Dissolved carbon as a component of net biome productivity of major land use systems

对陆地生态系统碳(C)固存的大气估算大于陆基估算，这归因于“缺少通量”，而目前的分析没有考虑到这一点。溶解的有机碳和无机碳通过土壤从陆地环境转移到水圈，可以很好地解释碳固存估计的差异。然而，对溶解C通量的研究几乎完全来自温带森林生态系统，这些研究中没有一项涉及溶解C通量与当地对C固存的估计。此外，对不同土地利用方式下土壤中溶解碳向水圈的输出也知之甚少。我们的假设是：1)土壤中溶解碳的输出填补了基于大气和基于陆地的碳固定估计之间的差距；2)土地利用按耕地、草地和落叶林、针叶林的顺序修正了土壤中溶解碳的通量。这些假设将通过测定土壤中溶解碳的通量来检验，这些通量与13个不同土地利用的地点的净生物群生产力的估计有关

Atmosphere-based estimates of carbon (C) sequestration in terrestrial ecosystems are larger than land-based estimates, which is attributed to `missing fluxes¿ that are not accounted for in present analysis. The transfer of dissolved organic and inorganic C from terrestrial settings to the hydrosphere through soils might well explain the differences in estimates of C sequestration. However, studies of dissolved C fluxes are almost exclusively from temperate forest ecosystems and non of these studies related dissolved C fluxes to local estimates of C sequestration. Also, little is known about dissolved C export to the hydrosphere from soil under different land use. Our hypotheses are i) export of dissolved C from soils fills the gap between atmosphere-based and land-based estimates of C sequestration; ii) land use modifies fluxes of dissolved C from soils in the order arable land > grassland > deciduous forest > coniferous forest. These hypotheses will be tested by determining fluxes of dissolved C from soils in relation to estimates of net biome productivity of 13 sites of different land use