While climate change is causing glacier retreats globally, in the Andes Mountains, a wild relative of the llama is assisting local environments in coping with these shifts by leaving behind significant amounts of dung.
A study published on December 30 in Scientific Reports found that the actions of these animals could shorten the time it takes for plants to grow on newly exposed land by over a century, revealing a surprising way that organisms adapt to climate change.
“It’s fascinating how the social behavior of these animals can enrich a new ecosystem that lacks nutrients,” remarked Cliff Bueno de Mesquita, one of the paper’s co-first authors and a research scientist at CU Boulder’s Cooperative Institute for Research in Environmental Sciences. However, he cautioned that the current rate of climate change is still faster than what species can handle in terms of relocating.
The key players in this adaptation are the vicuñas, one of the two wild South American camelids, along with the domesticated alpaca and llama. Vicuñas thrive in the high altitudes of the Andes.
While they may not be as well-known as llamas, vicuñas are remarkable, especially for their unique habit of choosing specific spots to relieve themselves.
These animals create communal “latrines,” much like how humans use restrooms, where multiple members of their social group defecate in a shared location.
For the past twenty years, Steven Schmidt, the paper’s senior author and a professor in the Department of Ecology and Evolutionary Biology, has researched how microbial communities and plants are responding to glacier retreat in the high-altitude Peruvian Andes.
The soils left behind by melting glaciers are severely lacking in nutrients and moisture, often consisting of barren rocks and gravel that can remain void of plants for over a century.
However, during their expeditions over the last decade, Schmidt and his research team started to spot patches of vegetation, all seemingly sprouting from the dung piles of vicuñas.
Teaming up with animal ecologist Kelsey Reider from James Madison University, the researchers traveled to sites in the Peruvian Andes, reaching altitudes of up to 18,000 feet that had formerly been covered by glaciers. They collected soil samples from vicuña latrines in these areas and discovered that compared to the empty soils just a few feet away, the latrine soils were significantly richer in moisture and essential nutrients like organic carbon, nitrogen, and phosphorus.
For instance, soil from latrines contained 62% organic content, while deglaciated soil exposed for 85 years in the same location without latrines had only 1.5% organic matter.
At high altitudes, temperatures can vary greatly throughout the day, regularly dropping below freezing at night even in summer. “It’s incredibly challenging for life to exist there, but the organic matter in the latrines stabilized the temperatures and moisture levels. They effectively created a unique microclimate,” Schmidt explained.
The researchers also observed high levels of DNA and a diverse range of microorganisms in the latrine soils, indicating that these latrines play a crucial role in enabling microbes and plants to flourish.
The study suggested that vicuña feces may hasten the process of plants colonizing a barren landscape by around a century. By depositing nutrients and seeds from lower areas through their dung, these animals stimulate germination in the deglaciated soil, attracting various organisms, including animals that graze on the new vegetation.
Camera footage indicated that these plant patches are drawing diverse wildlife, including rare species previously unobserved at such high altitudes and larger predators such as pumas. Interestingly, vicuñas also consume the plants growing in their latrines.
The transformation of the deglaciated land into grassland could take hundreds of years, potentially lessening the adverse effects faced by many species that prefer cooler environments as their habitats diminish because of climate change, Reider noted.
Yet, despite the vicuñas’ contributions, the speed at which new species are establishing themselves on fresh ground is significantly slower than the rate at which glaciers are shrinking.
Globally, glacier melting has accelerated in the past two decades. Between 2000 and 2019, glaciers outside of Greenland and Antarctica lost approximately 267 billion tons of ice each year. If the current warming trends persist, it could lead to a loss of 68% of the planet’s glaciers, according to earlier studies.
In various parts of the Andes and other mountain ranges, such as the Rockies, countless individuals rely on mountain snow and glacier runoff for their water supply. Estimates suggest that diminishing glaciers and snow cover could jeopardize water access for around 25% of the global population.
“While vicuñas may be aiding some alpine organisms, we can’t take it for granted that they will all survive; we are experiencing climate change at a pace unseen in Earth’s history,” Bueno de Mesquita commented. “Current human-induced climate change is likely one of the most severe crises our planet and all its life forms have faced in the last 65 million years.”
