摘要：Soils contain a large C pool, but temporal changes in the pool size are difficult to determine. Root and rhizosphere respiration (Ra) is a major component of soil C-balance, but it cannot be measured continuously with conventional methods. Here, we present a novel method for determining the contribution of Ra. This novel method is based on temperature fitting of soil CO2 effluxes (F0) over long and short time intervals using continuous chamber measurements. We show the contribution of seasonal changes to Ra and to total soil CO2 efflux in a Scots pine forest in southern Finland. Ra contributed about 42% of the total soil CO2 efflux. The seasonally extremely variable contribution from 17% in early April to 60% in late July followed the seasonal pattern of the GPP. The contribution of Ra was 45% of the annual total GPP (1154 g C m–2) of the forest ecosystem. The increase in Ra lagged behind the increase in GPP by 18 days, and the peak in Ra was observed about six weeks after the highest values of daily GPP were attained, which reflected the changes in the seasonal pattern in above- and below ground-allocation of assimilated C.
