous) biomass in these SPS. Implications: These results are useful to farmers and policymakers in developing and incentivizing climate-smart livestock production systems in line with the Sustainable Development Goals (SDGs). Conclusion: SPS are biodiverse and accumulate more carbon in biomass than pasture monoculture. The STP was the most biodiverse, followed by LF and FP, while carbon storage was higher in FP followed by STP and LF. An optimal tree cover with 14.5 m2ha-1 basal area can balance the trade-off between carbon sequestration and forage productivity in SPS.