Table 3. Repeated-measures ANOVA for the effects of five years of drought (-50% ambient rainfall) on species richness in grassland, shrubland and mixed vegetation (sites) in central New Mexico, USA. Statistically significant post-hoc comparisons (P<0.10) for significant interactions with treatment effects are also presented; d=drought treatment, a= ambient precipitation plots.

Factor / DF / SS / F / P / R2 / P / Contrasts
Forbs / Year / 4,4 / 0.63 / 3.14 / <0.001 / 0.91 / <0.001
Site / 2,2 / 1.17 / 161.34 / <0.001
Treatment / 1,1 / 0.00 / 1.25 / 0.269
Year x Site / 8,8 / 0.31 / 10.70 / <0.001
Year x Treatment / 4,4 / 0.12 / 7.95 / <0.001 / 2002 d<a. 2003 and 2005 d>a
Site x Treatment / 2,2 / 0.05 / 6.96 / 0.002 / Shrubland d<a, Grassland d>a
Year x Site x Treatment / 8,8 / 0.06 / 2.14 / 0.045
Grasses / Year / 4,4 / 0.59 / 16.01 / 0.001 / 0.69 / <0.001
Site / 2,2 / 0.24 / 13.23 / <0.001
Treatment / 1,1 / 0.15 / 16.21 / <0.001
Year x Site / 8,8 / 0.09 / 1.18 / 0.326
Year x Treatment / 4,4 / 0.09 / 2.48 / 0.053 / 2002 d<a, 2003 and 2004 d<a, 2005 d<a
Site x Treatment / 2,2 / 0.06 / 3.11 / 0.052 / Grassland d<a, Mixed d<a
Year x Site x Treatment / 8,8 / 0.01 / 0.17 / 0.994
Shrubs / Year / 4,4 / 0.32 / 27.19 / <0.001 / 0.82 / <0.001
Site / 2,2 / 0.40 / 68.50 / <0.001
Treatment / 1,1 / 0.00 / 1.30 / 0.258
Year x Site / 8,8 / 0.05 / 2.31 / 0.031
Year x Treatment / 4,4 / 0.01 / 1.16 / 0.340
Site x Treatment / 2,2 / 0.00 / 0.30 / 0.741
Year x Site x Treatment / 8,8 / 0.03 / 1.10 / 0.375
Proportion annual to perennials / Year / 4,4 / 0.01 / 1.28 / 0.290 / 0.83 / 0.001
Site / 2,2 / 0.00 / 0.45 / 0.641
Treatment / 1,1 / 0.05 / 19.20 / <0.001
Year x Site / 8,8 / 0.11 / 5.18 / <0.001
Year x Treatment / 4,4 / 0.09 / 9.21 / <0.001 / 2002 d<a, 2003 to 2005 d>a
Site x Treatment / 2,2 / 0.01 / 2.73 / 0.073 / Grassland d>a, Mixed d>a
Year x Site x Treatment / 8,8 / 0.02 / 1.09 / 0.383
Subdominants / Year / 4,4 / 0.70 / 29.62 / <0.001 / 0.84 / <0.001
Site / 2,2 / 0.82 / 69.93 / <0.001
Treatment / 1,1 / 0.01 / 0.97 / 0.329
Year x Site / 8,8 / 0.22 / 4.77 / 0.01
Year x Treatment / 4,4 / 0.08 / 3.39 / 0.014 / 2002 d<a
Site x Treatment / 2,2 / 0.03 / 2.92 / 0.062 / Shrubland d<a
Year x Site x Treatment / 8,8 / 0.07 / 1.52 / 0.168