# Can Vegetation Removal Successfully Restore Coastal Dune Biodiversity?
## 3 Results
### Abundance & Richness
Disturbed dunes were not monitored for annuals and un-treated semi-fixed dunes were used as the control. Significant differences were tested with generalized mixed models for beetles and reptiles (Poisson), and linear mixed models for rodents and annuals. \(p<0.05\) for treated dunes compared to * control and + reference dunes, respectively. Cover of annuals increased with increasing dune fixation so, treatment was expected to reduce % cover of annuals, making the treated dunes more similar to mobile dunes. However, on semi-fixed dunes, annual % cover did not significantly decrease in response to treatment, with % cover remaining similar to semi-fixed controls and significantly higher than in mobile dunes (Figure 2h). In treated fixed dunes, the % cover was significantly higher than both mobile and fixed control dunes, which meant the direction of response was opposite to expectations (Figure 2l). As with abundance, we tested the control dunes for differences in species richness (Figure 3a-d). For rodents and beetles there was a gradient of declining species richness with increasing perennial cover (fixation state) in control dunes (Figure 3a,c), which opposes the productivity-diversity theory (\(H_{2}\)). Thus, the expectations for treatment would be an increase in richness following removal, if treatment was successfully replicating mobile dune conditions and therefore biodiversity structure. Note that for beetles, the decline in richness was only significant between mobile and fixed dunes, so the semi-fixed treatment was expected to remain similar to both control and reference. Conversely, reptile and annual plant richness increased with increasing dune fixation (Figure 3b,d), supporting the theory that productivity increases diversity. The expectations for these latter taxa were thus that species richness would decrease in response to treatment. In semi-fixed dunes, no response of richness was seen in reptiles (Figure 3f) and annuals (Figure 3h) which meant an absence of expected effect, while beetle richness remained unchanged in response to treatment as expected (Figure 3g). In fixed dunes, rodent and annual richness showed no difference between treated and untreated fixed dunes, both remaining significantly different from mobile dunes (Figure 3i,l) and contradicting the expectations for a decrease (rodents) and increase (annuals) in response to treatment. The apparent reduction in reptile richness in treated dunes became similar to (i.e., not significantly different from) to mobile dunes (Figure 3j), but the decline was not large enough to become significantly different from the untreated control dunes (\(p=0.10\)) so the expected result was only half met. Beetles showed a small increase in treated fixed dunes towards mobile dunes compared to untreated fixed dunes, and thus beetle species richness did not differ significantly from the reference or the control (Figure 3k). Lastly, dunes disturbed by ORV had significantly higher rodent species richness compared to untreated semi-fixed dunes, similar to mobile dunes (Figure 3m). Reptiles were found to have significantly lower species richness on disturbed dunes compared to semi-fixed control dunes, but were not significantly lower than mobile dunes (Figure 3n). Beetle richness in treated semi-fixed dunes remained similar to richness in both untreated semi-fixed dunes and mobile dunes (Figure 3o).