Mixed-effects models for spider species richness and activity abundance.

Results for the fixed effects of the minimal mixed-effects models (numerator and denominator degrees of freedom DFn and DFd; F-value and probabilities P; terms dropped during model simplification are marked “−”) for activity abundance, original and rarefied species richness, and rarefied foraging guild richness of spiders as response variables.aCanopy cover, litter cover (trap surroundings), litter depth (trap surroundings), vegetation cover of the herb layer (trap surroundings) and interaction successional age:woody plant species richness (non-significant and excluded in all cases during model simplification) not shown.bSquare root-transformed.c(+) and (−) indicate positive and negative relationship, respectively.dFull model: fitted with the full set of fixed effects; minimal model: simplified model with lowest AICc.