One of the most iconic species of the Arctic could save the tundra landscape from disappearing as climate change alters the balance of the ecosystem. Reindeer – as well as smaller herbivores such as voles – could help protect the unique diversity of the far north.

Climate change is threatening the Arctic tundra. While more plants grow as temperatures warm, there are fewer species that can flourish. Biodiversity decreases and the landscape slowly becomes more monotonous.

Reindeer, a crucial part of life for many people living in the far north, are part of the answer to that, according to a study in the journal Nature Communications. The researchers used plots of tundra that were artificially heated using greenhouses for most of the year. In a window during the summer, reindeer were allowed to graze in some of the plots but were shut out from others with high fences.

The study was carried out in north-west Finland, where reindeer are semi-domesticated. On the plots where local reindeer, lemmings and voles were free to graze if they wished, the biodiversity of the plots stayed high. In the warm plots where there was no grazing, biodiversity fell compared with tundra that hadn't been warmed.

"One explanation for why this is happening is that reindeer and voles are eating tall and wide leafed species," study author Elina Kaarlejärvi told IBTimes UK. Kaarlejärvi is an affiliate researcher at the Climate Impacts Research Centre at Umeå University, who currently works at Vrije Universiteit Brussel in Belgium.

"By eating those they allow more light to access the lower levels of the vegetation. That means the smaller species can also exist there because they get enough light and they can also benefit from warmer conditions."

The dynamic of the tundra is constantly changing, Kaarlejärvi said. There are cycles of lemmings and voles on the tundra, and reindeer populations are increasing in some areas and decreasing in others. But overall a clear pattern is beginning to emerge.

"We are slowly seeing this kind of dynamic in diversity of the tundra as climate warms. In different places, there are different trends. But our results show that where herbivores are present, climate change is not rapidly decreasing species numbers," she said.

The findings are another reason that reindeer should be protected in the far north, Kaarlejärvi added. Reindeer are listed as vulnerable on the IUCN Red List.

"Large herbivores are important from that perspective. They improve the landscape in many ways and they belong to that land. It's just one of their functions that they can help to mitigate the effects of climate change on diversity."

Reindeer guard the historic tundra from climate change. Magne Thyrhaug