Dark Needle Conifer Stands Decline in Baikal Region
V. I. KHARUK1,2, S. T. IM1,2, I. A. PETROV1, M. N. YAGUNOV3
1V. N. Sukachev Institute of Forest, SB RAS, 660036, Krasnoyarsk, Akademgorodok, 50/28
2Siberian Federal University, 660041, Krasnoyarsk, Svobodnyi ave., 79
3Center fot Forerst Protection in Krasnoyarsk Krai, 660036, Krasnoyarsk, KrasnAkademgorodok, 50a
Keywords: усыхание лесов, леса Прибайкалья, Байкал, водный стресс, изменения климата, кедровые леса Хамар-Дабана, усыхание кедровников, stands decline, forests in Baikal region, Baikal, water stress, climate change, Khamar-Daban Siberian pine stands, Siberian pine stands decline
Abstract
The reasons for Siberian pine and fir decline were analyzed by remote sensing techniques, dendrochronology, GIS technology and in situ observations in Baikal region (Khamar-Daban). It was found that since the 1980s, there was a decrease in the value of the growth index ( R 2 = 0.69) and an increase of aridity of the climate SPEI ( R 2 = 0.72). In the mid-2000s, the increase in aridity led to the division of Siberian pine trees in two cohorts, “survivors” and “decliners”. The spatial distribution of these cohorts is different: dead and declining stands are located mainly on the relief elements with an increased risk of water stress (steep, convex slopes, southwest exposure). The growth index of the trees is closely related to the dryness index in June ( r 2 = 0.55). In addition to water stress, drying trees are exposed to stem pests and plant pathogens. The primary cause of Siberian pine decline is water stress due to increasing aridity. Weakened water-stressed trees are sensitized to pathogens. Synergism of climatic and biotic impacts led to observed decline of Siberian pine stands. In general, within the Khamar-Daban region heavily damaged and dead stands (> 50 % dying and dead trees) make up 8-10 % of the total area of dark needle conifers.
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