Hawaiian tropical dry forests contain diverse assemblages of woody canopy species, including many endemic and endangered species that warrant conservation attention before completely disappearing. Today, tropical dry forests in Hawaii are not viable ecosystems. Poor land use practices, fragmentation, non-native plant invasions, and inadequate native vegetation regeneration are all factors that have contributed to their endangerment. Only an ambitious restoration programme that includes non-native ungulate exclusion, weed control, fire management, and the outplanting of seeds and seedlings will be sufficient to enhance Hawaiian tropical dry forests. We selected a 25 ha preserve within the Kaupulehu Dry Forest Preserve, located in North Kona on the Island of Hawaii, to test dry forest restoration strategies. In 1997, the preserve was fenced and all non-native ungulates were removed. Altogether, 4892 outplants were planted from 1999?2006. In 2007, we surveyed all of the outplants. The survey found 1487 live plants, 3357 dead, and 48 plants missing. This equates to an overall survival rate of 30%. Survival by vegetation type indicated that vines had the highest rate of survival (63%) followed by trees (34%). Herbs had the lowest rate of survival (12%). Twelve of a total of 35 species that were outplanted in the Kaupulehu Dry Forest Preserve accounted for more than 90% of the total surviving plants species, while five federally listed species represent almost 60% of the total. The outplanting of dry forest species into the Kaupulehu Dry Forest Preserve considerably increased the population of many federally listed endangered species. However, the high mortality of many common and important plant species of tropical dry systems highlights the importance of an outplanting programme that emphasizes ecosystem sustainability rather that species success. In equal measure, the successes and failures of the Kaupulehu outplanting project have enhanced our ability to begin to restore this unique and endangered ecosystem.

Tropical dry forests (TDFs) are among the most at-risk ecosystems globally. In Hawai‘i, more than 45% of TDF species are threatened or endangered. Despite decades of active TDF restoration, there remains limited information on the potential for long-term success, since there are few studies of natural regeneration. We assess natural regeneration of endangered plants at Ka‘ūpūlehu dryland forest, a Hawaiian biocultural restoration initiative. Drawing on 6 annual censuses we (1) assess rates and patterns of natural regeneration across species and as a function of rainfall and (2) identify bottlenecks. Our surveys document natural recruits of 11 of the 12 endangered species first outplanted 15–20 years ago. Higher annual rainfall increased the number of new recruits per year and growth, but decreased survival of larger recruits. The total number of natural recruits increased three-fold over the study period and varied across species. For nearly half of the species, we documented a second generation of recruits. Successes appear to be a function of time, including a changing microclimate and adaptive management practices. Remaining bottlenecks include lack of seed dispersal, and seed predation and herbivory by introduced species. The success at Ka‘ūpūlehu highlights the potential for TDF restoration and the value of a biocultural approach.

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