Turning rain into internal precipitation and stem flow

observations of palm trees in an urban environment

Resumo

Numerous articles have quantified rainfall, internal precipitation and stem flow. However, few have documented how, in fact, rain turns into internal precipitation and stem flow. Given this gap, this note used palm trees (Roystonea regia) to illustrate how such a phenomenon occurs. When photographing rain events below the canopy, it is shown that effective precipitation reaches the ground mainly through water flowing from leaflets to the rachis and petiole. As water flows through the rachis and petiole, one portion becomes internal precipitation and another portion follows a path accumulating in the sheath and, after such compartment is full, it is drained toward the soil surface. Another variation of stem flow generation occurs when sheaths overlap.