Forest climatology near the tree line in Hawai'i

Abstract

One year of climatological measurements in a high elevation forest on the island of Hawai'i are analyzed to partially characterize the habitat of the palila bird, an endangered Hawaiian honeycreeper. At 2600 m, the site lies below the tree line, above the usual level of the trade wind inversion, and is strongly influenced by the diurnal thermal wind regime. The interaction of inversion, thermal circulation, and surface climate is documented for solar radiation, air and soil temperatures, humidity, wind direction and speed, rainfall, cloud water collection, and canopy throughfall. A comparison of air temperature, humidity, and soil temperature measurements between an open air site and beneath the canopy of an isolated mamane tree showed little difference, except that extremes in soil temperature were much greater in the open. Tree canopy throughfall exceeded open area rainfall during fog dominated precipitation events.