Vegetation can play a major role in the ecosystem service tradeoffs resulting from land use change by affecting the volume of rain water that reaches the ground surface and is thus available for water supply. We collected micrometeorological data at two sites on leeward Hawai’i Island for 20 months to look at rainfall and cloud interception in native forest.
Results/Conclusions

Rainfall rates are low and canopy interception of rainfall is high – only 65% of rainfall reaches the forest floor at one of the sites.  Cloud interception is an important source of water input, increasing throughfall to 120% of rainfall at the second site.  Increased throughfall at this site is not attributable to increased cloudiness.  Instead, taller trees and a denser mid-canopy are likely the dominant cause of the increased cloud interception.  The less-dense forest structure may result from grazing.  If that is the case, mixed use of forests may have unexpected impacts on water supply because of forest effects on rainfall partitioning.