Cattle
Animals in the Bible generally refer to spiritual activity, the things we actually do on a spiritual level. "Cattle," as typically used in the Bible, mean a collection of domesticated animals owned by one person or group (including other animals along with cows). It makes sense, then, that cattle would represent the spiritual activities we "own" and have "domesticated."
What are the good things we like to see in ourselves and encourage? What true ideas do we keep in mind, ponder, and use in our decision-making? These can come in great varieties and from many different sources, just as a variety of animals could be part of "cattle," but the key is that we own them, care for them and use them.
(Reference: Arcana Coelestia 415, 3786, 4105, 4106, 4391, 4440)
Tree
In general, trees represent the deepest and most significant intellectual concepts: the ones that come to us most directly from the Lord. This varies depending on us and our states: the people of the Most Ancient Church, who were in a state of loving the Lord, understood truth automatically and internally through what the Writings call "perception"; people in lower states (including most of us) have to work a little harder to learn it from the Word and by willing to follow the Lord. In other parts of the Bible, especially in the prophets and New Testament parables, the meaning of "tree" is broader, meaning not just a person's intellectual concepts but the whole person.
'Trees,' as in Joel 1:10-12, signify knowledges.