The Hidden Winter World of the Subnivean Zone
- IPWA
- 25 minutes ago
- 2 min read
By Rob Pudim and Kelly Prendergast
Life beneath the snow in the wilderness exists between snow and the ground. This ecosystem is called the subnivean officially and a kahr by the Swedes.
Once the snow gets deep enough (about 15cm) the subnivean, maybe an inch high, emerges in shallow hollows around fallen trees, rocks or under a willow branch snow blanket. The subnivean is like a natural igloo. The temperature above the snow might range from -12 to 4 degrees C but the ground temperature will remain a comfortable 1 degree C.
In the subnivean ecosystem roots, mammals, birds, arthropods, fungi and microbes hunt, breed and break down leaves and stuff into compost. The deeper the snowpack the larger and more varied is the population.
The hungry arthropods regulate the fungus and microbes. Springtails, centipedes, earwigs, spiders, rove beetles are there feeding, moving, looking for mates and breeding. Some of the species like the meshweaver spiders (Cicurina brevis), three species of rove beetles (Arpedium cribratum, Lestevia pallipes and Porrhoclites inflatus) have an impact of putting nutrients back into the soil and controlling pests.
The arthropods and roots are food for larger animals like lemmings, rabbits, pocket gophers, voles, ground squirrels, ptarmigans and deer mice who, in turn, are meals for ermines, martens and foxes. The martens slink in and out of the subnivean, go down into the snow and disappear (probably to hunt dinner) and pop out in another spot. Foxes are commonly seen diving headfirst into the snow to grab a vole or rabbit.
All we see snowshoeing over the subnivean is a white world of white stuff and maybe a blue sky and hear the thin whisper of the wind.
Naturalist column exploring high country flora, fauna and geography
IPWA volunteers are often asked by visitors not just about the trails, but about what they are seeing in the Indian Peaks and James Peak Wilderness Areas. This column will cover some of the plants, animals and geographic features that hikers, anglers and backpackers may come across in these areas.
About Rob Pudim
A long time Boulder resident, Rob describes himself as “a coal-miner's son from Pennsylvania, a "fallen" scientist (Chemistry, Rutgers University and Microbiology, Tulane University) an editorial cartoonist, an amateur lepidopterist, a Native Plant Master, and a long-time birder”. His affiliation with IPWA goes back to its founding in the 1980s.
About Kelly Prendergast
Longtime volunteer and former board chair: "My grandparents, who loved birds and plants, were a huge influence in my life growing up in the Hudson Valley and Catskill mountains of New York State. My siblings and I were encouraged to spend many hours exploring the nearby woods which fostered a lifelong curiosity and desire to learn more about the natural world. I'm continuously surprised by the abundance of things to discover and love hearing about and sharing new discoveries with others."