looks like rather than blending and mixing the compost with the native soil it was used as a top dressing, Im assuming the trees are as happy as the soil they were put in. For a 3 gallon tree i try to amend at least a 3x3x2 area for the roots to grow out I do this by mixing compost with the native soil and adding organic fertilizers.
Trees should receive water everyday now as we are bone dry in Florida, and especially simce they are newly planted.