The velocity of translocation in trees

Abstract

Reasons are advanced for mistrusting some published measurements that suggested velocities of translocation in trees around 2-4 m hr^-1. Estimates of the velocity in Acer pseudoplatanus L. have been made by following the rate of spread of labelled photosynthate in branches throughout a growing season. Speeds of label movement were not greater than in most herbaceous plants studied. The highest rates were about 17cm hr^-1 for a short period in autumn; for most of the year values were around 2cm hr^-1. During 24 hr following the application of ¹⁴C there can be extensive radial movement and fixation of carbon in wood laid down many years before. The measurements strengthen our distrust of the high velocities of translocation claimed in trees and emphasize the view of a tree as a slow-paced organism.