Radiation and temperature responses to a small clear-cut in a spruce forest

Effects of a small clear-cutting on solar radiation, soil and air temperature regimes were investigated by continuous field measurements in a spruce forest in Solling, Central Germany, during vegetation period of 2005. Five meteorological stations, installed in central part of a small clear-cut area (2.5 ha) and close to edges of a surrounding forest, allowed to quantify the spatial variability of meteorological parameters within the clear-cut and to describe the impacts of the forest on clear-cut microclimate. The differences of microclimatic conditions between the clear-cut and the surrounding forest were derived using an additional station installed inside the forest about 150 m from the clear-cut. Results showed that clear-cutting leads to significant changes of spatial and temporal patterns of solar radiation and soil temperature. Solar radiation at the clear-cut was very heterogeneously distributed and about 5-11 times higher than inside the forest. It reached maximum at northeastern part and minimum at southwestern part of the clear-cut. The daily maximal soil temperature at 10 cm depth was measured at northern parts of the clear-cut and it was by up to 6°C higher than in the forest. Daily minimal soil temperature at the clear-cut was about 1-3°C higher than in the forest, too. The main factors influencing the soil temperature patterns were seasonally changed incoming solar radiation, ground vegetation and its phenology, as well as soil moisture. The mean daily maximal air temperature measured at the clear-cut was by up to 2.5°C higher and the mean daily minimal temperature by up to 0.5°C lower than in the surrounded forest.