This is the second post in the Wetland Wednesday series, edited by Gabrielle McLaren.

---

If you could travel back a few millennia in a boat-shaped time machine and visit the wetlands along the lower 1,000 kilometres of China’s Yangtze river, you would encounter a land-and-waterscape that no longer exists. On land you might see elephants, rhinoceros, wild water buffalo and various species of deer. Alligators and huge turtles would be basking on the shores. The waters would teem with fish, some of them enormous, and you might also see freshwater dolphins. Above, you may see the vast flocks of migratory birds that visited the wetlands. Your boat could visit a much larger area if you visited in the summer since these wetlands were seasonal: monsoon floods submerged vast areas in the warm half of the year and then they gradually dried out over the winter. If you visit the region now, you will not see much wildlife, but rather a landscape that is home to hundreds of millions of people, its land intensively farmed and increasingly covered in asphalt and concrete. The environmental transformation is so extreme that it requires research to even imagine what the wetlands once looked like.

I am an environmental historian trying to reconstruct the ecology of these lost wetlands and trace the long history of how they were gradually replaced with farms. Unlike many other parts of the world, this region’s wetlands were not drained to make dry land but were instead turned into agricultural wetlands. Generations of farmers and government officials worked to replace the region’s natural wetland ecosystems with wet fields and ponds in which a handful of native domesticated species are intensively grown and reared. The most important is wet rice, domesticated in these wetlands from a native grass, and the main food source that allowed the region’s human population to grow. Rice is grown in paddies that mimic the monsoon cycle: it is planted in water whose level is gradually reduced until the rice is harvested from fry fields. Rice has been grown for at least 8000 years, and over the subsequent millennia people have domesticated other native wetland species including ducks, geese, lotuses, and several species of carp. Along with human beings and terrestrial domesticates like pigs and chickens, these are now the dominant species in these wetlands.

Humans have transformed these wetlands not by removing their water, but by controlling it. By building a system of dikes across the lowlands, people have replaced the seasonally flooded wetlands with agricultural ones in which they can carefully manage water levels for optimal productivity. This began over two thousand years ago, as revealed by wooden documents dug from the region’s waterlogged soils. For most of history, people built dikes along the relatively dry edges of the wetlands to protect against the largest floods, but as China’s population climbed into the hundreds of millions in the centuries after 1600, land-hungry farmers built dikes and polders in the deeper wetlands, often condemning themselves to a dangerous existence at the mercy of waterlogging and floods.

“Humans have transformed these wetlands not by removing their water, but by controlling it.”

Since the founding of the communist government in 1949, state power and modern technology have improved the quality of the dikes while eliminating most of the remaining wetlands, so that fishing for wild fish has largely been replaced with fish farming. China is by far the world’s leading producer of farmed fish. The transformation of the region’s hydrology culminated in the 1990s with the world’s largest dam, built across the Yangtze River in the Three Gorges region. The Three Gorges Dam has disrupted the seasonal flood cycle that had shaped wetland ecosystems in the region for millions of years, with profound effects on wetlands downstream. These changes are difficult for scientists in China to study because the dam is politically sensitive.

One of the biggest questions in reconstructing the region’s lost ecosystems is to understand what once grew along the edges of the wetlands, since these are the areas that people have been farming for thousands of years. Wetlands scholars frequently cite figures for how much of the world’s wetlands have been lost, but these figures tend to be based on a historically recent baseline, like 1800, and do not consider the effects of older civilizations on their environments. In the lowlands of the Mississippi River, whose climate and size resemble those of the Yangtze, there are seasonally flooded forests, and year-round swamps with cypress trees growing out of the water. It is unclear whether there was anything comparable in China. The subtropical forests that once blanketed the plains and hills of the Yangtze basin have been replaced by farms and tree plantations, and most of the region’s terrestrial wildlife is gone.

“Wetlands scholars frequently cite figures for how much of the world’s wetlands have been lost, but these figures tend to be based on a historically recent baseline, like 1800. These approaches do not consider the effects of older civilizations on their environments.” 

In recent decades even the fluvial wildlife has been decimated. The completion of the Three Gorges Dam was a disaster for the river’s larger inhabitants, and was followed by the extinction of the Yangtze River dolphin, the Yangtze sturgeon, the Chinese paddlefish—which may soon be followed by the critically endangered Chinese sturgeon. Most remaining alligators now live in concrete pens, and only two Yangtze softshell turtles remain, both male. While the Chinese government is making efforts towards conservation, these cannot compete with its primary goal, which is economic development. The histories of the wetlands of East Asia are inseparable from the history of agricultural societies that have been using them to grow food for thousands of years, and the wetlands have been lost through a process whereby the entire landscape has been in a sense domesticated.

For more information see my article: Brian Lander, “From Wetland to Farmland: How Humans Transformed the Central Yangzi Lowlands,” Asia Major 35.1 (2022), 1-31. https://www1.ihp.sinica.edu.tw/en/Publications/AsiaMajor/1145

Feature Image: View of the Yangtze waterfront in Xintan Town, near the mouth of the Neijing River. Image courtesy of Wikicommons, licensed under Creative Commons 3.0 Share-Alike License.