Tundran kasvilajit reagoivat yksilollisesti muutoksiin

Long-term research on plant communities in the endangered tundra

The combined effects of reindeer grazing and climate change on Arctic vegetation are largely unknown, says Risto Virtanen, Senior Curator at the University of Oulu Botanical Museum.

“The tundra is the real Arctic. There are individual plant species that react individually to these change factors. We are interested in what happens at the community level.”

Senior Curator Risto Virtanen's research area is plant ecology and especially the communities of Arctic vegetation. Kilpisjärvi in the municipality of Enontekiö in Lapland has been a key area of his research for decades. Virtanen mentions re-sampling as one of his methods, where the materials collected decades ago are compared with the current state of vegetation from the same places. This method provides information on longer-term changes.

“There may be dozens of species at the same spot. There are vascular plants, mosses, lichen, and microbes, and then there are herbivores that move from place to place. In Kilpisjärvi you can experience the real tundra; there are high fells and conditions are pretty much in line with what they are in the circumboreal region.”

According to Virtanen, the tundra can be considered to be endangered, as its area is predictably shrinking as the climate warms.

“Many of the habitat types in the fell area have been classified as endangered, partly because of the pressures of climate change, reindeer herding, and land use,” summarises a researcher who worked in the team assessing endangered habitat types.

Virtanen's special interest are bryophytes. According to him, studying them is important because their share of the biomass in a well-studied meadow is about 40 percent.

“The bryophytes are an important group of plants in the Arctic, and there is very little research on how they react to nutrient supplementation and grazing activities. It appears that bryophytes react very badly and generally go into decline.”

In a long-term study, Virtanen examines the pressures of reindeer grazing, willow ptarmigans and climate change on willows. The focus of the research is also on the main pest of mountain birches, the autumnal moth.

“The autumnal moth is an insect herbivore that has started to appear more widely in Lapland. It causes complete destruction in mountain birches, but the damage is also directed at the species of willows that we are researching.

According to Risto Virtanen, Senior Curator at the University of Oulu Botanical Museum, bryophytes are often challenging to identify. Microscopes help to increase species dispersion information. Photo: Matti Heinineva

Dispersion information for the general public

Virtanen notes that he did more research trips and observations gathering in the early stages of his career. Research methods vary quite a lot in their details. However, certain measurement protocols, for example, on willow experiments, are repeated from year to year.

The collections at the University of Oulu Botanical Museum have also benefited from some experimental research, but Virtanen says that during his earlier expeditions he gathered more samples that were to be examined later.

“For example, lichens and mosses are often quite difficult to identify, so they need to be sampled, and then the identification is done here at the botanical museum using a microscope,” says Virtanen, referring to two microscopes on his desk.

New species are rarely found, and the identifications are mainly used to raise awareness of the species’ prevalence.

“It is equally important to know how far certain species have spread and whether they occur at all in some areas. New methods bring new perspectives, because two visually similar-looking species can be genetically very different. Those are what we call cryptic species.”

The University of Oulu Botanical Museum is the third largest in its field in Finland. It has been part of the university since the 1960s, focusing on northern plant species. According to Virtanen, the physical collections of the museum's vascular plants have been digitised since the 1980s and for other plants this has been going on for about 10 years.

“The data is stored in databases, which then ends up in global databases. Digitised dispersion information rapidly spreads to the scientific community and to the general public. These facilities for biodiversity information are not so well known to the general public, but they are open to everyone.”

Small White Orchid in the municipality of Enontekiö. Photo: Risto Virtanen

Samples can be used for a long time

Last December, Virtanen returned to the Botanical Museum from Leipzig, where he worked at the German Center for Integrative Biodiversity Research Unit. Studies of bryophytes in the international network now continue from Oulu.

“I'm now trying to complete those studies. Writing a good research article takes a lot of time. My peer review tasks also take up a lot of my time. In addition, after a period of field work, there is a lot of laboratory work to do and arranging of the samples so that they can be easily analysed.”

Virtanen, who started a degree programme in Biology at the University of Oulu in 1983, deepened his research into renewable natural resources with a botanical focus. There were enough people aspiring to become a civil servant in the environmental administration, so Virtanen turned to Arctic research-oriented groups, came up with a subject for his dissertation and continued his work on his doctoral thesis on factors affecting Arctic vegetation.

“Back then, becoming a researcher was not as clear as it is today. For me, the turn may have happened when it became possible to apply for academic funding. Despite a small delay I managed to get two rounds of funding, first for a doctoral thesis and then for post-doctoral research. Both were related to Arctic research projects,” says Virtanen, who after his academic projects has settled into the role of Senior Curator at the Botanical Museum.

For his doctoral thesis, Virtanen collected vegetation samples from fells and from Arctic regions, even all the way from the Svalbard Islands. The experiments related to the impact of grazing animals on mountain vegetation communities.

“The samples collected at that time are still usable for many studies. I spent a lot of time collecting them and preserving them in good condition, and it is very rewarding that they can still be used.”

As one of the highlights of his career, he mentions a Swedish-Russian expedition to the Siberian Arctic in 1994. A lot of publications have been made based on the samples collected on that trip. For this plant scientist from Ruukki the opportunity for a two-month icebreaker trip was offered through international cooperation networks.

Text: Matti Heinineva

Reindeer herding on a reseach field. Photo: Risto Virtanen


Last updated: 4.6.2019