Alpine ecotone in the Siberian Mountains: vegetation response to warming

• Published in: Journal of mountain science 2021-12, Vol.18 (12), p.3099-3108
• Main Authors: Kharuk, Viacheslav I., Im, Sergei T., Petrov, Il’ya A.
• Format: Article
• Language: English
• Subjects: Air temperature; Bark; Betula tortuosa; Birch trees; Clusters; Earth and Environmental Science; Earth Sciences; Ecology; Environment; Geography; Growth; Habitat selection; Landsat; Mountains; Original Article; Photosynthesis; Pine trees; Precipitation; Remote sensing; Spring; Spring (season); Survival; Treeline; Tundra; Wind; Wind speed; Winds
• ISSN: 1672-6316; 1993-0321; 1008-2786
• DOI: 10.1007/s11629-021-6876-2

Birch ( Betula tortuosa ) is one of the treeline forming species within the Siberian Mountains. We analysed the area dynamics of birch stands and the upslope climb of birch treeline based on the Landsat time series scenes and on-ground data. We found that since the warming onset (1970 th ) birch area increased by 10%, birch stands and treeline boundary were moving upslope with a rate of 1.4 m/yr and 4.0 m/yr. Birch upslope shift correlated with air temperatures at the beginning (May-June) and the end (August-October) of the growth period. Meanwhile, no correlation was found between birch upslope migration and precipitation. Winds negatively influenced both birch area growth and birch upslope climb during spring, fall, and wintertime. In the windy habitats, birch, together with larch and Siberian pine, formed clusters (hedges) which mitigated the influence of adverse winds. These clusters are the adaptive pattern for trees’ upslope climb within windward slopes. The other adaptation to the harsh alpine ecotone habitat is non-leaf (bark) photosynthesis which supports tree survival. Thereby, Betula tortuosa upslope climb depends on the wind impact and warming in spring and fall that extended growth period. With ongoing warming and observed wind speed decrease on the background of sufficient precipitation, it is expected to further birch advance into alpine tundra in the Siberian Mountains.