Why don’t trees grow in the meadow?

Because the meadow is not rich in soil
Meadows are vast areas with herbaceous vegetation, located along the low-lying banks of rivers and lakes. In high water, the meadows are flooded with spring waters, in summer their soil is full of moisture.
Therefore, there are no trees in the meadow. They will not survive, they will get wet. Trees in meadows can be seen in small groups only in higher elevations where there is less moisture in the soil.