Locality:
KAUAI: Lumahai, very back of valley, southeast corner between 1800-2800 feet elev., Metrosideros lowland wet forest with Antidesma platyphyllum var. hillebrandii, Syzygium sandwicensis, Dubautia knudsenii, Cheirodendron platyphyllum, Pipturus kauaiensis, Hedyotis schlechtendahliana, Peperomia latifolia and P. tetraphylla, Sadleria pallida, Ciboteum glaucum, Vandenboshia cyrtotheca, Asplenium lobulatum
Comments:
Upper Lumaha`i Valley. On the windward side of north-central Kaua`i and within the forested slopes of upper Lumaha`i (above 1600 ft falls) lies a rich Metrosideros polymorpha lowland wet forest (lowland o'hia wet forest). This o'hia forest, with its windswept ridges and clear-flowing drainages, is nestled around ten kilometers to the south of Hanalei, below and to the north of Mahinakehau Ridge and to the west of the saddle ridge connecting the Alaka’i Plateau to Namolokama. This upper region of Lumaha`i represents one of the few lowland o'hia forests remaining on Kaua'i. It is a biologically rich, native ecosystem filled with an endemic flora and fauna, many of which exist only on Kaua`i. This eco-region remains relatively undisturbed by introduced (non-native) species of plants.
Lumaha`i’s rich, dark forests are botanically significant. Ancient trees of wide girth fill a forest that still retains a healthy, intact understory. Deeply carved drainages of riparian flora have dissected their way down to the lower falls. The dominant canopy trees are o`hia (Metrosideros polymorpha var. glaberrima), which average around 50 feet in height. Occasionally in the less steep regions, o`hia ha (Syzygium sandwicensis) becomes the dominant along with hame (Antidesma platyphyllum). Along the upper eastern drainages of Lumaha`i and above the 1600 ft falls area there are unique forests patches where Tetraplasandra oahuensis (`ohe mauka) becomes a co-dominant.
Within the overall matrix of upper Lumaha`i, the dominant understory trees include kopiko (Psychotria mariniana), manono (Hedyotis terminalis), na'ena'e (Dubautia knudsenii), and kanawao (Broussaisia arguta). Additional less common associate trees are kawa'u (Ilex anomala), `ohe (Tetraplasandra spp.), and lapalapa (Cheirodendron spp.).
Understory ferns include the dominant ho`i`o (Diplazium sandwichianum), along with 'ama'u (Sadleria spp.), and hapu'u (Cibotium spp.). The author has observed over 60 native species of ferns and considers this understory diversity of pteridophytes to be relatively rich. In the steeper regions of stream banks and ridges the fern diversity was limited to matting ferns such as uluhe (Dicranopteris linearis), and uluhe lau nui (Diplopterygium pinnatum).
Species of Campanulaceae (Lobeliodes) are well distributed throughout this region, as are Araliaceae, Gesneriaceae, Rubiaceae and Rutaceae. Yet Lamiaceae was only represented by three individuals of Phyllostegia renovans, a new mint species only found on Kaua`i and recently described by Warren L. Wagner.
Soils are moderately deep and appear to be a fine textured brown silty clay. In flat sections of forest it remains poorly drained. Along the sides of moderately steep ridges I've observed fine silty gray clay. Sections of stream and vertical ridge walls exhibit seeping outcrops of black basalt.
The stream drainages are botanically rich in spite of the recent invasion of goats and pigs. The upper drainages (2200 ft +) average around 25 feet broad with steeply carved walls of 60 feet or more. Lower elevation stream sections are broader (ca 35 feet), yet the banks are not very steep or high and can easily be climbed to access parallel drainages. Large boulders are scattered throughout these drainages.
Rare Plant Species of Lumaha`i. (see map section)
Bonamia menziesii. This robust forest vine in the morning glory family is known from all the main islands except Ni`ihau and Kaho`olawe, although it is now thought to be extinct on Moloka`i. The conservation status in Hawai`i includes around 28 populations totaling several hundred plants.
In Lumaha`i’s upper eastern drainages above 1600 ft falls, 3 plants were mapped during Jan 2000 at around 1800 ft elev. The three vines [5--7 m long] were observed in an open flat region, growing in Antidesma. Some of the vines were formidable at around 5 cm diameter near the base. They were growing in brown soil with gray, silty clay. The natural community that they grew in was a Metrosideros lowland wet forest with associated species of canopy trees that included Antidesma platyphyllum var. hillebrandii, Syzygium sandwicensis, Cheirodendron spp, Ilex anomala, and Tetraplasandra oahuensis. Understory plants included Dubautia knudsenii, Psychotria mariniana, P. hexandra, P. wawrae, Hedyotis terminalis, and Melicope spp. Ground covers of Diplazium sandwichianum, Dicranopteris linearis, Sadleria spp. and Cibotium spp, were common. Major threats to the plants were goats, pigs, rats, landslides, Sphaeropteris cooperi, Mariscus meyenianus, Juncus planifolius, Schizachyrium condensatum, Setaria gracilis, Erigeron karvinskianus, Pluchea symphytifolia, Clidemia hirta, Melastoma candidum, Rubus rosifolius, and Paspalum conjugatum.
Chamaesyce remyi var. remyi [Kaua`i endemic]. This rare akoko in the Euphorbiaceae family was observed along the ridges around our base camp. Approximately 100 plants were seen in flower and immature fruit. This is a vine-like shrub variety of C. remyi and never exceeded 1 m in height.
Chamaesyce remyi var. kauaiensis [Kaua`i endemic]. Around 50 trees of this variety were observed in the stream confluence flats at 1900 ft. Trees were observed up to 4 m in height. Additional small populations were seen around 2100 feet elevation in several smaller side drainages below the saddle ridge that runs to Namolokama.
Cyrtandra oenobarba [Kaua`i endemic]. This Gesneriaceae is relatively rare. It grows in cool, wet understory conditions. This rare Hawaiian haiwale was seen growing in several populations throughout my transects (2300--2500 ft elevation). A total of 50 plants were observed.
Labordia lydgatei [Kaua`i endemic]. This is one of the rarest of the Hawaiian kamakahala. Less than 20 individuals were known of L. lydgatei previous to this discovery in Lumaha`i. During this survey seven plants were seen below Mahinakehau Ridge to the NNE (ca. 2350 ft elevation). It was observed in flower and fruit and seed was collected and sent to Lyon for micro-propagation. A single tree was also observed at around 2000 ft elevation
Melicope paniculata [Kaua`i endemic]. A population of this rare alani was discovered during a Nature Conservancy survey in February of 1998. Previous to that discovery there were only a few individuals known from the north fork of the Wailua River. It is estimated that there are around 300 individuals in the back of Lumaha`i around the stream confluence flats at 1900 ft elevation and continuing down stream toward the major falls. Several small populations were observed along smaller stream drainages above 1900 ft.
This species is notable because of its tall stature of up to 35 feet. Its light brown trunk broadens up to 10 inches in diameter and will not branch until 10--12 feet. Its leaves are revolute and extremely large (ca 10 inches long). The leaves are dark, glossy green on top and paler green below. The pendant panicle of fruit can be quite long (up to 10 inches) and its cuboid fruit is anise-scented. The strong scent rivals that of the Kauaian mokihana with its pleasant odor.
Seeds were collected from several individual trees of this rare species. The National Tropical Botanical Garden (NTBG) nursery has been successfully growing Melicope species (Robert Nishek, pers. comm.) and is hopeful to perpetuate this highly attractive M. paniculata. Additional immature and mature seeds were sent to Lyon Arboretums’ micro-propagation lab for embryo culture trials and propagation.
Oligadenus periens. This rare fern in the Grammitidaceae family was seen in patches of forest below Mahinakehau Ridge at 2350 ft elev. where seven plants were observed pendant and epiphytic on Metrosideros polymorpha var. glaberrima. A single plant was also observed at around 2100 ft.
Phyllostegia renovans [Kaua`i endemic]. This new species of mint is occasional within the north shore valleys, and rare on the south and west side of Kaua`i. A single plant was observed below Mahinakehau Ridge at 2300 feet elev.
Platydesma rostrata [Kaua`i endemic]. Three individuals of this rare Rutaceae were observed between 2000--2100 ft elevation along several of the drainages that flow below the saddle ridge between the Alaka’i Plateau and Namolokama.
Pritchardia perlmanii [Kaua`i endemic]. This attractive palm has a slender caudex averaging 5--10 m in height. Around 50 trees of P. perlmanii were seen in scattered populations within this remote Metrosideros Lowland Wet Forest (1800--2800 ft. elev.). Previous to these collections, P. perlmanii was known from only Waioli Valley where it is estimated to have a population of ca. 500 trees (Wood & Perlman, 1992, unpublished report; Gemmill, 1998). Around five trees of Pritchardia waialealeana were also noted on the eastern side of upper Lumaha`i. The author, under the auspices of The National Tropical Botanical Garden (NTBG), is involved in a long-term project in which diverse genetic collections are being made of all species representing the genus Pritchardia.
Wikstroemia skottsbergii [Kaua`i endemic].
A population of around 30 mature trees and 3 juveniles were documented in Lumaha`i’s upper eastern drainages above the 1600 ft falls area and between 1900--2200 ft. The trees ranged between 4--5 m in height and 10--15 cm diameter at base. They were moderately branched with stems red-brown, and a corolla of green-yellow. No fruit were seen. The leaf bases have the distinctive sub-cordate feature that is a key morphological character for W. skottsbergii. In addition the leaf tips are acuminate to caudate. Previous to this discovery Wikstroemia skottsbergii was thought to be extinct and had not been documented since 1948.
Major Threats to Lumaha`i. Pigs and goats were observed throughout this area and will no doubt transform this Hawaiian ecosystem into a trashed, degraded weed patch in a short span of years if no conservation efforts are made. To date, the worst weed observed was the Australian tree fern (Cyathea cooperi), which has completely invaded this section of Lumaha`i and will certainly continue to displace the native flora if left unchecked. During my transects I beheaded many of these ferns in hopes of beginning a comprehensive eradication program. Around the base camp a few plants of Melastoma candidum were seen. We attempted to destroy those plants but a follow up will be needed to ensure success. It is important to note that Clidemia hirta, which is already a highly invasive weed within the north shore valleys of Kauai, appears to be just starting to get a foothold within the back of Lumaha`i.
Weedy grasses and sedges include Axonopus fissifolius, Mariscus meyenianus, Juncus planifolius, Oplismenus hirtellus, Sacciolepis indica, Schizachyrium condensatum, and Setaria gracilis. These introduced monocots were minor threats showing very little displacement of the native flora except in the stream confluence flats of our lower elevation transects (ca. 1800--2000 feet). Here they were covering large areas of the understory where few native trees were regenerating. This was also the location where I began to see Psidium guajava. This weedy species was not observed in my upper elevation transects. Still, this lower section was impressive with well-established populations of the rare Hawaiian alani, Melicope paniculata, along with large, old specimens of Syzygium sandwicensis, Antidesma platyphyllum, and Metrosideros polymorpha. Evidently Rubus rosifolius is still a minor threat in this area of Lumaha`i.
Landslides should be considered a threat in these areas as I have seen slides take out large sections of forest and of course, rare cliff dwelling species. I did map a recent landslide along the saddle ridge south of Namolokama. Pioneer species within that landslide area include Erigeron karvinskianus, Schizachyrium condensatum, and Mariscus meyenianus.
Birds of Lumaha`i. The most notable observations of birds in Lumaha`i were the large nesting colonies of `ua`u, or dark-rumped petrels (Pterodroma phaeopygia sandwichensis) which were heard in the evening of May 27—28, 1998, between 7:00—9:30 PM returning to their nests. The moon was a waning crescent, so we saw very little of these birds. Yet we heard several hundred 'ua'u nesting in the cliffs which surrounded us like an amphitheater.
In addition to the `ua`u, we also heard a smaller population (ca. 30 birds) of `a`o, or Newell's shearwater (Puffinus newelli) but were unsure if they were just passing over the valley or nesting within the valley walls.
During the day many native forest birds such as 'apapane (Himatione sanguinea), along with 'amakihi (Hemignathus virens) and 'elepaio (Chasiempis sandwichensis) were seen within the native forest canopy and understory shrubs and trees. Occasionally the author observed the 'ulili or wandering tattler (Heteroscelus incanus) and pueo (Asio flammeus sandwichensis).
Introduced forest birds such as the Japanese white-eye (Zosterops japonicus), Japanese bush-warbler (Cettia diphone), cattle egret (Bubulcus ibis), white-rumped shama (Copsychus malabaricus), and the melodious laughing-thrush (Garrulax canorus) were also seen within this forest region.
