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Tropical Rainforests in Hainan

2021-09-23 15:51:03

Ⅰ. Classification of Tropical Natural Forests on Hainan Island

Opinions differ on the classification of tropical natural forest vegetation types on Hainan Island. Here we list eight subtypes: the mangrove forest, savanna, lowland rainforest, tropical coniferous forest, tropical deciduous seasonal forest, montane rainforest, montane evergreen forest, and montane elfin forest.

The mangrove forest is a type of coastal rainforest formation with the roots in water almost all year round. Mangroves are capable of thriving in salt water, and have aerial roots that enable them to breathe in waterlogged habitats.

The savanna ecosystem is a type of secondary vegetation formed with the influence of monsoon climate after the area is deforested. Savannas in Hainan cover the vast plateau in the west of Hainan Island, which is about 170 km long and 3-20 km wide, extending from Yangpu and Changjiang counties to the coastal lowlands of Yinggehai in Ledong County. Most of the savannas here have been converted into agricultural land with the development of agricultural production in the past three decades. One of the remaining large sections is found in a few places such as a natural reserve for the protection of Hainan Eld’s deer in Dongfang County.

The lowland rainforest is mainly distributed in the central mountainous region of Hainan Island below 800 meters above sea level. It is the most typical type of rainforest on Hainan Island, dominated by species such as Vatica mangachapoi, Hopea hainanensis, Litchi chinensis, Homalium hainanense Gagnep, etc. Not many gymnospermous plants are found there.

The tropical coniferous forest is scarcely distributed, only in the BaWang Ling area, where the Pinus latteri Mason is the dominant species. This tree occupied a larger area in Hainan in ancient times, covering the western part of Hainan Island (Danzhou and Changjiang).

The tropical deciduous forest or monsoon forest is a vegetation type that grows at about 300 meters above sea level. It is typically found in dry areas receiving a small amount of annual rainfall. The trees in a monsoon forest usually shed their leaves during the dry season. The dominant plants are thorny trees. Their thorns are transformed from twigs in order to reduce water evaporation, and the green surface of the thorns allows photosynthesis. This is how plants adapt to the arid environment.

The montane rainforest is the most widespread tropical forest vegetation with more concentrated vertical natural vegetation on Hainan Island. This type of rainforest is scattered at the elevation of 700-1300 meters, dominated by species such as Dacrydium pierrei Hickel, Dacrycarpus imbricatus, Madhuca hainanensis, Cyclobalanopsis championii Oerst, and Schima superba Gardn. et Champ.

The montane evergreen forest is normally distributed on the slopes at an altitude of 1,100-1,500 meters. It has a simple vegetation structure dominated by elfin forest types. Tree ferns, woody vines, buttress roots and stem flowers are rarely seen or not found at all. It also provides habitats for coniferous plants including Keteleeria hainanensis Chun et Tsiang and Pinus fenzeliana.

The montane elfin forest occurs at the top of the peaks above 1,300 meters, especially in WuZhi Shan, YingGe Ling and HouMi Ling. The trees are typically short and curved, represented by Lannea coromandelica, Pentaphylax euryoides Gardn. et Champ., and Fagaceae trees. Abundant epiphytic mosses and lichens cover the ground, tree branches and leaves in the humid forest, creating a fairyland atop.

The Vegetation of China lists Hainan’s tropical forest into a “typical tropical forest belt formed by tropical rainforests and monsoon forests”, and zonal vegetation as tropical evergreen monsoon forest (Dipterocarp forest). The unique natural conditions and altitude changes have constituted a vertical vegetation belt around the forests here. For example, in the western and southwestern parts of the island, tropical semi-deciduous forests and savannas extend to lower elevations, while tropical montane rainforests and mossy elfin forests grow in high-attitude areas. By contrast, the southeastern regions of Hainan Island have more typical tropical rainforests.

Many scholars in China consider the Dipterocarp forest and montane rainforests on Hainan Island as “tropical rainforests” in a real sense, while the arid forests (e.g. tropical semi-deciduous forest) at low altitudes (below 300m, especially in the West and Southwest Hainan) as tropical monsoon forests. While the forests of the humid tropics (not all tropical areas are moist) are often referred to generically as tropical rainforests, they in fact appear in the forms of seasonally arid or semi-arid forests, which can be also taken as rainforests.

From a broad sense, the vegetation subtypes of tropical rainforests in Hainan can be divided into lowland rainforest, montane rainforest, montane evergreen forest, montane elfin forest and mangrove forest, a taxonomy supported by Professor Hu Yujia of Sun Yat-sen University. The rainforest on Hainan Island is typical rainforest vegetation in China. It correlates with the rainforest biome in Southeast Asia and shares similar origins both in terms of species and structure.

II. Changes of Tropical Natural Forests on Hainan Island

Palynology studies prove that the entire Hainan Island was covered by rainforests in ancient times. More than 700,000 years ago, most of the plains, hills and mountains of Hainan Island had plant species such as Cycadaceae, Moraceae, Annonaceae, Sapindaceae and Palmae. Archaeological findings also show that different types of rainforest vegetation were commonly discovered in many coastal areas in the eastern and northern parts of the island over 3,200 years ago, including ferns (Aquilaria sinensis, Cibotium barometz, etc.), gymnospermous plants (Podocarpus macrophyllus, Dacrydium pierrei Hickel, etc.), and angiosperms (Magnolia, holly, oak, etc.). In addition, tall mangroves occupied the coasts, estuaries and bays around the island.

Forests are the cradle of mankind and the basis for the existence and development of primitive agriculture. Cutting down forests is the men’s first step towards civilization. The changes of Hainan’s rainforests are inextricably linked to the history of land development in Hainan. How the land was used during the Republic of China period and how it was deforested has been revealed in the book Research on Land Development in the History of Hainan Island, written by Professor Situ Shangji of Sun Yat-sen University. His findings indicate that Hainan’s rainforests had been shrinking before 1980 as the local population increased.

According to his research and relevant historical materials, the development of rainforests on Hainan Island can be roughly divided into six stages as follows.

1. During the Han and Tang Dynasties, the coverage of tropical rainforests in Hainan began to retreat from coastal areas to inland regions.

According to Professor Situ, the establishment of Zhuya and Daner counties by Emperor Wu of the Han Dynasty made Hainan Island part of the Han empire, when 90% of natural forests covered the island. Historical data show that there were few Han people on the island from the beginning of Han Dynasty to the Southern Dynasties, while the Li nationality was a self-governing community. Slash-and-burn agriculture was a method of cultivation at that time and farmers only had rude production tools such as wooden bow and crossbow and bamboo arrows, which would cause minor damage to the rainforests. Ancient fishermen in Hainan used canoe as a tool probably made from local timbers. Modern archaeology has also found a large number of giant trees in the offshore strata. This is a proof of the widespread distribution of rainforest from the inland to the seaside. Since the Han Dynasty, the frequent wars in the Central Plains forced some Han people to leave their homes and invade the island. Their advanced production tools turned out to have destructive impacts on the local tropical forest ecosystem. During the Tang Dynasty, crops were cultivated around the island. The fast development of handicrafts and construction industries made things worse--quite a lot of coastal rainforests were lost due to deforestation. The exploding growth of population on the island, from less than 20,000 before Tang Dynasty to 70,000 thereafter, has been recorded in the History of Hainan Island edited by Chen Mingshu (1889-1965). Around the time when the Tang Dynasty took control over China, a large number of people settled down on the island after the military leader Mrs. Xian (522-602) ended the 580-year secession of Hainan Island. Still, the population of the island was under control before the Tang Dynasty, which would not pose a threat to the distribution pattern of local rainforests. As a result, the fragmentation and loss of rainforests occurred only in coastal areas of Hainan.

2. During the Song and Yuan dynasties, the destruction of coastal rainforests intensified as human activities began to affect the montane rainforests, and the rainforest ecosystem became fragmented.

The destruction of rainforests exacerbated since the Song Dynasty due to the flourishing trade and the increase of immigrants, as well as the wide application of iron tools in the areas surrounding the WuZhi Shan, the large supply of spices, rattan products and precious timber to the mainland, and the surging demand for arable land and wood. The logging focus was shifted from coastal rainforests to those growing in mountains. Though part of the rainforests extended to the seashore during this period, some deforested areas were converted into grassland and arable land, breaking the original rainforests into pieces. Still, some areas along the coast, especially the eastern coast of Hainan Island, were largely covered by tropical natural forests during the Song and Yuan dynasties, though mixed with cultivated land.

3. During the Ming and Qing dynasties, extensive damage wrought on the local rainforests, particularly those in central mountain areas of the Hainan Island.

During this period, local people deepened the development of the land and the population of Hainan Island ascended from 300,000 in 1393 to 1.25 million in 1835. Large-scale land reclamation and the cultivation of many new crops began to threat the survival of local rainforests. In the Ming Dynasty, Hainan was one of several shipbuilding centers in Guangdong. A large amount of wood was harvested and transported to the mainland provinces. The Ming Dynasty’s military crackdown on the Li ethnic groups and the march of the army accelerated the construction of roads and bridges, which raised the demand for large-scale logging. In 1887, Hu Chuan, father of the famous modern writer Hu Shi, was commissioned by the local governor Zhang Zhidong to visit the Li community in Hainan. In one of his travel diaries, he described what he witnessed in Nanfeng Town of Danzhou City and Fanyang Town of Wuzhishan City. He saw there were no vast wastelands or forests in the region, but lush vegetation was scattered around the mountains. Some tree species such as wenge, rosewood, Phoebe and Manglietia hainanensis Dandy were cut down, with only one or two trees left. The fertile land and species-rich forest, as what the region was reputed, no longer existed. His travel notes suggest that the rainforest degradation on Hainan Island back then was accelerating, and the rainforests in the central mountainous areas had been ruined.

4. During the Japanese invasion of China, the rainforest resources of Hainan Island were depleted with a sharp decline of rainforest cover rate.

The most devastated period for tropical rainforest resources on Hainan Island lasted from 1900s to 1940s. In nearly 1,500 years from 110 B.C. to 1368 A.D., the percentage of forest cover on Hainan Island decreased by only about 5%, with a one percent drop every 300 years. However, the figure fell by 15% from 1933 to 1950, an equivalent rate of one percent a year. Japan sent a group of experts to investigate the rivers, forests, minerals, and ethnic groups of Hainan before invasion. In the Sketch of Hainan Island published by Japan in the 1930s, resources including timber, eaglewood, iron ores, borax and other resources were clearly marked. During the Japanese occupation of Hainan Island, four Japan-funded enterprises cut down the rainforests in today’s Sanya, Lingshui, Dongfang, Changjiang, as well as other cities and counties on a large scale. They set up more than 20 timber processing plants, with a record of more than 14,000 m³ of forest harvested each year.

5. From mid 1940s to 1970s, the rainforests were destroyed to support the country’s construction projects.

In 1950, the People’s Liberation Army completely liberated the Hainan Island. The rainforest ecosystem in the island gave way to the country’s economic development. By 1979, the natural forest cover of Hainan Island was only 10.42% according to the data from the continuous inventory of forest resources in China, and the natural rainforest occupied a total area of less than 2.1 million mu.

6. Since China entered the new period of reform and opening up in 1978, deforestation was curbed and rainforests on the island were gradually protected and restored.

In July 1980, the State Council required that the management of forestry in Hainan follow the principles of protection, restoration and development. Since then, 11 state-owned logging enterprises based in forest regions such as JianFeng Ling, BaWang Ling and DiaoLuo Shan shifted their business focus from wood production to afforestation. The yield of the logs harvested decreased year by year. On July 30, 1993, the 3rd session of the Standing Committee of the 1st People’s Congress of Hainan Province approved the Regulations on Protection and Management of Forests in Hainan Province to try out a complete ban on commercial logging since the first day of 1994. This made Hainan the first province in the country to ban commercial logging of natural forest. In 1998, Hainan first proposed the construction of an ecological province. In 1999, the Hainan Provincial Government issued the Outline of Hainan Ecological Province Construction Plan. In 2000, China launched the Natural Forest Protection Program (NFPP) to protect natural forest resources in key areas of the country, including Hainan tropical forests. In 2004, China established a compensation fund system for forest ecological benefits. In 2007, the 5th Party Congress of Hainan Province set up the goal of constructing Hainan as an ecological province. These policies ensure the comprehensive and effective conservation of Hainan’s tropical forests from legal and financial aspects.

With great importance attached to ecological protection by successive provincial governments, the area of tropical natural forests in Hainan recovered to 9.89 million mu by 2018, registering a natural forest cover of 19.17%. Today, the percentage of forest cover on Hainan Island stands at 62.1%, the fourth highest among China’s provinces (cities and districts).

III. Distribution of Tropical Natural Forests on Hainan Island

The tropical natural forests of Hainan Island are mainly distributed in mountainous areas 500 meters above sea level or higher in the southeast, south central, southwest and central parts of the island. Short-term frosts that may occur in alp zones have little impact on the rainforest vegetation. At present, tropical natural forests on Hainan Island are primarily found in YingGe Ling, BaWang Ling, JianFeng Ling, LiMu Shan, DiaoLuo Shan, WuZhi Shan and Maorui Forest. These natural reserves cover about 10 cities and counties of Hainan, including Baisha, Qiongzhong, Changjiang, Ledong, Dongfang, Wanning, Lingshui, Baoting, Wuzhishan and Sanya.

National Park of Hainan Tropical Rainforest

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