The University of Tartu scientists collected a peat sample from Lääne-Virumaal Äntu nature reserve, which grew sprouts of Meesia longiseta moss, previously thought to be extinct. Now Tartu has anecdotes comparing the resurrection of moss to the resurrection of mammoths.
Meesia longiseta is thought to be a biological relic from colder climate times. It received its Estonian name from its very long – over 10 cm – sphorophytes, carrying pear-shaped pollen capsules. In addition to sphorophytes, this species is distinctive from a very similar Meesia trifaria because of its smooth leaf edges.
Estonia is a home to three kinds of Meesia moss; however, the last sighting of Meesia longiseta was from 82 years ago. That’s why it was thought to be extinct. Last year, University of Tartu scientists found the sprouts of the moss growing in their lab. It was a pleasant surprise, but far from miraculous.
University of Tartu bryologists [translation: moss scientists] collected peat samples in autumn 2016 from three Estonian bogs in order to measure diversity in the diaspore bank.
The diaspore bank of mosses reduces the extinction risk of an ecological system the same way as the seed banks of vascular plants. A relevant reminder: the main propagation means for vascular plants are seeds and spores, but for mosses spores and gemmae. Diaspore bank is the reserve of plant propagation means that stay underground in the earth or peat for a shorter or longer time in a restive state. Such a bank might sprout a new plant when suitable conditions arrive, such as reduced competition or a new environmental situation.
After collecting the samples of the diaspore bank, the scientists helped them grow in the botanical lab for six months. “Most of the mosses sprouted already in the first couple of months, but from one of the samples, (collected from the Äntu nature reserve) the sprouts emerged only during the fifth month, in April 2017,” said Kai Vellak, Director of Botanical Collections and Senior Scientist at the University of Tartu Natural History Museum.
Subsequent identification revealed the sprouts to be Meesia longiseta – until that moment thought to be extinct in Estonia.
Vellak, a plant ecologist by profession, says it is a very rare species in Europe, held to be a biological relic of colder climate periods.
The most recent documented data about its Estonian growth areas are from 1936 and the oldest from 1849.
“Our current finding grew from the samples collected from a bog in the Äntu nature reservation. The closest growth area to this bog is about 50 km southwards, in Jõgeva County, Kärde. Meesia longiseta was last collected from there in the middle of the 19th century,” noted Vellak.
Extinct moss becomes an endangered species
Urmas Kõljalg, Director of the Tartu Natural History Museum and botanical garden, explained that measuring the diversity of a diaspore bank takes a lot of time.
“Even propagating the sprouts to grow into a stadium necessary for identifying them took months. After this, the identification of the species was further checked by Swedish bryologists,” he said. “After verifying that we had identified the plant correctly, we took time to diligently investigate the surface vegetation [in the area].”
Despite thorough searching, the rare moss was not found growing above ground. It required a bit of thinking to evaluate if the species should still be considered extinct. The key question was if the specimen that had been grown from the diaspore bank during the experiment was good enough an evidence that this species has remained present in the Estonian moss flora.
The International Union for the Conservation of Nature was consulted. Their representative confirmed that endangerment of a species may be evaluated based on the specimen sprouted from the diaspore bank.
Thus, Meesia longiseta became a critically endangered (CR) species in Estonia. It had been designated as extinct about ten years earlier.
The results inspire scientists to further investigate the previous finding locations of the moss, and not only the surface vegetation.
Let’s hope the lime-rich bogs [õõtsik-madalsoo] suitable for its growth stay as they are.
“Let’s hope that this species finds good conditions to make its way into the surface vegetation. One should hope for the lime-rich bogs [õõtsik-madalsoo] supportive for its growth to stay as they are,” added Senior Scientist Kai Vellak.
The sample proving the Meesia longiseta to be part of Estonian ecosystem is stored at the moss herbarium of botanical collections. Those interested can find it by the number TU177022.