Fig. 4

Generalized additive model of the relationship between harvest year and retention level for coupes with retention > 0 (n = 73). The model has simplified to a linear model (edf = 1), but the relationship is not significant (p = 0.075). Shaded areas indicate the 95% confidence interval. d² is the proportion of the null deviance explained by the model. p values indicate the approximate significance of the single smooth term, while edf is the estimated degrees of freedom for the smooth term