AI Insight
NASA's Landsat 9 satellite captured imagery of Poland's Bieszczady National Park on October 8, 2026, documenting the autumn color transformation in its Carpathian Mountain forests. European beech trees and other deciduous species display seasonal reds and golds as decreasing temperatures and daylight trigger reduced chlorophyll production, revealing underlying pigments. The park contains ancient beech forests that are part of a UNESCO World Heritage network spanning 18 countries, with forests extending to approximately 1,000-1,260 meters elevation before transitioning to subalpine meadows called polonina.
Why it matters
This documentation illustrates the ecological importance of European beech forests as ice-age survivors that recolonized Europe after glacial retreat, and highlights the Bieszczady region's conservation value as habitat for reintroduced European bison, brown bears, and Eurasian lynx. Remote sensing technology enables monitoring of seasonal vegetation changes and forest health across protected ecosystems.
Understand the Science
As the air grows cooler and days shorter, brown bears prowl the Carpathian Mountains of southern Poland with the goal of fattening up ahead of winter hibernation. In a more conspicuous sign of autumn, beech and other deciduous trees blanketing the hillsides start to sport reds and golds. The seasonal transformation was underway in southeast Poland’s Bieszczady National Park on October 8, 2026, when the OLI (Operational Land Imager) on the NASA-USGS Landsat 9 satellite captured this image.
European beech (Fagus sylvatica) dominates the area’s forests, with other species such as sycamore maple (Acer pseudoplatanus) also contributing to vibrant color in the fall. Dropping air temperatures and waning daylight cause these trees to curtail the production of chlorophyll, the molecule that plants use to synthesize food. Without it, the leaves’ green pigments fade, allowing the yellows and reds of other pigments to show through.
A descendent of ice-age survivors, the European beech has persisted across millennia in a range of climates. After the glaciers retreated, beech forests spread northward across the European continent from isolated refugia in the Carpathians, Alps, and other mountain ranges, and played a crucial role in reforesting the previously ice-covered land. Portions of Bieszczady National Park are included within UNESCO’s network of ancient and primeval beech forests spanning 18 countries.
Expansive as their footprint across Europe may be, beech forests reach only so high in elevation—about 1,000 to 1,260 meters (3,300 to 4,100 feet)—in this area. Above that is the realm of the polonina, a Slavic term for subalpine meadow, consisting of open grasslands and shrubby thickets of rowan (mountain ash), willows, and green alder. Patches of polonina stretch across ridge tops to the east-southeast of Smerek and appear tan, having lost their summer greenness.
The Bieszczady Mountains are renowned not only for forests and mountain meadows but also for charismatic wildlife. European bison, once extinct in the wild, were reintroduced to the area in the 1960s and now roam the hills by the hundreds, according to recent surveys. Additionally, populations of brown bears and Eurasian lynx find refuge and ample food sources in the forests.
NASA Earth Observatory image by Michala Garrison, using Landsat data from the U.S. Geological Survey. Story by Lindsey Doermann.
References & Resources
- Bieszczadzki Park Narodowy, Bieszczady National Park. Accessed October 16, 2026.
- Mitka, J, et al. (2022) Subalpine woody vegetation in the Eastern Carpathians after release from agropastoral pressure. Scientific Reports, 12, 17897.
- UNESCO (2025) Ancient and Primeval Beech Forests of the Carpathians and Other Regions of Europe. Accessed October 16, 2026.
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