The Pathological Status of Pinus sylvestris L. Understory Affected by Anthropogenic Air Pollution Stress (Case Study of Forests near Krasnoyarsk)

Air pollution is the major anthropogenic factor in urban and industrial areas. Forests play the most important role in improving environmental quality in such areas. Long-term air pollution has an adverse effect on the entire biota in such forests and determines the nature of plant–pathogen interactions. The purpose of the present research was to study the pathological status of the understory in Pinus sylvestris L. stands subject to long-term anthropogenic air pollution. The study was conducted in the pine forests near Krasnoyarsk. Research methods included a detailed pathological inspection of the understory (including saplings and self-sown trees) in stands (mainly forest-steppe pine forests) growing from 10 to 30 km from the city and macroscopic and microscopic diagnostics of plant diseases, and the analysis of the data obtained was carried out using statistical criteria (Kolmogorov–Smirnov test (dK-S), Student’s t-test). Pathogens affecting young pines (nine species identified) are micromycetes of different parasitic strategies (semi-parasites predominate). The most common pathogens are Lophodermella sulcigena (causes needle cast), Cenangium ferruginosum (necrosis of branches), and Sarea difformis (stem and branches canker). The pathogens causing necrosis and canker are the most harmful for pine understory. As young plants mature, pathogen diversity and disease manifestations increase. In stands closer to the city, understory infestations with dominant diseases significantly decrease as the degree of their contamination with heavy metals and fluorine increases. The activity of pathogenic micromycetes is likely to be suppressed by the chemicals found in the plants.