In the Bible, trees are another symbol used to represent people. So the burned trees of the first trumpet symbolize people handed over to the fire of God's punishment, a third indicating a partial punishment. I will draw My sword out of its sheath and cut off both righteous and wicked from you. The first angel sounded. Just as the trees symbolize people, green grass, frail and short-lived, is often used to represent people, illustrating the short life of men.
All flesh is as grass, and all the glory of man as the flower of the grass.
The grass withers, and its flower falls away. Do not fret because of evildoers, nor be envious of the workers of iniquity. For they shall soon be cut down like the grass, and wither as the green herb. When the wicked spring up like grass, and when all the workers of iniquity flourish, it is that they may be destroyed forever. So the rich man also will fade away in his pursuits.