Abstract: Shrubland functions as an important carbon sink. However, uncertainties have still persisted regarding shrubland C storage and its underlying drivers. In this study, we conducted a field survey encompassing 45 sites to investigate all sectors of C stocks in shrublands distributed in northern China, in order to accurately estimate the regional C storage and to explore the potential drivers. Our results showed that the total C density of shrubland was 78.78 Mg C ha^–1, with soil C density, vegetation C density and litter C density contributing 75.16, 2.99 and 0.64 Mg C ha^–1, respectively. Distinct C density sectors were driven by different factors: vegetation C density was primarily driven by plant community richness, litter C density by shrub diversity and soil C density by total annual sunshine and soil total phosphorus in our study. Climate factors, plant community traits and soil properties independently explained 5.15%, 6.79% and 23.73% variation of the shrubland ecosystem C density, respectively. Furthermore, the interactions between community structural traits and climate factors, as well as between community structural traits and soil properties, can explain 10.44% and 18.50% of the variation, respectively. Our findings, based on direct field measurements, refined estimates of C storage in shrubland ecosystems in northern China, and these findings provided crucial data for the validation and parameterization of C models both within China and globally.

Key words: carbon density, shrubland, richness, diversity, total phosphorus content