pH1 / 5.06 ± 0.09 / 5.40 ± 0.07 / 24.21,83 / <0.001
Soil moisture (mL/mL) / 0.228 ± 0.005 / 0.243 ± 0.005 / 23.81,643 / <0.001
Soil temperature (°C) / 16.86 ± 0.23 / 16.79 ± 0.23 / 0.11,643 / 0.74
Total organic C1,2 / 2533 ± 129 / 2188 ± 111 / 6.21,82 / 0.02
Potential net N mineralization / 0.21 ± 5.90 / 6.29 ± 4.46 / 0.91,83 / 0.32
Potential net nitrification2 / 49.91 ± 6.32 / 53.22 ± 4.72 / 6.61,83 / 0.01
Total organic N / 160.7 ± 9.5 / 148.4 ± 8.7 / 2.11,82 / 0.15
Table 1 Soil properties (mean ± 1 SE) across all uninvaded and Microstegium vimineum-invaded plots.
F-values, degrees of freedom, and P-values are reported for the main effect of Microstegium vimineum. Where significant, P-values are shown in bold. Units for N and C pools are g m-2 at 10 cm depth. Potential N mineralization and nitrification are shown in µg m-2 d-1.
1 Craig et al. (2015)
2Statistics reported for natural-logarithm transformed data
Fig. S1 Microstegium vimieneum (MV) and other plant cover (non-MV) below 1 m height estimated within a 2 m2 area in each plot for the total dataset. Values are means ± 1 SE (n = 23). Asterisks indicate significant differences between invaded and uninvaded plots in total plant cover (*** P < 0.001).
Fig. S2 Relationship between M. vimineum biomass collected nearby invaded plots and estimated M. vimineum cover within each invaded plot (n = 48). Biomass data were previously summarized in Craig et al. (2015).
Fig. S3 Relationship between M. vimineum and total plant cover across all invaded and uninvaded plots (n = 96).
Fig. S4 Percent cover (<1 m height) of different plant functional groups across all invaded and uninvaded plots. Values are means ± 1SE (n = 48) and refer to the total dataset.
Fig. S5 Percent cover (<1 m height) of different plant functional groups for plots where ambient nitrate availability was lower than the median value for the data set. Values are means ± 1SE (n = 48) and refer to the total dataset.
Fig. S6 Short-term nitrogen availability (NH4+ + NO3-) collected from KCl extracts (n = 48) (a), long-term NO3--N (n = 46) (b) and NH4+-N (n = 46) (c) availability from in situ resin bag incubations, and particulate organic N (n = 47) (d) across all invaded and uninvaded plots. Resin data for uninvaded plots were previously reported in Craig et al. (2015). Values are means ± 1SE. Asterisks indicate significant differences between invaded and uninvaded plots (* P < 0.05, ** P < 0.01).
Fig. S7 Microbial biomass C from chloroform fumigation-extraction (a), phenol oxidase (phenox), peroxidase (perox), β-glucosidase (bg) and β-1,4-N-acetylglucosaminidase (nag) activities expressed on a per unit microbial biomass basis (b), and SIR:CFE ratios (c) across all invaded and uninvaded plots. Microbial biomass data as well as the effect of invasion on mass-specific enzymes previously reported in Craig et al. (2015). Values are means ± 1SE (n = 48). Asterisks indicate significant differences between invaded and uninvaded plots (* P < 0.05, ** P < 0.01, *** P < 0.001).
Fig. S8 Particulate organic carbon (a; Craig et al. 2015), dissolved organic carbon (b), and mineralizable carbon (c) across all invaded and uninvaded plots. Values are means ± 1SE (n = 47). Asterisks indicate significant differences between invaded and uninvaded plots (* P < 0.05, ** P < 0.01, *** P < 0.001).
Fig. S9 Results of SEM analysis for particulate organic matter carbon (a) and the ratio of long-term NO3- to particulate organic matter nitrogen (b) for all plots (n = 94). Thickness of lines corresponds to the strength of the relationship. “Mass-specific microbial activity” is a latent variable representing enzymes and substrate induced respiration on a per unit biomass basis.