Variation in tracheid characteristics along a latitudinal
gradient
Most of the traits, except for earlywood tracheid diameters (CTD, CRD),
showed a latitudinal pattern (Fig. 5). However, no significant trends
were found between traits and longitude (LON) and altitude (ALT)
(p>0.05). Generally, traits of latewood decreased faster
than those of earlywood as latitude increased, suggesting a climatic
shift along latitude is more related to the change of latewood than
earlywood traits.