Does the carbon pool vary among Ecuador's tropical dry forests and seasons? Experimental evidence from spatio-temporal assessments

Abstract

Tropical dry forests (TDFs) are critical carbon reservoirs, yet their carbon storage dynamics remain poorly understood, particularly across seasons, forest subtypes, and species′ contributions. This study examined carbon pools—soil organic carbon (SOC), aboveground biomass carbon (CAGB), and litterfall carbon (C-litterfall)—across three TDF subtypes along the Ecuadorian coast. Twelve 100 m² plots were monitored semi-annually during rainy and dry seasons, with extrapolations made to assess total forest patch carbon stocks. SOC was the dominant carbon pool across all subtypes and seasons, with rainy periods contributing to greater SOC stability (LSF, 75.51 Mg ha⁻¹; LDF, 70.01 Mg ha⁻¹; SPF, 69.27 Mg ha⁻¹) compared to dry periods (LDF, 54.70 Mg ha⁻¹; LSF, 53.35 Mg ha⁻¹; SPF, 39.39 Mg ha⁻¹). CAGB and C-litterfall displayed significant seasonal variation, with litterfall peaking in the dry season, particularly in LSF (0.4 Mg ha⁻¹). Across subtypes, total carbon densities averaged 94.0 Mg ha⁻¹ in LSF, 67.4 Mg ha⁻¹ in SPF, and 99.9 Mg ha⁻¹ in LDF. Plant species significantly influenced CAGB. In LSF, T. integerrima contributed the most to CAGB (6.4–6.7 Mg ha⁻¹), while C. eggersii dominated in SPF (4.5–4.4 Mg ha⁻¹). In LDF, C. lutea was the leading contributor, storing 13.8–13.9 Mg ha⁻¹ of biomass carbon. Extrapolation to forest patches revealed substantial spatial differences, with LDF sequestering the most carbon (526 133.3 Mg), followed by SPF (463 133.0 Mg) and LSF (3113.3 Mg). These findings underscore the critical roles of species composition, climatic variability, and forest structure in carbon sequestration, emphasizing the need for tailored conservation strategies to mitigate climate change impacts.