Integrated LiDAR-supported valuation of biomass and litter in forest ecosystems. A showcase in Spain

Abstract

Belowground components(biomass and soils) can stock as muchcarbonasthe aboveground component of forest eco systems. In this study, we present a fully-integrated assessment of the biomass budget and the three pools evaluated: aboveground (AGBD)andbelowgroundbiomassinrootsystems(BGBD)andlitter(LD).WeturnedNationalForestIn ventory data, airborne Light Detection and Ranging (LiDAR) data actionable to map three biomass compartments at 25-m resolution over more than 2.7 million ha of Mediterranean forests in the South-West of Spain. We assessed dis tributions and balanced among the three modelled components for the entire region of Extremadura and specifically for fiverepresentative foresttypes. Our results showedbelowgroundbiomassandlitterrepresentan important61%of the AGBD stock. Among forest types, AGBD stocks were the dominant pool in pine-dominated areas while its lowers contribution was found over sparse oak forests. The three biomass pools estimated at the same resolution were used to produce ratio-based indicators to highlight areas where the contribution of belowground biomass and litter can ex ceed AGBD and where carbon-sequestration and conservation practices should acknowledge belowground-oriented carbonmanagement.Therecognitionandvaluationofbiomass andcarbonstocks beyondtheAGBDisamuststepfor ward that the scientific community must support in order to properly assess living components of the ecosystem such asrootsystemssustainingAGBDstocksandtovaluecarbon-orientedecosystemservicesrelatedtosoil-waterdynamics and soil biodiversity. This study aims at enforcing a change of paradigm in forest carbon accounting, advocating for a better recognition and broader integration of living biomass in land carbon mapping.