On some biological features of Hepatica nobilis Mill. (Ranunculaceae) in the central part of European Russia

The main aim of this work was to study some biological features of Hepatica nobilis Mill. (Ranunculaceae), to generalize the information about the features of its habitats, and to obtain current data on seed productivity of this species in the central part of European Russia. We conducted our study in natural habitats of the species in the territory of Yaroslavl oblast in 2015-2016: Nekouz (58°03'41.2''N, 38°14'43.4''E), Myshkin (57°45'42.0''N, 38°26'42.1"E), and Uglich areas (57°37'10.0''N, 38°29'31.6''E; 57°33'24.5''N 38°16'32.1''E). To obtain data, we dug plants, and, depending on the nature of further studies, we either used them for morphological analysis, or placed them in the herbarium. At the sites of gathering, we determined the nature of the soil and the dominant species of trees and shrubs included in the upper and middle tiers. While studying the biomorphology of the generative sphere of plants, we measured the length of flower stalks, flower diameter, and the length and width of spathe leaves and leaflets of the simple perianth, as well as determined the number of stamens, carpels and nuts. We showed that in the center of the European part of Russia H. nobilis occurs, mainly, in spruce, spruce-broad-leaved, and mixed forests, rarely in deciduous forests, along forest-covered ravines and slopes, occasionally in bushes on forest edges. According to our observations, the species can grow in pine forests with well-developed small-leaved underwood. We established that going much further south the species is encountered in broad-leaved forests more often. Thus, in Arkhangelsk and Leningrad oblasts, H. nobilis is spread, mainly, in spruce-deciduous and light small-leaved forests. We noted that in the territory of Yaroslavl oblast, in addition to coniferous-small-leaved forests, H. nobilis can be found under the canopy of broad-leaved trees. In the territory of Nizhny Novgorod oblast the species prefers coniferous-broad-leaved and broad-leaved forests. We observed that flowering of H. nobilis in Yaroslavl oblast usually starts in the first decade of April and lasts 2.5-3 weeks. The period of blooming of H. nobilis is greatly influenced not only by atmospheric factors, but also by the relief features. Thus, the cooling effect of the Rybinsk reservoir in spring (May-June) leads to the fact that in more southern regions of Yaroslavl oblast H. nobilis blooming is observed 1-1,5 weeks earlier than in the north. The average diameter of flowers is 2.6±0.3 cm. Ripening takes place in the first decade of June. The fruit is polyspermous, presented by one-seeded nuts. We found that one H. nobilis flower forms, on average, up to 22.5±2.8 nutlets; 5.4±4.0 of them remain undeveloped. The actual seed productivity (ASP) of one plant varies from 45.1±5.6 to 180.6±22.8 nutlets/plant. But cases are known when ASP of one plant bearing up to 15-25 flowers reached 396.5±56.1 nutlets/plant. We found that in the territory of European Russia H. nobilis is a long vegetating, summer - winter green plant with early or middle spring blossom according to the phenorhythmotype. The life form is a plant with short rhizomes; it is a herbaceous perennial plant, polycarpic with implicitly polycentric type of biomorphs with partial late non-specialized morphological disintegration; it is a hemicryptophyte. We suggest that the disappearance of H. nobilis population is often caused by elimination of coniferous-deciduous forests in the region under study. Digging plants and picking up bunches of flowers affect negatively the structure and vital ability of the local populations. Restoration of hepatica populations in nature requires a long period of time. We propose the following measures for the species protection in the region: conducting activities aimed at protecting habitats, organizing specially protected natural areas (SPNA),and prohibiting tree felling in protected areas (selective felling). The article contains 34 References.

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