Figure 3. Direct interaction and higher-order interaction (HOI) effects grouped per species (as target or neighbor) at zero drought index (a, b; α coefficients in Eqn 1) and their change (c, d; β coefficients in Eqn 1) with increasing length of the longest consecutive period below permanent wilting point (PWP). Positive values indicate facilitative effects, while negative values indicate competitive effects. The number of interactions (number of blocks inside each bar) indicates how often a species is involved in a direct interaction or HOI with a different species or species pair. Direct interactions between the same species pairs from different models were averaged. The size and orientation of individual boxes indicates the size and direction (+/-) of effects (standardized effect sizes). Colors refer to functional group of the species (red: non-N-fixing Forb, green: Grass, blue: N-fixer). Non-significant interactions were excluded. For full species names, see methods section 3.1.