SELECTION AND EVALUATION OF ALTERNATIVE LANDSCAPE PLANTS IN RESPONSE TO INVASIVE SPECIES IN HAWAII

Landscape industry sectors across Hawaii grow, specify and use landscape plants to improve the urban environment. Unfortunately, some plants have the ability to disperse from their original environments and become invasive. This study identified the 10 most frequently used invasive landscape plants and their possible non-invasive alternatives. After the selection of 43 alternative species, only 17 native and exotic species were located in commercial nurseries. Plants were installed with or without fertilizer at three contrasting locations (Waimanalo, Poamoho and Waiakea Research Stations of the University of Hawaii). Growth and visual evaluations found differences between species, especially regarding locations. Plants growing for 24 months in Waimanalo and Waiakea tended to have higher growth rates and visual ratings, probably due to higher water availability and fewer soil limitations compared to the Poamoho site. Additionally, differences were observed among native species that are generally considered more tolerant to environmental stresses than exotic species. This research indicated that recommendations of non-invasive exotic and native species must include instructions for proper environmental and maintenance needs for each species, specially native ranges of each native species. These results are important to support current and future efforts for the promotion of non-invasive exotic and native species in the landscape industry.