Native tree phenology data from the Ka‘ūpūlehu tropical dry forest, Hawaiʻi

Native dry forests are one of the most threatened and rare ecosystems in the Hawaiian Islands, as they are worldwide. The Ka‘ūpūlehu Preserve is one of the few remaining examples of native dry forest on the Big Island of Hawaiʻi. Restoration efforts have been on going at Ka‘ūpūlehu since 1993 by various partners including the USDA Forest Service. To help with restoration efforts, the USDA Forest Service, Pacific Southwest Research Station, Institute of Pacific Islands Forestry designed an experiment to study the phenology of nine native dryland tree species at Ka‘ūpūlehu. The trees were measured monthly over a 6.3-year period from 2001 to 2007. In total, 10 species were studied; Diospyros sandwicensis (lama) was dioecious and had both male and female flowering trees. Four of the species, ‘Aiea (Nothocestrum breviflorum), Kauila (Colubrina oppositifolia), Alahe‘e (Psydrax odorata), and Maua (Xylosma hawaiiensis) could be classified as facultative, short-day plants, which had the bulk of their flowering in the winter months. Four other species including the ‘Āla‘a (Pouteria sandwicensis ), Hala pepe (Dracaena konaensis ), the facultative male lama and ‘Ōhi‘a (Metrosideros polymorpha) were clearly long-day plants flowering in the summer. Two species, male lama and ‘Iliahi (Santalum paniculatum) were day-neutral plants which flowered year-around. The species documented included 4 endangered species. The 84 total trees had 49-52 monthly observations of estimates of flowering, fruiting, and leaf flush in percent of the crown, over the 6.3 years. A number of abiotic factors, including precipitation, temperature, and photoperiod were measured during the same period at Ka‘ūpūlehu to test against phenology.
We studied the effect of long-term and seasonal periodicity in abiotic climatic variables such as light, rainfall, and temperature on the phenology; flowering, fruiting, and leaf flush, of in-situ grown, native, dry forest tree species at Ka‘ūpūlehu, Hawaiʻi.
For more information about these data and this study, see Cole and Cordell (in press).