If you aren’t familiar with floodplain forests, they are the bottomland, low-lying areas adjacent to streams, rivers, oceans, bays, and lakes. Floodplains are home to a diversity of wildlife. The damp soil creates a rich home for insects and amphibian breeding habitats, which then become prey for birds such as woodcocks and barred owls, for mammals such as raccoons and reptiles like snakes and turtles. The natural flooding is essential for numerous reasons. They carry nutrient-rich sediments which contribute to a rich environment for vegetation. Although floodplains are unnoticed by many, they are currently facing a huge threat.
The extraction of groundwater for industry and households is increasingly damaging floodplain forests in Europe given the intensity and length of drought periods in the summer. Floodplains play an essential role in controlling flooding and protecting the biodiversity in these areas.
Forest ecologist Prof. Dr. Jürgen worked alongside his team to investigate whether the overall decrease in oak trees within floodplains is due to the extraction of groundwater. After studying the annual growth rings of young and old trees in areas that are used for extraction vs. secure areas, he was able to conclude that oaks are in fact negatively affected by summer drought.
The trees grounded in extraction forests experienced harm since the start while untouched areas remain intact. Georgios Skiadaresis, Ph.D. student and lead author of the study, is: “Oaks with contact to groundwater can recover better in phases of favorable weather conditions, as can be seen from greater annual ring growth. But this is far less the case for oaks without contact to groundwater.”
One positive takeaway is that young oaks are less affected by decreasing groundwater. Whether they are more adaptable than the older ones is unknown.
The results clearly show that the combination of human extraction and climate change will continue to worsen the strength and growth of floodplain forests.