Table 1 Results from the first step of the analysis: the effect of a dense shrub layer on egg cluster and egg density and the mean egg number per cluster. We first used the subset of plots including sub-plot with a dense shrub layer; then, to test shrub composition, we excluded shrub layers composed of P. abies. Chi2 and P values result from a type II ANOVA. We implemented negative binomial distribution error in a generalized mixed model with “plot” as random variable
Response variables | Predictors | Shrub composition | d.f. | Estimates ± se | Chi2 | P value |
|---|---|---|---|---|---|---|
Egg-cluster density | Dense shrub presence | All | 1 | −1.5 ± 0.5 | 10.81 | 0.001 ** |
Dense shrub presence | Beech | 1 | −1.4 ± 0.4 | 12.06 | 0.0005 *** | |
Egg density | Dense shrub presence | All | 1 | −1.3 ± 0.6 | 5.34 | 0.02 * |
Dense shrub presence | Beech | 1 | −1.2 ± 0.6 | 4.43 | 0.04 * | |
Eggs/cluster | Null | |||||