Assessment of the Assimilation Potential (of Carbon) of Urban Green Areas (Using the City of Penza as an Example)

The dependence of carbon assimilation in mixed plantings of the city of Penza on the influence factors used in the ROBUL algorithm was studied. Specific carbon assimilation in the city depends by 99% on the forest cover of the residential area, the assimilation age rank, and the average conversion coefficient. The first factor impacts carbon assimilation the most, whereas the conversion coefficient is of the least significance. The average carbon assimilation by the residential zone tree stand was 0.199 t/year/ha (43.6 kg/year/person). The highest indicators were in the districts with forest park zones; the lowest ones were in the districts developed not earlier than 2000. A positive carbon balance is observed relative to respiration of the population, but this balance is negative within the administrative borders of districts. A comparison of specific carbon assimilation at the Penza agglomeration sites calculated using the ROBUL algorithm and the obtained general regression assimilation model (RMA) showed no significant differences between them with a significant difference in the labor intensity of obtaining results in favor of the RMA model. The RMA model can be used to determine the temporal dynamics of carbon assimilation based on the planned area and composition of plantations. For the maximum possible share (42.6%) of the green residential area of Penza, the potential carbon assimilation according to the RMA model for mixed species is 0.44 t/year/ha and is achieved in 40 years from tree planting, after which there is a decrease due to natural thinning.