Spatial and Temporal Features of Birch Vegetation on the Territory of the Russian Federation in the Period 1948–2016

Aim . To study geographical differences and assess trends in the vegetation period of downy birch and silver birch within their range across the natural zones of Russia (forest-tundra, taiga, mixed and broad-leaved forests, monsoon mixed forests, forest-steppe, and steppe). Methodology . Calculations and assessments were conducted for the average long-term dates of leaf unfolding (greening) and complete leaf color change (full yellowing) of birch trees ( Betula pubescens, Betula pendula Roth.) at 290 observation points during the period from 1948 to 2016, and for leaf lifespan from 1964 to 1995. Data was collected through classical phenological field observations using the primary method of recording dates of seasonal events within specified territories. Observational data were sourced from programs of the Ural Society of Natural Science Enthusiasts, the Phenological Commission of the All-Union Geographical Society, the Russian Geographical Society, and Russia’s network of protected areas. The study utilized phenological data from protected areas such as Voronezh, Central Forest, Zhiguli, Volga-Kama, Denezhkin Kamen, Basegi, Pechoro-Ilych, Vishera, Bashkir, Visim, Ilmen, South Ural, Shulgan-Tash, Shaitan-Tau, Orenburg (Burtinsky and Aytuarsky sectors), Malaya Sosva, Olekminsky, Kedrovaya Pad, Altai, Barguzinsky, Zeisky, and Sikhote-Alinsky nature reserves, as documented in the Phenological Sections of Nature Chronicles of these reserves. Statistical analysis included the calculation of average long-term event dates (X avg.), variance ( σ² ), standard deviation (error) of the mean ( σ ), and extreme event registration dates. The speed of seasonal event progression was calculated in kilometers traveled per day. For interpolation and visualization of spatial phenological processes, the cross-platform Geographic Information System (GIS) QGIS Desktop version 3.14.16 was used. Results . The timing and speed of birch greening and yellowing, the latitudinal phenological gradient, birch leaf lifespan, and their trends were calculated, mapped, and analyzed. During the period from 1948 to 2016, the speed of the greening wave across the European part of Russia ranged from 30 to 56 km/day, while in the Asian part, including the Far East, it ranged from 30 to 57 km/day. The speed of the yellowing wave for the same time frame was 43–60 km/day in the European part and 56–230 km/day in the Asian part. The Birch leaf lifespan ranged from 170 days in the steppe zone to 100 days at the northern range boundary. The propagation of greening and yellowing waves from 1948 to 2016 spanned 63 and 42 days across European Russia and 53 and 21 days in the Asian part, respectively. The progression of these waves is influenced by regional climate characteristics and major mountain ranges. Research implications . The study of spatial-temporal features of vegetation in indicator species enhances our understanding of biota development patterns and their responses to climate change. The findings can be used for developing forest management strategies, planning forestry activities, and monitoring forest conditions. The study of spatial-temporal features of vegetation in indicator species enhances our understanding of biota development patterns and their responses to climate change. The findings can be used for developing forest management strategies, planning forestry activities, and monitoring forest conditions.