Rainfall interception in temperate evergreen broadleaved forest and Japanese cypress plantation with abundant lower-layer vegetation in south-west Japan

The interception of rainfall in conifer plantations has been intensively studied. However, research on broadleaved forests is limited, although the broadleaved forests dominate approximately half of forest area in Japan. Here, we compared the throughfall and stemflow of each vegetation layer to clarify interception in a naturally regenerated temperate evergreen broadleaved forest (lucidophyllous forest) and a Japanese cypress plantation over a three-year period. Both forests were approximately 100 years old and had abundant lower-layer vegetation. We found that approximately a quarter of rainfall was intercepted in both forests, although the half of that interception in the Japanese cypress plantation was owing to the abundant lower-layer vegetation. This indicated that the interception in the evergreen broadleaved forest was twice that of the Japanese cypress upper canopy. The well-developed layer structure in the evergreen broadleaved forest efficiently intercepted rainfall. From the point of view of water resource management, this study implies that both evergreen broadleaved forests and Japanese cypress plantations with abundant lower-layer vegetation can decrease the amount of water infiltrating soils.