In the context of plant biology, what is cavitation and what causes it? How can this concept be applied to explain the observed differences between spring and summer wood?

Cavitation in trees is when they lost water.

Explanation:

All the vascular plants have xylem, mainly made of water, but this liquid has a certain pressure. Since trees are so tall, the water pressure can be the same as the atmospheric pressure, but in some ocassions, the pressure increseas and the water column is broken. The water can not reach all the parts of the tree and stars to get dry in some parts. That is the reason why in summer most of the trees loose leaves and branches.