The reindeer as an ecosystem engineer?
On the Yamal Peninsula in western Siberia, nomads Nenets They have a long tradition of reindeer herding in arctic tundra. However, in recent decades, the tundra has changed, as have the ways reindeer interact with it.
The Yamal Peninsula is shown above in a natural-color image acquired by the MODIS sensor on NASA’s Terra satellite on July 8, 2021. At that time of year, Nenets herders were likely making their summer migration into the North.
In the Arctic, temperatures have risen faster than anywhere else in the world. Climate change has been altering plant communities in the tundra and taiga (boreal) ecosystems. As growing seasons get longer and warmer, plant growth has increased, an effect called arctic greening. In addition, the tundra grasses and small plants that normally grow here are being replaced by taller, more wooded trees and shrubs, a change called arbustification. These changes in vegetation affect the tundra ecosystem, including its carbon cycle, human and wildlife habitat, and susceptibility to wildfire.
But the changes have not been uniform across the Arctic. For example, an investigation supported by him NASA Arctic-Boreal Vulnerability Experiment ( Arctic-Boreal Vulnerability Experiment, ABoVE) he found that instead of greening, some cooler, drier areas have experienced browning. The following map is based on Landsat satellite observations between 2000 and 2016 showing that approximately 22 percent of the Arctic became greener while 5 percent became browner.
For decades, satellite instruments have monitored vegetation from space. Terrestrial studies have shown how reindeer, the only large herbivore in many arctic areas, can affect vegetation, which includes reduce greenery and lichen abundance, slow down shrub encroachment, and increase soil nitrogen. Satellites are now being used to investigate interactions between vegetation and reindeer.
In a 2020 study, researchers used 30 years of Landsat imagery data to map changes in shrub cover on the Yamal Peninsula. They discovered that remained stable between 1986 and 2016, despite warmer weather and a 75 percent increase in the reindeer population during that time.
“Our results, therefore, point towards increases in the pressures of large herbivores that have compensated for the warming of the Peninsula, stopping the vegetation of the area.“the authors wrote in the Journal of Environmental Management. “This suggests that strategic semi-domesticated reindeer husbandry, which is a common practice in the Eurasian Arctic, could represent an efficient environmental management strategy to maintain open tundra landscapes in the face of rapid climate change.“.
However, another 2020 study of the Yamal reindeer found that this strategy may have its limits. Using Landsat imagery, along with terrestrial studies based on fecal pellets, the scientists attempted to quantify land use by reindeer. They found that while foraging and trampling stunt the growth of low-growing bushes, they don’t seem to prevent further growth or expansion of already established taller bushes because these are areas where reindeer are unlikely to forage.
“Our results suggest that reindeer use of the landscape, and thus their effects on the landscape, correlates with landscape structure.“, the authors wrote in Environmental Research LettersThey added that more research will be needed to assess the role of “reindeer as ecosystem engineers capable of mediating the effects of climate change.”
images of the NASA Earth Observatory by Lauren Dauphin, using MODIS data from NASA EOSDIS LANCE and GIBS/Worldview and using data from Berner, Logan, et al. (2020) . Story of Sara E. Pratt.
NASA Earth Observatory