Water deficiency – Forests in danger?

During a dry spring as typical in Brandenburg, water is limited for the forests. Does the water deficiency cause damage to the forest? How long can the forests bear this lack of water? It is known, that trees are adapted differentially to water shortage. But there is still a need for further research in the amount of loss in increment during long dry periods and dry successive years (droughts).

Water deficiency occurs if a plant needs more water than is available. Plants, soil and the meteorological conditions interact. At the Thünen-Institute we identify regions in Germany with recent and potential risk of water deficiency. By the use of models it is possible to reproduce how the water deficiency and decreasing available soil water affect trees.  

Especially young trees are vulnerable, as their roots are not deep and cannot reach deeper soil water. Thus they are in the focus of our experiments. In a rain-shelter experiment (Drylab) with eight lysimeters we examine the sensitivity of beeches with different origins to drought stress under controlled conditions. Out of this we derive indicators of critical drought stress.