The state of cenopopulations of a rare species Brachanthemum krylovii Serg. (Asteraceae) in the Altai Republic

Brachanthemum krylovii Serg. is a narrow-endemic of the Central Altai. It was included in the Red Book of the Altai Republic as a vulnerable species. B. krylovii is a taproot polycarpic plant, shrub or half-shrub, forming several lignified skeletal axes. It reproduces only by seeds. The state of populations, the variability of morphological characteristics and the life form of plants in natural conditions, as well as adaptive possibilities of the species have not been studied so far. The paper describes the state of B. krylovii cenopopulations (CP) in Ongudai region (Altai Republic) (See Table 1). In each CP, we studied a random sampling of 10 to 20 mature generative individuals without external signs of caudex disintegration in 2013-2015. We investigated 14 metric and allometric morphological quantitative characteristics of the vegetative and generative sphere. We calculated seed productivity indicators per one infructescence: potential seed productivity (PSP), real number of formed seeds (RNS) and the percentage of seminification: the ratio of RNS to PSP, expressed in percentage. The average seed productivity per individual was determined as the product of the mean values of the number of seeds in the infructescence, the number of inflorescences on the shoot, and the number of generative shoots in the individual. We established that individuals from undisturbed habitats are shrubs with orthotopic shoots, with an average height of up to half a meter, and with a small number of annual shoots (on average, 11.0 ± 1.1) (See Table 2 and Fig. 1). The life-form of plants varies from a shrub with a few shoots to a forced dwarf shrub under the influence of anthropogenic impact (grazing). We noted that the annual shoots were damaged by farm animals; their lignification was disturbed under the impact of grazing. In this case, the plant height was significantly lower, and we revealed a much larger number of annual shoots (for example, in individuals from CP 2A-14, on average, up to 77.0 ± 9.3) (See Table 2). Thus, all B. krylovii representatives have an adaptive potential that helps maintain the integrity of cenopopulations. We found out that under anthropogenic influence (intensive grazing), the process of orthotopic shoot growth in plants is disrupted. The meristematic potential of individuals is reoriented to increase the number of annual shoots. As a result, B. krylovii forms as a dwarf shrub instead of a shrub. We showed that without human impact (grazing), plants form as shrubs, which creates qualitatively different conditions for realization of their seed reproduction potential. We established that potential seed productivity of B. krylovii plants reaches, on average, 2500-7000 ovules per individual (See Table 2). Despite this, the seed renewal of B. krylovii individuals is extremely unstable, and, probably, does not take place every year, since we did not find shoots and young individuals. Comparison of seed productivity parameters of B. krylovii from CP 1 and CP 2 demonstrates that in the more humid and cool 2013 the representatives from CP 1 showed significantly higher PSP values. PSP of its individuals did not vary in different years of observation. We determined that RNS was significantly higher in 2013, compared to 2015 (See Fig. 2). In addition, more rounded infructescences formed in 2013, and in 2015 they were narrower and more elongated (See Table 3). There was no evidence of individuals in the pre-regenerative period in the studied habitats. Under unfavorable weather conditions (hot dry weather), the length of the annual shoot reduces in plants, and the proportion of generative shoots and the number of inflorescences decrease in communities where grazing is practised. As a result, seed production deteriorates, but larger seeds are formed. As a way of preserving B. krylovii species, introduction proved to be ineffective in the forest-steppe zone of Western Siberia. Nevertheless, in the laboratory, we obtained seedlings, which can be used as a donor for restoration of natural populations. It is also necessary to monitor natural populations where grazing is practised. If their state deteriorates, environmental measures should be implemented to maintain the regulated anthropogenic load and restore these populations by the method of "translocation" (seeds) and "reintroduction" (seedlings). The paper contains 2 Figures, 3 Tables and 36 References. Acknowledgments: The equipment of the collective use center of the Central Siberian Botanical Garden (Novosibirsk), Siberian Branch of the Russian Academy of Sciences was used during the study. We used the materials from the "Bioresource Collection of the Central Siberian Botanical Garden, Siberian Branch of the Russian Academy of Sciences and "Collections of living plants in open and closed ground" USU 440534.

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