Baku, February 13, AZERTAC
In recent decades, boreal forests—the taiga—have experienced the most rapid warming of any forest biome (average annual temperatures have increased by more than 1.4°C). This warming has led to significant changes, according to a group of international researchers who analyzed the longest-running forest cover observation series.
As reported by AZERTAC, citing Copernicus, scientists processed 224,026 images from Landsat 4, 5, 7, and 8 satellites, using machine learning methods to create annual tree cover maps with a 30-meter resolution across the boreal zone. To improve accuracy, calibrated MODIS Vegetation Continuous Fields data were used, allowing for the creation of a continuous 36-year time series with high spatial detail.
The analysis showed that during this period, the area of ​​boreal forests increased by 0.844 million km²—approximately 12%. At the same time, the average tree line shifted north by 0.29° latitude. The most pronounced increase was recorded in the range of 64°–68° north latitude.
Beyond territorial expansion, the study revealed the important climatic role of young forests. Forests up to 36 years old contain an estimated 1.1 to 5.9 petagrams of carbon and, with continued growth, are capable of accumulating an additional 2.3 to 3.8 petagrams. This confirms their significant contribution to the carbon balance and their potential as a natural mechanism for mitigating climate change.
Tree cover reaches its highest density in the southern part of the taiga biome and gradually decreases northward, where sparse coniferous stands, sparse woodlands, grassy areas, and barrens—in short, the transition to Arctic tundra—are found. North of 71° N, trees are virtually absent, according to scientists from the Chinese Academy of Sciences, NASA Goddard Spaceflight Center, and the Max Planck Institute.
In North America, the largest increases were recorded in the northernmost boreal zone, while losses occurred where fires or bark beetle and other insect infestations occurred. Such events occurred in Western Canada, interior Alaska, British Columbia, and Quebec.
In Eurasia, forest loss has been observed along the eastern part of the Russian-Chinese border, in agricultural zones south of the Urals, and near the Russian-Finnish border, where logging occurred in the 1990s. Increases have been observed in Russia in post-agricultural landscapes and in areas where permafrost is thawing.
In Northern Europe, the growth of taiga forests is associated with reforestation and fire suppression.
In Asia, in the post-Soviet space, there is a net increase in areas where agriculture was abandoned. Forests are also growing near the permafrost zone in Yakutia, where larch forests are expanding into the tundra. Here, forests are recovering from the forest fires of the 1990s, and thawing permafrost is fueling increased productivity.
Of course, tree growth rates depend on local climates, soil properties, and forest management. Although this issue has not yet been fully studied, the authors note an increase in the proportion of deciduous forests along the southern boundaries of boreal forests.
Of the total forest area in 1985, 5.29% had been damaged and restored by 2020. Young forests (up to 21 years old) are concentrated in regions of intensive forestry, including Scandinavian plantations, as well as in areas recovering from forest fires, such as in Siberia. The study’s authors note that imagery analysis revealed an increase in the frequency and scale of fires in Siberia since the late 20th century.
Young trees (up to 36 years old) occupy 15.4% of forest area and contain 1.1–5.9 petagrams of carbon (equivalent to 1.1–5.9 gigatons C) in aboveground biomass, with the potential to absorb an additional 2.3–3.8 petagrams C if allowed to mature. Greening the northern regions is essential for maintaining the global CO2 balance. Therefore, it is crucial to understand the state of our planet’s reserves of these powerful greenhouse gas sinks.
In total, the biomass of natural coniferous forests contains 38 ± 3.1 petagrams of carbon. These biomes account for 20.8% of the global forest CO2 uptake.
The authors emphasize that Landsat’s long-term, high-precision archive makes it possible to track ecosystem transformations on a decadal scale. For the rapidly warming boreal zone, one of the most climate-sensitive regions, such data is critical for assessing long-term trends and predicting future changes.
Google machine translated