Table 1

Analyses, using general linear models, of the effects of number of planted species (continuous variable; entered first using type I SS) and of functional group composition (categorical variable; entered second) on total biomass and on aboveground biomass, showing results for each year when measured. N = 168. Overall model df = 28 and error df = 139. Species number df = 1, composition df = 27. The last columns show type III effects of species number (entered second, after functional group composition).

Variable analyzedYearOverallSpecies number (entered first)Functional group comp. (entered second)Species number (entered second)
R2F value PF value PF valuePF value P
Total biomass 1997 0.32 2.26 0.001 9.80 0.0022.06 0.004 3.880.051
Total biomass 19980.47 4.37 <0.001 43.8 <0.001 2.91 <0.0012.38 0.13
Total biomass 1999 0.607.31<0.001 94.2 <0.001 4.09 <0.001 7.110.009
Total biomass 2000 0.68 10.5 <0.001152. <0.001 5.27 <0.001 12.3 <0.001
Aboveground biomass 1996 0.41 3.28 <0.001 15.5<0.001 2.83 <0.001 3.80 0.053
Aboveground biomass 1997 0.39 3.02<0.001 12.3 <0.0012.60 <0.001 0.52 0.47
Aboveground biomass 19980.49 4.80 <0.001 31.8 <0.001 3.81 <0.0012.56 0.11
Aboveground biomass 1999 0.56 6.27<0.001 90.7 <0.001 3.15 <0.001 14.9<0.001
Aboveground biomass20000.61 7.80<0.001 111. <0.001 3.97 <0.001 10.7<0.001