Britain was once covered in forests

Do forests rise the land mass via eating sunlight and combing their energy with nutrients found underground? Then over 100s of years of collecting sunlight does this energy begin to create mass on the surfaces of our planet when the trees die? If yes then without this constant accumulation is this why we are now seeing floods? When we us concrete with stop the accumulation process. Soil is not naturally found on planets without nature as its a byproduct of it.
Trees eat sunlight, if we did this all-day every day we would become bigger and gain mass.
Without nature would we be only a water world? As sunlight bounces off the planets, nature absorbs it.

Another question is if I get a sun tan do I become slightly heavier?