Ecological Archives A017-034-A1

Fritz Gerhardt and Sharon K. Collinge. 2007. Abiotic constraints eclipse biotic resistance in determining invasibility along experimental vernal pool gradients. Ecological Applications 17:922–933.

Appendix A. Statistical relationships between performance and water depth and neighbor richness, density, mass, and identity.

TABLE A1. Statistical relationships between performance of five exotic species and water depth and neighbor richness, density, mass, and identity in a greenhouse experiment examining abiotic and biotic resistance to plant invasions. See Notes.

Parameter Water depth Richness Density Mass Identity
1-species 2-species
Brassica rapa (N = 60)
Survival 60.745*** 0.619 -0.327 -2.561* 0.046 0.034
Overall MANOVA 4.064* 0.030 1.778 1.036 0.655 1.332
Total mass 0.118 0.016 5.137* 1.202 1.911 0.841
No. inflorescences 0.398 0.005 4.195* 3.259 0.488 2.327
Leaf:height ratio 9.278** 0.013 1.089 0.242 0.199 0.584
Centaurea solstitialis (N = 99)
Survival 51.545*** 2.530 -0.975 -3.418** 1.971 2.733
Overall MANOVA 4.622* 1.058 1.508 2.289 9.881** 2.077
Total mass 9.247** 2.177 2.682 4.576* 19.291** 3.149
No. inflorescences - - - - - -
Leaf:height ratio 0.785 0.037 0.644 0.004 1.843 0.116
Hordeum marinum (N = 96)
Survival 2.218 2.156 - - 1.615 -
Overall MANOVA 15.033*** 1.344 2.831* 7.661*** 0.691 2.271
Total mass 32.738*** 0.013 7.150** 17.892*** 0.011 0.311
No. inflorescences 17.034*** 0.521 3.698 9.177** 0.090 0.000
Leaf:height ratio 9.418** 0.571 0.002 0.292 0.774 2.698
Lolium multiflorum (N = 102)
Survival 4.598 2.296 -0.124 -0.073 - 3.423
Overall MANOVA 12.975*** 2.008 3.527* 6.104** 0.137 2.976*
Total mass 37.623*** 4.040* 8.945** 11.602** 0.087 8.588**
No. inflorescences 28.939*** 0.192 5.572* 13.106*** 0.018 1.865
Leaf:height ratio 6.185* 0.303 0.024 0.005 0.338 0.795
Vicia villosa (N = 115)
Survival 45.928*** 0.061 -0.361 -1.574 2.031 1.318
Overall MANOVA 3.793* 1.107 2.310 1.772 0.348 0.557
Total mass 2.538 0.007 2.976 2.455 0.252 0.648
No. inflorescences 1.741 0.212 1.322 1.008 0.779 1.047
Leaf:height ratio 10.391** 0.452 2.291 0.992 0.054 0.005

   Notes: Survival was analyzed by likelihood ratio Χ2 test (water depth and neighbor richness, and identity) or Student’s t test (neighbor density and mass); the remaining parameters were analyzed by MANOVA (water depth and neighbor richness and identity) or MANCOVA (neighbor density and mass). All analyses of plant neighborhood, except survival, included water depth as a covariate. Values are F statistics, except for survival, which are Χ2 statistics (richness and identity) or t statistics (density and mass). Significant relationships are highlighted in bold; significance levels are * P<0.05,** P<0.01,and *** P<0.001. A dash (-) indicates that there were insufficient samples for analysis or that no inflorescences were produced (C. solstitialis).


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