Yangtze River ecosystem

Category: Inland Aquatic Biomes.

Geographic Location: Asia.

Summary: The longest river in Asia, the Yangtze supports a wide array of biodiversity and ecosystems but continues to be heavily reshaped by human activities.

The Yangtze River (also known as the Cháng Jiāng, or Long River) is the longest river in Asia and one of the world’s major waterways, along with the Amazon in South America and the Nile in Africa. It flows through a wide array of ecosystems and environments, and supports rich biodiversity, although environmental degradation has worsened in recent decades. The river and its main tributaries have been immensely important in China’s culture, economy, and history, providing water for a significant portion of the population.

Numerous historical sites along river banks reveal interconnectedness between the river and people. Nowadays, the Yangtze River is a major tourist destination, with some of China’s most spectacular natural scenery. The lower reaches, especially the Yangtze River Delta, represent a major industrial and urban region. The ecosystems have not fared well, generally.

Scope of the River

The Yangtze River is 3,977 miles (6,400 kilometers) in length. Its source consists of glacial melt waters and tributaries in the northeast of the Tibet Autonomous Region. The upper course flows eastward through the Qinghai-Tibetan Plateau, a vast elevated area in central Asia covering most of Tibet and Qinghai Province, and then southeast through Sichuan Province in southwest China. The middle course, between Sichuan and Hubei Provinces in central China, flows through the Three Gorges (Qutang, Wuxia, and Xiling Gorges), a region of 75 miles (120 kilometers) in length, noted for its dramatic natural beauty, cultural importance, and the recently constructed mega-dam, Three Gorges Dam.

The lower course of the Yangtze traverses the lowland plains of central and eastern China, including the Yangtze River Delta. This delta covers 38,456 square miles (99,600 square kilometers) and is an economic and urban center, with major cities such as Hangzhou, Shanghai, Suzhou, Ningbo, and Nanjing. Finally, the river widens into a large estuary and enters the East China Sea near Shanghai.

The Yangtze traverses several regions as it makes its way through China. Together, these areas are inhabited by more than 400 million people, or about one-third of the country’s population. The human population is unevenly distributed along the river. The upper reaches are remote and mountainous, and sparsely populated by subsistence farmers who use natural resources for daily living. By contrast, the middle and lower reaches, especially the Yangtze River delta, represent major industrial, manufacturing, and urbanized areas with high population densities.

Environment

The Yangtze River flows through a wide array of ecosystems. Along its course, dense forests, deep valleys, grasslands, mountains, lakes, rivers, and wetlands support rich biodiversity. The river itself is an important freshwater biome, consisting of numerous other ecosystems, and is home to more than 600 species of aquatic plants and 378 species of fish.

Surrounding areas in the drainage basin are habitats for hundreds of terrestrial animal and plant species, including 280 mammal species, 145 amphibian species, and 166 reptile species. There are endemic—found only here—and endangered species in the Yangtze, such as the Chinese alligator (Alligator sinensis), finless porpoise (Neophocaena phocaenoides), Chinese paddlefish (Psephurus gladius), and Yangtze sturgeon (Acipenser dabryanus). The Yangtze River dolphin or baiji dolphin (Lipotes vexillifer), was declared extinct in 2006. The giant panda (Ailuropoda melanoleuca) can only be found in the wild in the forests of the upper Yangtze region.

In recent decades, environmental degradation of the Yangtze River has intensified. Urban development and an increasing human population, especially in the delta, have converted large areas of natural habitat. Commercial uses of the river include agriculture, forestry, fishing, flood control, land reclamation, and tourism. Environmental problems include deforestation, desertification, soil erosion (especially in the upper and middle sections), increased runoff in floodplains, water pollution from sewage and industrial waste, reduction of lake and wetland areas, high sediment load and siltation, and exhaustion of fish resources.

Poverty in some areas, and dependence on livestock and fuelwood, with few viable economic alternatives, has contributed to unsustainable use of resources. Unsuccessful economic and social campaigns in China’s past have also caused massive environmental damage, such as the Great Leap Forward (1958–60).

Conservation Efforts

Some areas of the Yangtze are protected as nature sanctuaries. An example is the Sanjiangyuan Nature Reserve, or Three Rivers Nature Reserve, at 2.3 million acres (939,441 hectares), sur-rounding the headwaters of the river. Conservation and habitat recovery initiatives being under-taken by both Chinese and international organizations include water conservation, environmen-tal protection and sustainable development, assistance for local governments, environmental education and public awareness, scientific research and monitoring, restoration and sustainable use of wetlands, and initiatives to improve the livelihoods and economic opportunities of local inhabitants. Conservation efforts by provincial governments protected about 6,400 square miles of the river. In 2015 the Chinese environment ministry blocked attempts to construct a hydropower dam on a section of the river which is an important spawning ground for many species of fish. That same year, the central government released a comprehensive plan to significantly improve the water quality of seven major rivers, including the Yangtze. And, in January 2016, President Xi Jinping declared that environmental protection of the river would become a “dominant focus” of plans to develop the Yangtze.

Cooperation among local and provincial officials, representatives of nongovernmental organizations, and representatives of international organizations have led to collective and integrated approaches to river management and environmental and social issues. However, many of these efforts are still in a preliminary stage. Several reserve areas have been awarded United Nations Educational, Scientific, and Cultural Organization (UNESCO) World Heritage Site status.

Floods and Droughts

Flooding is frequent along the Yangtze River, especially in the lower course, which is surrounded by low-lying terrain. Flooding is a natural event attenuated by high precipitation in the mountainous areas of the upper reaches, and also by seasonal heavy rains and monsoons. However, the frequency and magnitude of Yangtze floods have been altered by human activities, particularly deforestation, which increases river runoff and silt deposition on the riverbed, as well as the loss of lakes and wetlands, which reduces water storage capacity and tidal influence. Global warming effects in this region include heavier precipitation events, which also add to flooding woes and erosion.

Catastrophic floods have occurred periodically throughout history, killing hundreds of thousands of people, destroying millions of homes and farms, and disrupting all types of habitats. Flooding along the Yangtze left hundreds of people dead and raised water levels in the Three Gorges Dam to the highest levels since it became operational in 2003. Flood control measures along the river include dams, dikes, embankments, levees, reservoirs, reforestation, and wetland restoration. Though most were created recently, sophisticated flood controls have existed in the Yangtze since ancient times, such as the Great Jinjiang Levee in 1548.

More recently, the Chinese government, with the guidance of international organizations, has developed flood control and prevention plans. A major objective of the Three Gorges Dam was to reduce flooding in the middle and lower stretches of the river, although its success is questionable. It should also be noted that floodwaters can benefit ecosystem functioning by cycling nutrients, fertilizing soil, and providing water resources to arid regions.

Irregular rainfall distribution in some areas of the Yangtze attenuates drought. A severe drought in 2011 and an even worse one in 2022, which on both occasions lasted several months, rendered hundreds of thousands of people without access to adequate drinking supplies. The drying of lakes, reservoirs, and wetlands threatens a large proportion of wildlife. Substantial agricultural and industrial losses have resulted from power rationing in industrial districts, closure of parts of the river to shipping, reduced cargo loads, and stranding of boats.

To alleviate this drought and its consequences, the reservoir of the Three Gorges Dam was partially opened in 2011, and tens of thousands of fish were released in the river to replenish fish populations. The drought of 2022 was part of China's worst-ever heat wave. Climate change is projected to deepen the region’s latent drought conditions, and countermeasures and preventive efforts will have to be redoubled.

Human Interaction

The Yangtze irrigates a large proportion of the country’s total agricultural land and crop production; dominant crops are rice, barley, beans, cotton, corn, hemp, and wheat. Cultivation is intensive in the lower reaches and delta, where climatic conditions and fertile soils are highly favorable for agriculture. There are also extensive aquaculture and fishing industries. Most of these activities displace some proportion of native species; however, the human activity here has been going on for millennia, with consequent co-evolution of fauna and flora in many of the habitats.

According to a 2021 study published in the journal Advances in Water Science, the Yangtze River is slowly drying up, having fallen by an average of 0.8 inches (2 centimeters) every five years since the 1980s. The study blames human actions such as the changing of the river’s course and the construction of dams for the problem.

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