subnivium
The seasonal microenvironment beneath the snow.
Voles and shrews thriving in networks of tunnels in the subnivium would experience a loss of their snowy refuge and face greater metabolic demands to cope with more-frequent and harsher exposure to the elements.
Where it comes from
From sub- (“under”) + Latin nix (“snow”) + -ium.
Adapted from the Wiktionary entry subnivium (CC BY-SA 4.0).