COOPERATIVE NATIONAL PARK RESOURCES STUDIES UNIT UNIVERSITY OF HAWAII MANOA Department of Botany 3190 Maile Way Honolulu, Hawaii, 96822 (808) 948-8218 Technical Report 59 STATUS OF NATIVE FLOWERING PLANT SPECIES ON THE SOUTH SLOPE OF HALEAKALA, EAST MAUI, HAWAII A. C. Medeiros, Jr., L. L. Loope, and R. A. Holt U.S.Department of the Interior National Park Service Haleakala National Park P.O. Box 369 Makawao, Maui, Hawaii 96768 UNIVERSITY OF HAWAII AT MANOA NATIONAL PARK SERVICE Frontispiece. Revnoldsia mauiensis (Araliaceae), a summer deciduous tree species, growing at 1550 ft near the Auwahi/Kanaio district boundary, south slope of Haleakala, Maui, Hawaii. ABSTRACT In an attempt to provide a basis for conservation measures for the remaining leeward native vegetation of East Maui, an assessment was made of the past and present status of all flowering plant species known from the area. The unpublished 1920 field notes of C. N. Forbes provided a major source of information on past status. Present status was determined by field exploration. A total of 237 native species in 70 families and 139 genera once occurred in the study area, which extends from sea level to 3000m (10,000 ft). Of the native flowering plants of the study area 86% are endemic to the Hawaiian Islands; 28% are endemic or have infraspecific taxa endemic to the island of Maui. Fourty-six (19%) of the species once present in the study area have neither been encountered by this survey nor recently noted by others and are considered extirpated. Of these, 23 species have surviving populations elsewhere in the Hawaiian Islands, though in some cases the study area populations represent endemic subspecific taxa. The remaining 23 species (10%) are apparently extinct. Of these extinct species, 20 species were endemic to East Maui. Extinct endemic species of the study area include: Canavalia forbesii, Cladocar~a his~ida, Cvanea arborea, C. comata, Cvrtandra besoniaefolia, Gouania lvdgatei, E. pil&a, Hedvotis foliosa, Hibiscadel~h* wilderianus, Pelea tomentosa, Phvllosteaia hillebrandii, Schiedea im~lexa, Sicvos hillebrandii, Solanum haleakalaense, Stenosvne cinerea, S, glabrata, S. haliakalae, and S. vaaans. Major factors currently contributing to the continuing serious decline of native vegetation and flora of leeward East Maui include : browsing and grazing by feral goats and feral and domestic cattle; feeding and digging by feral pigs; and displacement of reproduction of native plant species by introduced plant species - especially Pennisetum clandestinum, Holcus lanatus, and Bidens pilosa. Although most native species consistently produce flowers and fruits, this survey found little or no evidence of successful reproduction of most woody species. Dodonaea eriocama and Wikstroemia monticola are the only native species which appear to be maintaining vigorous, abundantly reproducing populations in spite of habitat degradation. Although Haleakala National Park appears to provide a relatively secure nrefugellfor many species of the study area, the park by no means includes a representative sample of the vegetation and flora of leeward East Maui. Of the 237 species of native flowering plants recorded in the study area by this survey, only 108 species (46%) have also been recorded as naturally occurring within the park. However, in spite of the advanced deterioration of East Mauils native leeward vegetation, sites containing significant remnants of the former vegetation still exist outside the park and provide opportunities for preservation. TABLE OF CONTENTS Page ABSTRACT ......................... i TABLE OF CONTENTS .................... LISTOFTABLES ...................... v LIST OF FIGURES ..................... vi ACKNOWLEDGMENTS .....................viii INTRODUCTION....................... METHODS ......................... 1 LEEWARD FORESTS OF THE HAWAIIAN ISLANDS: A PERSPECTIVE. VEGETATION ZONATION ON THE SOUTH SLOPE OF HALEAKALA ... 10 AN OVERVIEW OF CLIMATE. GEOLOGY AND SOILS OF THE . 18 STUDY AREA HISTORY OF LAND USE AND DEGRADATION OF NATIVE ECOSYSTEMS . 20 ADVERSE IMPACTS ON NATIVE FLORA AND VEGETATION . 24 Anthropogenic Fire .................. 24 FeralGoats ..................... 25 Cattle ........................ 26 FeralPigs ...................... 27 Axis Deer ...................... 28 Introduced Rodents, Birds, and Insects ........ 28 Displacement by Introduced Plants .......... 29 ILLUSTRATIONS OF VARIOUS ASPECTS OF SOUTH SLOPE ECOLOGY . 34 STATUS OF INDIVIDUAL NATIVE FLOWERING PLANT SPECIES ON THE SOUTH SLOPE OF HALEAKALA .............. 50 DICOTYLEDONES Aizoaceae . ....... Amaranthaceae ....... Anacardiaceae ....... Apiaceae ... ....... Apocynaceae . ....... Aquif oliaceae ....... Araliaceae . ....... Asteraceae . ....... Begoniaceae . ....... Boraginaceae . ....... Brassicaceae . Capparidaceae . Caryophyllaceae CsPastraceae . Chenopodiaceae . Convolvulaceae . Cucurbitaceae . Ebenaeeae ... Epacridaceae . Ericaceae ... ~upkorbiaceae . Fabaceae .... Flacourtiaceae . Geraniaceae . Gesneriaceae . Goodeniaceae . Lamiaceae ... Lauraceae ... Lobeliaceae . Lsganiaceae . Loranthaceae . Malvaceae ... Menispermaceae . Moraceae .... Myoporaceae . Myrsinaceae . Myrtaceae ... Nyctaginaceae . Oleaceae .... Papaveraceae . Phytolaccaceae . Piperaceae ... Pittosporaceae . Plantaginaceae . Plumbaginaceae . Polygsnaceae . Portulacaceae . Primulaceae . Ranunculaceae . Rhamnaceae ... Rosaceae .... Rubiaceae ... Rutaceae .... Santalaceae . Sapindaceae . Sapotaceae ... Saxifragaceae . Solanaceae ... Sterculiaceae . Thymeliaceae . Urticaceae ... Violaceae ... Zygophyllaceae . iii MONOCOTYLEDONES Cyperaceae ................... 153 Iridaceae .................... 156 Juncaceae .................... 156 Liliaceae .................... 157 Pandanaceae ................... 159 Poaceae ..................... 159 Ruppiaceae ................... 165 SELECTED FERNS AND FERN ALLIES Lycopodiaceae .................. 166 Ophioglossaceae ................. 166 DISCUSSION ....................... 167 Overview of the Distribution and Status of Native Plant Species in Study Area ............. 167 Why Worry about Loss of Plant Species of Leeward EastMaui? ...................... 174 Prognosis for Recovery of South Slope Vegetation under Reduced Browsing Pressure ........... 176 Failure of the Weakest Link in Plant Life Cycles .... 179 POTENTIAL FOR CONSERVATION OF NATIVE VEGETATION OF LEEWARDEASTMAUI ................... 182 Potential for ex situ Preservation of Rare Leeward East Maui Species ................. 182 Potential for in situ Preservation .......... 183 LITERATURE CITED .................... 188 APPENDIX I: NATIVE FERNS AND FERN ALLIES OF LEEWARD HALEAKALA by Robert Hobdy and A . C . Medeiros ...206 APPENDIX 11: ELEVATPONAL DISTRIBUTION AND STATUS OF NATIVE FLOWERING PLANTS OF LEEWARD HALEAKALA: A SUMMARY LISTING .................... 209 APPENDIX 111: SELECTIONS FROM THE FIELD NOTES OF C.N.FORBES ...................... 223 LIST OF TABLES Table 1. Generalized classification of zones and subzones of remnant native vegetation on the south slope of Haleakala, Maui, Hawaiian Islands in relation to classification systems of Rock (1913) and Ripperton andHosaka (1942). ................... 2. Mean January and July high and low temperatures for 1982, a representative year, at three sites on the west side of East Maui, Hawaiian Islands and probably indicative of conditions at comparable elevations on the south slope. (Source: U.S. Department of Commerce, 1982). .................... 3. Characteristic introduced species of each vegetation zone on the south slope of Haleakala, Maui, Hawaiian Islands .................... 4. Summary status of native vascular flora on Haleakalats leeward slopes, Maui, Hawaiian Islands ......... 5. Numbers of native flowering plant species occurring in each of twenty 500ft elevational bands on Haleakalals south slope, Maui, Hawaiian Islands. .......... LIST OF FIGURES Figure Frontspiece. Revnoldsia mauiensis (Araliaceae), a summer deciduous tree species la. Maps showing study area location and place names on Makena quadrangle. .................... lb. Place names, Lualalilua quadrangle ......... lc. Place names, Kaupo quadrangle. ........... 2. Illustration of rugged nature of south slope terrain withHanalavas.. .................... 3. Remnant of mesophytic cloud-belt forest, at 4500ft above Puu Pane, south slope of Haleakala, Hawaii ..... 4. Illustration of typical terrain on the west slope of Haleakala, Hawaii, where relatively deep soils have developed on the older Kula lavas. ............ 5. Root system of *ohilatree (Metrosideros polvmor~ha) exposed by massive soil erosion, south slope of Haleakala, Hawaii. .................... 6. Severe degradation of vegetation and soil erosion caused by decades of browsing, grazing and trampling by feral goats, south slope of Haleakala, Hawaii. ...... 7. Former Stvwhelia shrubland in which most shrubs have been killed by goat browsing, south slope of Haleakala, Hawaii .......................... 8. Landscape denuded by feral goats, western Kaupo Gap, Haleakala National Park. ................. 9. Illustration of ridgetop disturbance by feral animals, south slope of Haleakala, Hawaii. ........ 10. Isolated trees of Streblus sandwicensis in Kepuni Gulch, Maui, Hawaii. ................... 11. Illustration of damage caused by semi-feral cattle, south slope of Haleakala, Hawaii ............. 12. Rat-gnawed fruit of Alectrvon macrococcum, from the south slope of Haleakala, Hawaii ............. 13. Upper dryland forest at 3800 ft. in Auwahi district,