Abstract
The results indicate that the effects of genetic diversity on stand productivity may be transient and suggest that the conclusions of short-term studies on diversity effects should be evaluated carefully: Genetic diversity had a significant effect on stand productivity in the 1st year but not in the 2nd or 3rd year. The results also suggest that individual clones are not complementary and that the properties of the stands are mainly additive results of the properties of the constituent clones: In most cases, the observed yield was not significantly different from the total expected yield.
The biomass of the mixtures never outperformed the biomass of the most productive clone, suggesting that clone identity is an important determinant of total biomass.