Forest-tundra larch forests and climatic trends

Abstract

Climate-related changes that occurred in the Ary-Mas larch forests (the world’s northernmost forest range) in the last three decades of the 20th century have been analyzed. An analysis of remote-sensing images made by Landsat satellites in 1973 and 2000 has provided evidence for an increase in the closeness of larch forest canopy (by 65%) and the expansion of larch to the tundra (for 3–10 m per year) and to areas relatively poorly protected from wind due to topographic features (elevation, azimuth, and slope). It has also been shown that the radial tree increment correlates with summer temperatures (r = 0.65, τ = 0.39) and the amounts of precipitation in summer (r = −0.51, τ = 0–41) and winter (r = −0.70, τ = −0.48), decreases with an increase in the closeness of forest canopy (r = −0.52, p > 0.8; τ = −0.48, p > 0.95), and increases with an increase in the depth of soil thawing (r = 0.63, p > 0.9; τ = 0.46, p > 0.9). The density of undergrowth depends on temperatures in winter (τ = 0.53, p > 0.8) and summer (r = 0.98, p > 0.99, τ = 0.9, p > 0.99) and the date of the onset of the growing period (r = −0.60, p > 0.99; τ = −0.4, p > 0.99) and negatively correlates with the amount of precipitation in summer (r = −0.56, p > 0.99, τ = −0.38, p > 0.99).