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Hin Nam No National Protected Area

Date de soumission : 03/08/2016
Critères: (viii)(x)
Catégorie : Naturel
Soumis par :
Lao National Commission for UNESCO
État, province ou région :
Khammouane Province, Boualapha District
Coordonnées N17 15- 40 E105 43 - 106 09
Ref.: 6158
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Description

Hin Nam No National Protected Area (NPA) is situated in central Lao PDR, where the Central lndochina Limestone meets the Annamite Mountain Chain. lt is one of the original National Biodiversity Conservation Areas (now called NPAs) of Lao PDR established in 1993 by Decree 164 of the Prime Minister. lt encompasses 82,000 ha of a large, dissected karst plateau which continues across the border into Vietnam where a large portion of the contiguous Phong Nha - Ke Bang karst has been designated as a national park and Natural World Heritage site.

The complexity and diversity of geologic and geomorphologic features on display in Hin Nam No NPA provide an outstanding example of major stages in the formation of a mature and spectacular karst landscape. The geologic history of the exposed rocks dates back to the early Carboniferous period, with the karst geomorphology evolving to the present day. The characteristic landscape style of the Hin Nam No karst is that of a dissected plateau of karst massifs that are almost completely bordered by bare limestone walls or cliffs rising up to 500 m above intervening alluvial plains and flat-bottomed basins, known locally as kouans. The limestone massifs have been eroded into a classic fengcong karst of clustered cones, with steep cones together with deep fissures and dolines on the summit surfaces, and spectacular landforms such as karren and pinnacles. The Xe Bang Fai river has cut a 7 km underground course through the limestone karst, creating one of the largest active river cave passages in the world, which is superbly decorated with many large and beautiful cave formations.

Hin Nam No NPA has been recognized as a site of global significance for the conservation of biodiversity because its variety of habitat and forest types provided by the landscape geomorphology support a high diversity of animals and plants, including a number of globally threatened species, endemic species and karst specialist species. In particular, Hin Nam No contains 7 species of primate, 5 of which are globally threatened. The Red-shanked Douc Langur (Pygathrix nemaeus) and the Southern White-cheeked Gibbon (Nomascus siki) are charismatic 'flagship' species of Hin Nam No, and along with the Black Langur (Trachypithecus hatinhensis) are globally endangered. Hin Nam No harbors the largest and one of the last viable populations of these two endangered langurs in the world. Other charismatic species include 4 species of hornbill Bucerotidae), one of which, the Rufous-necked Hornbill (Aceros nipalensis), is globally threatened.

Justification de la Valeur Universelle Exceptionelle

Hin Nam No NPA is considered of outstanding universal value for the evolution of its complex and spectacular karst landscape (criterion viii), and its variety of habitats that support high biodiversity, including a number of globally threatened species, endemic species and karst specialist species (criterion x).

Criterion (viii): The complexity and diversity of geologic and geomorphologic features on display in Hin Nam No NPA provide an outstanding example of major stages in the formation of a mature and spectacular karst landscape. The geologic history of the exposed rocks dates back to the early Carboniferous period (350 Ma), with the karst geomorphology evolving to the present day. The Khammouane Formation, the 1100 m thick principal limestone sequence, was formed during the middle Carboniferous to early Permian period. Morphogenetic evolution of the karst is the result of a complex tectonic history. The lndosinian orogeny occurred in the middle Triassic (247 Ma). This significant compression, uplift, and erosion episode affected much of Southeast Asia, bringing many carbonates into subaerial positions, and resulting in a prolonged karstification episode. The karst was subsequently buried under thick layers of late Triassic, Jurassic and early Cretaceous sandstones and shales. A new uplift began in the Paleogene (65 Ma), leading to large scale erosion. As the limestone became progressively re-exposed karst evolution resumed in earnest. lndosinian karst landforms have been exhumed and rejuvenated and play a significant role in the evolution of the modern karst.

The massively bedded Khammouane limestone has evolved into a holokarst; a karst area with little or no surface runoff or streams, characterized by well-developed, mature karst surface topography and extensive subsurface karst features like caves. The characteristic landscape style of the Hin Nam No karst is that of a dissected plateau of karst massifs that are almost completely bordered by bare limestone walls or cliffs rising up to 500 m above intervening alluvial plains and flat-bottomed basins, known locally as kouans, and as poljes to karst specialists. The limestone massifs have been eroded into a classic fengcong karst of clustered cones, with steep cones and pinnacles together with deep fissures and dolines on the summit surfaces, making them virtually inaccessible. The advanced diagenesis and purity of the limestone makes the rock extremely hard, and fracturing and weathering produces sharp-edged and spectacular landforms such as karren and pinnacles, from which Hin Nam No derives its riame (i.e. spiky rocks in English). The allochthonous water of the Xe Bang Fai River has cut a 7 km underground course through the limestone karst, creating one of the largest active river cave passages in the world. The active river passage averages 76 m in width and 53 m in height, with a maximum width of 200 m and a maximum height of 120 m. In addition to the size of the cave passages, the cave is superbly decorated with speleothems, including many large and beautiful stalagmites, flowstone draperies, cave pearls and gour formed in a cave.

The Hin Nam No karst, together with the adjacent Phong Nha - Ke Bang karst in Vietnam, is one of the finest and most distinctive examples of a complex karst landform with high geodiversity and many geomorphic features of global significance.

Criterion (x): Hin Nam No NPA is of global significance for the conservation of biodiversity because its variety of habitat and forest types provided by the landscape geomorphology support a high diversity of animals and plants, including a number of globally threatened species, endemic species and karst specialist species. Hin Nam No NPA is situated where the Central lndochina Limestone meets the Annamite Mountains. The property lies within the boundaries of the Northern Annamites Rain Forest Ecoregion, one of the Global 200 Ecoregions considered most crucial to the conservation of global biodiversity. More specifically, within this ecoregion the Central lndochina Limestone has been identified as a priority landscape which is critical and globally significant for the conservation of primate species and limestone specialist species.

In total, 11 major habitat types have been identified in Hin Nam No NPA, including 7 forest habitats, 2 wetland habitats, bare rock (or sparse, stunted forest on limestone) and cave habitats. For example, lowland evergreen forest occurs in the kouans or flat valleys within the karst, hill evergreen forest occurs on the steep karst slopes, upper evergreen forest occurs at upper elevations capped with sandstone, and bare rock occurs at the top of the karst or on cliff faces. This diversity of habitats, some of them quite specialized, provides for high levels of biodiversity and endemism.

Surveys of surface habitats in Hin Nam No have recorded 452 vascular plant species, and 377 vertebrate species including 55 mammals, 184 birds, 21 reptiles, 21 amphibians and 96 fish. Of these, 37 species are of conservation interest, with 11 of these being globally threatened. Most notably, Hin Nam No contains 7 species of primate, 5 of which are globally threatened. The Red-shanked Douc Langur (Pygathrix nemaeus) and the Southern White-cheeked Gibbon (Nomascus sik1) are charismatic 'flagship' species of Hin Nam No, and along with the Black Langur (Trachypithecus hatinhensis) are globally endangered. Hin Nam No harbors the largest and one of the last viable populations of these two endangered langurs in the world. Other charismatic species include 4 species of hornbill (Bucerotidae), one of which, the Rufousnecked Hornbill (Aceros nipalensis), is globally threatened. Other globally threatened species include: Bear Macaque (Macaca arctoides), Pig-tailed Macaque (Macaca nemestrina), Southern Serow (Capricornis sumatraensis), Sambar Deer (Rusa unicolor), Smooth-coated Otter (Lutrogale perspicillata), Crested Argus (Rheinardia ocellata), and Asiatic Softshell Turtle (Amyda cartilaginea). The Sooty Babbler (Stachyris herberti) is a bird species endemic to the Centrallndochina Limestone.

Recent initial surveys of cave habitats in Hin Nam No have recorded at least 70 fauna species, with 7 of these being new species and 5 endemics, including a cave-adapted fish species (Bangana musaei) which is endemic and globally threatened. The caves of Hin Nam No are also home to the Giant Huntsman Spider (Heteropoda maxima), the world's largest spider by leg-span.

Despite high rates of speciation and endemism in karst habitats, flora and fauna communities on limestone are relatively poorly known throughout Southeast Asia, a situation that holds true in Hin Nam No NPA. The species numbers presented above likely reflect the limited flora and fauna survey work conducted in Hin Nam No rather than its biodiversity per se. Given the integrity of the karst, the range of habitats and micro-habitats, and its biogeographic setting, additional surveys of flora and fauna covering different terrain and other taxa are nearly certain to reveal many more species records and species new to science.

Déclarations d’authenticité et/ou d’intégrité

Hin Nam No NPA contains a sizable area of one of the largest and most significant limestone karst plateaus in Southeast Asia, which comprises the property itself and the contiguous Phong Nha - Ke Bang National Park and World Heritage site in Vietnam. Nearly the entire area of the karst plateau in Lao PDR is contained within the 82,000 ha of the Hin Nam No NPA. On the Vietnam side, the karst plateau covers an area of 200,000 ha, with 126,000 ha within the boundaries of Phong Nha - Ke Bang National Park.

All of the geologic and geomorphologic processes and features that convey the Hin Nam No NPA's outstanding universal value under criterion viii (see above) are represented within the current boundaries of the property. For example, although the limestone karst with its associated features is represented over most of the area, the limestone is still capped by Jurassic and Cretaceous sandstones on Phou Chuang, which is the highest point (1492 m) in the property.

Similarly, the most important habitats for the conservation of biodiversity (criterion x) are contained within the current boundaries of the property. Lowland evergreen forest is the most important habitat for conservation of the 3 endangered primate species and the 4 hornbill species. This habitat type occurs in the kouans or poljes, many of which are closed valleys deep in the karst, which affords natural protection to the forest and fauna that live there. For species whose preferred habitat is forest on limestone karst, such as the endemic Sooty Babbler, the rugged nature and expanse of the karst habitat provides them natural protection.

As water quality management of allogenic streams draining into karst is the key issue of environmental management in any karst area, this issue needs to be assessed with regard to the upper catchment of the Xe Bang Fai River, which lies outside of the Hin Nam No NPA boundary. Additionally, the Xe Bang Fai River itself is the western boundary of the property, not the watershed boundary to the west.

The rugged and steep topography of the landscape, its limited accessibility, and limited areas with agricultural potential mean that Hin Nam No has been subjected to low developmental pressure, apart from the peripheral margins and river valleys. The overall integrity of the property is high and the key threats of wildlife poaching and illegal logging are being addressed by patrolling and enforcement measures, and through the current eo-management approach. A eo-management plan was approved by the Lao Government in 2010 and the State is responsible for the continuing protection and effective management of the Hin Nam No NPA. The eo-management plan will be updated every 5 years.

During the World Heritage nomination and inscription process for Phong Nha - Ke Bang the state parties of Vietnam and Lao PDR were urged to have discussions about a transboundary agreement that would integrate Hin Nam No and Phong Nha - Ke Bang as two separate properties operating on agreed and equivalent management protocols. Further, it was suggested that should such integration take place, it would result in the most important karst protected area in Southeast Asia. In response, there has been formalized cooperation between the two protected areas since 1998, which has recently been strengthened. The two neighboring provincial and protected area authorities have organized annual working visits and exchange activities for closer transboundary cooperation on biodiversity conservation and protected area management.

Comparaison avec d’autres biens similaires

Hin Nam No NPA is part of a large, dissected karst plateau which also comprises the Phong Nha - Ke Bang National Park and Natural World Heritage site across the border in Vietnam. Thus, there are many similarities, but some key differences between the two properties. One of the key differences is the climate on the two sides of the border. On the Vietnam side the prevailing climate is generally moist throughout the year as a result of the influences of the South China Sea and the Truong Son Range, which forms an important divide between the Phong Nha - Ke Bang and Hin Nam No portions of the karst plateau. In comparison, Hin Nam No NPA has a tropical, monsoonal climate with a distinct wet season and a long, hot, dry season. These differences in climate have influenced the vegetation and possibly the geomorphology of the two properties.

In terms of vegetation, habitats and biodiversity (criterion x), Hin Nam No is estimated to be 31% forested, with 20% of dense or mature forest, whereas Phong Nha- Ke Bang is estimated to be 94% forested with 84% of dense or mature forest. Above 700 m elevation, the Phong Nha - Ke Bang side of the plateau supports submontane and tropical moist evergreen forests on limestone karst. The forests in the east of Hin Nam No are the only example of tropical moist evergreen forest on limestone on the Lao PDR side of the plateau. In other areas of Hin Nam No the exposed limestone karst supports a sparse, stunted, open, deciduous forest community of mainly xerophytic species. Hin Nam No generally has lower levels of recorded biodiversity than Phong Nha Ke Bang. For example, Hin Nam No has 452 species of vascular plants, and 377 vertebrate species comprised of 55 mammals, 184 birds, 21 reptiles, 21 amphibians and 96 fish. Corresponding figures for Phong Nha - Ke Bang are 2744 species of vascular plants and 785 vertebrate species comprised of 128 mammals, 314 birds, 117 reptiles, 58 amphibians and 170 fish. However, the 7 primate species recorded for Hin Nam No compare favourably with the 9 primate species recorded for Phong Nha - Ke Bang. lt is unclear to what degree these differences in biodiversity reflect differences in climate or other factors, and how much they may reflect the limited field studies and sampling in Hin Nam No.

In terms of geology and geomorphology (criterion viii), in Hin Nam No the exposed geology dates back to the early Carboniferous (350 Ma, Boualapha Formation), whereas it dates to the late Ordivician – early Silurian (450 Ma, Long Dai Formation) in Phong Nha- Ke Bang. However, an Ordivician-Silurian, Koduk Formation (a corollary of the Long Dai Formation) occurs along the Xe Bang Fai River just south of the southern boundary of Hin Nam No. The karst of Hin Nam No is formed in the Carboniferous-Permian Khammouane Formation, whereas in Phong Nha - Ke Bang the karst contains a Devonian period limestone member, The Phong Nha Formation, which underlies the Carboniferous-Permian Sac Son Formation. The Sac Son formation constitutes the main area of the limestone massifs of Phong Nha – Ke Bang, however cave entrances such as Phong Nha Cave, Dark Cave, etc. occur in the Phong Nha Formation. As for geomorphology, in Phong Nha - Ke Bang the fengcong karst landscape is not quite as dramatic, rising more gently above the river valleys, with less of the high fringing cliffs that so distinguish the Hin Nam No karst.

Compared with other World Heritage karst sites in Southeast Asia, the karst of Hin Nam No is older and more complex, or of a very different character than the karsts of Ha Long Bay in Vietnam, Gunung Mulu in Malaysia, Puerto-Princesa Subterranean River in the Philippines, and Lorentz in Indonesia. Hin Nam No generally has lower recorded fauna and floral biodiversity compared to other karst or biodiversity properties in Southeast Asia, such as Gunung Mulu, Lorentz, and Thungyai-Huai Kha Khaeng and Dong Phayayen-Khao Yai in Thailand. However primate diversity of Hin Nam No is greater than Mulu and equivalent to that at Dong Phayayen-Khao Yai.

On broad criteria that take into account the totality of the karst system, Hin Nam No is probably one of the most significant karst sites in Southeast Asia. There is, however, a lack of knowledge and previous research in many aspects of the site, so its significance will only be fully identified when it has been studied as thoroughly as the other World Heritage properties with which it is compared.