36-1 



Hauiiii — Our Livifig Rcsinines 



35 62 71 79 82 91 

 Year 

 Fig. 1. Number of silversword 

 plants counted by investigators on 

 a single cinder cone, Ka Moa o 

 Pele. within Haleakala Crater 

 ILoope and Crivellone 1986; 

 Kobayashi 1993). 



I <5cm 

 I 5-20 cm 



r~l >20 cm 

 I I Flowered 



82 83 84 85 



Year 



Fig. 2. Number by diameter class- 

 es of Haleakala silversword in 

 fixed monitoring plots. 1982-89. 

 Summary of data from eleven 5 m 

 X 20 m (16.4 X 65.6 ft) plots in 

 representative sites in Haleakala 

 Crater (Loope and Medeiros 

 1994). 



For further information: 



Lloyd L. Loope 



National Biological Service 



Haleakala National Park 



PO Box .^69 



Makawao. Maui, HI 96768 



64.800 (Kobayashi 1993). The cunent popula- 

 tion of Haieaivala silversword is about 16 times 

 larger than the estimated population in 1935. 



Annual trends in 1 1 fixed plots, 5 m x 20 m 

 (16.4 X 65.5 ft), from 1982 through 1989, sug- 

 gest occurrence of substantial annual fluctua- 

 tions in the recruitment and survival of 

 seedlings (Loope and Crivellone 1986: Loope 

 and Medeiros 1994; Fig. 2). 



Data on Silversword Flowering 



The Haleakala silversword flowers from June 

 to September, with annual numbers of flowering 

 plants varying dramatically from year to year. 

 Reliable counts of flowering plants were inade in 

 1935 (217 flowered) and in'^1941 (815 flowered; 

 Loope and Crivellone 1986). Numbers recorded 

 in recent years have ranged from zero in 1970 to 

 6.632 in 1991. The environmental stimulus for 

 flowering or nontlowering of silversword within 

 a given annual flowering season is still 

 unknown. An apparent relationship of the 1991 

 mass flowering event to stratospheric alteration 

 by the eruption of Pinatubo Volcano in the 

 Philippines is intriguing. 



Threats 



As a result of management within Haleakala 

 National Park, the most serious former threats 

 to the Haleakala silversword have been virtual- 

 ly eliminated: human vandalism and browsing 

 by goats and cattle. To date, no introduced plant 

 species competes significantly with silver- 

 sword. Cooperative interagency efforts are 

 being made to exclude the non-native mullein 

 (Verhasciim thapsus) and fountain grass 

 {Pennlsi'titm setaceiim) from becoming estab- 

 lished on Maui; since these plants occupy simi- 

 lar habitat on other Hawaiian Islands, they 

 might compete with silverswords. 



The greatest threat to the silversword 

 appears to be potential loss of endemic pollina- 

 tors because of the invasion of silversword habi- 

 tat by the Argentine ant Uridomynnex luiniilis). 

 This ant species occupies two disjunct areas 

 between 2,070 m (6,792 ft) and 2,850 m (9.351 

 ft) elevation in Haleakala National Park, with a 

 total area of 175 ha (432 acres; Cole et al. 

 1992). Because queens are unable to fly. the 

 spread of this species is relatively slow. This 

 alien ant species negatively affects the locally 

 endemic arthropod fauna (Cole et al. 1992). 

 including pollinators that evolved in the absence 

 of ant predation. A marked expansion in the 

 ant's range was noted in 1993, especially at 

 higher elevations (Medeiros et al. 1994). Unless 

 this ant species is controlled, it could cause 

 potentially catastrophic effects on locally 

 endemic biota, including the silversword, which 



is associated with several endemic insect 

 species (Loope and Crivellone 1986) and which 

 requires cross-pollination for successful seed 

 set (CaiT et al. 1986). Experimental control 

 effoils are under way. 



Trends 



Recovery of the Haleakala silversword is one 

 of the most dramatic single-species conservation 

 success stories known. The primary factor con- 

 tributing to its decline, human vandalism, was 

 effectively addressed by the National Park 

 Service beginning in the 1930's. Over the past 60 

 years the species has steadily recovered through 

 protection within Haleakala National Park. It is 

 increasing in numbers and expanding its range. 

 Continued protection from human vandalism and 

 feral ungulates, such as goats and cattle, is essen- 

 tial, and potential threats from the Argentine ant 

 and alien plants must be addressed. Given the 

 plant's limited range and precarious life cycle, 

 the long-term prognosis for survival of this 

 species appears remarkably favorable. 



References 



Baldwin. B.C., D.W. Kyhos. J. Dvorak, and G.D. Carr. 1991 . 

 Chloroplast DNA evidence for a North American origin of 

 the Hawaiian silversword alliance. Proceedings of the 

 National Academy of Science 88:1840-1843. 



Carr. G.D., E.A, Powell, and D.W. Kyhos. 1986. Self-incom- 

 patibility in the Hawaiian Madiinae (Compositae): an 

 exception to Baker's rule. Evolution 40:430-434. 



Cole. F.R.. A.C. Medeiros. L.L. Loope. and W.W. Zuehlke. 

 1992. Effects of the Argentine ant Uridomynnex hiimilis) 

 on the arthropod fauna of high-elevation shrubland, 

 Haleakala National Park. Maui, Hawaii. Ecology 

 73:1313-1322. 



Kobayashi, H.K. 1973. Ecology of the silversword. 

 Haleakala Crater. Hawaii. Final Rep. HALE-N-3. 124 pp. 



Kobayashi, H.K. 1993. Census report on the Haleakala sil- 

 versword Argyroxiphium scmdwicense dc. (Compositae) 

 ssp. macrocephalum (Gray) Meyrat for 1980 and 1991. 

 Hawaii Natural History Association and Haleakala 

 National Park. 12 pp. 



Lamb. S.H. 1935. First progress report, silversword project. 

 March 1935. Second progress report, silversword project. 

 July 1935. National Park Service. 



Loope, L.L., and C.F. Crivellone. 1986. Status of the silver- 

 sword in Haleakala National Park: past and present. 

 Cooperative National Park Studies Unit. University of 

 Hawaii at Manoa. Department of Botanv, Tech. Rep. 58. 

 33 pp. 



Loope, L.L., and A.C. Medeiros. 1994. Impacts ot biological 

 invasion on the management and recovery of rare plants in 

 Haleakala National Park, Maui, Hawaii. Pages 143-158 in 

 M. Bowles and C.J. Whelan, eds. Restoration of endan- 

 gered species, Cambridge University Press, Cambridge, 

 UK. 



Medeiros, A.C, FR. Cole, and L.L. Loope. 1994. Patterns of 

 expansion of an invading Argentine ant ilridomynnex 

 humilis) population in Haleakala National Park, Maui. 

 Hawaii. (Abstract) Bull, of the Ecological Society of 

 Amenca 75:1.50-151 



Robichaux, R H., G.D. Carr, M. Liebman, and R.W. Pearcy. 

 1990. Adaptive radiation of the silversword alliance 

 (Compositae: Madiinae): ecological, morphological, and 

 physiological diversity. Annals of the Missouri Botanical 

 Garden 77:64-72. 



