Separating the impact of climate change and human activities on runoff is an important topic in hydrology, and a large number of methods and theories have been widely used. In this paper, we review the current papers on separating the impacts of climate and human activities on runoff, summarize the progress of relevant research methods and applications in recent years, and discuss future research needs and directions.

Greenhouse gases emitted from soil play a crucial role in the atmospheric environment and global climate change. The theory and technique of detecting stable isotopes in the atmosphere has been widely used to an investigate greenhouse gases from soil. In this paper, we review the current literature on greenhouse gases emitted from soil, including carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O). We attempt to synthesize recent advances in the theory and application of stable isotopes in greenhouse gases from soil and discuss future research needs and directions.

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 aimsWe investigated the SOC dynamics following artificial and natural 2 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. 13 C 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.

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 afforestation 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, clarify SOC source under different afforestation, examine comparability of the study areas and find how soil aggregate size classes control SOC dynamics, finally to evaluate effect of reforestation project.Results The 0-10cm and 10-20 cm SOC stocks were significant higher than other two land-use system. At other depths, there is no significant difference among the three land-use system. Total top soil SOC stocks, C:N and C:P of differently sized soil aggregates significantly increased following afforestation. 13C results and Radiocarbon models indicated that the SOC decomposition rate and new SOC input rate were lower under natural afforestation than artificial afforestation. Conclusions Afforestation can accumulate SOC in top soils mainly resulting from in topsoil changing. SOC resource is mainly from macroaggregate formation provided by fresh plant residues. SOC loss from soil respiration was derived from microaggregates during afforestation. The“space-for-time substitution” method is suitable for comparability of the study areas.

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.