Arctic tundra's knee-high jungle grows taller, reshaping climate feedbacks

In Alaska’s North Slope near Toolik Lake, a team of scientists has observed a shift from a knee-high “jungle” of dwarf birch, mosses and liverworts to taller, darker shrubs as the area has warmed about 4.8 °F in the last 40 years. The phenomenon, called shrubification, reduces surface albedo, captures additional sunlight, and holds more snow that releases methane during winter, thereby accelerating Arctic amplification.

Expanding willow stands also shade streams, influencing fish, insects and bird habitats. Researchers are probing plant interactions, noting that the parasitic Arctic lousewort’s vivid purple flowers attract scarce bumblebees, potentially aiding pollination of nearby species. To test this, graduate students manually transfer pollen between plants, seeking evidence of mutualistic trade rather than pure competition. The work aims to determine how Arctic ecosystems may genetically adapt to climate stress and what feedbacks they generate for the global climate system.