highly significantp < 0.001
To explicitly account for species identity, species was included as a random effect in linear mixed‐effects models; these relationships remained highly significant (vessel‐fiber: coefficient = −0.669, p < 0.001; parenchyma‐fiber: coefficient = −0.714, p < 0.001; Table S4 ). 4.3 The Trade‐Offs Among Different Tissue Fractions Across Different Vertical Strata For each vertical stratum, there are clear and strong trade‐offs between vessel and fiber fractions, and between parenchyma and fiber fractions (Figure 4 ).