# Can Vegetation Removal Successfully Restore Coastal Dune Biodiversity?
## 3 Results
### Composition  
To examine the effect of treatments on composition we used constrained multivariate ordination. Firstly, we conducted a redundancy analysis (RDA) of all dune states together, in order to compare the relative composition of all dunes in the study, and to visualize the relative magnitude of the effect across press and pulse treatment types (Figure 4a-d). We then tested the treatment effect in each dune state separately, in order to meet the assumptions for the statistical tests (Figures 5-7). For all taxa, composition was a good indicator of dune state as expected under hypothesis \(H_{2}\), as seen by the strong clustering and gradient from fixed control to mobile dunes in all taxa along the first RDA axis (RDA1). Explained variation was much higher in RDA1 than RDA2 for all taxa (Figure 4). Rodent assemblages in Nizzanim coastal dunes were heavily dominated (98%) by two gerbil species _Gerbillus pyramidum_ and _G. andersoni allenbyi_. Therefore, ordination formed an arc effect along the first axis (Figure 4a) as the ratio between the two species shifted from only _G. allenbyi_ in fixed dunes, to only _G. pyramidum_ in disturbed dunes. The disturbed dune centroid was located beyond (further left) the mobile dune's along RDA1 (yellow arrow, Figure 4a), since both species are present in the latter. Figure 4: Overall summary of redundancy analysis (RDA) analyses with all dune types included for (**a**) rodents; (**b**) reptiles (**c**) beetles and (**d**) annual plants. Arrows depict direction of treatment effect along RDA1. Significance testing was performed in each dune type separately (see Figures 5–7). Figure 5: Redundancy analysis for (**a**) rodents, (**b**) reptiles, (**c**) beetles and (**d**) annual plants in treated semi-fixed dunes (pale blue triangle) compared to un-treated semi-fixed (control) dunes (dark blue square) and Mobile dunes (orange square) which are the treatment reference. Distance bars along the 1 st RDA axis show the treatment effect (blue arrow) as a percentage of total distance between control and reference (black dashed). Significant differences were tested using pairwise Permanova. * and + represent \(p<0.05\) for treated dunes compared to control and reference dunes, respectively. Both semi-fixed and fixed dunes showed minor shifts towards mobile dunes (the expected direction for our restoration goals), as a result of treatment for faunal taxa (blue and green arrows in Figure 4a-c), which supported hypothesis \(H_{4}\). A small and insignificant shift in the opposite direction was seen for annuals (green arrow; Figure 4d). Annuals in both semi-fixed control and treated dunes were similar to mobile dune in RDA1 (Figure 4d). ORV disturbed dune composition was virtually identical to mobile dune composition for beetles (Figure 4c), and was similar for reptiles along RDA1, but was distant along RDA2 (yellow arrow; Figure 4b). Overall, press treatment (ORV) appeared to be more similar to reference dunes, compared to pulse treatments, in accordance with hypothesis \(H_{5}\). Changes in response to treatment were tested for each dune type separately, comparing each treatment to the reference (mobile) dunes, and their control dunes for semi-fixed (Figure 5), fixed (Figure 6) and disturbed dunes (Figure 7). Pairwise Permanova results are given in Table S4. Rodent composition shifted 30% along RDA1 towards the reference as a response to treatment (Figure 5a). Their composition was significantly different between treated and control dunes for semi-fixed dunes. In other words, the ratio between the two rodent species changed significantly as a result of the semi-fixed treatment. Reptiles and beetles shifted along the 1 st RDA by 17% and 12% respectively, towards the reference centroid in response to treatment in semi-fixed dunes (Figure 5b,c). The annual plants' centroid shifted away from the reference centroid by 9% along RDA1 (Figure 5d). The centroid shifts detected for these three taxa were not significant in pairwise Permanovas.