Overstory dynamics regulate the spatial variability in forest-floor CO2 fluxes across a managed boreal forest landscape

The forest-floor represents an important interface for various carbon dioxide (CO2) fluxes, however, our knowledge of their variability and drivers across a managed boreal forest landscape is limited. Here, we used three-year (2016?2018) data set biometric- chamber-based flux measurements to investigate the net CO2 exchange (NEff) its component fluxes 50 stands spanning different soil types, tree species, age classes within 68 km2 catchment in Sweden. We found that acted as source with 10th–90th percentile (used hereafter describing reported variations) ranging from 149 399 g C m?2 yr?1. Among key attributes, stand strongly affected most NEff whereas species type effects were weak absent, respectively. Specifically, emissions increased due declining understory gross primary production, between 77–275 49–163 yr?1, Furthermore, observed higher production rates pine than spruce stands. Across stands, total respiration ranged 340 549 yr?1 spatial variation was primarily regulated by autotrophic components, i.e., root respiration, which displayed divergent increasing decreasing age-related trends, heterotrophic remained relatively narrow range (154–290 yr?1), possibly owing compensating gradients properties. further identified biomass major driver landscape-scale variations likely attributable modulating on resource availability growing conditions. This implies growth responses management global change will be particularly regulating magnitudes forests.