Climate change is now a key driver in the decimation of the Black Forest in southwest Germany, with over 40% of the forest gone from dry summers, the need for moisture is evident. Environmentally, any change in climate can negatively or positively affect the surrounding environment, from water quality to precipitation levels, to the health of the soil. Unfortunately, the gradual changes in climate have become extreme over the past few years, and that has caused a greater negative effect on the planet, especially for the water balance. The Black Forest has seen a strong influence on its specific water balance: precipitation and evapotranspiration. Professor Dr. Hans-Peter Kahle and Professor Dr. Heinrich Spiecker from the University of Freiburg conducted a long-term study that displays the results of the climate influence on the trees.
The researchers used consistent data found from 1953 to 2020 that covers the annual mortality rate of the trees across an almost 250-thousand-hectare acre region of land. They took this data and compared it to another set of data that analyzes the water balance within that region from the months of May to September. Together, they analyzed the effects of heat and drought; they examined the trees that died from various factors: insect or fungal infestation, atmospheric deposition, frost or drought, and other causes. The time series on water balance, which covers over 140 years (1881-2020), has shown a downward trend, with a steady start of 12% at the end of the century, but since then that percentage has increased to a 40% decrease in sustainable growth. That percentage is seven times the average mortality rate in the 1953 to 2017 time duration.
Another striking observation is the cool-humid and dry-warm durations that have been regularly occurring for about 14 years now. That regularity has become skewed, with the cool-humid periods becoming weaker while the dry-warm periods getting more severe. Without the stability or even slight increase in moisture in this region, these statistics can become more and more alarming as time goes on. The full study has been published in the scientific journal Global Change Biology.