Accurate quantification of biomass and carbon accumulation in olives is crucial for optimizing agronomic management and assessing their role to climate change mitigation. This study, developed destructive and non-destructive methodologies to quantify above- and belowground biomass and carbon content in 7.5-year-old trees of two common olive cultivars (Arbosana and Picual) under Mediterranean conditions. The approach included the removal of three whole-trees per cultivar and combined assessment of above- and belowground biomass, rarely available for olive trees. Picual tended to accumulate more biomass (36.5 kg tree−1, on average) than Arbosana (27.5 kg tree−1), due to a greater investment in trunk and non-primary branches, whereas Arbosana allocated more biomass to leaves. In both cultivars, around 60% of the root biomass was within the top 25 cm of soil, and over 55% was concentrated in the root ball. Weighted average carbon concentration was 47% in aboveground biomass and 42% in roots. At the orchard scale, soil was the main organic carbon pool, around 76 t C ha−1, compared to 13–16 t C ha−1 in the tree biomass. Annual carbon accumulation in olive biomass ranged from 1.68 t C ha−1 yr−1 (Arbosana) to 2.16 t C ha−1 yr−1 (Picual), within the range of C fixation rates in Mediterranean agroecosystems. Destructive sampling better captured cultivar differences in biomass allocation and carbon accumulation, while the non-destructive method proved suitable for large-scale use. These results support integrating biomass allocation and carbon permanence into cultivar selection and management to enhance carbon sequestration and sustainability of olive grove systems. Picual cultivar showed a total biomass 33% higher than Arbosana cultivar. 60% of root biomass was found in the top 25 cm of soil in both cultivars. Organic carbon concentration averaged 47% in shoots and 42% in root biomass. Destructive method detected cultivar differences in biomass with greater precision. Mean C sequestration rates by olive trees were 1.68 (Arbosana) and 2.16 (Picual) t C ha−1 yr−1.
Torrús-Castillo et al. (Sat,) studied this question.