Seasonal changes in water absorbability of some litterfall components in Scots pine stands differing in age

Understanding the water-holding capacity of the litter layer is of interest when constructing forest hydrology models, where the presence of litter affects soil moisture content and fire behavior. However, to understand the process of water storage in the litter layer it is not only important to know (i) how much water the litter layer can store, but also (ii) how much water particular litter components can store. Little is known about the role of organic matter chemistry in water absorption and saturation of its internal capillarity. We hypothesized that water absorption of freshly fallen organic matter changes with stand age and during the year, i.e. the term when organic matter falls (month of the year or season) affects its water absorbability. Thus, we determined seasonal changes in water absorption time, carbon and nitrogen contents, and the C/N ratio of bark and needles taken from Scots pine stands of different ages during laboratory tests. Pine needles and bark were collected every month for one year in five stands in north-western Poland. The time of water absorption for bark was about 30% shorter than that of needles. The age of the stand did not affect the time of water absorption in the litterfall components. We observed that the term when litter falls (month of the year or season) significantly affected the water absorption time. It indicates that organic matter reaching the forest floor and forming the litter layer is characterized by different output properties affecting the water storage capacity of the litter layer.

Automated summary

Understanding the water-holding capacity of the litter layer is crucial for constructing forest hydrology models, with organic matter chemistry and season impacting the water absorption process in the litter layer.