Just how easy was it for plants and animals to travel from Russia to Alaska or vice versa in the past?

It may surprise you, but travel between Asia and North America was quite easy for prehistoric animals, plants, and humans during several geological intervals. Experts have shown three geological epochs when glaciers expanded, resulting in a drop in sea levels to such an extent that the entire eastern Alaska shoreline was connected to western Asia. This landmass, the Bering Land Bridge, lies at one of the world’s greatest crossroads: a migration corridor for terrestrial biota between the New World and Old World, and when opened a major seaway allowing migration of marine animals between the Pacific, Arctic, and Atlantic oceans.

The first of these connections occurred some 12 – 15 million years ago followed by several openings (interglacials) and closings. About 10,000 years ago the Bering Strait re-opened as we see it today with shallow seas of the strait separating Alaska and Siberia.

During those glacial ebb and flow events, temperatures, precipitation rates, and ultraviolet light intensities radically changed with the shifting shorelines. As a result, the evolution of Alaska’s flora and fauna were influenced, creating an early version of the boreal forest in the Eocene (56 to 33.9 million years ago) and forest-tundra in the late Pliocene/Quaternary (1.5-1.0 million years ago).

As a professor of botany and curator of the plant collection (herbarium) here at the University of Alaska Museum, Beringia is an area of special interest.

History of the development of the concept of Beringia

The Beringia region as we know it today extends from the McKenzie River in western Canada and to the east as far as the Lena River in Siberia. Numerous textbooks, research articles, and websites have focused on the origins of the Bering Land Bridge.

Arguably one of the most important contributions came from Swedish botanist Eric Hultén’s doctoral dissertation in 1937 at Stockholm University entitled: “Outline of the history of the Arctic and Boreal biota during the Quaternary period.” Hultén, who is credited with the coining of the term “Beringia”, created the foundation for future scientific investigations in its development and impact on Alaska’s flora.

Based on the analysis of distribution maps of over 2,000 Beringian plant species, Hultén postulated that plants radiated concentrically around their place of origin, but their distribution over time would be modified by a number of factors, most importantly glaciations, resulting in patterns of persistence on these ice-free areas. Most of Beringia would have been available to act as a “refugium” of plant life. Arctic shrubs and herbs would have survived/persisted in these ice-free areas during subsequent ice ages. Today we find a higher concentration of plant diversity present in those ice-free areas as opposed to the other circumpolar glaciated areas around the globe.

Hultén’s theories, which are widely accepted, are a body of work important to the story of the assembly of the flora of Alaska. His 1968 “Flora of Alaska and its Neighboring Territories ” is a fabulous textbook containing an unrivaled synthesis of his work and serves as the best manual for the flora of Alaska today.

First botanical explorers

Before Hultén’s theories were put to the test, most of the exploration of Alaska’s flora was through marine botanizing, an interesting phenomenon of relatively safe travel on spacious ships exploring the continents.

The earliest known western botanist to collect plants in Beringia was the German naturalist George Steller who joined Vitus Bering on the second Kamchatka Expedition and early explorations of the Bering Strait in 1741. Next to collect in Alaska was naturalist and surgeon William Anderson on Captain Cook’s third voyage in 1778.

The most important historical collections of Alaska plants were made by Adalbert von Chamisso and Johann Friedrich von Eschscholtz during the Kotzebue circumnavigation between 1815-1818. Up until Alaska was purchased by the U.S. from Russia in 1867 the Interior remained mostly uncollected, with its exploration becoming more common at the turn of the 20th century.

One notable collector was Jacob Peter Anderson, a native of Iowa who lived in Juneau, and travelled extensively throughout Alaska from 1914 to 1953. He founded the Juneau Botanical Club and continued to collect and organize his collections throughout his life. He returned to Iowa in 1941 with the largest collection of Alaskan plants, which he expanded through exchange with other botanists.

Anderson prepared a flora of Alaska which he published in nine parts in the Iowa State Journal of Science with some 30,000 plant specimens at hand. These and additional collections at the University of Alaska Museum’s Herbarium comprise the largest assemblage of Alaskan plant specimens in the world. Much of our understanding of Ice Age Beringia is based on these botanical specimens.

Future of research on plant disjunctions in Beringia

Today botanists classify Beringia’s floristic elements into three distinct categories: Those occurring on both sides of the Bering Strait (amphiberingian), those exclusive to the western (Russian) side, and the those only occurring on the eastern (Alaskan) side of the strait. A final category classifies plants on both continents occurring in pockets or scattered populations.

As researchers we are asking several questions: Which plants are refugial? Are individual plants recent arrivals and if so, when did they first occur in Alaska? Why were some plants able to migrate across the bridge while it acted as a barrier for others?

Guests will be able to discover more about plants in Alaska and Beringia in an upcoming exhibit “Expedition Alaska: Plants at the Crossroads of Beringia” planned to open in summer 2022 at the UA Museum of the North.

Stefanie M. Ickert-Bond is the curator of the herbarium at University of Alaska Museum of the North.

Discover UAMN online, including an ethnobotany video series, on the Virtual Museum page at bit.ly/3q3YH6J.

The museum is open daily from 10 a.m. — 5:30 p.m. For more information about the museum’s collections, programs, and events, visit www.uaf.edu/museum or call 474-7505.

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