From Venezuela to Tierra del Fuego: In search of new habitats, more and more plant species are migrating to higher mountain sections in the Andes. In doing so, they displace rare mountain plants in the high Andes. The reason for this is the rising temperatures caused by human activity. A study recently published in the journal Global Ecology and Biogeography suggests that this development will continue to accelerate in the future.
The “Global Observation Research Initiative in Alpine Environments” (GLORIA), a long-term monitoring and research program coordinated by the Austrian Academy of Sciences (OeAW) and the University of Natural Resources and Life Sciences (BOKU) Vienna, used plant community data collected from 720 long-term observation plots on 45 mountain summits in the high Andes between 2011 and 2019. For the first time, data covering a large part of the mountain range are now available. The greater tropical Andes region is the largest center of biological diversity on earth.
Rapid species change in the mountains
The mapping of biodiversity along height gradients shows the impact of climate change on the composition of ecosystems. The Andes boasts particularly diverse and unique ecosystems due to a combination of complex landscape structure and tropical climate. “The upward shift of species can be observed at most of our observation points on the mountain summits. However, the changes can be quite different, with some areas experiencing an increase in overall vegetation cover, while others see a decrease,” says study co-author Harald Pauli. He is a high mountain ecologist at the Institute for Interdisciplinary Mountain Research of the OeAW and heads the GLORIA network.
“On average, every two and a half years, one plant species is added to the monitoring areas, in some areas more. That is a very short period of time for cold mountain habitats,” the ecologist says. It is a worrying development that Pauli and his team have already observed in various mountain ranges in Europe.
Intensive farming and imported species from Europe
The number one contributor to species extinction globally is intensive agriculture, including deforestation, he explains. In the Andes, too, the mountains are grazed. “Areas are often burned down in the dry season because the grazing animals prefer to eat the young grass that grows afterwards. But that has massive consequences for diversity,” Pauli says.
In addition, there is a phenomenon that is particularly virulent in many parts of the Andes: imported European meadow plants – from cocksfoot to red clover. The warmer it gets, the more they can spread at higher altitudes, the researcher says. And with global warming, ground temperatures continue to rise. This was also confirmed by the measurements.
Mountain plants as living sensors of biodiversity loss
“Mountain plants are living sensors. They are indicators that can provide information about the state of the ecosystems and can be used to evaluate future forecasts,” high mountain ecologist Pauli says. Preserving the diversity of the different locally distributed species, which occupy a wide variety of ecological niches, is essential, especially in times of climate change. After all, intact ecosystems are responsible for around 30 percent of CO2 sequestration.
Although biodiversity monitoring cannot stop the rapid loss of biological diversity, it can at least provide information about it. “Society, and especially policymakers, carry the responsibility to address and mitigate the situation,” Pauli says.