Chapter 19 The Forest as Water Pump
...each summer, trees use up to 8,500 cubic yards of water vapor per square mile, which they release into the air through transpiration. This water vapor creates new clouds that travel farther inland to release their rain. As the cycle continues, water reaches even the most remote areas. This water pump works so well that the downpours in some large areas of the world, such as the Amazon Basin, are almost as heavy thousands of miles inland as they are on the coast.

There are a few requirements for the pump to work: from the ocean to the farthest corner, there must be forest. And, most importantly, the coastal forests are the foundations for this system. If they do not exist, the system falls apart.
...It didn't matter if they were studying a rain forest or the Siberian taiga, it was always the trees that were transferring life-giving moisture into land-locked interiors. Researchers also discovered that the whole process breaks down if coastal forests are cleared.

Chapter 23 A Sense of time
In many latitudes, forests drop leaves in the fall and leaf out in the spring, and we take this cycle for granted. But if we take a closer look, the whole thing is a big mystery, because it means that trees need something very important: a sense of time. How do they know that winter is coming or that rising temperatures aren't just a brief interlude but an announcement that spring has arrived?

...How often have we experienced warm spells in January or February without the oaks and beeches greening up? How do they know that it isn't yet time to start growing again? We've begun to solve the puzzle with fruit trees, at least. It seems the trees can count! They wait until a certain number of warm days have passed, and only then do they trust that all is well and classify the warm phase as spring.

...And how do trees register that the warmer days are because of spring and not late summer? The appropriate reaction is triggered by a combination of day length and temperature. Rising temperatures mean it's spring. Falling temperatures mean it's fall. Trees are aware of that as well. And that's why species such as oaks or beeches, which are native to the Northern Hemisphere, adapt to reversed cycles in the Southern Hemisphere if they are exported to New Zealand and planted there. And what this proves as well, by the way, is that trees must have a memory. How else could they inwardly compare day lengths or count warm days?

Chapter 24 A Question of Character
On the country road between my home village of Hummel and the next small town in the Ahr valley stand three oaks. They are a commanding presence out in the open fields, and the area is named in their honor. They are growing unusually close together: mere inches separate the one-hundred-year-old trunks. That makes them ideal subjects for me to study, because the environmental conditions for all three are identical. Soil, water, local microclimate - there can't be three separate sets of each within a few yards. This means that if the oaks behave differently, it must be because of their own innate characteristics. And they do, indeed, behave differently!

...Whereas the oak on the right is already turning color, the middle one and the one on the left are still completely green. It takes a couple of weeks for the two laggards to follow their colleague into hibernation. But if their growing conditions are identical, what accounts for the differences in their behavior? The timing of leaf drop, it seems, really is a question of character.

...The tree on the right is a bit more anxious than the others, or to put it more positively, more sensible. What good are extra provisions if you can't shed your leaves and have to spend the whole winter in mortal danger? So get rid of the lot in a timely manner and move on to dreamland! The two other oaks are somewhat bolder. Who knows what next spring will bring, or how much energy a sudden insect attack might consume and what reserves will be left over afterward? Therefore, they simply stay green longer and fill the storage tanks under their bark and in their roots to the brim.