Total Carbon Assessment in Reforested High-Andean Caesalpinia Spinosa Stands and its Viability under the Voluntary Carbon Market

Abstract

Total carbon assessment in reforested high-Andean Caesalpinia spinosa stands and its viability under the Voluntary Carbon Market. No species- and site-specific carbon inventory exists for mature Caesalpinia spinosa (tara) in high-Andean reforestation, leaving Peruvian Voluntary Carbon Market (VCM) projects on borrowed pantropical equations. We quantified total carbon — soil organic carbon (SOC) to 0.30 m and aboveground biomass (AGB) — in mature tara of Incahuasi (Ferreñafe, Lambayeque, Peru; 2,807 m a.s.l.) and tested its VCM viability. A hierarchically nested destructive design (3 plots × 5 trees, n = 15) covered 120 ha. SOC was measured by Walkley–Black at 0–0.15 and 0.15–0.30 m and recomputed under IPCC Tier-2 with bulk density in g cm⁻³. DBH and height were recorded before felling; component dry biomass at 75 °C. Linear, quadratic and power forms were compared by R², AICc, BIC, RMSE and leave-one-out cross-validation, with plot as random intercept; uncertainty was propagated by 10,000 Monte Carlo iterations (NAITO et al., 2024). Mean SOC reached 15.79 TC ha⁻¹, with 0–0.15 m holding the higher share. AGB carbon averaged 65.44 TC ha⁻¹; mean DBH 6.80 cm and mean height 5.05 m. The quadratic (R² = 0.875) was only marginally above the linear (R² = 0.856), the difference closing under information-theoretic penalties. Scaled to 120 ha the inventory yielded 35,434.84 TCO₂; under realistic Andean VCM prices (ANGEL et al., 2026) the credit envelope narrows relative to EU-ETS benchmarks. Our research delivers the first locally calibrated baseline for mature tara and an MRV-ready scaffold for VCM entry.