The forest significantly influences the microclimate, flow rate and retention of water in the landscape. The cooling effect of the forest is clearly noticeable on hot summer days when the temperature in the forest is significantly lower than in the surrounding open areas. The energy of sunlight causes evaporation from the soil and trees (evapotranspiration) and this process causes the forest to cool. Inside the forest, the wind speed is also significantly lower than in the open countryside. Any water entering the soil (infiltration) is greatly increased in the forest by preferential flow in canals along the roots, which are known as macropores. The quantity and quality of tree litterfall plays an important role in infiltration and evaporation from the forest soil.
When it rains, the forest
- replenishes groundwater supplies (by reducing surface runoff, increasing infiltration and distribution of water in the soil),
- reduces the risk of flooding.
In the dry season, the forest
- slowly releases water,
- refills springs,
- keeps water in watercourses,
- increases the overall availability of water.
In the context of climate change and the search for mitigation strategies, there is a need for a more detailed understanding of the impact of forests on the water cycle and temperature profile in the landscape. The aim of our monitoring is to contribute to the understanding of the hydrological and microclimatic effect of forests. Within different vegetation, we measure soil moisture, soil potential (the energy by which water is kept in the soil), air humidity, airflow direction and velocity, throughfall and leaf wetting. We continuously monitor the water level in the boreholes. We measure ground level air temperature and temperature at 2 meters above the ground, as well as soil temperature at various depths below the surface. We measure the behaviour of the forest stand itself (growth or shrinkage of trees in the dry season) using increment meters (dendrometers).
