South China Degraded Land Issues

With per capita arable land as low as 0.03 ha in some parts of South China, further loss of productive land is a serious problem. A challenge exists now to blend old Chinese technologies with Western science and technology into new systems for land improvement in South China and to apply them to solve the degraded/abandoned land problem. China’s population is still growing at about 7-8 million per year placing increased importance on improving their degraded land “resource”. “Rehabilitation of degraded places may become the dominant activity of conservationists in the twenty-first century” (Soule, 1989).The climate, parent rock, and topography of South China predispose it to soil erosion problems. Human-induced factors such as rural industrialization, spreading urbanization, expanded transportation systems, over-exploitation of forest resources, opening new agricultural lands, and poor farming practices compound the situation (Zhou G., 1991). To a certain degree, this is a result of early Chinese policy that identified tropical South China as the “nation’s breadbasket” and a corresponding goal of having each province become self-sufficient in food production.

China’s approaches to reducing soil erosion

Chinese scientists, technicians, and innovative farmers have developed a variety of approaches to reduce erosion quickly (Parham et al., 1993). Commonly, they combine engineering and biological measures first to stop or slow damaging erosion. Plantings include trees, shrubs, grasses, and legumes. However, many of the plants are exotic species and, thus, may have adverse effects on the long-term success of reestablishing China’s wildlife population. In addition, establishing a new vegetative cover on barren or highly degraded lands may provide a habitat for unwanted organisms such as insect pests, disease vectors, or poisonous snakes. Engineering measures to reduce soil erosion in hilly regions that are used in conjunction with biological methods focus on check dams constructed of local materials, hillside catchments, hillside diversion channels (cascade ways), and terraces. Check dams placed at the gully mouth, slow runoff and trap sediments, ultimately raising the elevation of the gully’s mouth. In cases of severe gully erosion, terraces sometimes are constructed on gully slopes to promote vegetation establishment.

Walter Parham, Ph.D.,  Sept. 2010