The technicolor world of life after glaciers

Now a thin shred of ice, the last glacier in Venezuela is about to vanish before the unforgiving march of climate change.

Venezuelan-born graduate student Mariana Cardenas feels the loss deeply.

“The first time I got to the Humboldt’s Peak glacier, I sat on a rock and cried,” says Cardenas, who studies lichens through the Ecology, Evolution and Behavior graduate program. “When I kept going, it was with tears in my eyes because I was thinking, ‘The next time I come back, this glacier isn’t going to be here anymore.’”

Besides a sense of personal loss, she is keenly aware that the shrinking of glaciers endangers people around the globe who depend on glacial meltwater for drinking water, hydropower, and agriculture.

As the glaciers retreat, they leave stretches of rough, bare rock. Hiking these high-altitude, volcanic Andean landscapes “is like walking on the moon,” Cardenas says.

Carpeting the high country

But the bare rock is also an open invitation to hardy pioneers that prepare the way for plants and animals. Soon the moonscapes are mottled with red, orange, gray and green lichens. These organisms form when various combinations of fungi and algae, plus Cyanobacteria or yeast, join forces in a symbiotic partnership. The fungi provide structure and unlock some nutrients from the rock, while the algae provide energy through photosynthesis. And Cyanobacteria can turn nitrogen from the air into ammonia, a form of nitrogen that plants can grow on.

Cardenas chose to study at the U of M’s Cedar Creek Ecosystem Science Reserve, located an hour north of the Twin Cities. She wants to discover, among other things, how the presence of lichens and mosses influences primary succession—the earliest stage in the colonization of a lifeless terrain—in recently deglaciated landscapes.

“We understand these systems primarily through theories designed for temperate zones, and they are fundamentally different from those in the tropics,” Cardenas says.

“Primary succession is occurring faster than expected in the tropical Andes, yet we still lack the data to comprehend all the factors driving this succession and how it can affect the formation of new ecosystems and long-term ecosystem functioning.”