Results of testing the significance of the slope of fitted linear models.

*N = 15.A two-tailed t-test was applied to test the null hypothesis that a given slope was equivalent to zero. A significance level of 0.05 was used to determine if the null hypothesis could be rejected. The values are the t-value and p-value reported by the lmList function of the R package lm rounded to two decimal places. N-values represent the number of data points used in each model fit. The t-test degrees of freedom are therefore N–2.