Large herbivores slow Arctic tundra diversity losses associated with sea ice decline

Tundra diversity, including plants, lichens and fungi, declined over a 15-year experiment in the Arctic due to warming temperatures mediated by the disappearance of sea ice, according to Eric Post and colleagues. However, the presence of large herbivores such as caribou and musk oxen slowed this decline, by affecting the plant understory with their different browsing behaviors, the researchers concluded. Their findings offer support for the idea that encouraging herbivore diversity in the tundra could temper some of the impacts of climate warming. Post et al. observed the interacting effects of warming temperatures, sea ice changes, tundra diversity and herbivore exclusion in an experiment that ran from 2002 to 2017 near Kangerlussuaq, Greenland, where some plots within the area were also experimentally warmed. They found that rates of tundra diversity declined across all experimental conditions as the study progressed, a trend explained by sea ice loss over time. However, tundra diversity declined almost twice as fast when herbivores were excluded from a tundra plot, and declined most slowly in plots where herbivores were allowed to graze under experimental warming conditions.