Vertical and radial profiles in tracheid characteristics along the trunk of Douglas-fir trees with implications for water transport

摘要: The main stems of three young Douglas-fir (Pseudotsuga menziesii var. (Mirbel) Franco) trees were dissected to obtain samples secondary xylem from internodes axially along the trunk and radially within each internode. From these samples, measurements obtained tracheid diameter, length, number inter-tracheid pits per tracheid, diameter pit membranes. In addition, trunks old growth also a small sample roots for measurement diameter. A gradient was apparent in all measured anatomical characters vertically sequence among outer rings. These gradients arose not because internodes, but strong present at internode rings out pith. Tracheid characteristics correlated: wider longer tracheids had more numerous pits, such that total area about 6% wall independent size. stem model combining parallel series allowed estimates whole conductance as function tree age. Conductance (xylem specific conductivity) declined during early trees, appeared approach stable value aged.