N. S. Sannikova’s research while affiliated with Main Botanical Garden Of Russian Academy of Science and other places

Simulation of fire impact on forest floor renewal in pine forests was based on predictions for 2100 by the Canadian Climate Centre for increase in temperatures of by 4.5 °C and total precipitation by 14% in the West Siberian pre-forest-steppes and empirical regression relationships between them and the degree of burnt forest floor, as well as amount of Pinus sylvestris L. regeneration. It was predicted that by 2100, pine regeneration on fire prone sites under the canopy of the dominant forest type will increase by 29–54% compared to the 1980s but on adjacent open sites, regeneration will decrease twice as much. This means that the regeneration potential and pine population stability in pre-forest-steppes will become as poor as it is today.

The dates of appearance of a representative portion of Pinus sylvestris L. pollen in palynospectra (≥20%) have been analyzed as a parameter reflecting the spread of leading-edge pine populations from central and eastern Europe to the Lofoten region via probable alternative routes of population immigration. It has been found that they could reach this region not earlier than 6500–7000 years BP, i.e., 2500–3000 years later than the factual palynological date, even at the maximum possible rate of their spread (300–500 km/1000 years). Therefore, the probability of the origin of Lofoten P. sylvestris populations from adventive populations that migrated to Scandinavia from adjacent European regions is excluded. The generalization of the results of studies on the chronopalynology and rate of Holocene expansion of P sylvestris and data on paleoglaciology, paleomarinology, paleobotany, and modern genogeography and ecology of Scots pine has confirmed the hypothesis about the survival of autochthonous refugial populations of this species on the Lofoten Islands during the last glacial phase and their expansion during the Holocene.

As a result of allozyme analysis, Nei’s genetic distances were determined between the phylogeographic group of seven populations of Pinus sylvestris L. in the “glacial” zone of the range in Central Yakutia and 25 populations of its hypothetical Pleistocene refugia of the southern nonglacial zone within the entire range of the species in Northern Eurasia. The location of the most likely “avant-garde” refugium of the modern yakutian populations of the Scots pine is Northern Priamur’e (Tynda), as well as less likely Siberian (Romanovka, Irkutsk), South Ural (Kryktytau), and Central European (the Czech Republic) refugia.

Allozyme analysis of 18 Pinus sylvestris L. populations from seven landscape-geographic groups has been performed in the Greater Caucasus, Crimea, and Russian Plain. The results show that populations of the Mt. Elbrus region (isolated by high mountain ridges) are characterized by lower polymorphism and most distinct differentiation (at the level of geographic race) from other populations, which are differentiated from each other at the level of geographic groups. Genetic gradients (boundaries) between populations reach a maximum on transects across the Greater Caucasus Range, and Transcaucasian populations are more similar to populations of the Russian Plain, compared to North Caucasian populations, which confirms the hypothesis of ancestral connections between their gene pools.

The paper is devoted to the analysis and generalization of the results of stationary studies on differentiation of factors of the epi-soil environment, natural forest regeneration, and formation of secondary dendrocenoses on burns and clean cuts in two pine forest types most prevalent in the pre-forest–steppe subzone of Western Siberia (Pripyshmiskian pine forests). It is shown that the same primary forest type (or even biogeocenosis) in burns, on the one hand, and in clean cuts, on the other hand, is replaced by two types of biogeocenoses that are alternative to each other in terms of structure and functions and represent qualitatively different, diverging ecodynamic series of natural regeneration and development of the primary, autochthonous forest type.

Recolonization of Scandinavia by populations of Pinus sylvestris, on the one side, and of Picea abie and P. obovata on the other in the Holocene Period is analyzed: its paths, rates, and delays are compared. The dispersal rate of the populations, beginning from 12000 years BP, is evaluated by the published data of radiometric method of pollen dating. It has been revealed that P. sylvestris migrated into central Scandinavia from the Alps via the Denmark Isthmus at the rate of 500–1250 km/ka about 8200 years BP. The fast dispersal may be mainly explained by the hydrochory of pine seeds, which is by an order of magnitude quicker than anemochory. The rate of P. sylvestris expansion to Fennoskandia from the Russian Plain was lower (520 km/ka). Populations of Picea species dispersed from the same regions at a rate three to ten times lower (131–164 km/ka). That is why the invasion of Picea abies from the Alps to Scandinavia via the Denmark Isthmus did not take place before the formation of the Kattegat Strait. The populations of both Picea species reached the northern areas of Scandinavia 3500 years BP, its central part 2000 years BP, and the southern area 1500 years BP by a roundabout route via Karelia. In general, they reached Scandinavia by 4000, 6200, and 8500 years later than P. sylvestris, respectively. This is obviously related to the fact that pine trees begin to seed two times earlier than the spruce, and pine seedlings were more tolerant to the extreme climatic conditions of the periglacial habitats of the Mid-Holocene Period.

The results are presented of comparative analysis of pathways, rates, and timing of recolonization into Scandinavia, in Holocene, of Pinus sylvestris populations and those of Picea abies and P. obovata. The dispersion rate, starting from 12 thou years before present (BP), is calculated using palynological data from scientific literature on radiometric dating. It is found out that P sylvestris spread into Central Scandinavia from the Alps via the Danish Isthmus about 8.2 thou years BP with the speed of 500-1250 km per 1 thou years. A hypothesis is put forward suggesting that such a fast speed is due to pine seeds hydrochory, which is much faster than anemochory according to our researches. From the northern part of the East European Plain, P. sylvestris spread into Fennoscandia with lower speed (520 km per 1 thou years). Populations of Picea species dispersed from the same regions with speed (131-164 km per 1 thou years) 3-10 times lower than that of P. sylvestris. Therefore, invasion of Picea abies from the Alps into Scandinavia via the Danish Isthmus did not have time to happen before the formation of the Kattegat Strait. By circumferential pathway, through Karelia, both species of Picea reached the northern parts of Scandinavia only 3.5 thou years BP, its central parts - 2 thou years BP, and its southern parts - 1.5 thou years BP, i.e., later than P. sylvestris by 4, 6.2, and 8.5 thou years respectively. Probably, this may be explained by the fact that in pines the time to seeding is twofold shorter, while their sprouts were more tolerant to climatic extremums in periglacial habitats in middle Holocene.

The history, distribution routes, and phenogeographic structure of the Scots pine (Pinus sylvestris L.) in the northeast of the Russian Plain were studied on the basis of paleogeographic data and results of our own phenotypic and allozyme-genetic studies. It is assumed that, after the maximum Dnieper glaciation, P. sylvestris populations could successfully distribute to the northwest and north from the refugia of the South and Middle Urals as a result of seed dispersal by Belaya, Ufa, Chusovaya rivers (in Holocene, by Severnaya Dvina, Mezen', and Pechora rivers). On the basis of the hypothesis of "migration complexes" and the theory of hydrochory for coniferous species, a scheme of formation of a population structure of the Scots pine in the northeast of the Russian Plain is proposed.

Quantitative ecological and genetic studies in the pine forests of North Eurasia based on the example of Pinus sylvestris L. have allowed the constructive population genetic and ecological principles and parameters for selection, assessment, and classification of forest genetic reserves (FGRs) to be grounded. The genetic parameters of FGR populations (the minimum area, disturbance by cutting, and the influx of foreign pollen) are regarded as undoubtedly top-priority factors, as tree-stand vitality and germination capacity are regarded as key ecological factors. We propose to give a general estimate for the class of FGR quality using an integral ranking scale for five genetic and ecological parameters based on the class of the FGR area. This class increases by 0.5 with an increase (deterioration) by one class of any other considered parameter. This system provides the possibility to create a unified system for ecologically and genetically grounded selection of FGRs and assessment of their classes.