Forest carbon sink estimation models: Progress, challenges, and opportunity of space–air–ground integrated assimilation

: Estimates of forest carbon sinks are essential for global carbon cycle studies, forest stewardship, and monitoring, reporting, and verification (MRV); nonetheless, current methodologies exhibit limitations regarding scale conversion, mechanistic restrictions, spatial continuity, and uncertainty management. This document comprehensively evaluates seven methodological categories—empirical statistics, remote sensing inversion, ecological processes, biogeochemistry, flux observations and atmospheric inversion, machine learning, and integrated models—while contrasting their data prerequisites, relevant scales, and principal uncertainties. The research suggests that a singular model faces challenges in achieving a balance among estimation precision, ongoing coverage, dynamic process characterization, and result verifiability; thus, incorporating multi-source observations and models is essential for improving the dependability of forest carbon sink evaluations. This document suggests a “verifiable,” cohesive “space–air–ground” evaluation system. This system employs terrestrial observations to establish authenticity limits, aerial remote sensing to connect scales, and extraterrestrial observations to facilitate regional growth. In conjunction with data assimilation and uncertainty analysis, it facilitates the synchronized evaluation of carbon reserves, variations in carbon reserves, carbon fluxes, and net carbon sinks. Future endeavors ought to concentrate on delineating disturbance-recovery mechanisms, forest stewardship, and lateral carbon transfers linked to timber extraction to enhance forest carbon sink evaluations from static cartography to dynamic, interpretable, and verifiable comprehensive analyses.