Drivers of native species richness
At large grain (3 x 3 m), northness and slope were significantly
positively related to native species richness, and distance to nearest
drainage negatively influenced species richness. Native species richness
decreased with elevation, but at low elevation, richness was higher in
the presence than absence of A. selago , and at high elevation
lower in the presence than in the absence of A. selago (Figure 3,
Table 1a).
At small grain (1 x 1 m), species richness decreased with elevation,
while slope and TWI were positively related to species richness (Figure
3, Table 1a).
No further action was taken for the subset of the plots where alien
species were absent (results shown in Table A3). Results were similar at
both large and small grains for native richness when only plots with
alien cover less than 10% were considered, with some exceptions
(highlighted in Table A4, Figure A2, e.g., richness decreased with
hillshade at both large and small grains and the effect of northness on
richness was dependent on elevation).
Both elevation and TWI negatively influenced native
Δ9-1, whilst northness and presence of A. selagopositively influenced native Δ9-1 (Figure 3, Table 1b).
Similar results were obtained for the dataset of plots with alien cover
< 10%. However, higher native Δ9-1 occurred
in distances closer to drainage lines compared to further away only when
alien cover was below 10% (Table A4).