Backgrounds A multitude of studies have applied different methods to study the dynamics of soil organic carbon (SOC), but the differential impact of artificial and natural vegetation restoration on SOC dynamic are still poorly understood.
Methods and aims We investigated the SOC dynamics following artificial and natural afforestation in Loess Plateau of China, characterizing soil structure and stoichiometry using stable isotope carbon and radiocarbon models. We aim to compare SOC dynamics under both natural and artificial afforestation and examine how soil aggregate size classes control SOC dynamics based on stoichiometry and soil respiration.
Results Total top soil SOC stocks, C:N and C:P of differently sized soil aggregates significantly increased following vegetation restoration. 13C results and Radiocarbon models indicated that the SOC decomposition rate and new SOC input rate were lower under natural afforestation than artificial afforestation and revealed the highest SOC decomposition rate under natural afforestation compared to other two ecosystems.
Conclusions Vegetation restorations can accumulate SOC in top soils. Soil aggregates alternately play a dominant role in SOC accumulation following vegetation restoration; SOC loss from soil respiration was derived from microaggregates during afforestation. Recovery time is a key factor for the accumulation of SOC following afforestation.