The wisdom of trees consists largely in the fact that they require no wisdom. They grow, flourish, die, and recycle; nothing more is required; nothing more need be said. We who question life and seem to require a raison d'etre can, however, learn wisdom from trees. This wisdom resides in an understanding of the essential primacy of life. Life happens, and we, as self-conscious beings, are a particular expression of it. The wisdom of trees is the realization that, like trees, we do not possess life, but are rather an expression of it. In this, we begin to see how we might follow along with life, rather than trying to force life to comply with our agenda. In this is freedom.
In the pivotal story of Yan Hui's realization that he "has not yet begun to exist" found in the fourth chapter of the Zhuangzi, we are told that this understanding happens when he "finds that which moves" him. What is this, if not life? It is life; but it is also something more; or rather, it is something much less: it is qi (vital force), "an emptiness, a waiting for the presence of beings". That which moves us is not us.
Throughout Daoist literature is the metaphor of life as a spontaneous up-welling out of a nameless source, ever-flowing, yet never emptied. It is the mysterious springtime of being. Yan Hui had a glimpse of this up-welling and realized that he did not possess life, but rather was possessed of it. And this sufficed to shake him loose from his sense of being a distinct entity required to exercise control over life and the events it manifests. In this is freedom.
To surrender into life, to let life be what it is and manifest as it will, this is but to surrender into Dao. It is not other than "opening (oneself) broadly to the vastness at the root of things, abandoning (oneself) to it, even unto the very depths".
The primacy of life applies only to the living, for it is the living that experience it. We are in no position to declare the ultimate primacy of anything. We can only speak to and out of this particular experience, and this also is something discovered when we find that "emptiness" which moves us.
You can check out Scott's writings on Zhuangzi here.