I have an ancient forest near where I live in Switzerland. In the core zone of the forest they do no maintenance whatsoever. The trees live, they get gigantic and very old. They die. At some point the top breaks off and then many years later the rest of the tree is so fungus-eaten it tips over too and rots on the ground.

Sunlight never reaches the ground because of the tall giant trees so there's no undergrowth. It's just dead leaves and mushrooms.

Something that was completely 100% noticeable was that during this drought of several months this forest was still incredibly healthy. You walk into the forest and the temperature drops several degrees Celsius and the ground still seems wet. I could tell that the groundwater level sunk maybe 4 feet by looking at some pits that normally have water. But still the ground didn't feel dried out.

I compared this to a forest where they do maintain the forest and harvest giant trees for wood. They don't clear it but just by cutting out these tall trees they let sunlight reach the ground and dry the forest out.

Well, I also have an oak forest just in front of my balcony here in western Switzerland. Most of it is natural reserve, around half is literal scientific reserve. They don't harvest, let everything where it falls unless it completely blocks one of few pedestrian paths, then they use horses to drag it aside. It has few small streams (with crayfish!!) and one river flowing through

That forest was crispy dry, almost dusty in recent weeks. One spark could burn it all down easily. We had... 2 properly rainy days through whole summer? Few thunderstorms but they were very local, and all of them avoided directly our area and that forest like plague.

At least those crayfish managed to survive as I've seen 2 last week, they are more susceptible to water pollution and some brutal fungal infection which can be brought from other streams and basically sterilize whole stream (happened in other parts of our canton around Lausanne). Water somehow didn't stop. Back where I come from in eastern Europe their local crayfish weren't often so lucky - streams bone dry.