Simulating the effect of forest fires, cuttings, and increased nitrogen deposition on dynamics of key forest ecosystem properties and processes in Russian North-West

Abstract

The improved version of simulation model EFIMOD 2 was used for the estimation of forest ecosystem dynamics and analysis of basic linkages between stand structure, environment, and external factors, such as cuttings, forest fires, increased nitrogen deposition, which were considered both separately and in combination, in different boreal forest types of European Russia. According to the simulation results, increasing role of Norway spruce during the undisturbed development resulted in enrichment of forest floor and mineral soil by nitrogen by 5 and 10%, respectively. In contrast, fires promoted increase in Scots pine portion in stand composition, decrease in forest floor pool by 31%, in comparison with undisturbed development. Cuttings had the impact on stocks of soil organic matter through the decreased litter fall input that resulted from partial removal of tree biomass. The combined effect of fires and cuttings on ecosystem carbon pools was about 17% smaller than could be expected from the simple sum of the effects of both factors, which means that impact of one factor reduces (by affecting the same components of ecosystems) the possibility for negative influence of another one. The gradual increase in nitrogen deposition from 1.5 to 3.0 kg ha−1 year−1 for northern taiga and from 3.0 to 4.5 kg ha−1 year−1 for middle taiga by the end of 100-year simulation period had a positive influence on the carbon and nitrogen accumulation in trees’ biomass and soil organic matter (35% higher than in scenario without disturbances), thus partly overwhelming the impact from fires and cuttings. The important feature of the study is that the quantitative differences of stand and soil parameters between forest site types were revealed as well.