Tropical forests are becoming increasingly alien‐dominated through the establishment of timber plantations and secondary forests. Despite widespread recognition that afforestation results in increased evapotranspiration and lower catchment yields, little is known of the impacts of timber plantations on water balance relative to native forest. Native forest trees have been claimed to use water conservatively and enhance groundwater recharge relative to faster‐growing alien species, and this argument should motivate native forest preservation and restoration. However, data have been available primarily for leaf‐level gas exchange rather than for whole‐plant and stand levels. We measured sap flow of dominant tree and tree fern species over eight weeks in native Metrosideros polymorpha forest and adjacent alien timber plantations on the island of Hawai‘i and estimated total stand transpiration. Metrosideros polymorpha had the lowest values of sap flux density and whole‐tree water use (200 kg·m⁻² sapwood·d⁻¹, or 8 kg/d for trees of 35 cm mean diameter at breast height, D), substantially less than timber species Eucalyptus saligna or Fraxinus uhdei (33 and 34 kg/d for trees of 73 and 30 cm mean D, respectively). At the stand level, E. saligna and F. uhdei trees had three‐ and ninefold higher water use, respectively, than native M. polymorpha trees. Understory Cibotium tree ferns were most abundant in M. polymorpha‐dominated forest where they accounted for 70% of water use. Overall, F. uhdei plantation had the highest water use at 1.8 mm/d, more than twice that of either E. saligna plantation or M. polymorpha forest. Forest water use was influenced by species composition, stem density, tree size, sapwood allocation, and understory contributions. Transpiration varied strongly among forest types even within the same wet tropical climate, and in this case, native forest had strikingly conservative water use. Comparisons of vegetation cover in water use should provide additional resolution to ecosystem valuation and land management decisions.

Spatially continuous data products are essential for a number of applications including climate and hydrologic modeling, weather prediction, and water resource management. In this work, a distance-weighted interpolation method used to map daily rainfall and temperature in Hawaii is described and assessed. New high-resolution (250 m) maps were developed for daily rainfall and daily maximum (T_max) and minimum (T_min) near-surface air temperature for the period 1990–2014. Maps were produced using climatologically aided interpolation, in which station anomalies were interpolated using an optimized inverse distance weighting approach and then combined with long-term means to produce daily gridded estimates. Leave-one-out cross validation was performed to assess the quality of the final daily grids. The median absolute prediction error for rainfall was 0.1 mm with an average overprediction (+0.6 mm) on days when total rainfall was less than 1 mm. On days with total rainfall greater than 1 mm, median absolute prediction errors were 2 mm and rainfall was typically underpredicted above the 10-mm threshold. For daily temperature, median absolute prediction errors were 3.1° and 2.8°C for T_max and T_min, respectively. On average, this method overpredicted T_max (+1.1°C) and T_min (+1.5°C), and errors varied considerably among stations. Errors for all variables exhibited significant seasonal variations. However, the annual range of errors was small. The methods presented here provide an effective approach for mapping daily weather fields in a topographically diverse region and improve on previous products in their spatial resolution, time period of coverage, and use of data.

Indigenous crops, tremendously valuable both for food security and cultural survival, are experiencing a resurgence in Hawaiʻi. These crops have been historically valued by agricultural researchers as genetic resources for breeding, while cultural knowledge, names, stories and practices persisted outside of formal educational and governmental institutions. In recent years, and following conflicts ignited over university research on and patenting of kalo (Hāloa, Colocasia esculenta), a wave of restoration activities around indigenous crop diversity, cultivation, and use has occurred through largely grassroots efforts. We situate four crops in Hawaiian cosmologies, review and compare the loss and recovery of names and cultivars, and describe present efforts to restore traditional crop biodiversity focusing on kalo, ʻuala (Ipomoea batatas), kō (Saccharum officinarum), and ʻawa (Piper methysticum). The cases together and particularly the challenges of kalo and ‘awa suggest that explicitly recognizing the sacred role such plants hold in indigenous worldviews, centering the crops’ biocultural significance, provides a foundation for better collaboration across multiple communities and institutions who work with these species. Furthermore, a research agenda that pursues a decolonizing approach and draws from more participatory methods can provide a path forward towards mutually beneficial exchange among research, indigenous, and farmer communities. We outline individual and institutional responsibilities relevant to work with indigenous crops and communities and offer this as a step towards reconciliation, understanding, and reciprocity that can ultimately work to create abundance through the restoration of ancestral crop cultivar diversity.

While the Hawaiian Islands are experiencing long‐term warming, spatial and temporal patterns are poorly characterized. Drawing on daily temperature records from 309 stations (1905–2017), we explored relationships of surface air temperatures (T_max, T_min, T_avg, and diurnal temperature range) to atmospheric, oceanic, and land surface variables. Statistical modeling of spatial patterns (2006–2017) highlighted the strong negative influence of elevation and moisture on air temperature and the effects of distance inland, cloud frequency, wind speed, and the local trade wind inversion on the elevation dependence of surface air temperature. We developed time series of sea level air temperature and surface lapse rate by modeling surface air temperature as a simple function of elevation and found a strong long‐term (1905–2017) warming trend in sea level T_min, twice that of T_max (+0.17 vs +0.07°C/decade), suggesting regional warming, possibly enhanced by urbanization and cloud cover effects. Removing this trend, sea level T_max and T_min tracked SST and rainfall at decadal time scales, while T_max increased with periods of weakened trade winds. Sea level air temperatures correlated with North Pacific climate indices, reflecting the influence of regional circulation via SST, rain, clouds, and trade winds that modulate environmental warming across the Hawaiian Islands. Increasing (steeper) T_max surface lapse rates for the 0‐ to 1,600‐m elevation range (into the cloud zone) over 1978–2017 coincide with observations of marine boundary layer drying and rising cloud base heights, suggesting a need to better understand elevation‐dependent warming in this tropical/subtropical maritime environment and associated changes to cloud formation and persistence.