Tree stand dynamics, changes in the ground vegetation and soils, and species diversity of wood-decaying fungi were studied in pristine middle boreal spruce forests affected by a surface fire in the Vodlozersky National Park (Arkhangelsk Region, Russia) in 2011. In the third year after the fire, the burnt area was dominated by birch, which contributed an average of 72% to the total amount of major tree species regeneration. In sites affected by a high-severity fire, the ground vegetation cover did not exceed 40%, with Chamaenerion angustifolium (L.) Scop. and Marchantia polymorpha L. dominating in the first years after. By the tenth year, the diversity of the newly forming tree layer increased from 5 to 11 species and natural thinning of deciduous tree regeneration was already underway, although its amount was still over 100,000 plants per hectare throughout. By the end of the first post-fire decade, Picea abies (L.) H. Karst. and Pinus sylvestris L. accounted for 11% of the total regeneration. The occurrence and cover of pyrogenic species Chamaenerion angustifolium and Marchantia polymorpha declined sharply at this stage. Vegetation in sites affected by mid-severity fire was mostly regenerating through propagation of the survivor Avenella flexuosa (L.) Drejer, Vaccinium myrtillus L., V. vitis-idaea, etc. In the burnt area, the species diversity of wood-destroying fungi was reduced compared to the adjacent unburned areas, and it was the same in both heavily and moderately burnt areas. This is probably due to the fact that the downed deadwood in post-fire sites was trunks of the same age and in the same degree of decay whereas the total amount of downed deadwood in the control (unburnt forest) was lower but featuring all stages of decay and, furthermore, there were plenty of fungi-populated dead standing and weakened overmature trees.

It is shown that the chemical composition of the litter falls and wood of deciduous and coniferous trees is different. On the background of aerotechnogenic pollution, accumulation of individual heavy metals, an increase in ash content was noted. There was revealed the anthropogenic dynamics of the accumulation of heavy metals in the wood of trees: the maximum number during the period of diesel traction; as the railway site is electrified, the accumulation of elements decreases. The obtained data can be recommended to be used for phytoremediation at sites subject to pollution. The obtained data will be the basis for assessing the phytoextractive potential of woody plants, in diagnosing aero-technogenic pollution of the environment, solving the problem of reducing environmental risks, as well as during the modernization and planning of environmental measures in the field of railway infrastructure.

Приведены результаты исследования экотонного комплекса 90-летнего ельника черничного и 35-летнего осинника злаково-разнотравного, появившегося на месте сплошной рубки. Выявлено, что после 35 лет естественного восстановления леса на вырубке по ряду признаков определяется переходная зона, распространяющаяся примерно на 10 м в обе стороны от границы примыкания сообществ. Максимальные размеры переходной зоны – 10 м от границы сообществ – определены по изменению радиального прироста, который был в среднем выше, чем в центральной части ельника черничного в течение двух десятилетий после рубки. В переходной зоне, в отличие от других зон экотонного комплекса, отмечается максимальная густота подроста ели. Минимальная протяженность куртин Hylocomium splendens (Hedw.) Bruch et al. на стволах осины в ельнике черничном отмечается у границы с осинником, максимальная – на самом удаленном вглубь ельника дереве. Насыщенность еловыми корнями верхнего слоя почвы снижается в направлении от ельника черничного к осиннику злаково-разнотравному...

In a natural regeneration process, a community dominated by birch and aspen forms in the site 35 years after a bilberry-type spruce stand is logged down. The newly formed ecotone complex consists of four zones, each characterized by certain features of the ground vegetation and epiphytic vegetation structure. The transitional zones and the mature bilberry-type spruce forest feature a clear dominance of boreal dwarf shrubs (bilberry and cowberry). Another feature of the transitional zone is a greater role of hygrophytic mosses of the genera Polytrichum and Sphagnum. Meanwhile, the true mosses Pleurozium schreberi and Hylocomium splendens dominate under spruce forest canopy, and the moss cover in the young deciduous stand is virtually nonexistent. The structure of epiphytic vegetation depends on the habitat conditions—the surface of tree trunks in the transitional zone is better lit and drier than inside the tree stand, which results in a higher abundance of epiphytic lichens of the genus Cladonia. The deciduous–coniferous fine root biomass ratio is dependent on the tree stand structure and is unrelated to ecotone zones. Overall, studies have demonstrated that transitional zones have certain characteristic ecological and community features, which persist for a long time after tree stand removal.