5127/2015 Ecoregion Description The Nature Conservancy Hawaiian High Islands Ecoregion Pmtecting nature. Preserving life ~ This page last revised 21 July 2007 Home Introduction Ecoregion Description Ecoregion Conservation Targets Location and context Viability Goals The Hawaiian High Islands Ecoregion lies in the north Portfolio central Pacific Ocean. It is comprised of the ecological TNC Action Sites systems, natural communities, and s~ecies ~ssociated Threats with the terrestrial portion of the mam archipelago of Strategies the Hawaiian Islands (eight major islands and Acknowledgements immediately surrounding islets). These islands have a <I total land area of 1,664,100 hectares (4,062,660 acres). Tables This terrestrial ecoregion excludes the Northwestern Maps &Figures Hawaiian Islands (belonging to Hawai'i coastal/marine The Hawaiian ecoregion contains highly diverse physiography. CPT Database ecoregion) and the surrounding marine environment. Appendices The Hawaiian High Islands Ecoregion lies within the Glossary Hawaiian Biogeographic Province, which encompasses Physiography Sources all of the above ecoregions and occupies the northern portion of the Oceanian Realm. The Hawaiian High Islands Ecoregion is marked by a very wide range of local physiographic settings. These Boundary include fresh massive volcanic shields and cinderlands reaching over 4000 m (13,000 ft) elevation; eroded, faceted topo- graphies on older The Hawaiian High Islands Ecoregion Boundary islands; high sea cliffs (ca 900 m [3,000 ft] in height); is defined by the TNC/NatureServe National raised coral plains ~ and amphitheater-headed Ecoregional Map. It is a modification ofBaile~'s . valley/ridge systems with alluvial/colluvial bottoms. Ecoregions of the United States. The World W1ldhfe Numerous freshwater stream systems are found The Hawaiian High Islands Ecore;Pon lies in Federation (WWF) recognizes four ecoregions for the the central north Pacific Ocean. primarily on the older, eroded islands, but also ~n Hawaiian Islands (Hawai'i Tropical Moist Forest the wet, windward slopes of even the youngest island, [OC0106], Hawai'i Tropical Dry Forest [OC0202], Hawai'i (Juvik & Juvik 1998). Hawai' i Tropical High Shrubland [OC0701 ], and Hawai'i Tropical Lowland Shrubland [OC0702]) (Gon & Olson 1999, Ricketts et al 1998). Climate http://www.hawaiiecoregionpl an.inf<Yecoregion.ttml 1/5 5127/2015 Ecoregion Descri!Xion The Hawaiian High Islands Ecoregion contains three The general climate is tropical/subtropical, but with major habitat types: Tropical Moist Broadleaf Forest, combinations of elevation and orographic rainfall Tropical Dry BroadleafForest, and Tropical Grasslands, patterns that yield extremely wet (> I 000 cm [>400 Savannas & Shrublands. The boundaries of the inches] annual rainfall) to extremely dry (<25cm [<10 Hawaiian High Islands Ecoregion correspond to the inches] annual rainfall) settings within a short distance collective sea-level island boundaries of the main of each other (<40 km [25 miles]), topped by alpine Hawaiian Islands and immediately surrounding islets. deserts on the youngest and highest islands Remark~e physiographic Cl1d climatic There are no contiguous terrestrial ecoregions. (Giambelluca & Schroeder 1998). All but two of the <iversity marks the ecaegioo. eight main Hawaiian Islands rise to montane (continued next column) elevations(> 1000 m [>3000 ft]). The general patterns of climatic variation found on the largest of the Hawaiian islands are shown diagrammatically below: Sane of the woods wettest regioos lie in the ecaegion's montane systems At>ne 3000m SU!llil1>tne 2000m The Hawaiian High lslcrlds Ecoregion (right, !Aonlllne yellON oval) lies within the Ha.Naiian Province 1000m (red oval), in the Oceaiian Biogeographic Realm. HAWAl'I HICH ISLANDS ECOREGION • High island orographic dimate results in both extremes of wet and dry, • • while broad elevational reach yields tropical hot to alpine temperature regimes. (Click on the image above to i.;ew a larger version). Biodiversity Significance Endemism The Hawaiian High Islands Ecoregion is marked by Biological diversity in the Hawaiian Islands is spread extremely high endemism (e.g., ~90% endemism of among the main high islands because of island-level native flowering plants ~ >98% endemism of native endemism. Each island contains species unique to that terrestrial invertebrates) (Loope 1999). An estimated island. For example, of 1,050 described taxa of native 15,000 endemic species occur in the ecoregion flowering plants, there are three found only on http://www.hawaiiecoregi<Jn?an.inf<Yecoregion.llml 215 5127/2015 Ecoregion Description ecosystem endemism of any ecore!Jion. (Eldredge & Evenhuis 2003). The Hawaiian flora of Ni'ihau, 225 restricted to Kaua'i, 157 found only on about 1,200 vascular plant species is disharmonic, that O'ahu, 40 known only from Moloka'i, 12 unique to is, lacking many genera and families that typically mark Uina'i, 96 found only on Maui, 2 reported only from tropical island systems (Sohmer & Gon 1995). Rare and Kaho'olawe, and 106 known only from Hawai'i endangered taxa, including endangered plants, forest (Wagner et al 1990). birds, and land snails comprise >25% of the fauna. Hawai'i includes more endangered species than any Because of all of these island-level endemics, fewer other state in the U.S . (USFWS 2005). WWF includes than half the flowering plant taxa ( 409) show multi­ the Hawaiian Islands as the site of four of their "Global island distributions. Fewer than 150 can be found on The flora is clisharmonic, lacking maiy of the 200" priority ecoregions (Olson & Dinerstein 1998). all six of the higher main islands. The situation is even typical tropical genera ~ families. more pronounced among invertebrates, which In addition to species, all but a handful of the comprise the majority of species-level diversity, and approximately 150 described terrestrial native natural show remarkable diversification and geographic communities are endemic Vegetation includes endemism even within a single island setting. grasslands, shrublands woodlands, and forests in lowland. submontane, montane, subalpine, and alpine Multiple examples of ecological systems across the settings (Pratt & Gon 1998). Hawai'i supports more archipelago are clearly required to adequately Holdridge life form categories than any other ecoregion represent species level biological diversity. For broad­ known (Tosi et al 2001 , Ewell 2004). Lists of the scale planning, a geographic stratification approach is Hawai'i includes more endoogered species than natural communities and rare/endangered species of the needed, and was developed as part of this 2nd any ether state of the U.S. ecoregion can be found in the appendices. interation plan. Land Use Patterns Socioeconomic Setting Human residence and extractive land uses are largely The general setting for conservation in Hawai'i is concentrated below 600 m (2000 feet) elevation. Land relatively stable. There is none of the sometimes uses include high-density urban, residential, violent instability that plagues many tropical agricultural, grazing, and lands dedicated to military biodiversity hotspots. Hawaii's economy is marked by training. Higher elevation areas are more natural, are low unemployment, and is largely based on tertiary Significant portions of the lowlands have been dispolaced by human development largely zoned for conservation, and include many areas services related to tourism. The military also plays a in protective status such as national parks, natural area large economic role, as Hawai'i has been a strategic reserves, forest reserves, preserves, and refuges. Upland hub since World War II. Plantation agriculture (sugar watersheds on most of the main islands are included in and pineapple) was the primary economy in the early http://www.hawaiiecoregionplan.lnfo'ecoregion.html 3/5 5127/2015 Ecoregion Description informal public-private cooperative management areas 20th century, but has been declining in importance. called watershed partnerships, managed for maintenance and management of forested watershed. Over 30% of Large tracts of former agricultural lands are being the ecoregion is privately-owned, 29% in state holdings, converted into residential areas or are left fallow, approximately 8% in federal lands, and the remainder in often creating vectors for weed invasions or wildfire. county and other tenure. These proportions also apply to Rapidly rising land and property costs (among the the biologically intact island interiors, necessitating highest in the U.S.) have created a high cost ofliving, Bringing active management to priaity land­ state, federal, and private participation in exacerbated by our geographic isolation and need to scapes is the overall goal. comprehensive conservation efforts (Hawai'i GAP import many/most necessities (food, shelter, clothing, 2005). fuel) . Economically depressed rural areas occur on all islands where subsistence hunting/fishing persists. The consequences of past land use practices can be seen Business centers can be found in Honolulu (O'ahu), on Maui island (figure below). Anthropogenic and Kahului (Maui), Lihu'e (Kaua'i), Hilo and Kailua­ alien-dominated regions, shown in pink, dominate the Kona (Hawai'i). Societal stratification includes lowlands, while native-dominated ecological systems everything from the very rich to the working poor, prevail at higher elevations. Typically there is little or with a growing gap between the two. no native vegetation below 600 m (2000