CO 2 efflux from the biological soil crusts of the High Arctic in a later stage of primary succession after deglaciation, Ny-Ålesund, Svalbard, Norway

•We measured not-well known soil CO2 efflux from BSCs with black color during summer.•The coverage and quality of BSCs-B affected the spatial variation of soil CO2 efflux.•The soil CO2 efflux showed positive correlations with the enzyme activities in BSCs-B.•The measured soil CO2 efflux significantly contributed to the surface carbon budget.