this study, we used a chronosequence approach to explore the process
of vegetation change as meadows are replaced by forests. Bunchgrass
Ridge provides an ideal setting for this approach: open meadows
and forests of vary age (young to old) lie in close proximity, sharing
similar topography and soils. We asked the following questions:
do the composition, abundance, and richness of meadow and forest
understory species change during the transition from open meadow
to old forest?
rapidly, and to what extent, are meadow species lost from these
quickly do forest species colonize and how does composition change
with forest age?
attributes of forest structure (light availability, tree density,
basal area) exhibit the strongest controls on meadow and forest
was conducted within the 1-ha plots used to reconstruct tree
invasion history at Bunchgrass Ridge, and in adjacent meadow
openings. We sampled a total of 356, 10 x 10 m subplots.
(See subplot sampling design, below.) Within
each subplot we measured the following:
structure (density and basal area by tree species)
availability (hemispherical photos)
of all plant species (1m2 quadrats)
grouped subplots into seven encroachment classes by similarity in
age structure, using an agglomerative, hierarchical classification.
(See box, right)
species were classified into two groups, based on habitat affinity
group of species, we calculated total cover and richness of each of
the seven encroachment classes.
species (n = 43)
understory species (n = 48)