World Natural Heritage Sites

The Yanbaru Region in Okinawa Island

Yanbaru (or Yambaru in the Okinawan dialect) is not a specific place name but a term that broadly refers to the forested environment in the northern part of Okinawa. In terms of well-preserved ecological areas, Yanbaru generally encompasses the northern three villages: Kunigami Village, Ogimi Village, and Higashi Village. It particularly refers to the area north of the “India Mongoose northward prevention fence” set up between Shioya Bay and Taira Bay. The core forested area in this region was designated as the “Yambaru National Park” on September 15, 2016.

The vegetation in the Yanbaru region is dominated by the Okinawa Castanopsis (Castanopsis sieboldii) of the Fagaceae family, constituting 70% of the biomass in Okinawa’s forests. It plays a crucial role in the Yanbaru ecosystem’s food chain, serving as a food source for species such as the Okinawa Rail, wild boars, and even freshwater crabs that feed on the acorns of the Okinawa Castanopsis. During the breeding season, the Okinawa Woodpecker creates nest cavities in these trees, and after the breeding season, owls and Ryukyu Tree Rats may use these empty tree holes.

The decaying wood chips produced from the center of the tree trunks serve as the growth substrate for the larvae of the Yanbaru Long-armed Scarab Beetle. Therefore, only forests with towering Okinawa Castanopsis trees can nurture the Yanbaru Long-armed Scarab Beetle. The intricate ecological interactions within the Yanbaru region highlight the importance of preserving this unique and biodiverse habitat.

Tokunoshima

Tokunoshima is located between Okinawa Island and Amami Oshima. The central and northern parts feature Okinawa Castanopsis forests similar to those in Yanbaru and Amami Oshima. However, the southern part is characterized by cave formations created from limestone, resulting in a distinctly unique geological landscape. The biodiversity on Tokunoshima is similar to that of Amami Oshima. Additionally, species such as the Tokunoshima Goniurosaurus (Goniurosaurus splendens) and the Tokunoshima Tokudaia (Tokudaia tokunoshimensis) can only be found on Tokunoshima.

Amami Oshima

Amami Oshima’s highest peak, Mt. Yuwan, stands at 694 meters, creating a cloud and mist zone with high humidity, fostering a diverse array of epiphytic plants. In the past, Amami Oshima and the northern part of Okinawa Island were connected landmasses, leading to similarities in the biota between the two. However, recent phylogenetic studies have gradually classified species on Amami Oshima as different subspecies or species from those on Okinawa Island.

For instance, a species that was once considered the Okinawa Ishikawa Frog (Odorrana ishikawae) along with Okinawa is now recognized as the independent Amami Ishikawa Frog (Odorrana splendida). The separation between Amami Oshima and Tokunoshima occurred more recently, resulting in similarities between the species on the two islands. However, certain species, such as the Lidth’s Jay (Garrulus lidthi) and the Amami Tokudaia (Tokudaia osimensis), are only found on Amami Oshima.

Iriomote Island

Iriomote Island is primarily composed of sandstone, and its coastline is predominantly covered by mangrove forests, making it the Japanese island with the highest diversity of mangrove species. The island boasts a high percentage of primary forest coverage, featuring numerous waterfall formations. Among the notable species on Iriomote Island, the Iriomote cat stands out as the most famous, with only around 150 individuals remaining, making it extremely rare. In addition to the Iriomote cat, the island is also home to species with similarities to those found in southern China and Taiwan, such as the Yellow-margined Box Turtle (Cuora flavomarginata evelynae) and the Sakishima Habu Snake (Protobothrops elegans).

外來種

Environmental Issues of World Natural Heritage

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Roadkill

On many islands, public transportation is not very convenient. After being designated as a World Natural Heritage site, with the increase in tourists, traffic flow has also risen. The mountain roads, lacking traffic signals, are generally open, and some drivers unconsciously exceed the speed limit, especially after rainfall when amphibians like newts and frogs may appear on the roads. Predators such as snakes, birds, and even Iriomote Cats feed on these small animals. To prevent Iriomote Cats from scavenging roadkill, the authorities on Iriomote Island move the carcasses off the road. However, addressing the issue at its source by avoiding collisions with small animals is the fundamental solution.

2023/11/30There have been 43 accidents involving long-haired mice in the Yanbaru region this year, marking the highest number in history.Link1
2023/5/20There was an increase in roadkill incidents involving Amami Rabbits on Amami Oshima and Tokunoshima.Link1

The Environmental Impact of Tourist Crowds

With the registration of these four islands as World Natural Heritage sites, there has been a significant increase in visitors to the area. Without proper control over entry into the forested environment, there is a risk of environmental degradation, which could be detrimental to ecological conservation. Therefore, eco-tourism should be subject to reasonable restrictions, and visitors should explore these areas with certified local ecological guides who are familiar with the environment. Currently, various regions have licensed guides, with some locations allowing entry only with certified guides, while others require advance permission.

2023/11/29To protect specific natural resources, five attractions on Ishigaki Island are expected to start restricting the number of visitors from March 2025.Link1
2023/2/3Starting from March, environmentally friendly electric vehicles (EVs) will be used for buses on Iriomote Island.Link1

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