Size of raindrops and their striking force at the soil surface in a red pine plantation

It is usually assumed that a forest canopy breaks the force with which rainfall strikes the soil, thus protecting it from erosion. To show that this is frequently untrue and that the protective value of the forest to the soil must, therefore, be due to lesser vegetation or to the layers of unincorporated organic material lying on the soil surface is the purpose of this paper. Measurements were made of raindrop size beneath a red pine canopy and in an adjacent open field near New Haven, Connecticut during several storms in 1946 and 1947. By reference to published tables of velocities of falling water drops, the kinetic energy at the soil surface of the rain under the pine canopy and in an open field was determined. It was found that at rates of precipitation less than two inches per hour the kinetic energy of rainfall beneath the red pine canopy exceeded that of rainfall in the open.