Plant Richness, Evenness, and Diversity
We observed a total of 41 plant species in our 20 plots across the four
sampling periods (Tables S1, S2). We found that tortoise exclusion led
to a 15% reduction in plant richness (Figure 1A,X2 = 6.674; p = 0.01 ), which equates to
the loss of ~ two species per plot. Additionally, we
observed a significant exclusion × sampling period interaction
(X2 = 10.72; p = 0.013 ) indicating that
the effect of tortoise exclusion on plant species richness became more
pronounced as the growing season progressed. Tortoise exclusion also led
to a 6% reduction in plant evenness (Figure 1B,X2 = 5.657; p = 0.02 ). We observed a
12% reduction in Shannon diversity due to tortoise exclusion (Figure
1C, X2 = 19.62; p < 0.0001 ).
We found no evidence that tortoise exclusion impacted plant evenness
(Table S3, X2 = 2.669; p = 0.19 ) or
diversity (X2 = 2.667; p = 0.45)
differently across sampling periods i.e. no interactive effect.
Thus, reduction of plant diversity following gopher tortoise exclusion
is the result of a simultaneous loss in plant richness and shifts in the
dominance of species within our plots.