Improving Sustainable Hawaiian Sandalwood Silviculture and Endemic Species Conservation with Mixed Stand Management

Project Overview

Project Type: Graduate Student
Funds awarded in 2024: $30,000.00
Projected End Date: 04/30/2026
Grant Recipient: University of Hawaiʻi at Manoa
Region: Western
State: Hawaii
Graduate Student:
Principal Investigator:
Dr. Travis Idol
University of Hawaii
Principal Investigator:
James Friday
University of Hawaiʻi at Manoa


  • Additional Plants: native plants, trees


  • Crop Production: forestry, forest/woodlot management
  • Education and Training: extension, focus group, on-farm/ranch research, workshop, youth education
  • Natural Resources/Environment: afforestation, biodiversity, habitat enhancement
  • Sustainable Communities: employment opportunities, new business opportunities, partnerships, social networks

    Proposal abstract:

    In Hawaiʻi, endemic sandalwood (Santalum) species
    (“ʻiliahi” in the Hawaiian language), were over-exploited for
    their fragrant oils, but landowners are interested in their
    reforestation and restoration of associated dry forests. Because
    sandalwood species are root hemiparasites, restoration and
    silviculture of these mixed-species forests present novel
    challenges. Field experiments initiated in 2019 reforested
    abandoned pastures with ʻiliahi alongside native host species. In
    one experiment, ʻilahi was outplanted simultaneously with either
    koa (Acacia koa), a fast-growing nitrogen-fixing tree or
    ʻaʻalili (Dodonaea viscosa), a fast-growing shrub. All
    three species have important economic and cultural values. In
    another experiment, ʻiliahi was underplanted in a 10-year old koa
    plantation. We will use a mixed stand management approach to find
    optimal planting designs and oversotyr thinning to balance growth
    and survival of all species. Objectives are: (1) to estimate the
    optimum ratio of ʻiliahi and host plants to balance long-term
    survival and growth, and (2) to evaluate the influence of
    overstory host thinning on growth of ʻiliahi saplings. Plant size
    and growth will be measured along with soil nutrient availability
    and foliar nutrient content. Competition, facilitation, and
    parasitism will be estimated from models using species
    composition, comparative growth of individual plants within a
    plot, and overall growth in the plot. Individual and stand growth
    models will be used to project long-term outcomes of planting
    designs and effects of overstory thinning. Results will provide
    recommendations for planting designs and mid-rotation management.
    They will also be used for producer training, educational
    activities, and scientific presentations and publications.

    Project objectives from proposal:

    (1) to estimate the optimum ratio of ʻiliahi and host plants in
    balancing competition, facilitation, and parasitism related to
    their long-term survival and growth, and (2) to evaluate the
    influence of host thinning on the growth of ʻiliahi at three
    years post-establishment

    Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.