{'fraction_non_alphanumeric': 0.02852153667054715, 'fraction_numerical': 0.018626309662398137, 'mean_word_length': 5.329650092081032, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Vegetation of the Wet Windward Slope of Haleakala, Maui, Hawaii

The vegetation on the wet windward slope of Haleakala was studied for community organization along a transect between 350 m a.s.l. and the summit (3055 m). The plant communities classified by the Braun-Blanquet synthesis table technique showed a hierarchical arrangement and were correlated with altitude. First, the forest and the treeless vegetation were differentiated by two major species groups. The boundary between the two was coincident with the trade wind inversion (ca. 1900 m a.s.l.) where the wet, low to mid-altitudinal climate changed abruptly upslope to an arid high-altitude one. These two wide-ranging vegetation types were subdivided into three units, corresponding to three broad altitudinal zones: the lowland, the montane, and the high-altitude zones. The three units were further partitioned into seven plant communities, which indicated six altitudinal subzones and one dieback belt. The floristic composition of the communities, the community structures, and their environmental relationships are briefly described with a summarized differential table. The depauperate and disharmonic nature of the Hawaiian flora is reflected in such altitudinal patterns as the low species turnover and the depressed forest line. THE HAWAIIAN ISLANDS, biogeographically the world's most isolated archipelago, support high endemism in their flora (956 flowering plant species with 89% endemic; Wagner et al. 1990). The extreme isolation has acted as a sieve allowing only a limited number of species to cross the ocean. As a result, the flora has become disharmonic (Hubbell 1968). For instance plants with larger disseminules are not common in the native inland forests in Hawaii. The flora is also depauperate, and the number of potential canopy species is low (Mueller-Dombois 1987). The taxonomic disharmony and relative biotic impoverishment resulted in widespread monodominance of the native rainforests by Metrosideros polymorpha (Mueller-Dombois 1981a). This is a myrtaceous tree species with capsulate fruits, which produce very small wind-dispersed seeds. The species dominates 1 This project was supported in part by a grant from the National Tropical Botanical Garden. Manuscript accepted for publication 2 May 1991. 2 Department of Botany, University of Hawaii at Manoa, Honolulu, Hawaii 96822. the wetter Hawaiian habitats (MuellerDombois 1987). The monodominance of M. polymorpha seems to be a factor in the recurring phenomenon of canopy dieback (Mueller-Dombois 1986, 1987). Metrosideros polymorpha, being shade-intolerant in the sapling stage (Burton and Mueller-Dombois 1984), depends on canopy openings to maintain its regeneration. Consequently, episodic stand-level regeneration in response to canopy dieback of M. polymorpha seems to have worked as a mechanism for successive generations. The process of dieback has been discussed as primarily a demographic phenomenon of cohort senescence, interacting with abiotic stresses (Mueller-Dombois 1988a). We also suspect that the monodominance is manifested in reduced interspecific competition. Therefore, some distributional attributes of plant communities that are released from high species competition may be displayed on the slopes of the Hawaiian high mountains. Investigations have been done to compare species turnover along mountain transects. One of the analyses relates to Haleakala,