Changes to the water repellency and storage of different species of deadwood based on decomposition rate in a temperate climate

The aim of this study is to demonstrate the changes to the physical properties and water repellency (WR) of deadwood depending on the species and rate of decomposition. An innovative element of this study is the measurement of droplets' contact angle to the surface of the wood. Five species of trees at three different stages of decomposition were selected for the present study. The deadwood Silver Fir (Abies alba), Common Hornbeam (Carpinus betulus), Common Ash (Fraxinus excelsior), Common Alder (Alnus glutinosa), and Common Aspen (Populus tremula) were selected. The WR of the wood was determined based on water drop penetration time; and the surface free energy (SFE) was determined based on the measured angles. Moreover, Owens-Wendt and Van Oss-Chaudhury-Good models were used to determine SFE. The advancement of deadwood decomposition can be determined by observing the physical changes to the wood. Marked changes in density, moisture, porosity, and weight loss in subsequent stages of degradation were found in the wood of all tested species. Changes to the physical properties of wood result in changes to its WR and wettability. As the degree of decomposition increases, different species of wood may absorb water more quickly, and the surface of the wood may become more hydrophilic. Our results indicate that deadwood increases water storage in forest ecosystems. Assuming that deadwood covers approximately 5.7 m(3)/ha in a Polish forest, total water storage could increase from 0.8 to 4.7 m(3)/ha depending on the wood species and decomposition rate.