Mountain Soils - Mountain Geography: Physical and Human Dimensions - page 302

atodes, can thrive in moist, cool conditions. Certain groups of bacteria and fungi have
adapted to extremely cold and water-scarce conditions, even on Mount Everest, through
mechanisms that include the production of antioxidant enzymes and antifreeze proteins
(Margesin 2012). They play an important role in decomposing organic matter and recyc-
ling nutrients. On the upper slopes of Mount Kinabalu, Borneo, and Mount Kosciusko,
Australia, large earthworms and microorganisms incorporate surface litter into the soil
(Costin et al. 1952). In the Luquillo Mountains of eastern Puerto Rico, the faunal species
with the greatest biomass is thought to be earthworms. Termites transfer one ton of soil
per hectare per year in the tropics, while ants are effective soil movers in tropical and
temperate-zone soils (Bridges 1997).
Small burrowing animals are important to the alpine tundra. The pocket gopher ( Tho-
momys spp.) is a common occupant of North American mountain meadows. Searching
for plant roots, these little creatures create complex networks of shallow tunnels un-
der the soil. The excavated material is taken above the surface and stuffed into similar
tunnels in the overlying snow. The following spring, soil in these snow tunnels appears
on the ground as interwoven soil casings. On Niwot Ridge, Colorado, researchers found
pocket gopher mounds to contain less soil organic matter and significantly different
amounts of total carbon, total nitrogen, and total phosphorus than their surroundings
(Sherrod and Seastedt 2001). They concluded that erosion from pocket gopher mounds
increased the redistribution of soil mass and soil nutrients.
Mixing and overturning of soil by burrowing animals increase its vulnerability to
erosion (Butler 1995). This is particularly evident on slopes (Imeson 1976; Yoo et al.
2005). Price (1971) found material moved downslope by the arctic ground squirrel ( Ci-
tellus undulatus ) in the Ruby Mountains in Canada's Yukon Territory to be around 0.36
tons per hectare per year. Years earlier, Grinnell (1923) had estimated that pocket
gophers in Yosemite National Park, California, excavated 0.04 tons of soil per hectare
per year. In comparison, earthworms have been estimated to move 20-300 tons per hec-
tare per year (Goudie 1988).