Pulsatilla vulgaris is one of the rarest vascular plant species in Russia. In the Red Data Book of the Russian Federation, it is classified as critically endangered (category 1). The only population of P. vulgaris in Russia is known from the Leningrad Region and it is rapidly declining. The analysis of the population ontogenetic structure demonstrates low level of the population self-sustainment due to lack of seed reproduction. One of the factors that prevent P. vulgaris generative reproduction is the biotope transformation caused by succession. Typical habitats of P. vulgaris are heaths, sparse and low pine forests, dry low-grass meadows and pastures. Successful seed reproduction of the species requires the factors that inhibit woody vegetation development and lead to the damage of dense ground cover and soil (i.e. moderate grazing, weak ground fires etc.). To avoid a complete loss of the species in Russia, artificially damaged sites suitable for successful seed regeneration of P. vulgaris were formed in 2020–2021 in “Nizhnevolkhovskiy” Protected Area (Leningrad Region, Volkhovskiy District). Trees uprooting, grass vegetation removal or damage, soil damage were performed to form exposed and well-warmed sites with sparse vegetation ground cover. These measures have significantly increased germination capacity of the seeds on the managed plots compared to the left untreated (control) areas. Over a two-year period, the population of P. vulgaris has increased by more than 10%. The success of the measures applied allows to recommend them for the restoration of rare and highly specialized species populations growing in similar habitats.
Helianthus occidentalis is poorly studied embryologically, but it may be very useful in breeding due to its high resistance to pests and diseases. Significant variation in the viability and size of pollen grains in the samples of different origin is characteristic for this species. No essential deviations in the anther development were noticed before microsporogenesis start. Further, the following anomalies were found: late chromosomes outside of the spindle; dyads with one nucleus being degenerating on anaphase I; formation of micro- and macronuclei during the second division of meiosis; degeneration of several nuclei within a tetrad; formation of triads, dyads and monads of microspores instead of tetrads. We have noticed significant heterogeneity of pollen grains by size. Deformed and compressed ones were noticed, as well as those with the structure of dyad or tetrad of cells within their wall. There is some data in literature on similar anomalies both in plants of other taxa and in Helianthus plants, mainly of the hybrid origin. One of the supposed reasons of the multiple anomalies in development and deterioration of pollen quality in the sample of H. occidentalis under investigation is a possible introgression of chromosomes from one of closely related diploid species as a result of hybridization that took place in the natural population. The conducted study once again confirms the need for cytological analysis to identify potential pollinating plants for sunflower breeding.
St. Petersburg is the largest city in the world north of 60° N. Urban areas neighbor on relatively undisturbed sites with natural south taiga landscapes (about 30% of the city area). The conventionally primary vegetation is represented by spruce, pine and black alder forests, different types of bogs, maritime meadows, coastal-aquatic vegetation. Secondary vegetation includes small-leaved forests and upland meadows. For many years, comprehensive environmental surveys of the city territories have been carried out in St. Petersburg in order to justify the feasibility of creating natural protected areas there. Currently, there are 17 protected areas of regional status in St. Petersburg with a total area of 92 km2. Another 17 territories (about 70 km2) have been surveyed and recognized as having a high conservation value. One of the tasks of geobotanical research is to identify plant communities rare in the city and needing protection. The existence of these communities is due to a number of factors related to the geographical location and history of the city’s development. The conservation value of communities The communities conservation value is based on their rarity and is determined by a number of criteria. Based on these criteria, four categories are proposed: floristic (dominance of a rare species), structural (combinations of structural components formed by species with contrasting ecological-coenotic characteristics), ecotopic (presence of rare ecotopic conditions), rare communities (encountered 1 to 3 times over the entire research). Totally, more than twenty types of rare communities have been identified. The first category includes communities with the species listed in the Red Book of St. Petersburg – Myrica gale, Viola uliginosa and Euphorbia palustris. The second category includes forest communities of Kotlin Island with structural features of the lower layers. The third, largest category includes small-leaved nemoral forb forests, maritime meadows, extrazonal broad-leaved forests and hazel bushes. Their existence is determined by rare ecotopic conditions, which depend on the coastal position and geological and geomorphological features of the city. The fourth category includes old-growth spruce forests, plant communities with rare species Equisetum hiemale and Carex brizoides, and unique for the city ridge-hollow-lake complex on the Sestroretskoye bog. The location within the city, characteristic habitats and dominants of the layers are described for each community. For many types of communities, tables with relevés are provided.
Helianthus occidentalis is poorly studied embryologically, but it may be very useful in breeding due to its high resistance to pests and diseases. Significant variation in the viability and size of pollen grains in the samples of different origin is characteristic for this species. No essential deviations in the anther development were noticed before microsporogenesis start. Further, the following anomalies were found: late chromosomes outside of the spindle; dyads with one nucleus being degenerating on anaphase I; formation of micro- and macronuclei during the second division of meiosis; degeneration of several nuclei within a tetrad; formation of triads, dyads and monads of microspores instead of tetrads. We have noticed significant heterogeneity of pollen grains by size. Deformed and compressed ones were noticed, as well as those with the structure of dyad or tetrad of cells within their wall. There is some data in literature on similar anomalies both in plants of other taxa and in Helianthus plants, mainly of the hybrid origin. One of the supposed reasons of the multiple anomalies in development and deterioration of pollen quality in the sample of H. occidentalis under investigation is a possible introgression of chromosomes from one of closely related diploid species as a result of hybridization that took place in the natural population. The conducted study once again confirms the need for cytological analysis to identify potential pollinating plants for sunflower breeding.
The article characterizes psammophytic herb communities on fallow lands, treated as two new associations Berteroo incanae–Hieracietum umbellati ass. nov. and Polytricho juniperini–Viscarietum vulgaris ass. nov. within the class of psammophytic herb vegetation Koelerio–Corynephoretea canescentis Klika in Klika et Novák 1941. Their communities represent secondary vegetation at different stages of regenerative succession on the site of oligotrophic pine forests. Based on floristic comparison, assessment of ecological regimes of community habitats and NMDS-ordination of coenofloras based on the H. Ellenberg’s optimal scales, the differences between the new syntaxa of the Southern Nechernozemye (Non-Chernozem region) of Russia from previously established European units are demonstrated.
