| Popis: |
The boreal biome exchanges large amounts of carbon (C) with the atmosphere and thus significantly affects the global climate. A managed boreal landscape typically consists of various sinks and sources of carbon dioxide (CO2), methane (CH4), and dissolved organic and inorganic carbon (DOC and DIC) across forests with different stand ages, mires, lakes, and streams. Due to the spatial heterogeneity, a full understanding of the landscape-scale C balance requires capturing all C fluxes. Here, we investigate the five-year interannual variability in the net landscape carbon balance (NLCB) by compiling terrestrial and aquatic fluxes of CO2, CH4, DOC, DIC, and harvested C obtained from 2016 to 2020. For that purpose, we applied tall-tower eddy covariance measurements, stream monitoring, and remote sensing of biomass stocks (i.e. harvested C via clearcutting) to estimate the landscape-scale C fluxes across the land-water-atmosphere continuum for an entire boreal catchment (~68 km2) in Sweden. Our results show that this managed boreal forest landscape was a net C sink during 2016-2020 (123 ± 63 g C m-2 yr-1) with the lowest and highest sink-strength occurring during a wet year 2017 (16 g C m-2 yr-1) and a drought year 2019 (182 g C m-2 yr-1), respectively. The net landscape-atmosphere CO2exchange was the dominant component of NLCB, followed by the C export via harvest and streams. We further found that global radiation and vapor pressure deficit regulated the inter-annual variations of NLCB, whereas forest biomass and source area contribution of mires determined its spatial variability. Overall, our multi-year NLCB investigations provide a holistic understanding of the inter-annual variations in NLCB of managed boreal forest landscapes to better evaluate their potential for mitigating climate change. |
