Table 1.

Relative abundance and frequency, biogeographic origin and life form of the 14 species used in this study. Abundance refers to the average percentage cover in 160 plots (area 1 m² per plot) across the study area, not including plots where they are absent. Frequency refers to the number of the 160 plots occupied by each species.

species	origin	life form	frequency (per 160 plots)	abundance (1 s.d.)
Sanicula crassicaulis	native	perennial forb	159	9.4	11.8
Vicia sativa	exotic	perennial forb	152	7.8	5.3
Poa pratensis	exotic	perennial grass	121	46.2	23.1
Cytisus scoparius	exotic	perennial shrub	108	3.2	2.3
Dactlyis glomerta	exotic	perennial grass	103	19.4	12.2
Camassia quamash	native	perennial forb	99	5.4	4.1
Bromus cariantus	native	perennial grass	76	10.8	12.4
Dodecatheon hendersonii	native	perennial forb	66	4.4	3.2
Lomatium utriculatum	native	perennial forb	48	5.6	4.7
Lapsana communis	exotic	perennial forb	11	2.7	2.5
Elymus glaucus	native	perennial grass	6	3.5	1.8
Lactuca biennis	exotic	perennial forb	2	3.5	2.5
Hypochaeris radicata	exotic	perennial forb	2	1	1
Lupinus bicolor	native	annual forb	1	1	1