dripline

The circle on the ground directly beneath the outermost edge of a tree's canopy — where rain collects on the leaves and drips to the earth below. The dripline is a boundary: inside it, the ground is sheltered, shaded, and fed by nutrients washing off the leaves; outside it, the exposure changes. Roots extend well beyond the dripline, but the dripline is where the tree's influence is most visible on the surface.