The productivity of some dominant forage herbaceous plants of the Zavyalov island (Magadan oblast)

In connection with the expert assessment of the pasture suitability of the territory for breeding musk oxen (Ovibos moschatus Zimm.), in the summer of 2018, an express assessment of the productivity of 3 species of dominant herbaceous plants of Zavyalov Island, located in the sea of Okhotsk, not far from Magadan, was carried out. By the method of model plants developed by V.N. Andreev, the stock of aerial phytomass of Hierochloe alpina, Aconogonon tripterocarpum, Oxytropis evenorum was determined. Since the rhizomes of Oxytropis evenorum are used in the diet of many species of herbivores, a reserve of underground phytomass at a depth of 22–25 cm was determined for this species. It was found that the resource of the above-ground phytomass of model plants Hierochloe alpina, for which the height of generative shoots reached 33–34 cm on the record day (30.06.2018), varies from 9,2 to 12,3 g of air-dry mass (10,7 g on average). The fraction of dead grass in this species accounts for about 10 % of the total phytomass. For Aconogonon tripterocarpum, the average height of shoots varied from 33 to 48 cm. The resource of the phytomass of a single generative shoot in this species ranged from 0,89 to 1,59 g (1,25 g on verage). A significant part of the phytomass (from 30 to 66 %; 45 % on average) in this species is located at an altitude of up to 20 cm above ground. The total phytomass of model plants Oxytropis evenorum, including rhizomes, varies from 68,3 to 162,2 g (115,3 g on average). The average resource of the green mass of O. evenorum model plants was 23,4 g, living branches of the caudex – 57,9 g, rhizomes – 16,2 g, mort-mass – 17,7 g. Presumably, the resource of above-ground phytomass of the studied plants may increase by 15-20% by the end of the growing season. Our results can be evaluated as a primary assessment of the productivity of the most promising forage plants of this territory. These data can serve as a preliminary indicator of the productivity of the species considered. For a deeper and objective determination of the forage potential of the vegetation on the Zavyalov Island and its pasture capacity for herbivorous animals, it is necessary to accumulate statistical data, expand the range of observed plants, observe the dynamics of phytomass, etc. This report is part of a series of publications devoted to the adaptation of the musk ox to Zavyalov Island conditions.

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