<p>Electronic Supplementary Material (ESM)</p><p>S1 Table: Repeated measures (RM) ANOVA results comparing High Invasion x Control with </p><p>High Invasion x Removal Control for all taxa that showed significant effects of Litter treatment. </p><p>Because we were comparing only two treatments we analyzed data with a single factor (combing</p><p>Invasion level with Litter). Insignificant p-values for within-subjects analysis of year and </p><p>Invasion level/Litter indicated Removal Control treatments did not differ significantly from </p><p>Control treatments.</p><p>Anystidae Sminithurid Forelius Solenopsis</p><p>Taxa: mites collembola mccooki xyloni nu</p><p>Between m den subjects DF DF F p F p F p F p Invasion level/Litter 1 14 3.04 0.01 1.81 0.20 0.76 0.40 0.33 0.58 Within subjects Year 2 26 21.41 <0.0001 35.49 <0.0001 3.42 0.048 6.54 0.005 Year x </p><p>Invasion level/Litter 2 26 2.24 0.127 2.53 0.099 0.23 0.79 0.12 0.887</p><p>Wolkovich et al. Ground arthropods Supp S2 Table: Arthropod taxa responses to the non-native grass litter manipulation, as assessed by repeated measures (RM) ANOVA on square-root transformed data for each taxa.</p><p>Entomobryid</p><p>General Anystidae Non-Anystidae and isotomid Sminithurid Spiders and taxa: mites mites collembola collembola harvestmen nu de</p><p>Between m n subjects DF DF F p F p F p F p F p Invasion level 1 42 22.66 0.001 51.52 <0.0001 6.64 0.014 1.47 0.23 0.62 0.44 Litter 2 42 3.36 0.044 0.94 0.40 1.15 0.33 0.33 0.72 2.87 0.12 Invasion level x </p><p>Litter 2 42 0.57 0.57 0.13 0.88 2.32 0.11 0.67 0.52 1.98 0.15 Within subjects Year 2 82 31.43 <0.0001 13.27 <0.0001 7.26 0.001 66.35 <0.0001 4.34 0.02 Year x </p><p>Invasion level 2 82 3.21 0.046 0.04 0.96 1.69 0.19 8.20 0.001 6.15 0.003 Year x </p><p>Litter 4 82 5.32 0.001 0.52 0.72 1.24 0.30 3.95 0.006 0.44 0.78 Year x </p><p>Invasion level x litter 4 82 1.01 0.41 2.01 0.10 0.64 0.64 4.61 0.002 0.41 0.80</p><p>Ant Forelius Pheidole Pheidole Solenopsis Solenopsis species: mccooki clementensis vistana molesta xyloni nu de</p><p>Between m n subjects DF DF F p F p F p F p F p Invasion 1 42 18.21 <0.0001 8.16 0.007 19.80 <0.0001 3.26 0.08 0.64 0.43</p><p>Wolkovich et al. Ground arthropods Supp level Litter 2 42 1.49 0.24 0.67 0.52 4.66 0.015 1.72 0.19 1.13 0.33 Invasion level x </p><p>Litter 2 42 0.44 0.64 0.33 0.72 0.73 0.49 1.34 0.27 2.21 0.12 Within subjects Year 2 82 2.45 0.09 0.93 0.40 24.71 <0.0001 21.57 <0.0001 19.91 <0.0001 Year x </p><p>Invasion level 2 82 1.10 0.34 0.14 0.87 0.14 0.87 1.16 0.32 1.94 0.15 Year x </p><p>Litter 4 82 2.55 0.045 0.15 0.96 0.21 0.93 0.81 0.53 0.29 0.88 Year x </p><p>Invasion level x litter 4 82 0.53 0.72 0.44 0.78 0.48 0.75 1.30 0.28 2.59 0.043</p><p>Wolkovich et al. Ground arthropods Supp</p>