Unit) (Unit) Sand, Clay (% Or Class) (%) (Cmol Charge/Kg) (Cm, First Horizon

Supplementary Table 2. Geologic, soil, and vegetation characteristics of Wildomar (WILD), Elsinore Peak (ELSI), Caspers (CASP), Aliso (ALIS), Laguna (LAGU), and Califia (CALA) study sites each comprised of four plots (25 m2) along the mediterranean shrubland environmental gradient as determined by soil maps and published data sets (see methods). Dominant vascular plant species are: AC = Artemisia californica Less., AF = Adenostoma fasciculatum Hook. & Arn., BM = Bromus madritensis L., DS = Dudleya spp., EF = Eriogonum fasciculatum Benth., OL = Opuntia littoralis (Engelm.) Cockerell, HA = Heteromeles arbutifolia (Lindl.) M. Roem., HS = Heuchera spp., SB = Selaginella bigelovii Underw., YW = Yucca whipplei Torr.

Site Geologic Type Soil Type Soil Composition pH Organic Matter CEC at pH 7 Horizons, Depth Dominant Plants

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(unit) (unit) Sand, Clay (% or class) (%) (cmol charge/kg) (cm, first horizon)

WILD mesozoic basic intrusive Cajaico 68.8, 15 6.7 0.75 7.5 3, 33 AF, BM

ELSI basalt and meszoic granitic Cieneba 67.9, 12.5 6.2 0.75 9.2 2, 18 AF, EF, SB

CASP eocene marine Rock Outcrop (sandstone) rock na na na na AC, AF, BM, YW

ALIS middle miocene marine Cieneba 67.9, 12.5 6.2 0.75 9.2 2, 18 AC, BM, EF, OL

LAGU middle miocene marine Yorba 65.9, 15 6.1 0.75 9.6 3, 8 AC, OL, HA

CALA upper miocene marine Xeralfic Arents loam na na na na AC, BM, DS, HS