Data from: Linking disturbance and resistance to invasion via changes in biodiversity: a conceptual model and an experimental test on rocky reefs

Biological invasions threaten biodiversity worldwide. Nonetheless, a
unified theory linking disturbance and resistance to invasion through a
mechanistic understanding of the changes caused to biodiversity is
elusive. Building on different forms of the disturbance-biodiversity
relationship and on the Biotic Resistance Hypothesis (BRH), we constructed
conceptual models showing that, according to the main biodiversity
mechanism generating invasion resistance (complementary vs. identity
effects), disturbance can either promote or hinder invasion. Following the
Intermediate Disturbance Hypothesis (IDH), moderate levels of disturbance
(either frequency or intensity) are expected to enhance species richness.
This will promote invasion resistance when complementarity is more
important than species identity. Negative effects of severe disturbance on
invasion resistance, due to reductions in species richness, can be either
overcompensated or exacerbated by species identity effects, depending on
the life-traits becoming dominant within the native species pool.
Different invasion resistance scenarios are generated when the
diversity-disturbance relationship is negative or positive monotonic.
Predictions from these models were experimentally tested on rocky reefs.
Macroalgal canopies differing in species richness (1 vs. 2 vs. 3) and
identity, were exposed to either a moderate or a severe pulse disturbance.
The effects of different canopy-forming species on the seaweed, Caulerpa
cylindracea, varied from positive (Cystoseira crinita) to neutral
(Cystoseira barbata) to negative (Cystoseira compressa). After 2 years,
severely disturbed plots were monopolized by C. compressa and supported
less C. cylindracea. Our study shows that the effects of disturbance on
invasion depend upon its intensity, the main mechanism through which
biodiversity generates invasion resistance and the life-traits selected
within the native species pool. Disturbance can sustain invasion
resistance when promoting the dominance of competitively subordinate
species possessing traits that allow outperforming invaders.