Modelling carbon and nitrogen dynamics in forest ecosystems of Central Russia under different climate change scenarios and forest management regimes

The individual-based stand-level model EFIMOD was used for large-scale simulations using standard data on forest inventories as model inputs. The model was verified for the case-study of field observations, and possible sources of uncertainties were analysed. The approach developed kept the ability for fine-tuning to account for spatial discontinuity in the simulated area. Several forest management regimes were simulated as well as forest wildfires and climate changes. The greatest carbon and nitrogen accumulations were observed for the regime without cuttings. It was shown that cuttings and wildfires strongly influence the processes of carbon and nitrogen accumulations in both soil and forest vegetation. Modelling also showed that the increase in annual average temperatures resulted in the partial relocation of carbon and nitrogen stocks from soil to plant biomass. However, forest management, particularly harvesting, has a greater effect on the dynamics of forest ecosystems than the prescribed climate change.     

Modelling dynamics of soil organic matter under different historical land-use management techniques in European Russia

We have analyzed an influence of the traditional agricultural system techniques on the soil organic matter dynamics using the model of carbon and nitrogen cycling in forest ecosystems EFIMOD linked with the model of SOM dynamics ROMUL. Forest stands on the loamy soddy-podzolic soils (Alfisoils) located in the Central European Russia have been taken for the case study. The following land-use management scenarios were simulated: (a) slash-and-burn system with 3 years for crops and 120, 60 and 25 years for forest; (b) three-field crop rotation system with organic fertilization (dung) every 3 and 9 years and the same rotation without fertilization; and (c) short-term field-forest shifting system with 10 years for crops and 10 and 25 years for forest. Analysis of the results showed that the frequency of agricultural use in mixed field-forest land-use systems was crucial for soil organic matter dynamics. Under the short interval between agriculture, the stocks of all soil organic matter pools decreased. Under all scenarios except the three-field crop rotation with fertilization and the slash-and-burn system with 120 years for forest, a strong reduction of soil organic matter occurred after 30-130 years of the agricultural impacts. The highest reduction rates were modelled under the short-term field-forest shifting system and three-field rotation without fertilization. Fertilization led to stabilization of soil organic matter pools and gave a possibility for a long time stable agricultural use.