The Influence of Air Temperature on Seasonal Growth of Coniferous Forest-Forming Species in the Taiga Zone (Republic of Karelia)

Abstract

Seasonal growth of forest-forming species is widely studied by russian and foreign scientists. The research purpose is to analyse the growth features of vegetative organs of coniferous forest-forming species in the taiga zone. The study objects were Scots pine (Pinus sylvestris), Norway spruce (Picea abies) and Siberian larch (Larix sibirica). The time frames of beginning, culmination and cessation of growth of vegetative organs are determined by both species biology and weather conditions. In late April, needles appear at Larix sibirica trees; in late May - at Pinus sylvesfris trees; in early June - at Picea abies trees. In mid-May, shoots start growing at Pinus sylvestris trees; in late May - at Picea abies and Larix sibirica trees. Wood trunk grows in early June in Scots pine and in mid-June in Norway spruce. The maximum intensity of increment of Scots pine and Siberian larch shoots is timed to mid-late June, and European spruce shoots - mid-July; larch needles - in late May, pine and spruce needles - in mid-late July; Scots pine and Norway spruce trunks - in mid-June. Needles growth at Larix sibirica trees ends in mid-June, and at Pinus sylvesfris and Picea abies trees - in late August; shoots growth at Larix sibirica trees - in late June, at Pinus sylvestris and Picea abies - in late July; trunks growth - in late August. The duration of shoots formation at Pinus sylvestris, Picea abies and Larix sibirica trees is 77, 57 and 48 days, respectively; needles formation - 98, 78 and 45 days; trunks formation - 72 and 74 days. The growth intensity of shoots and needles at the trees of studied species is mainly determined by the air temperature during the period of their enhanced growth (July). The least fastidious (for growth processes) to the air temperature regime is Larix sibirica, than Pinus sylvestris, and finally Picea abies.