Chosenia arbutifolia (Salicaceae): life strategies and introduction perspectives.
Chosenia arbutifolia A. Skvorts. is a relict endemic of the Asian Pacific Coast adapted to flood activity of mountain rivers. The studies were executed in Russia in south and central areas of Magadan Oblast (the flood plains of the rivers Yana, Chelomdzha, Kolyma, Dukcha) and in the south of Primorsky Krai (the river flood plain Partizanka). The range, habitats, research history, and economic value of chosenia are described in the article. The species features of chosenia, distinguishing chosenia from willow are noted. Based on the analysis of biology and ecology of chosenia in the Russian Far East, three types of the species' life strategies have been distinguished and characterized: 1 - secured anchoring of juveniles in substrate during the colonization of pebble floodplains (up to 3-4 years old); 2 - maximal manifestation of habitat-forming functions during the period of active growth (from 4-5 to 25-30 years); 3 - providing for the species' advancement onto new pebble deposits (from 25-30 to 70-100 (120) years old). The experience of chosenia introduction in Russia (southern Siberia) and USA (Massachusetts) by sowing seeds and breeding of grafts with growth stimulants was analyzed. Due to ecological plasticity of the species and its specialized habitats, any unwanted chosenia invasions were excluded. Major reasons for the absence of chosenia from street plantings are analyzed and most perspective ways of its introduction are suggested. There are difficulties of the reception of the planting material in sufficient quantities in connection with quick loss germinating ability, high frailty of seedling roots, plants' inability for vegetative reproduction, high requirement for good drainage and moisture of substratum. An experiment with raising seedlings in stationary capacities with sandy-pebble substrate is essential for a solution of the given problems. These boxes should be placed directly in areas of natural chosenia habitats along the edge of flooded deposits.