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| River Basin Aching for Forests |
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Originating in alpine forests in western Sichuan Province, the 735-kilometre-long Minjiang River is one of the major tributaries of the Yangtze River. Along the upper reaches of the river nestle the ancient Dujiangyan irrigation system and Huanglong, two sites on the world heritage list of the United Nations Educational, Scientific and Cultural Organization (UNESCO). One of the country's oldest ethnic minorities, the Qiangs, live along the Minjiang River as well. While a growing number of tourists are flocking to the region looking for spectacular landscapes and exotic cultural sites, Chinese scientists are racing against time, searching for ways to restore its degrading ecosystems. During a recent trip I made with a group of scientists to Wenchuan, Maoxian, Songpan and Lixian counties of the Aba Tibet and Qiang Autonomous Prefecture, I got a glimpse of their work on a project termed "the restoration and rehabilitation of degraded ecosystems on the upper reaches of the Minjiang River." Minjiang project Before the trip, Dr Wu Ning, director assistant of the Chengdu Institute of Biology (CIB) of the Chinese Academy of Sciences (CAS) and the leading scientist of the project, told me that the upper reaches of the Minjiang River are an important ecological transition area between the Qinghai-Tibet Plateau and the Sichuan Basin. Forests originally covered the region, which is a major source of water for the Yangtze River. What takes place in these forest ecosystems has far-reaching effects on the areas downstream. However, large-scale deforestation and population growth over the last four decades have led to serious ecological degradation in this region. It is estimated that in just four decades the forest coverage has shrunk from 40 percent of the land area to 10 percent. Since the end of the 1990s, the central government, recognizing the importance of ecological restoration, has given priority to building an ecological shield in the upper reaches of the Yangtze River. A national campaign to protect natural forest and return farmland on steep slopes to vegetation has also been going on in the area. The project Wu is now heading was launched in January 2000 to provide technical support and demonstrations for restoration of the degraded ecosystems in the upper reaches of the Minjiang River. Managed by CIB, the 5-year project has attracted participation of several other institutes of CAS and colleges in Sichuan. A fund of more than 30 million yuan (US$3.6 million) has been pooled by CAS, the Ministry of Science and Technology and the provincial government of Sichuan. Now three and a half years have passed and Wu said it was time to revisit the area and re-evaluate the progress of their work. Arid valleys Wenchuan County, about a one-and-a-half-hour drive from Chengdu, the provincial capital, was our first stop. The Minjiang River roared past us on the right side of the road. We started to climb. Soon we entered winding valleys in which most of the steep slopes are barren, and landslides scar the landscape everywhere. "We have entered the dry valleys," said Dr Pan Kaiwen, a researcher with CIB. According to the scholar, located between 1,020 and 2,600 meters above sea level, the dry valleys, enjoying warm weather, are the major agricultural areas of the region. With their steep topography, limited rainfall, excessive evaporation, frequent natural disasters and increasing pressures of population, these areas have a very fragile ecological environment. "So here is one of our major working areas," Pan said. He said that it was almost impossible to restore forests in the dry valleys, especially on the sunny slopes, with the country's present level of economic development. "What we can do is to help local people develop cash crops, plant more shrubs and trees, decrease land erosion, and improve the ecological environment of the arid valleys," he said. "Doing this will build up a strong supporting system for our ecological construction in the future." Here, a large part of the steep slopes is covered with Chinese prickly ash trees. The local farmers invariably clean wild weeds and shrubs under the trees for they think that it will help increase the yield of Chinese prickly ash. However, it is certainly not a good way to prevent land erosion on the steep terrain, Pan said. Under the project, scientists have begun to work with the farmers and encourage them to grow plants of the bean family under the trees in the prickly ash plots. "These plants will not only bring the farmers more income, but also will help raise the fertility of the degraded land and decrease land erosion in the valleys," Pan said. In Maoxian County, the second one we visited, we saw green vegetables covering some plots and plump grapes hanging down from grapevines in other plots in the 107 hectares of experimental and demonstration field. "If we had come earlier, we might be able to taste sweet cherries in the streets of Maoxian," he said. At the Daheba Tree Species and Seedling Base in Maoxian County, greenhouses line 3.3 hectares of land, where seedlings of more than 200 tree species collected and selected by scientists are being grown. Most of them are broad-leaved tree species endemic to the region, Dr Wu Ning said. The monoculture, which often leads to the decline of biodiversity and degradation of forests, has restricted the country's afforestation for a long time, he said. It is mainly caused by the lack of diverse endemic tree species. "Our base will provide rich species resources to solve the problem," he said. Central mountain areas Next we arrived at Dagou valleys, about a 15 minutes drive from the county town of Maoxian. There, plots of dense planted forests and shrubs cover the slopes. We were in what the scientists call the central mountain areas of the upper Minjiang River. According to Dr Bao Weikai, a scholar with CIB, the central mountain areas are the transition areas between the dry valleys and the cold and humid sub-alpine and alpine areas, between 1,700 and 2,800 metres above sea level. As a forest ecosystem close to human settlements, it has suffered from a lot of ecological problems. Heavy logging has led to the rapid decline of bio-diversity. Tree planting in the past has not reversed the decline because of the planting of a single species of trees. At present, 80 percent of the areas are occupied by deciduous shrubs left after logging and 10 per cent of the areas with planted trees. Wu said that CIB began ecological rehabilitation work some 15 years ago at Dagou. Today, most of the slopes are covered with densely planted forests. Under the Minjiang project, scientists have begun to demonstrate and promote a new technology for vegetation rehabilitation and restoration on the slopes close to the Dagou Ecological Station of CIB. On the terraced slopes originally covered by shrubs, the researchers have mixed preserving belts and plantation belts. In the preserving belts, the shrubs originally growing on the slopes are maintained. In the plantation belts, the shrubs are removed and seedlings of more than 20 endemic broad-leaved tree species are planted. The shrubs can help decrease soil erosion before the seedlings grow into forests, explained Wu Ning. "More importantly, they also help maintain biodiversity of the ecosystem," he said. Similar experimental and demonstration plots dot the valley. One plot, under the jurisdiction of Songpan County, covers more than 333 hectares. Here, Wu and his colleagues are trying to help trees grow quickly, Wu said. On the slope scientists use a technology called selective cutting. That is, they cut down certain shrubs around the "target" saplings. With no "competition," the young trees can grow much faster. "There might be better models for ecological restoration in this area," the biologist said. "But we find this the cheapest model at present." The State's subsidy to the local governments for the return of farmland to forest is 3,000 yuan (US$362) per hectare, he said. "By helping young tree saplings grow faster, the local farmers can save 30-40 per cent of their cost in afforestation," he said. Alpine areas Songpan was our third stop. Dr Luo Peng, another researcher with CIB, has spent more time in Songpan, whose ecosystem consists of sub-alpine conifer forest, alpine meadows and the transitional area between them. The alpine areas, the water source areas of the Minjiang River, are important for water conservation of the whole watershed, he said. Seasonal grazing has been the traditional way of land use there. Local people, mainly Tibetans, herd sheep and yak on the alpine meadows in the warm season between May and September. In the cold season between October and April of the next year, they graze their livestock on the shrubs and forests in the transitional areas. As a result, overgrazing has led to ecological degradation of not only rangelands, but also the transition areas. Overgrazing has also disturbed natural rejuvenation of forests in turn. Thus, Luo and his colleagues have taken up the job of helping the local nomads to develop high-yield meadows for the cold season. They've mainly worked on a stretch of artificial meadow by the road heading to Jiuzhaigou National Nature Reserve in the county. It covers an area of 27 hectares and is some 35 kilometers north of the Huanglong Airport which is under construction. On this meadow, the scientists cultivated more than 40 species of forage grass. Another 67-hectare seed base of high-yield grass has been opened nearby. At the meadow fenced by branches of a species of willow which will grow into hedgerow, we saw green grass growing profusely. "We expect this kind of artificial meadow will help raise efficiency of animal husbandry in the areas and alleviate the grazing pressure upon alpine forests," Luo Peng said. About five kilometers north of the meadow lies Mount Gonggangling, the source area of the Minjiang River. In the gentle valley of the mountains, water streams in from all directions. After looking through his binoculars, Dr Bao Weikai said that he saw obvious traces of degradation around the winding forest line of a plot of alpine forest on a slope of Mount Gonggangling. "Most of forested areas below the timber line have been replaced by shrubs and meadows," he said. Dr Wu Ming said he and his colleagues must work harder and promote the findings of our research among the local communities and governments over the next two years. "This is among the lines of defence," Wu said. "We must work to slow down or stop further ecological degradation in this area." (China Daily August 22, 2003) |
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