Plant Ecology - Online Resource 1
Root biomass and soil δ13C in C3 and C4 grasslands along a precipitation gradient
Courtney L. Angelo1* and Stephanie Pau1
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Department of Geography, Florida State University, 113 Collegiate Loop, Bellamy Building,
Room 323, Tallahassee, FL 32306-2190
Telephone: 850-644-1706; Fax number: 850-644-5913; courtneyangelo@gmail.com
*corresponding author
Supplemental figures
Fig. OR1 Bar graph of total C3 individual species root biomass (g/m2) shows a combination of
more C3 species and of increasing C3 root biomass for some species across our precipitation
gradient (Fig. 5). Each bar represents three replicate root samples per species
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Fig. OR2 Bar graph of total C4 individual species root biomass (g/m2) reflects a similar nontrending pattern of C4 root biomass across our precipitation gradient (Fig. 5). Each bar represents
three replicate root samples per species
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Fig. OR3 The relationship between soil carbon content (%) and a soil δ13C (per mil) and b mean
annual precipitation (MAP) mm. a Soil δ13C did not decrease with soil carbon content (P = 0.26,
r = -0.42, n = 9). b Soil carbon content did not change across our precipitation gradient, with
wetter sites having similar soil carbon content as dry sites (P = 0.89, r = 0.05, n = 9). Data shown
are plot averages (five samples each plot) of soil carbon and δ13C
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Fig. OR4 Percent cover of C3 woody vegetation across climatic gradient. Data shown are plot
averages (five samples each plot) of % C3 woody cover
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Fig. OR5 Average plant height (cm) for C3 species (black bars) and C4 species (gray bars) based
on Wagner et al. (1999) across our precipitation gradient. C3 and C4 species height did not vary
across our gradient (P = 0.13, r = -0.63 and P = 0.20, r = 0.47, respectively). C3 plant height
stays relatively consistent across our gradient
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Fig. OR6 Average leaf area (cm2) for C3 species (black bars) and C4 species (gray bars) based on
Wagner et al. (1999) across our precipitation gradient. C3 leaf area stays relatively consistent
across our gradient. C3 and C4 species leaf area did not vary across our gradient (P = 0.45, r =
0.34 and P = 0.18, r = 0.53, respectively)
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Fig. OR7 Relationships between average substrate age years (yrs) and a soil δ13C (per mil), b C3
and c C4 foliar δ13C (per mil) values. a Soil δ13C did not vary across substrate age, with older
sites having similar soil δ13C values as younger substrates (P = 0.59, r = 0.21, n = 9). Data shown
are plot averages (five samples each plot) of soil δ13C. b C3 foliar δ13C values did not decrease
across substrate age (P = 0.31, r = -0.51, n = 6). c C4 foliar δ13C values did not vary across
substrate age, with older sites having similar foliar δ13C values as younger substrates (P = 0.48, r
= 0.29, n = 8). C3 and C4 foliar data shown are foliar δ13C averages for the dominant species
found at each site
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