This video segment adapted from "Hope in a Changing Climate" examines efforts to restore agricultural productivity to areas of China and Ethiopia. First, filmmaker John Liu tells the story of China's 640,000-square-kilometer Loess Plateau. He details how thousands of years of farming and grazing led to unparalleled erosion and a loss of soil fertility, and explains how scientists and engineers implemented a plan to reverse the destructive process. Liu then shows us steps taken to restore vegetation to the eroded Ethiopian landscape, which had been devastated by drought. Both restoration efforts have helped fight global climate change, biodiversity loss, flooding, drought, hunger, and poverty.
Scientists and economists agree that the natural world is in a steep and accelerating decline. The world has lost 40 percent of its forests in 300 years and 50 percent of its wetlands in 50 years. There is increasing soil loss, severe erosion, and growing water scarcity. We have reached the point that unless urgent remedial action is taken, population growth and global climate change will lead to further decline.
All around the world there are areas that could benefit from ecosystem restoration—that is, a reversal of destructive processes and a return to healthy and sustainable conditions. In some places, innovative approaches and technologies have already been used to clean and manage contaminated waterways, such as rivers that have long been polluted by industrial waste, and contaminated land, such as former military installations. China's Loess Plateau has recently become an inspiring example of a land restoration effort that has transformed agriculture and the local environment.
The Loess Plateau of northwest China covers some 640,000 square kilometers (about the size of Alaska). It is built of alternating layers of soil that reflect the region's climate. During dry periods, strong winds blow in a finely ground, yellow sediment from the desert. This material is called loess. During wet periods, a darker, more humus-rich soil develops. Loess soils are high in mineral nutrients, including nitrogen, potassium, and phosphorus, and retain water. Thus, they are highly productive despite the region's seasonally dry climate. Because the Loess Plateau is well suited to agriculture, natural forests were largely replaced centuries ago by cropland and pasture for livestock, especially goats, which accelerate soil erosion even more than sheep do.
Loess provides good agricultural soil, but it is prone to wind and water erosion. With the loss of forest cover, erosion increased—to the point that scientists regarded the plateau as the most eroded place on Earth. To reduce the land degradation, the Chinese government made efforts to restore the ecological integrity of certain areas. The primary objective of restoration of the Loess Plateau was to increase the agricultural production over about 30,000 square kilometers of land—about the size of Maryland—and the incomes of the local farmers. The project was designed to establish high-yield crop production over some of the land while banning subsistence farming by the poorest farmers and grazing on the slopes.
The Chinese rebuilt the landscape, planting tree cover along the hilltops and creating farming terraces, or level sections of land, below. They planted the short sections of slope left between the terraces with shrubs and grasses to stabilize the ground and lessen sediment run-off. They also constructed dams in the valley below to stop the sediment that did run off before it could clog up the river downstream. By engineering the landscape and replanting vegetation across key ecological areas, the Chinese changed the environment in ways that allowed produce to fill the markets and lifted farm incomes threefold. It also achieved an environmental benefit with respect to climate change. By replanting the area, the Chinese are able to offset some of the greenhouse gas emissions produced by their growing industrial economy. Plants, through photosynthesis, convert carbon dioxide into oxygen.
Here are suggested ways to engage students with this video and with activities related to this topic.
For more media and information about the topics in these teaching tips, see these links:
To learn more about the many ecosystems that make up Florida's Everglades, check out An Everglades Visit.
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