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?

Sampling design

Plots consisting of three quadrats were used to sample vegetation on gopher mounds and in adjacent meadow.

Sampling. Three open meadows (1-8 ha) were selected for sampling in Jul 2004. 74 mounds were chosen to represent two age classes: young and old (photos, far right). (Fresh mounds were not sampled because they did not have plant cover.)

Vegetation was sampled using plots (10 x 30 cm) located fully on mounds or in adjacent meadow (figure, right). Within each plot, we recorded the presence of all species and estimated total cover of forbs and graminoids in each of three quadrats (10 x 10 cm).

Analyses. For each age class (young mounds, old mounds, and adjacent meadow), we compared the following community measures:

• Cover. Total, graminoids (grasses and sedges),
  and forbs
• Richness. Mean number of species per quadrat (10 x 10 cm) and per plot (10 x 30 cm)
• Heterogeneity. Species heterogeneity at two spatial scales: (a) within plots (among quadrats) and (b) among plots. Heterogeneity was measured by Sorensen’s index which ranges from 0 (quadrats or plots share all species in common) to 1 (no species in common).