Wood trait measurements
For measurement of initial wood traits considered relevant to the WES and to decomposition, each 2-cm sub-sample was stored in a sealed plastic bag immediately after collection in the field, and kept cool until processing. Within 12 h, after the bark had been removed, a sub-sample was cut from each disk to obtain fresh mass initial volume using Archimedes’ principle of water displacement (Williamson & Wiemann 2010).
All wood sub-samples were dried at 75 °C for 72 h to determine dry mass. Initial wood density (g·cm-3) was calculated as dry mass per volume. Initial water content, i.e., (fresh mass﹣dry mass)/ fresh mass, was used to calculate the initial dry mass of the litter-bag samples. Initial wood sub-samples were ground in a laboratory mill and passed through a 0.15 mm sieve. Thereafter, 0.2 g sub-samples were digested using concentrated H2SO4 to determine N and P concentrations on an infrared spectrophotometer (Smartchem 200, Alliance, France). Lignin content was determined by acidolysis -titration method, and cellulose content was determined by anthrone-sulfuric acid colorimetry (Poorter & Villar 1997).