IDENTIFICATION, SELECTION, AND FUNCTIONAL ANALYSIS OF ALTERNATIVE ORNAMENTAL TREES FOR HAWAII LANDSCAPES

• Sponsoring Institution: National Institute of Food and Agriculture
• Project Status: COMPLETE
• Funding Source: HATCH
• Reporting Frequency: Annual
• Accession No.: 0220532
• Project Start Date: Oct 1, 2009
• Project End Date: Sep 30, 2014
• Program Code: [(N/A)]- (N/A)

Recipient Organization
UNIV OF HAWAII
3190 MAILE WAY
HONOLULU,HI 96822

Performing Department
Tropical Plant & Soil Science

Non Technical Summary
The objective of the project is to identify ornamental trees to diversify the community of trees used in Hawaii landscapes. Recent infestations of insects have decimated one of the popular ornamental trees, Erythrina variegata, while others are at risk from introduced pests. The palette in use both by landscape architects and city and state street tree departments has focused on perhaps two dozen species, some of which have become invasive as well. Trends in urban tree usage call for use of smaller trees, columnar trees, adaptability to the urban environment, and trees that can modify the urban environment by reducing run-off, improving air quality, and maximizing shade. The project will determine efficient propagation and production practices for alternative trees and evaluate existing specimens in botanical gardens for both positive attributes and problems. Trees will be planted into sites at a CTAHR Research Station (Waimanalo) and, in cooperation with the Urban Forestry Division of the Honolulu City & County Parks & Recreation Department, at sites in the drier, leeward area of Oahu where growth rates, adaptability, and management practices will be determined. The PI, cooperators, county agents and stakeholders will make periodic evaluations and disseminate the results via field days, workshops, conference reports, and publications. Success will be demonstrated by the adoption of new tree germplasm by the nursery and landscape industries of Hawaii, but it should be cautioned that this will require time beyond the 5-year duration of the project because of the time it takes to produce trees to appropriate sizes for installation in landscapes.

Animal Health Component

(N/A)

Research Effort Categories

Basic

(N/A)

Applied

(N/A)

Developmental

(N/A)

Classification

Knowledge Area (KA)	Subject of Investigation (SOI)	Field of Science (FOS)	Percent
202	2110	1020	50%
204	2110	1020	40%
203	2110	1080	10%

Knowledge Area
204 - Plant Product Quality and Utility (Preharvest); 203 - Plant Biological Efficiency and Abiotic Stresses Affecting Plants; 202 - Plant Genetic Resources;

Subject Of Investigation
2110 - Ornamental trees and shrubs;

Field Of Science
1080 - Genetics; 1020 - Physiology;

Keywords

nursery practices

ornamental traits

ornamental trees

street trees

tree propagation

tropical trees

tree management

urban trees

Goals / Objectives
The long term objectives of this project are to produce production guidelines (propagation, container/in-field production practices) for 30 ornamental tree species and to identify advantages and disadvantages to their use in Hawaii landscapes. Where specimens exist in botanical gardens or private collections, information will be collected on ultimate size, shape, management needs (e.g., pruning), and root system aggressiveness. The short term objectives are: 1) collecting seed and determining germination requirements, 2) protocols for production by cuttings, and 3) initial evaluation of growth rates (height, caliper, branching, root systems). Timelines: Evaluate candidate trees in otanical gardens & arboreta, parks and public landscapes to select 30 alternative species (years 1,2); Collect and germinate seed to determine germination requirements (years 1,2,3); Initiate vegetative propagation where seed propagation is not feasible (years 1,2,3); Develop nursery production protocols (years 3,4,5); Transplant to field conditions and evaluate growth (years 3,4,5); Evaluate management needs (years 4,5); Evaluate site adaptability (years 4,5); Field days for extension agents,nursery growers and landscapers(years 4,5); Dissemination of results, develop publications (years 2,3,4,5). OUTPUT INDICATORS Determination of new and superior plant germplasm for use in the ornamentals and landscape industries, improved germination of seedlings, improved percentages of rooting and root quality of cuttings, success in micropropagation, reduced losses of plant materials following removal from the propagation system, and recommendation of underutilized or new trees for use in residential areas, as street tree or in parks. In addition to presentations to local industry organizations (LICH, nursery organizations, ASLA), research reports will be prepared for Floriculture, Ornamentals, and Landscape News (CTAHR/TPSS), "Instant Information pages," short articles in Hawaii Landscape, annual CSREES narrative, publications in leading journals. Inclusion in Propagation of Native Hawaiian plants database. CTAHR on-line publications will be used to provide summaries of the characteristics of selected species, as well as photographs documenting tree form, flowers, leaf characters, etc.

Project Methods
Lists of tree species that have been recommended or identified from personal recommendations and publications. Evaluation of potential invasiveness will be sought through the Weed Risk Assessment process (http://www.botany.hawaii.edu/faculty/daehler/wra/default2.htm. Thirty species will be selected for planting out based on desirable characteristics and availability. Selection criteria will include principal use potential, flowering, shade, branching habit (shape), and space requirements. Seeds will be sourced from the Lyon Arboretum and other Hawaii botanical gardens. Seed treatments, such as scarification, soaking, or bottom heat, will be applied as deemed necessary. Transplanting to larger containers will take place as seedlings develop, and shifts to larger containers will be made until a size sufficient for out-planting in the field is achieved. New tree production technologies such as fiber grow bags and corrugated growing cylinders to reduce root circling and induce fibrous root production will be employed. Where seed material is not readily available, vegetative propagation will be attempted, although root systems of cutting-derived plants are less supportive of tree growth as root systems of seedlings. Percent rooting, rooting index, and time to root will be recorded. Transplanting will take place when sufficient root mass has developed until a size sufficient for out-planting in the field is achieved. New tree production technologies such as fiber grow bags and corrugated growing cylinders to reduce root circling and induce fibrous root production will be employed. From the time that seedlings or liners have been set out into the field, the plants will be staked and managed to develop a single axis. A minimum of 10 trees will be evaluated for clonal material and 20-25 for seed-grown material. Height and spread measurements will be recorded at 2 month intervals. Other parameters such as flowering, branch styles, bark color, foliage texture, and plant general architecture will also be determined. Adverse traits will also be noted. The GRIN system of evaluation can be applied for many of these traits (http://www.ars-grin.gov/npgs/). Selection for specific kinds of landscape functions will be made. The Director of the Urban Forests unit of the City & County of Honolulu has offered cooperation to find additional sites where trees could be grown out for evaluation. These should include the warm dry areas on Oahu where much of the new residential development is planned. Outputs: The ultimate outcomes would be the specification of alternative trees by landscape designers, the production of alternative trees by commercial nurseries, and a more varied community of trees in Hawaii landscapes. These outcomes may occur beyond the initial 5-year project period because of the time it takes to grow trees to appropriate sizes for installation in landscapes. Near term outcomes would be the initiation of production of recommended trees by nurseries and the willingness of landscape architects and the City of Honolulu's Parks & Recreation Department to specify and use them in future landscape projects.

Progress 10/01/09 to 09/30/14

Outputs
Target Audience:The objective of the project was to identify ornamental trees to diversify the community of trees used in Hawaii landscapes. This was.is extremely important due to recent infestations of insects which have decimated one of the most popular ornamental landscape trees, Erythrina variegata, while others are at risk from introduced pests. The palette in use both by landscape architects and city and state street tree departments has focused on perhaps two dozen species, some of which have become invasive as well. Trends in urban tree usage call for use of smaller trees, ie. Columnar trees, adaptability to the urban environment, and trees that can modify the urban environment by reducing runoff, improving air quality, and maximizing shade. The project hasdetermined efficient propagation and production practices for alternative trees and evaluate existing specimens in botanical gardens for both positive attributes and problems. Trees were planted into sites at a CTAHR Research Station (Waimanalo) and, in cooperation with the Urban Forestry Division of the Honolulu City & County Parks & Recreation Department, at sites in the drier, leeward area of Oahu where growth rates, adaptability, and management practices were also determined. The PI, cooperators, county agents and stakeholders made periodic evaluations and disseminated the results via field days, workshops, conference reports, and publications. Success will be demonstrated by the adoption of new tree germplasm by the nursery and landscape industries of Hawaii, but it should be cautioned that this will require time beyond the 5-year duration of the project because of the time it takes to produce trees to appropriate sizes for installation in landscapes. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?The opportunities of this project was to produce production guidelines (propagation, container/in-field production practices) for 30 ornamental tree species and to identify advantages and disadvantages to their use in Hawaii landscapes. Where specimens exist in botanical gardens or private collections, information will be collected on ultimate size, shape, management needs (e.g., pruning), and root system aggressiveness. The short term objectives were: 1) collecting seed and determining germination requirements, 2) protocols for production by cuttings, and 3) initial evaluation of growth rates (height, caliper, branching, and root systems). Final opportunities of this project are outlined at field days for extension agents, nursery growers and landscapers, as well as disseminated results, through publications. Additionally, presentations to local industry organizations (LICH, nursery organizations, ASLA). How have the results been disseminated to communities of interest?Nine alternative trees were written up by two graduate students for online insertion into the CTAHR Free Publications website. Six additional tree write-ups are in progress. Graduate student accompanied Dr. Criley in presenting results to the annual conference of the Landscape Industry Council of Hawaii. What do you plan to do during the next reporting period to accomplish the goals? Nothing Reported

Impacts
What was accomplished under these goals? The long term objectives of this project are to produce production guidelines (propagation, container/in-field production practices) for 30 ornamental tree species and to identify advantages and disadvantages to their use in Hawaii landscapes. Where specimens exist in botanical gardens or private collections, information will be collected on ultimate size, shape, management needs (e.g., pruning), and root system aggressiveness. The short term objectives are: 1) collecting seed and determining germination requirements, 2) protocols for production by cuttings, and 3) initial evaluation of growth rates (height, caliper, branching, and root systems). Timelines: Evaluate candidate trees in botanical gardens & arboreta, parks and public landscapes to select 30 alternative species (years 1,2); Collect and germinate seed to determine germination requirements (years 1,2,3); Initiate vegetative propagation where seed propagation is not feasible (years 1,2,3); Develop nursery production protocols (years 3,4,5); Transplant to field conditions and evaluate growth (years 3,4,5); Evaluate management needs (years 4,5); Evaluate site adaptability (years 4,5); Field days for extension agents, nursery growers and landscapers(years 4,5); Dissemination of results, develop publications (years 2,3,4,5). OUTPUT INDICATORS Determination of new and superior plant germplasm for use in the ornamentals and landscape industries, improved germination of seedlings, improved percentages of rooting and root quality of cuttings, success in micropropagation, reduced losses of plant materials following removal from the propagation system, and recommendation of underutilized or new trees for use in residential areas, as street tree or in parks. In addition to presentations to local industry organizations (LICH, nursery organizations, ASLA), research reports will be prepared for Floriculture, Ornamentals, and Landscape News (CTAHR/TPSS), "Instant Information pages," short articles in Hawaii Landscape, annual CSREES narrative, publications in leading journals. Inclusion in Propagation of Native Hawaiian plants database. CTAHR on-line publications will be used to provide summaries of the characteristics of selected species, as well as photographs documenting tree form, flowers, leaf characters, etc.

Publications

• Type: Other Status: Published Year Published: 2013 Citation: Kaufman, A., Criley, R., Kawabata, A., Cox, L., and Ricordi, R. 2013. Green and Healthy Hawaii: Identifying and Introducing Alternative Ornamental Landscape Plants in Response to Invasive Species Issues. Landscape L-31, October 2013.
• Type: Other Status: Published Year Published: 2014 Citation: Montoya, J., Criley, R., and Ricordi, A. 2014. Expanding Tree Diversity in Hawaiis Landscapes: Naio, Bastard sandalwood, Myoporum sandwicense. Landscape L-22, March 2014.
• Type: Other Status: Published Year Published: 2014 Citation: Montoya, J., Criley, R., and Ricordi, A. 2014. Expanding Tree Diversity in Hawaiis Landscapes: Nau, Nanu; Forest Gardenia; Gardenia brighamii. Landscape L-23, March 2014.
• Type: Other Status: Published Year Published: 2014 Citation: Montoya, J., Criley, R., and Ricordi, A. 2014. Expanding Tree Diversity in Hawaiis Landscapes: Lonomea, Hawaiian soapberry, Sapindus oahuensis. Landscape L-29, March 2014.
• Type: Other Status: Published Year Published: 2014 Citation: Montoya, J. and Criley, R. 2014. Expanding Tree Diversity in Hawaiis Landscapes: Shaving-Brush Tree, Pseudobombax ellipticum. Landscape L-30, March 2014.
• Type: Other Status: Published Year Published: 2014 Citation: Criley, R. 2014. Expanding Tree Diversity in Hawaiis Landscapes: Hispaniolan Rosy Trumpet Tree, Tabebuia berteroi. Landscape L-32, March 2014.
• Type: Other Status: Published Year Published: 2014 Citation: Montoya, J., Criley, R., and Ricordi, A. 2014. Expanding Tree Diversity in Hawaiis Landscapes: Aalii, Kumakani; Dodonaea viscosa. Landscape L-24, March 2014.
• Type: Other Status: Published Year Published: 2014 Citation: Montoya, J., Criley, R., and Ricordi, A. 2014. Expanding Tree Diversity in Hawaiis Landscapes: Colvilles Glory, Colvillea racemosa. Landscape L-25, March 2014.
• Type: Other Status: Published Year Published: 2014 Citation: Montoya, J., Criley, R., and Ricordi, A. 2014. Expanding Tree Diversity in Hawaiis Landscapes: Hong Kong Orchid Tree, Bauhinia blakeana Landscape L-26, March 2014.
• Type: Other Status: Published Year Published: 2014 Citation: Montoya, J., Criley, R., and Ricordi, A. 2014. Expanding Tree Diversity in Hawaiis Landscapes: Alahee, Psydrax odorata. Landscape L-27, March 2014.
• Type: Other Status: Published Year Published: 2014 Citation: Criley, R. 2014. Expanding Tree Diversity in Hawaiis Landscapes: Lignum Vitae, Guaiacum officinale. Landscape L-33, March 2014.
• Type: Other Status: Published Year Published: 2014 Citation: Montoya, J. and Criley, R. 2014. Expanding Tree Diversity in Hawaiis Landscapes: Beach Heliotrope, Tournefortia argentea. Landscape L-28, March 2014.
• Type: Other Status: Published Year Published: 2014 Citation: Criley, R. 2014. Expanding Tree Diversity in Hawaiis Landscapes: Pride-of-Bolivia, Rosewood, Tipuana tipu. Landscape L-34, March 2014.
• Type: Other Status: Published Year Published: 2014 Citation: Criley, R. 2014. Expanding Tree Diversity in Hawaiis Landscapes: Fern Pine, Afrocarpus gracilior. Landscape L-35, March 2014.

Progress 10/01/12 to 09/30/13

Outputs
Target Audience: Landscape industry stakeholders including: Nursery operators and Landscape Architects and Designers in Hawaii, as well as residential homeowners in Hawaii. Changes/Problems: A study on improved root structure for container-grown trees was installed late in 2012 with initial results being quantified. What opportunities for training and professional development has the project provided? Nothing Reported How have the results been disseminated to communities of interest? Currently in revision. What do you plan to do during the next reporting period to accomplish the goals? Compile and analyze the library research, obtained photographs, and data that has been collected. Once data has been analyzed and written information has been edited, presentations; and final results for submission to the CTAHR publications office will begin.

Impacts
What was accomplished under these goals? Nine alternative trees were written up by two graduate students for online insertion into the CTAHR Free Publications website. Six additional tree write-ups are in progress. Graduate student accompanied Dr. Criley in presenting results to the annual conference of the Landscape Industry Council of Hawaii.

Publications

Progress 10/01/11 to 09/30/12

Outputs
OUTPUTS: Nine alternative trees were written up by TPSS PhD candidate, John Montoya and Architecture PhD candidate Alberto Ricordi for online insertion into the CTAHR Free Publications website. Six additional tree write-ups are in progress. Montoya and Ricordi joined Dr. Criley in presenting results to the annual conference of the Landscape Industry Council of Hawaii. PARTICIPANTS: John Montoya, PhD candidate in TPSS, did the library research, obtained photographs, and prepared the write-up. Alberto Ricordi, PhD candidate in Architecture, contributed information to 5 of the write-ups. R. Criley approved the selection of trees, contributed photographs, and edited the write-ups for submission to the CTAHR publications office. TARGET AUDIENCES: Nursery operators and Landscape Architects and Designers in Hawaii. Residential homeowners in Hawaii. PROJECT MODIFICATIONS: A study on improved root structure for container-grown trees was installed late in 2012 with initial results expected in 2013.

Impacts
The alternative tree write-ups that are in process of being placed on the CTAHR Free Publications website provide information to nursery growers about propagation and to landscape designers about characteristics such as shape, ultimate size, and both desirable and undesirable qualities. The information allows both public and residential landscape sites to choose trees that are not widely used in Hawaii's landscapes. They can avoid some of the problems associated with alien pests and invasive species.

Publications

• No publications reported this period

Progress 10/01/10 to 09/30/11

Outputs
OUTPUTS: Seedlings of Colvillea racemosa, Tabebuia impetiginosa, T. chrysantha, and Gardenia carinata were provided to the Urban Forestry Division of the City & County of Honolulu Parks & Recreation department to grow out for future installation in a variety of sites. Also contributed were rooted air layers of Ficus binnendyckii Alii. Seedlings of Wallaceodendron celebicum were not only slow to germinate, but are slow growers, reaching only about 8 - 10 inches in the course of the year. Information pages profiling some alternate trees for residential, parks, and street tree usage were prepared for: Gardenia brighamii, Dodonaea viscosa, Pseudobombax ellipticum, Colvillea racemosa, Myoporum sandwicense, Bauhnia blakeana, Pittosporum hosmeri, Tournefortia argentea, Sapindus oahuensis, and Psydrax odorata. PARTICIPANTS: Urban Forestry Division of the City & Country of Honolulu Parks & Recreation Department is cooperating on growing on of tree species and will outplant them and cooperate in evaluating them in landscape settings. TPSS Graduate student John Montoya prepared the tree profiles. TARGET AUDIENCES: Target audiences include nursery growers, landscape contractors, landscape architects, grounds managers, and urban public seeking alternative trees to install in residential grounds, hotel and other public grounds such as park and golf courses, and as street trees. PROJECT MODIFICATIONS: The PI for this project retired 31 December 2010. Dr. Andrew Kaufman has agreed to take over the project as he has a similar project with funding.

Impacts
As the seedling trees were not of a size that would permit installation into landscape settings, the city nursery is shifting them into larger containers and will plant them into diverse settings where they can be evaluated. The tree profiles, when placed on-line, will be available for landscape architects, production nurseries, and the general public to refer to when making choices for alternative trees. While most such resources tout the positive factors for each species, this resource will also include disadvantages and problems in their use.

Publications

• No publications reported this period

Progress 10/01/09 to 09/30/10

Outputs
OUTPUTS: Twenty-one alternative tree species were identified that are less commonly used in Hawaii landscapes or as street trees in residential areas. Weed Risk Assessment values have been determined for 13 species, while WRA ratings are pending for the others. Propagative materials for some species may not be available in local botanical gardens and sources are being sought. Among species for which propagation studies were initiated, germination was rapid (under 2 weeks) for Tabebuia impetiginosa, Gardenia coronaria, and Colvillea racemosa. Wallaceodendron celebicum germinated erratically with about 50% germination over a six week period. Seed of a thornless Prosopis pallida, which is not on the alternatives list, germinated rapidly with 81% germination in 21 days time. Ficus binnendyckii air layers required 6 to 8 weeks to develop sufficient roots that the layers could be removed and potted up. Growth rate of these layers was rapid after additional roots developed, with about one-third more height added per plant. Layers of Butea monosperma were variable in length of time to root sufficiently for removal from the tree, ranging from 8 weeks to 4 months. PARTICIPANTS: Seed of Gardenia coronaria was obtained from a tree at the CTAHR Pearl City Urban Garden Center. Seed of Colvillea racemosa was obtained from trees on the Universitiy of Hawaii campus and from the Honolulu Zoo (supplied by zoo horticulturist Ronald Kodama). Seed of Tabebuia impetiginiosa and Wallaceodendron was obtained from trees on the University of Hawaii campus. Layers of Butea monosperma were set and obtained from a tree at the Honolulu Botanical Garden. TARGET AUDIENCES: Commercial nurseries that supply plants to the landscaping industry are the principal targets at this time. Eventually, as plants are large enough for the landscape industry to observe, the audience for this work will be expanded. PROJECT MODIFICATIONS: Since the PI will retire at the end of December 2010, Dr. Andrew Kaufman has agreed to take over the project at least until a new hire in ornamental production comes on board.

Impacts
For seed-produced species such as Tabebuia impetiginosa, Colville racemosa, and Gardenia coronaria, nurseries can generate quantities of young plants sufficient for shifting to 1-gallon pots in 4 to 6 months time. The Ficus binnendyckii air layers require time to prepare and to root and rate of increase is limited by mother tree size; however, plants suitable for 2-gallon pots result and plants can be shifted up to larger size containers within a year. The time to outplanting in landscapes is yet to be determined. Butea monosperma may be a satisfactory substitute for the loss of Erythrinas in Hawaii landscapes as a result of the Erythrina gall wasp infestations. B. monosperma is not susceptible to the Erythrina gall wasp.

Publications

• No publications reported this period