An island is a closed ecosystem separated from the mainland by geographical distance. Especially regarding oceanic islands, this distance works as a barrier to organisms dispersing from the mainland to the island. This is the main reason that the plant and animal components on an oceanic island are usually ‘disharmonic’ compared to those observed on the mainland. An island ecosystem often lacks particular taxonomic groups of plants and animals, which would otherwise have an important role in structuring the mainland ecosystem. Another distinctive characteristic of an island ecosystem is its evolutionary uniqueness. Since Darwin’s era, oceanic islands have been recognized as evolutionary laboratories, where unique evolution has taken place in many phylogenetic groups. In this sense, island ecosystems are worth paying attention to from the viewpoint of conservation of biodiversity, in spite of the fact that islands occupy only a small proportion of the world’s landmass.

　Biologically unique species often exist as small-sized and/or fragmented populations on a single or few islands. These species are susceptible to extinction in nature due to stochastic disastrous events. With increasing impacts of human activities on island ecosystems, the risk of extinction has markedly increased. Extinction may occur implicitly at a DNA level, possibly caused by hybridization with genetically close exotic species. Now, conservation of biodiversity of islands should be recognized as a global environmental issue.

　Biological uniqueness of island ecosystems has recently received the attention of tourists, islanders and governments as a sustainable natural resource, which is called an ‘ecological service.’ Ecotourism seems an attractive approach to the unique island ecosystem aiming to promote coexistence of humans and nature. However, in consideration of the biological uniqueness of islands, we have to be careful in developing island ecotourism.

　In this special issue of Global Environmental Research, nine papers are presented from a variety of backgrounds. The first three papers introduce our present understanding of the biological uniqueness and conservation of the Bonin (Ogasawara) Islands, a subtropical group of oceanic islands of Japan. The fourth paper reviews the status of unique vegetation on the Galapagos Islands in relation to the impact of alien species. The fifth and sixth papers deal with biological uniqueness and conservation of the Izu Islands, in a warm-temperate region of Japan. The seventh paper reports on the impact of alien animals on endemic mammals of Amami Island in the Nansei Archipelago in a subtropical region of Japan. The eighth paper proposes an alternative way for humans and nature to coexist against development of a nuclear power plant on an island in the Seto inland sea of Japan. The last paper describes the challenging activities of a prefectural government for conservation of Yakushima Island, which is listed as a World Natural Heritage Site. We are still on the way and hopefully the right way to coexistence of humans and the unique nature of islands.

　The Ogasawara (Bonin) Islands are oceanic islands in the northwest Pacific Ocean. Their origin goes back to the Tertiary, the present islands having emerged at least several million years ago. The climate is subtropical and typhoons pass by the islands every year. The islands were first inhabited in 1830, ruled by the U.S. for 23 years after World War II, and returned to Japan in 1968 after which they were treated administratively as a new village. As oceanic islands, they are poor in flora and fauna compared with continental or mainland areas, lacking big mammals, snakes, frogs and Fagaceous trees, while the endemic ratio is high in many groups. The islands are called “the Oriental Galapagos.” The vegetation is classified into seven types according to habitat, physiognomy and dominant species. A pine wood nematode invaded the islands killing many pine trees in the early 1980s. A large typhoon hit the islands and did much damage to the forests in 1983. After this disturbance, Bishofia javanica (introduced sp.) invaded the natural forests rapidly taking the place of native trees. A Bishofia eradication project started in 2002. Feral goats which destroyed the forests of the Mukojima group were completely removed recently to restore the vegetation. Some critically endangered species were bred artificially and transplanted to the original habitats, but regeneration by itself has not been successful. An airport construction plan which was proposed by the Tokyo Metropolitan Government in 1989 was finally withdrawn in 2001.

　Recently, people of isolated islands worldwide, especially those at low latitudes, have begun to take an interest in ecotourism. The Ogasawara Islands have good potential for ecotourism because of their unique ecology and great distance from the mainland. I therefore studied the situation regarding the islands’ nature, history, culture, lifestyle, industry, environmental disruption and conservation, research, sightseeing and ecotourism, and hereby present my discussion on the perspective of ecotourism in the Ogasawara Islands. Five colonizations occurred historically in the Ogasawaras (Conventional, Old, New and New New Islanders and the ‘Shimakko’). Each of these waves of people added in various ways to the cultural heritage. There is unique nature such as many endemic species and karsts. Ecological disruptions, however, have proceeded rapidly. The introduction of an express ship in 2005 will increase environmental disruption. Despite its small size, Chichijima Island is home to eight institutes. In addition, 24 universities, institutions and museums have visited Chichijima and Hahajima in the Ogasawaras. Three guide training systems were established in 2001 and 2002. About 6%-7% of the local people participated in each guide training system. In 2002, the Bonin Ecotourism Commission was also established. I suggest that it will be necessary to establish a Guide Center for promoting ecotourism to the Ogasawaras, making use of the three guide training systems, and an Institute of Natural Science for Sightseeing, making use of much available information from studies for sightseeing. I believe it would also be desirable to aim for registry with the World Heritage (Natural Heritage) in order to obtain a consensus of opinion on ecotourism among the five colonies.

　The endemic land snails, genus Mandarina of the Ogasawara Islands, have diversified into arboreal, semi-arboreal and ground ecotypes. Shell morphologies of Mandarina species have a clear relationship with their respective ecotypes. In addition, marked geographical variations in morphology and genes are found within species. Phylogenetic relationships based on mitochondrial DNA (mtDNA) sequences suggests that Mandarina evolved from Euhadra, a genus distributed on the mainland of Japan. The inferred phylogeny suggests that similar morphologies and ecotypes appeared independently and rapidly in different lineages and islands at different times. This rapid evolution produced some incongruities among phylogenetic relationships, morphology, species taxonomy, and the level of reproductive isolation. Interspecific hybridization occurs between sympatric species due to environmental change, resulting in an admixture of genetic and morphological characteristics. These findings reveal the importance of Mandarina as a model system for evolutionary study. However, a predatory land snail and flatworm have recently been introduced into the Ogasawaras. These predators may rapidly cause the extinction of Mandarina, and thus, a conservation program is needed for Mandarina. In the conservation program for Mandarina, species taxonomy should not be used as a criterion for selection of populations for captive breeding because of incongruence among the phylogeny, morphology, ecology, species taxonomy and reproductive isolation. In addition, the danger of interspecific hybridization should be considered when captive-bred snails are reintroduced into restored or secure habitat.

　The Galápagos Islands, located 1,000 km west of the South American coast on the equator in the easternmost Pacific, are of volcanic origin. The vascular plant flora is poor and disharmonic, comprising ca. 200 endemic taxa. The vegetation is altitudinally arranged, roughly related to the increase in precipitation, from the maritime and dry zones in the lowlands, through the transition and moist zones, to the treeless highland zone. The zonation is deflected upward in elevation on the leeward side of each island and on leeward islands, due to the rainshadow of the southeastery trade winds which bring moisture to the islands. The treelessness of the highlands is attributed to the fluctuation of weather conditions between extreme dryness and extreme moisture saturation, to which no tree species adapted to such fluctuation has migrated and in which no endemic trees have evolved. Of the flora, an endemic genus Scalesia (Compositae) has attracted special attention. The genus consists of 15 heliophilous species, of which 12 are shrubs distributed in the dry lowlands and three are trees found in the moist zone. All the species are allopatric in distribution. Scalesia pedunculata, the largest tree of the genus, 12 m high and 15 cm in DBH, predominates in the moist zone of Santa Cruz Island. The canopy population of the dense forest is a cohort of the same age, and nearly all the trees die synchronously at maximum maturity, triggered by a large amount of El Niño rainfall or by extreme drought in La Niña years. Such a stand-level dieback resets the cohort generation, and then self-cyclic succession starts with no successors or shade-tolerant trees. The same was observed in an S. cordata forest on Sierra Negra Volcano of Isabela Island. Alien plants, introduced intentionally or accidentally to the islands, are spreading into semi-natural and natural areas as well as in disturbed habitats. Aliens have increased since the first half of the 19th century and now exceed 600 in number of species. Naturalized aliens include tree species that establish self-recruiting populations filling gaps in habitats and tree niches, since the flora is poor in tree species. El Niño rainfall creates favorable conditions for invasive aliens and accelerates their expansion to semi-natural and natural vegetation. Some of the endemic taxa are declining to endangered status due to invasion by alien plants and grazing by introduced animals like goats and donkeys. The vegetation is changing not only in agricultural and town areas but also in part of the Galápagos National Park despite its strict regulations for protection and conservation.

　Terrestrial vertebrates of the Izu Islands are the subset of species indigenous or endemic to the Japanese main islands, but their species composition is extremely disharmonic both taxonomically and ecologically. Mammals, amphibians and freshwater fishes are impoverished due to isolation, the small area, reduced habitat diversity and lack of permanent freshwater habitats, whereas birds and reptiles are rather rich in endemic species or subspecies with unique ecological characteristics, and those groups of vertebrates maintain higher population densities particularly on the islands without mammalian carnivores. The snake Elaphe quadrivirgata, a top predator on most of the islands, shows remarkable diversification in food habits and body size in accordance with inter-island difference in intensity of interspecific competition with other snake species and in availability of prey. The lizard Eumeces okadae, a small insectivorous predator in intermediate trophic level, shows variation in life history traits in relation to different predation pressures. The lizard populations exhibiting delayed maturity and lower reproductive rates due to less than annual reproduction exist only on the islands without snakes or mammalian carnivores. Introduction of the weasel for controlling rat pests in agricultural products almost extirpated lizard populations with little adaptation to novel predators, and subsequently caused significant changes in entire island food web structures.

　An active volcano, Mt. Oyama in Miyake-jima Island of the Izu Islands, Japan, erupted in 2000, and all the inhabitants were evacuated from the island. A new crater was formed, and since then, a large quantity of volcanic gas containing high concentrations of SO₂ and H₂S has been emitted. Indigenous plants and animals of the island have been heavily damaged by the volcanic deposits and gas. In this paper, we introduce the terrestrial ecosystem of Miyake-jima Island before the 2000 eruption, and then describe the damage to and recovery of vegetation after the eruption, with implications for restoration of the island’s ecosystem. The damage to vegetation was extensive around the summit area, where some indigenous plant species may be extinct. The damage decreased at more distant sites from the crater. In 2001, damaged areas gradually extended toward the eastern leeward side, which was more frequently exposed to volcanic gas, while recovery of vegetation was observed on the northern side where volcanic ash was heavily deposited soon after the eruption of 2000 but was relatively less influenced by poisonous gas thereafter. The important process of vegetation recovery in damaged forests is stem sprouting shown by completely defoliated trees. On Miyake-jima Island, many engineering works (e.g., check dam construction and revegetation work) have already been underway, on demand for improvement of island’s security. Such construction, on the other hand, is likely to influence the island’s ecosystem. We propose that restoration programs should be established considering utilization as well as conservation of the indigenous nature.

　Amami Island has many terrestrial wildlife species and subspecies that are endemic to the Nansei Archipelago. Many of them live in the forest ecosystems, while young secondary forests have replaced the majority of the original forests due to the past clear-cutting forestry. Of those species, the great scaly thrush Zoothera dauma major, Owston white-backed woodpecker Drendrocopos leucotos owstoni, long-haired rat Diplothrix legata and Amami pygmy woodpecker Dendrocopos kizuki amamii, appear to be so dependent on the mature forests (uncut for at least 50 years after selective felling) that their numbers must have decreased at least for the last few decades. On the other hand, the populations of Amami rabbit Pentalagus furnessi, purple jay Garrulus lidthi, Amami woodcock Scolopax mira, Ryukyu robin Erithacus komadori and spinous rat Tokudaia osimensis have decreased in the central part of the island, where mongoose numbers have skyrocketed in recent years. In the mean time, forestry practices that turned out to be economically unprofitable have resulted in a precipitous decline in production in the early 1990s. Mongoose control has also encountered critical financial problems due to the ignorance of the local community. These situations are rooted in a local economy that has been deeply dependent on government subsidies, which facilitated various development activities.

　The Chugoku Electric Power Company (CEPC) has plans for constructing a nuclear power plant (two reactors, 137.3 megawatts each) on Nagashima Island of Kaminoseki Town situated in the Suo-nada Sea, the Western-most portion of the Seto Inland Sea National Park, Japan. The Seto Inland Sea, the biggest half-closed water system in Japan, has suffered from deterioration of its natural environment since the 1970s caused by landfilling, dredging, and industria1 sewage from the deve1opment of industrial complexes. lnthe1980s, the pollution here became one of the most serious social and environmental problems of Japan. It has been revealed recently that the biodiversity of the Suo-nada Sea is exceptionally well conserved in spite of such pollution. Nagashima Island is on the east end of this Suo-nada Sea. and thanks to the warm Kuroshio current washing its untouched coastlines, which are immune from artificial banks, it has by far the best conserved shallow water maritime biodiversity in today's Japan. The Japanese government launched the Environmental Impact Assessment Law in June1999, and the proposed Kaminoseki Power Plant became the first case of a nuclear power plant in Japan to which this new law was to be applied. The Committee for Techno1ogical Evaluation of Environmental Impact Assessment of Yamaguchi Prefecture judged the Preparatory Report made by CEPC (April 1999) as unsatisfactory, and the Eco1ogical Society of Japan (ESJ) expressed their academic concern about the conservation of biodiversity around Nagashima (March 2000), and it demanded a re-assessment (March 200l). Although the project was accepted as a national one by the Japanese government in July 2001, it is still at a stand-stil1owing to many obstacles and opinions against the project: not all the landowners agreed to sell their land, a fishing cooperative at nearby Iwaishima Island has refused to accept any compensation for the possible loss of their fishing rights, and so on. The authors illustrate some of the recent discoveries from their research, and propose an alternative project of an eco-museum for a more sustainable use of the island ecosystem and the surrounding sea. Nagashima Island wi11become a focus of ecotour and environmental education that will ensure a wise and more sustainable use of the Seto Inland Sea than constructing nuclear power plants in the midst of this sanctuary worthy of its nomination as a World Heritage Site.

　The mountain area of Yakushima Island was inscribed on the World Nature Heritage List in 1993 because of its unique fauna, flora and landscape. The area is also conserved by national organizations under four types of nature protection systems. These are “wilderness areas,” “national parks,” “forest ecosystem reserves” and “natural monuments.” The Kagoshima Prefectural Government has also been making some efforts for nature conservation on Yakushima Island according to the Yakushima Environmental Culture Village Concept. These include establishment of a foundation, advancement of environmental education, nature protection activities, and supporting NGO activities. Furthermore, Kagoshima Prefecture oversees the Yakushima Mountain Utilization Measure Council which is expected to deal with current problems such as mountain facilities, overuse, eco-tourism and expenses.

　An altitudinal survey of correspondences between fruiting phenology of fleshy-fruited tree species and seasonal dynamics of frugivorous birds was carried out for 50 weeks across three vegetation types on Mt. Kinabalu, Borneo: a hill forest (800 m a.s.l.), a lower montane forest (1,700 m a.s.l.) and a subalpine forest (3,100 m a.s.l.). In the hill forest, a large fruiting peak following the general flowering period was observed during October–November in 1996 and a marked fruitless period was observed during February–April in 1997. During the fruitless period, the number of resident frugivorous birds decreased in some families. In the lower montane forest, a bimodal fruiting pattern was observed. A large number of frugivorous temperate migrants occurred and removed a lot of the fruit when the fruiting peak occurred. The number of resident frugivorous birds increased and several lowland bird species were observed when the number of resident birds decreased in the hill forest. In the subalpine forest, more continuous and irregular fruiting patterns without outstanding peaks were observed and the number of resident frugivorous birds was more stable throughout the year. These suggested (1) temperate migrants visited mainly the lower montane forest to obtain fruit resources and (2) altitudinal movements of lowland bird species to montane vegetation might occur seasonally, revealing that seasonal movements and migrations to track fruit resources might be common among frugivorous birds occurring on Mt. Kinabalu.

　The proposed Sustainable Development Bill (SDB) is a comprehensive piece of legislation, which proposes to lay the foundation for appropriate policies for the management of the environment in Fiji. Many developing countries are having difficulty in developing appropriate institutions to protect and sustainably manage their environment. In many cases, legislation enacted by governments fails to deliver results for environmental quality because it is not implemented effectively. This paper briefly discusses the proposed legislation from the point of view of its shortcomings for effective implementation and its implications for environmental degradation due to climate change.