Asia: Phong Nha-Ke Bang National Park, Viet Nam

Map

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Location Overview

Weather & Climate

Our weather and precipitation data will be taken from Dong Hoi, Vietnam (17.46885° N 106.62226° E) which is a nearby city to Phong Nha-Ke Bang National Park (17.5911° N, 106.2833° E).

The average temperature each month in Dong Hoi, Vietnam does not tend to fluctuate much throughout the year. Temperatures generally fall between 67-87° F, with the average of the entire year being 77° F. May through October is considered the summer season, where the average temperature of both June and July is 87° F. The coldest months are from November to February. The average temperature range for these months is 67-73° F. (1)

Vietnam has a wet and dry season. Wet seasons vary across Vietnam depending if the location is northern, central, or southern. In Dong Hoi, the wettest months are September, October, and November with a precipitation range of 14.2-21.4 in. On average, half of the days during these three months are rainy with September having 16 rainy days, October having 17, and November having 15. This is drastic compared to February only having 1.7 in. of rain and 3 rainy days per month. The annual precipitation in Dong Hoi is about 82.3 in. with 104 rainy days. (1)

Vietnam is located in both tropical and temperate zones. Vietnam has sunlight, heavy rainfall, and high humidity levels. Phong Nha Ke Bang national park’s climate is that of tropical, hot, and humid. Regions in the mountains have more temperate and slightly cooler climates.

Humidity & Fog

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There are two villages, Arem and Ma Coong, living at the core of the park. The people within these villages tend to exploit the forest for their livelihood. Wild pig, binturong, rare ells and primates are the major targets of poaching. But many other species face the devastating effects of poaching. Rare wood, such as Go Mun wood and Go Hue wood, and limestone also draw locals to harm the forest. The harvesting of these resources force many animals to be pushed away from their regular habitat.

While the Ho Chi Minh Highway has provided access to the park, constant assessment is required to check the environmental impact of it. New road construction or tourist development plans are subjected to rigorous review to determine if they will be detrimental to the park. This is because tourism has increased water pollution, as well as trash pollution throughout the park.

The most recent development that has environmentalists concerned is the approval of a coal-fueled thermoelectric plant in the Quang Trach district, only about 25 miles northeast of the park (10).

This place perennial rains, leading to erosion of soil and caves, In addition to the need to prevent violations of alien species (21).

Ecoregion and Biome

Part of the Annamite moist forest ecoregion. There are mainly tropical and subtropical, moist, broad leaved forests. This means that there is low variability in temperature and high rainfall in the area. The forests are dense and have close to the highest amount of species diversity. Forests such as these are home to half the world's species. Another key characteristic is the explosive growth of vegetation. A tree may grow 75 in only 5 years. These tall trees create a canopy which is home to many kinds of monkeys and birds. This canopy is a defining characteristic of the biome.

Topography

Vietnam’s topography is very diverse with hills, mountains, plains, and coasts. The topography influences the distribution of plants and animals in many different ways. Around 85% of the mountain ranges in Vietnam are under 1,000 meters. Only 1% is over 2,000 meters.

The soil has a low cation exchange capacity which means most of the nutrients have been lost and makes it difficult to hold nutrients which makes crop site selection more particular. Over two-thirds of the population lives in the lower regions due to rich soil from mountain ranges.

Climate: Plant & Animal Life

Considering this national park of Vietnam is found in the Annamite moist forest ecoregion and are mainly comprised with subtropical, moist, brad leafed forests, this greatly influences the development and type of plant and animal life found in this area. Climate in this area is quite temperate to warm with average temperatures in the mid 70s through the majority of the year. Additionally, part of the year is defined by being the wet season and can get quite severe with monsoons and flooding.

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There is a wide variety of plant life in Vietnam, but the majority of plant life falls under the category of tropical or subtropical broadleaf trees. As it is sunny for the majority of the year, the broad leaf trees are able to grow and flourish creating a canopy over the ground. While these trees are able to grow, plants that are closer to the surface often do not survive. Although, there are few plant species that benefit from the cool yet humid atmosphere under the larger trees and are able to flourish. Along with this, the growth of bamboo is quite common and frequent in this area. Taking into account the typhoons and other natural disasters that occur during part of the year, and causes the canopy to open and provides a clearing for the bamboo to grow. (10,12)

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This area is also a host for a wide variety of animal life. The most common animals are ones such as Indian elephants, various types of bears, Indochinese tigers/leopards, multiple types of monkeys, bats, flying squirrels, turtles, otters, crocodiles, snakes, and lizards. Elephants have adaptations such as large ears to fan themselves, as well as trunks that are able to assist them in cooling off as the climate in Vietnam is fairly hot. Based on the climatic influences of plant life in this area, Flying Squirrels have the ability to glide easily between tall deciduous trees without risking their lives on the ground level. Finally, the Indochinese leopards are quite adaptable to their environment. In Vietnam, the environment is ideal as they spend their nights hunting and often take their prey into trees so others do not feed off of what they have killed. The environment that has been influenced by the climate is ideal for this species as it provides many of the ideal habitat features they are looking for. (10, 11,13, 14)

Factors Influencing Vegetation and Wildlife

Altitude, moisture, location the slope of the area, and thickness of the soil are all factors that have an influence on what type of vegetation and wildlife exist. During the summer time, rain hurts the vegetation in the park by causing floods. These floods overwhelm the plants and slow down the growth process. The thickness of the soil plays a role in the growth process as well. The soil thins out during the winter season and the dryness prevents growth for vegetation. This then leads animals to struggle and find food. Also, the park is in a position where the weather changes rapidly and unexpectedly. This is due to the low altitude of 41 ft and the park being near an ocean. The environment allows rainforest type of animals to live here and vegetation to sprout.

Common Rock Types And History

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Phong Na-Ke Bang is the oldest and largest karst area in Asia. This means that its landscape consists of weathered limestone which create its rocky caves and cliffs. It is one of the the world’s largest limestone regions that is still intact. This was caused by the rising and lowering of sea levels in the area as well as tectonic uplift over millions of years as Vietnam as a whole is very close to a plate boundary. The iconic caves of the park consist of all limestone as it is a weaker rock that can easily be weathered down and has actually caused the park to house the largest Cave in the world, Hang Son Doong (Mountain River Cave) (36). There are areas of the part that are not limestone but they are a minority and less specific to the park.

Weathering and Erosion

Phong Na-Ke Bang is located in the middle of the Annamite Mountain Range in Quang Binh province. Here, the park experiences significant erosion mainly from rain and the wind. Within the park, many rivers and caves are affected due to heavy rain that occurs between the seasons of August and December. Storms such as monsoons occur regularly during these months and with limestone being the main source of rock in the region, the natural formations deepen. As a result of this, a karst landscape is formed due to the weathering of the limestone. (20)

Other Landforms

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The formation of karst landforms from the Paleozoic (about 4 billion years ago) is the oldest karst landscape in Asia, and the buds and gabbands are all of the same plains. Limestone is not continuous. Shale and sand are found in the deposition layer. A region of slate and granite can also be found. These rocks come together to form a unique terrain. There is also a cavern of about 700 meters of water depth in the park. Because the water level rises sometimes, a large number of stalactite caves are also found beneath the ground. (22)

Liquid Water Impact

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There is an extreme abundant amount of water in Vietnam. The rivers that traverse Vietnam have about 255 billion m^3, but due to inadequate infrastructure and poor financial capability they only utilize about 53 billion m^3 per year. The upland A’vuong watershed system is one of the few on the Thu Bon river. Phong Nha Ke Bang is home to the largest underground river. The large majority of the caves have been formed by the Son and Chay Rivers. There are tons of incredible streams and waterfalls throughout the cave as well. (23)

Plate Boundaries

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As a result of the splitting up of Gondwana and the later collision of what is now India and the rest or Asia, ruby deposits formed in Luc Yen, Vietnam. Granitic rocks at Luc Yen intruded into limestone and spinel deposits were also formed. (25)

Like previously stated, the karst in Phong Nha-Ke Bang has been evolving from the karst in the Paleozoic era which dates back to over 400 million years ago. Changing sea levels and tectonic uplift have led to seven different levels of karst development. Phong Nha-Ke Bang is also home to the Phong Nha cave which holds four records. These records include containing the longest underground river, the highest and longest cave, the broadest fine sand beaches in the cave, and for the stalagmites and stalactites. (10)

While Vietnam does not have any plate boundaries within its borders, it is relatively close to multiple. West of Vietnam in Myanmar, is the Burma Plate or the Sagaing Fault. This strike-slip fault (or transform boundary) is about as long as the San Andreas Fault and also has an average slip rate of 18-20 mm each year. (26) Farther west of this fault is the convergent boundary between the Indian Plate and the Eurasian Plate. The Indian Plate moves northward about 4-6 cm per year. The compression and folding of plates created the Himalayas and the Tibetan Plateau. (27) East of Vietnam is the Philippine Plate. This plate is moving westward towards the Eurasian Plate. This plate movement has created a line of numerous volcanoes all along the Philippines. (28)

Plate Boundary Formations

Phong Nha-Ke Bang National Park is located in the midst of the Annamite Mountain Range. This range of mountains created by the convergence of the Eurasian and Indian plate boundaries and Euruasian and Phillipine plate boundaries, runs parallel to the Eastern coast of Vietnam and ranges for about 700 miles. (27) Additionally, there are a significant amount of volcano formations in this area of Vietnam as well. Located in Southeast Vietnam, The Bas Dong Nai volcanic field with an elevation of just over 1,000 feet is located but has been inactive for many years. While there are many other volcanoes in the area or off the coast of vietnam (Haut Dong Nai, Toroeng Prong and Veteran for example) there is limited information on these formations as they have been deemed “holocene” or have only had their last eruption approximately 11,700 years before now. (31, 32, 33)

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