Forest cover change in Germany after a series of drought years (2018-2020) – a remote sensing perspective

Kurzfassung

The years 2018 to 2020 were characterized by exceptional weather situations in large parts of Germany. There were repeated, sometimes prolonged, periods of drought and heat, record temperatures were measured repeatedly, and river levels reached alarming lows. Extensive heavy rainfall events were only able to compensate for the general water deficit to a limited extent, especially in western and northeastern Germany. In the low mountain ranges, hardly any snow fell, so that water reservoirs there could not be replenished as usual. The accumulation of prolonged dry phases, unusually long periods of heat and too little winter precipitation led to favorable conditions for pests. The consequences of these dry and warm weather conditions as well as pests are devastating for the forests: large areas have died, and the trees are often removed to avoid even greater economic damage. While selective logging was common practice for decades, the recent situation changed forest management and particularly forest harvest strategies. Consequently, small-scale timber harvesting was replaced by large-scale clear cutting, which favors medium resolution remote sensing. In this presentation, I demonstrate how remote sensing methods can be used to quantify the recent forest damage in Germany. The results show unprecedented forest loss in large parts of the country. However, these changes are not only due to the heat and drought of the past few years. The drivers are manifold and complex. Some examples will demonstrate the need of better understanding of this complexity to allow for appropriate forest management.