Two-dimensional representation of the standardized indices of loss for each forest survey (points, n = 1154) plotted on the two first principal component (PC) axes, which explain 64% of the variation in the indices of loss. Arrows and their length represent the vectors of loss, i.e. the direction and strength of each individual index of loss. The more aligned the arrows, the more correlated the indices are. The average of all indices of loss is highlighted by a colour scale for each survey ranging from dark red (high losses) to blue (gains).