Hin Nam No National Protected Area

Description

Hin Nam No National Protected Area (HNN NPA) is situated in central Lao PDR, where the Central Indochina Limestone meets the Annamite Mountain Chain. It 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. It 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 (PNKB) karst bas been designated as a National Park and Natural World Heritage site.

The characteristic landscape style of the Hin Nam No karst is that of a dissected plateau of karst massifs that are 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 dissected by karst processes into polygonal karst relief, with deep depressions (cockpits) surrounded by residual conical hills (fengcong). White most of the area is forested, bare rock surfaces on the massifs and fengcong have frequently been eroded into sharp and spectacular pinnacles. The Xe Bang Fai River has cut a 6.4 km underground course through the limestone karst, creating the largest active river cave passage 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 at least 10 species of primates, 9 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 ebenus) 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 at least 4 species of hornbill (Bucerotidae). one of which, the Wreathed Hornbill (Rhyticeros undulatus), is globally threatened.

Justification of Outstanding Universal Value

Hin Nam No NPA is considered of outstanding universal value (OUV) based on the development of its complex and spectacular karst landscape (criterion viii), significant on-going biological processes especially évident in speciation events within surface and subsurface karst ecosystems (criterion ix), and its wide variety of pristine habitats supporting high biodiversity, including a number of globally threatened species, endemi species and karst specialist species (criterion x).

Criterion (viii): Hin Nam No NPA is an exquisite natural property whose karst landscape illustrates superbly the complex variability of humid tropical karst landforms and hydrology. Its landform style and intensity of dissection displays huge variety as the Hin Nam No karst plateau is traversed. The plateau has become dissected by karst processes into polygonal karst relief; a topography similar to an enormous egg-tray, where a multitude of deep depressions (cockpits) are surrounded by residual conical hills (fengcong).

In addition to the surface landforms, the subterranean hydrological features of Hin Nam No are also striking, even on a global scale. This is because of the monsoonal climate that, in a short season, delivers huge quantities of water to the karst. Then, as is characteristic of the polygonal karst landscape style, this torrential rain is drained rapidly underground and discharged by efficient subterranean conduits to huge springs. Thus, the discharge of water from the Xe Bang Fai Cave during the wet season has the largest peak flood flows of any karst spring worldwide.

The Hin Nam No karst has many landform features in common with Phong Nha-Ke Bang, which is to be expected, as they are developed in the same karst block with a similar geological and climatic history.Thus, Hin Nam No shares and adds depth to the Outstanding Universal Values under criterion viii already recognized at Phong Nha - Ke Bang. In addition to the rich variety of polygonal karst, these include very large river caves, and ancient episodes in the development of the karst, recognized as paleokarst.

The large annual discharges of water through the Xe Bang Fai Cave have created the largest active river cave passage in the world. The active river passage follows a 6.4 km underground course, and averages 76 m in width and 53 m in height, with a maximum width of 200 m and a maximum height of 120 m. The volume of the active river passage has been measured by 3D laser scanning to be 23.8 million cubic meters, above the dry season river level. In addition to its immense size, the Xe Bang Fai Cave is superbly decorated with speleothems, including many large and beautiful stalagmites, flowstone draperies, cave pearls and gour pools, including a 61 m long gour basin considered to be the world’s largest single gour pool to have formed in a cave. 

The paleokarst evidence in Hin Nam No points to the formation of a Late Triassic karst landscape which was subsequently buried by thick deposits of Jurassic and Cretaceous terrigenous sediments, thus creating a paleokarst. Then renewed tectonism associated with the Himalayan orogeny, between 70 and 50 million years ago, led to further uplift and faulting and initiated a new phase of erosion during which much of the clastic cover beds were stripped off, in the process exhuming and rejuvenating the Triassic paleokarst. In the Hin Nam No area, patches of Mesozoic cover beds still remain, especially on Phou Chuang mountain, where craggy isolated outcrops of underlying limestone protrude on the lower slopes. These emerging limestone hills are exhumed remnants of the late Triassic landscape. 

Hin Nam No is also internationally significant because the combined area of Hin Nam No plus Phong Nha-Ke Bang is possibly the largest still-natural region of humid tropical karst in the world, hence it is extremely special because of the rarity of such pristine environments. Thus, Hin Nam No provides a rare opportunity to considerably enhance the integrity of the existing World Heritage property by creating the largest unspoilt karst reserve in the world. Furthermore, the excellent condition of the area's monsoon forest permits natural geomorphic processes to continue unimpeded and will do so for the foreseeable future; thus allowing landscape features to be naturally maintained.

Criterion (ix): Hin Nam No NPA forms a sizable portion of one of the most notable, large karst landscapes (Phong Nha - Ke Bang - Khammouane Karst Landscape) in Southeast Asia, which straddles the Annamite Range running roughly along the international border between Laos and Vietnam. This landscape represents the most significant and essentially intact karst ecosystem component within the Annamites Range Moist Forests, Global 200 priority ecoregion with outstanding biodiversity value that are currently represented on the World Heritage List solely by the PNKB World Heritage Site (WHS).

Considering its geological and ecological characteristics, the vast area of HNN supports significant on-going biological processes especially evident in speciation events within surface and subsurface karst ecosystems. The mixture of geological characteristics, topographies, climatic conditions, and the underlying complex landscape and climatic history are basis for the development of these diverse ecosystems and evolution of a multitude of endemic species. It also allows the continued development and evolution of these ecosystems. With HNN located in the zone of convergence of the Central Indochinese Limestone and the Annamite Mountain Chain, the special endemisms of both areas produced a mixed fauna and flora adding to the biodiversity conservation value. The tops of the remnant limestone formations in HNN represent true ecological islands in the vast flatland areas of Eastern Indochina and are home to many relict and migrant species stemming from the prehistorical climate fluctuation periods. These species have since evolved into their own endemic Indochinese taxa - a process that mirrors the continuous transformation of unique terrestrial ecosystems and habitats.

The on-going biological processes in HNN date back to the period of the last glacial maximum when arguably, the area functioned as a refuge for forest-dependent taxa. Here, the species underwent allopatric speciation increasing the diversity even more within these groups. In addition, it appears that other species separated into several (sub-) species following the fragmentation of their habitat by the ever-progressive erosion of the limestone plateau into separated outcrops. Examples for this process include the Lao Rock Rat, Bent-toed Geckos and several strictly endemic floral elements. Furthermore, the HNN karst has a multitude of subsurface levels, which provide ideal conditions for speciation. The isolation-driven speciation in those caves is quite apparent particularly in the Heteropoda spiders and blind cave fish.

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.

In total, 6 major pristine vegetation types have been identified in Hin Nam No NPA. Other important habitats include bare rock on karst mountain tops, riverine, lacustrine, and cave ecosystems. Specifically, lowland evergreen forest is present in the valleys within the karst (locally known as khouans), hill evergreen forest grows on the steep karst slopes, upper evergreen forest is located at higher elevations found on sandstone, and bare rock occurs at the top of the karst or on cliff faces. This diversity of habitats, some of them offering special conditions, provides for high levels of biodiversity and endemism.

Surveys of surface habitats in Hin Nam No have recorded 1520 vascular plant species, and 543 vertebrate species including 95 mammals, 254 birds, 98 reptiles and amphibians and 96 fish. Of these vertebrates, at least 48 species are globally threatened. Most notably, Hin Nam No contains 10 (11) species of primates, 9 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 ebenus) 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 Wreathed Hornbill (Rhyticeros undulatus), is globally threatened. Other globally threatened species include: Bear Macaque (Macaca arctoides), Southern Pig-tailed Macaque (Macaca leonina), Large-antlered Muntjak (Muntiacus vuquangensis), Sambar Deer (Rusa unicolor), Sunda Pangolin (Manis javanica), and Asiatic Softshell Turtle (Amyda cartilaginea). The Bare-faced Bulbul (Nok hualon), the Limestone-Leaf Warbler (Phylloscopus calciatilis) and the Sooty Babbler (Stachyris herberti) are bird species endemic to the Central Indochina 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 five endemics, including a cave-adapted fish species (Speolabeo musaei) which is endemic to Hin Nam No 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 and its strict endemic cavernicolous sister species Heteropoda steineri.

Despite the many occurrences 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.

Statements of authenticity and/or integrity

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 94,121 ha of the Hin Nam No NPA. On the Vietnam side, the karst plateau covers an area of 200,000 ha, with 123,326 ha within the boundaries of Phong Nha - Ke Bang National Park.

All geologic and geomorphologic processes and features that convey Hin Nam No NPA's outstanding universal value under criterion viii (see above) are represented within the current boundaries of the property. 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 co-management approach. A co-management plan was approved by the Lao Government in 2015 and the State is responsible for the continuing protection and effective management of the Hin Nam No NPA. The co-management plan is updated every 5 years.

During the World Heritage nomination and inscription process for Phong Nha - Ke Bang (date of inscription: 2003; extension: 2015), the States Parties of Vietnam and Lao PDR were urged to discuss a transboundary agreement that would integrate Hin Nam No and Phong Nha - Ke Bang, as this would create the most important protected karst area in Southeast Asia. The formalized cooperation between the two protected areas since 1998 is currently gaining increased importance, as an official commitment has been made on the central level of the States Parties of Lao PDR and Viet Nam to nominate the HNN NPA as an extension to the PNKB WHS, thus resulting in a single transboundary WH property. The corresponding MoU has been signed on 10th January 2018 between the Ministry of Information, Culture and Tourism of Lao PDR and the Ministry of Culture, Sports and Tourism of the Socialist Republic of Viet Nam.

Comparison with other similar properties

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 of the two properties.

In terms of vegetation, habitats and biodiversity (criteria ix, x), Hin Nam No supports pristine forests at nearly all appropriate environments, with percentages of coverage comparable to Phong Nha - Ke Bang with estimated 94% forest. The forests in the east of Hin Nam No are the only example of tropical moist evergreen forest on limestone on the Lao 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 including high numbers of strict endemics. Hin Nam No generally has lower levels of recorded biodiversity than Phong Nha - Ke Bang. For example, Hin Nam No has 1520 vascular plant species, and 543 vertebrate species including 95 mammals, 254 birds, 98 reptiles and 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 10 (11) primate species recorded for Hin Nam No surpass the 9 primate species recorded for Phong Nha – Ke Bang as well as many other areas if this latitude. Experts suggest that the differences in numbers are due to the comparably lesser amount of studies conducted in HNN.

Hin Nam No generally has lower recorded faunal and floral biodiversity compared to other karst or biodiversity properties in Southeast Asia, such as Gunung Mulu in Malaysia, Lorentz in Indonesia, and Thungyai - Huai Kha Khaeng and Dong Phayayen - Khao Yai in Thailand. However, the primate diversity of Hin Nam No is unparalleled by comparable sites and unusually high for a site at this latitude.

In terms of geoheritage values (criterion viii), it is most relevant to compare Hin Nam No with other humid tropical or subtropical cone and tower karst sites developed on compacted carbonate rocks of Paleogene or greater age, which are on the World Heritage or Tentative List. Such World Heritage sites include: the South China Karst, Lorentz National Park in Indonesia, Gunung Mulu in Malaysia, Trang An Landscape Complex in Vietnam, and the neighbouring Phong Nga - Ke Bang in Vietnam. On the Tentative List, there are two such karst sites in Papua New Guinea.

The karst landscapes of Hin Nam No and Phong Nga-Ke Bang have many landform features in common, particularly a rich variety of polygonal karst and very large river caves. This is to be expected, because they are developed in the same geological block with a similar geological and climatic history. Ancient episodes in the development of karst are recognised as paleokarst, both in Phong Nga-Ke Bang and Hin Nam No.

Compared with the other karst sites listed above, it is clear that the qualities of the karst landscape at Hin Nam No are spectacular, highly varied and unusual, possibly only matched on the island of New Guinea. No other World Heritage or Tentative List site presents such a variety of polygonal karst features, except for neighbouring Phong Nga - Ke Bang. The combined area of Hin Nam No plus Phong Nga - Ke Bang is possibly the largest still-natural region of humid tropical karst in the world, hence it is extremely special because of the rarity of such pristine environments.

Considering the entirety of its karst System, Hin Nam No sharehs and adds depth to the Outstanding Universal Values under criteria viii, ix and x already recognized at Phong Nga - Ke Bang. By being immediate adjacent, Hin Nam No provides a rare opportunity to considerably enhance the integrity of the existing World Heritage property by creating the largest unspoilt karst reserve in the word, 2.3 times larger in core area than the celebrated South China Karst and all in one piece, so providing much more security for its associated ecological and biodiversity values and being much easier to manage.