Forest expansion in abandoned agricultural lands has limited effect to offset carbon emissions from Central-North Spain

Abstract We assessed the process of carbon (C) accumulation as a consequence forest expansion in abandoned agricultural lands over period 1977–2017 vast (9.4 million ha) area Mediterranean continental environment Central-North Spain. achieved this objective, through obtaining AGC and BGC estimations based on direct field measurements taken 30 plots (25 m × 25 m), extrapolating to landscape using Synthetic Aperture Radar (SAR) satellite data from 2018. Using aerial photographs maps, we found that 145,193 ha land 1957 (1.54% study regions’ total area) has since then regenerated naturally forests woodlands. Although mean densities were modest (i.e. 18.04 6.78 Mg C −1 ), they reached relatively large maximum values 60 21 ). The stock was also very large, representing 37.3% (10 Tg) accumulated. However, detected annual sink 0.25 Tg C·year which barely offset 1.22% regional CO 2 emissions. Our findings point smaller sequestration potential under than temperate-cold conditions. Nonetheless, affected by could be larger many recovering might have not still their uptake peak. If such are used store C, strongly advocate for application active management measures increase potential.