( A RARE PLANT SURVEY IN THE OAHU FOREST NATIONAL WILDLIFE REFUGE, KOOLAU MOUNTAINS, OAHU, SEPTEMBER 3-5, 2003 Hawaii Natural Heritage Program ( University of Hawaii at Manoa Center for Conservation Research and Training Honolulu, Hawaii November 2003 l ( Table of Contents INTRODUCTION AND BACKGROUND 3 METHODS ..................................................................................•.....................3 RESULTS 5 RARE PLANT TAXA OBSERVED WITHIN THE REFUGE. 5 RARE PLANT TAXA OBSERVED JUST BEYOND THE REFUGE BOUNDARy 7 DISCUSSION............•........................................................................................8 CITATIONS 8 TABLE 1. RARE PLANT DATA FIGURE 1. SURVEY AREA FIGURE 2. SURVEY ROUTES FIGURE 3. RARE PLANT LOCATIONS ( )' ( Introduction and Background This rare plant survey was funded by the Koolau Mountains Watershed Partnership as part of an effort to obtain information on the current status ofrare plants in areas of the Koolau Mountains where such information is lacking. The survey was conducted by the Hawaii Natural Heritage Program (HINHP) in the U.S. Fish and Wildlife Service's Oahu Forest National Wildlife Refuge, located in the central leeward section of the Koolau Mountains. The refuge is comprised of the eastern, upper elevation part of the land section ofWaipio, and includes most of the native forest in the land section. The refuge inoludes the headwaters of the Waikakalaua and Kipapa Gulches, along with the northernmost portion of the Waiawa Gulch's headwaters. The two major trails in the refuge are the Koolau Summit Trail and the Kipapa Trail. The Koolau Summit Trail runs along the summit divide of the Koolau Mountains from the Pupukea area in the extreme northern end of the Koolau Mountains to the southern portion of the Oahu National Wildlife Refuge. Most of the Kipapa Trail runs along the ridge between the Kipapa and Waiawa Drainages. At the Koolau summit area it joins the southern end of the Koolau Summit Trail. The Kipapa Trail is the only established trail that provides access to the refuge from the west. There is little current information on the rare plants of the refuge, and the historical rare plant records are few. Much of the recorded information on rare plants of the Waipio land section is from the first half of the 1900's. A large proportion of the historical rare plant records for the refuge was gathered during fieldwork in the early 1930's by E. Y. Hosaka in connection with his floristic and ecological study of Kipapa Gulch (Hosaka 1937). In recent decades, little botanizing has taken place on the land now included in the refuge because of a combination of the relative remoteness of the area, restricted access to the formerly privately-owned land, and poor maintenance of the Kipapa and Koolau Summit Trails. Methods The rare plant survey was conducted on September 3-5, 2003 by a HINHP botanist, 1. Q.c. Lau, and a botanist contracted by HINHP, K. R. Wood. They were accompanied by and assisted by personnel of the U.S. Fish and Wildlife Service's Oahu National Wildlife Refuge Complex and personnel from the state of Hawaii's Division of Forestry and Wildlife of the Department of Land and Natural Resources. Survey participants were divided into two teams, and each team was flown by helicopter to a campsite in the summit region on the morning of September 3. The field teams were flown out by helicopter in the afternoon of September 5. The survey participants spent the nights at the campsites. Fieldwork was conducted on day hikes starting from the campsites. The targeted plant taxa were those considered to be globally rare by HINHP and are currently being tracked and mapped by HINHP. These include Jll native Hawaiian plants that are federally listed as endangered or threatened, as well as ones that are candidates for listing as endangered or threatened. Also included are certain taxa that have not been listed as 3 '\ endangered or threatened, nor have been designated as candidates for listing, but which are nevertheless globally rare. ( This survey was intended to serve as an initial effort to create a comprehensive inventory of the refuge's rare plants. A goal of the survey was to document the occurrence of as many taxa of rare plants as possible within the limited timeframe of the survey. The survey area was therefore delineated in the high elevation wet zone of the refuge adjacent to the Koolau summit divide. This zone is thought to harbor the largest number of rare plant taxa based on the recorded patterns of distribution of rare plants in the areas of the central and northern Koolau Mountains that have been most intensively searched for rare plants, such as certain portions of the Kawailoa Training Area and Schofield Barracks Military Reservation's East Range to the north of the refuge, and portions of the Waimano land section to the south of the refuge. This zone is also expected to have denser concentrations of rare plant populations than any other zone of the refuge. The survey area included the upper reaches of Waikakalaua and Kipapa Gulches up to the main dividing ridge of the Koolau Mountains. A map showing the survey area is given in Fig. 1. In order to locate as many rare plant taxa as possible, all major habitat types were examined, but special attention was paid to those habitats with the best potential for harboring rare plant taxa based on the field experience of the botanists on the survey teams. Much of the land in the survey area is difficult to traverse due to the steep terrain and the relatively impenetrable vegetation due to the prevalence of the uluhe (Dicranopteris linearis), which is a fern whose fronds form a tangled layer usually 0.5-2 m deep. In order to gain quick access to areas of interest, the survey routes oJten followed trails, ridge tops, and streambeds. The survey routes ( are shown in Figure 2. Areas of interest were not identified until the survey participants were in the field and able to scan the landscape for vegetation that appeared to have a high potential for rare plants. At vantage points along the survey routes binoculars were used to help locate rare plants. Certain rare plants of the refuge are readily identifiable from a distance, particularly the tree Tetraplasandra gymnocarpa. The locations of T gymnocarpa identified only from afar were plotted as accurately as possible by comparing the topography of the area with topographical maps. Attempts were made to take Global Positioning System (GPS) readings for rare plant locations and important locations along the survey route. Readings for some points were obtained. However, at other points, particularly in the gulches, readings were not obtainable. In such cases, rare plant locations and survey routes were mapped as accurately as possible by consulting topographic maps and utilizing altimeters and compasses. 4 ( Results Six rare plant taxa were found on the survey, including five listed endangered taxa. Another rare plant taxon is not listed as endangered or threatened, but is considered to be a "species of concern" by the USFWS. Two ofthe listed endangered taxa were seen just outside the refuge boundary, but could possibly occur within the refuge as well. The locations of the observed rare plants are mapped in Figure 3, and information on the rare plants is included on Table 1. Rare Plant Taxa Observed Within the Refuge Chamaesyce rockii (C. Forbes) Croizat & Degener Hawaiian Name: Akoko Family: Euphorbiaceae Federal Status: Endangered Chamaesyce rockii is a shrub or small tree endemic to the Koolau Mountains of Oahu, where it occurs in wet forests and shrublands. The species was seen on survey at a location in Waikakalaua Gulch and at a second location in Kipapa Gulch. The Kipapa Gulch colony of C. rockii, which had not been recorded prior to this survey, consisted Qf seven mature shrubs. At the Waikakalaua Gulch site 1. Lau was able to ( locate eight mature shrubs in a population that he first observed in 1989, when he estimated the population to number 40-50 mature plants (1. Lau, pers. com. 2003). These plants are scattered in an area adjacent to a newly established campsite and its associated helipad. While the accessibility of the plants will allow for frequent monitoring and management of the plants and their habitat, care should be taken that activities associated with the campsite and helipad do not adversely affect the population. Cyanea humboldtiana (Gaudich.) Lammers, Givnish & Sytsma Hawaiian Name: Ohawai, haha Family: Campanulaceae Federal Status: Endangered Cyanea humboldtiana is a shrub endemic to wet forests and shrublands of the Koolau Mountains of Oahu. Four immature plants of this species were found growing within 2 m of the Koolau Summit Trail in a small drainage upslope of the trail. The plants were growing within a few centimeters of one another and could possibly be the result of vegetative reproduction. They are growing in the deep shade of a heavy undergrowth of Koster's Curse (Clidemia hirta), whic~ is a serious invasive alien l 5 shrub. A gradual thinning of this undergrowth so that more sunlight can reach the ( Cyaneas would likely be beneficial to the plants. As the observed plants were immature and vegetative, they could not be identified with absolute certainty as C. humboldtiana. There is a slight chance that they instead represent C. crispa, which is also a federally listed endangered species. However, that seems unlikely on the basis of the vegetative characteristics of the plants and the recorded distributions and habitat requirements of the two species. Doodia lyonii Degener Hawaiian Name: ­ Family: Blechnaceae Federal Status: None; considered a "Species of Concern" by the Pacific Islands Ecoregion office of the U.S. Fish and Wildlife Service Doodia lyonii is a fern endemic to the Hawaiian Islands.