Soil disturbances by the western pocket gopher, Thomomys mazama, are conspicuous features at Bunchgrass Ridge and in meadows throughout the Cascades. Through their tunneling and mounding activities, gophers (box, right).

• initiating succession by removing or burying plants
• reducing the dominance of grasses and increase the diversity of less competitive forbs (and the animals and insects that depend on them)
• increasing the heterogeneity of species composition on mounds and at larger spatial scales within meadows
• providing sites for establishment of disturbance-dependent species which would otherwise be absent.

Western pocket gopher, Thomomys mazama. Photo © William Leonard.

Most studies of the relationships between gopher disturbance and plant community structure have been conducted in low-elevation prairies or grasslands of central and eastern North America; studies from higher elevation mountain ecosystems are rare.

At Bunchgrass Ridge we examined patterns of succession and community heterogeneity associated with mound formation and aging. We asked the following questions:

1. How do plant cover and species diversity change as mounds undergo succession?

2. Does gopher activity shift the relative abundance of grasses vs. forbs? Does this relationship change as mounds undergo succession?

3. Are communities of species on mounds more heterogeneous (variable) in composition than those in adjacent meadows? Does this variability decline as mounds succeed to meadow?

4. Do mounds provide germination sites for species that are absent from, or uncommon in, undisturbed meadow?