Retrospective assessment of the dynamics of nitrogen availability in pine forests of the near-Moscow region based on the data of phytoindication

Abstract

Earlier published data on the long-term geobotanic monitoring in permanent pilot plots have been used to analyze changes in trophic conditions and estimate nitrogen nutrition availability to pine forests of the Serebryanyi Bor Forestry located in the Moscow oblast. The assessments of habitats based on the ecological scales of soil richness with nitrogen, which were developed by D.N. Tsyganov and G. Ellenberg, and analysis of the dynamics of stenobiont species have revealed the properties of changes in the species composition and conditions of nitrogen availability to forests for the period from 1957–1961 to 2003. The results indicate increased nitrogen availability to forests in the studied period for all permanent plots, but reflect different intensities of the trend of eutrophication in different monitoring stages. A more intense growth in soil richness with nitrogen in all permanent plots was in the period since 1957–1961 to 1989–1990. In the next years, the level of nitrogen availability to phytocenoses almost did not change. The improvement in the trophic conditions was accompanied by the growth in total species richness and increase in the number of stenobionts with high requirements to nitrogen nutrition. The results from analyzing the dynamics of stenobionts confirm the division of the period under consideration into two stages. From 1957–1961 to 1989–1990, changes in the species composition of plant communities in the pine forests under consideration were similar but differed in intensity. From 1989–1990 to 2003 (against the background of total deceleration of the eutrophication trend), the similarity of species dynamics in the communities was disturbed. The impact of air pollution by NOx on nitrogen nutrition availability to forests was examined with consideration for the fact that the studied area is within the capital agglomeration. The dynamics of the intensity of air nitrogen deposition is in good agreement with the revealed changes in the species composition of phytocenoses and nitrogen soil richness. It gives reasons to suppose that the trend of forest eutrophication in the 1960s–1980s was strengthened by the impact of increased levels of atmospheric nitrogen deposition.