Soil moisture regime under different forest types

An understanding of the spatial and temporal variation of soil moisture is essential for studying other hydrological, biological, or chemical soil processes, such as water movement, microbial activity, and biogeochemical cycling. The study focuses on the description of soil water dynamics at several sites with different types of forests and their health status. Specifically, the results are based on the thorough description of the soil water regime under spruce forest in two mountainous plots. At one plot the measurements are supplemented with site influenced by bark beetle attack and at another site the comparison with beech forest. The analysis was based on soil water regime measurements from several vegetation seasons (comprising wet and dry years). We investigated both column average soil water content and also its vertical distribution. The water balance of the soil column was studied by the bucket-type soil water balance model.

It was shown that the forest type is an important factor controlling the rate of evapotranspiration which in turn influences the soil water regime, especially in dry periods. In wet periods, the differences among particular sites were negligible. In dry periods, the soil was slightly wetter in the site affected by the bark beetle outbreak in the surface soil layer and drier in the deeper soil layer. Similarly, the beech and spruce forest differences were most pronounced in dry periods. In this case, the beech forest was more efficient in terms of evapotranspiration water consumption which resulted in drier soil compared to spruce covered plot. In the spruce site, the soil was regularly drier only at the beginning of the season which was given by different interception rates during winter. The differences between spruce and beech forest were based namely on the water consumption efficiency and differences in interception rates, vertical distribution of the roots, and soil hydraulic properties.

This research was supported by the Technological Agency of the Czech Republic (SS05010124), SoilWater project (EIG CONCERT-Japan), and the institutional support of the Czech Academy of Sciences, Czech Republic (RVO: 67985874).