The trees are there for quite long time and are not disturbed by the water.
What lurks beneath?
Carps, trout, and turtles.
Very interesting, Michael! It does seem a beautiful area and providing a rich habitat for diverse life.
Here, we have an issue with oak root fungus. It, and other fungi, are endemic in all forests and woodlands around the planet. Here in the USA, when the trunk, above the roots are subjected to in ability to dry out, the fungus flourishes. However, there are complex controlling factors and influences. I have controlled the fungus by simply increasing the volume of green leaves the tree can have by removing alternate trees that are close together.
It could be that these trees, if indigenous to the area, have adapted to such flooding as all the more susceptibly trees have died off from fungus attack. It also could be that the flood plane is only a few years old and the extent of damage is entirely below the waterline!
Asher