The phrase "more tree-covered" suggests an area that has a significant amount of trees. If you want to use synonyms to convey the same message, you can use phrases such as "denser forested," "lush with trees," "abundant in foliage," or "greenery-packed." Other adjectives that represent the same meaning include "wooded," "sylvan," "forested," "leafy," and "verdant." All these words describe an area that has many trees and green vegetation. By using these synonyms, you can add more depth to your language and make your writing more descriptive and vivid while conveying the same message.