استفاده از یک رویکرد اقتصاد محیط زیست برای حمایت از بازسازی سقوط آبگذرها در جنوب چین

Land degradation and poverty are problems that must be tackled together for environmental conservation to succeed. However, it is rarely possible to move a population from degraded land to another area where the people can be more easily sustained. To find a new strategy that achieves both conservation and economic gains without the need to relocate a population, we examined/investigated a sustainable combination of ecological and economic development suitable for the restoration of areas of China with collapsing gullies, where the frequent steep slopes make restoration difficult. The results showed that the degraded land may contain significant benefits that were previously unappreciated, thereby transforming a problem into an opportunity. Our results suggest that the new approach can both improve the livelihoods of local citizens and promote environmental conservation, leading to successful ecological restoration.

In areas that receive more precipitation than the soil can absorb, erosion caused by the resulting runoff can create gullies with steep slopes that are formed by a combination of intense runoff and gravity (Avni, 2005 and Zhang, 2010). Where there is insufficient vegetation to prevent the runoff from creating gulley erosion, steep slopes develop and subsequently collapse under the influence of gravity (Fig. 1, top). This phenomenon is common where the slopes are steeper than 75°; in the red clay soils region of southern China, the annual erosion in these areas averages 50 kt km−2, which is more than 50 times the erosion on gentler slopes or on slopes with a high vegetation cover (Zhang, 2010). There are hundreds of such degraded ecosystems in China's Loess Plateau (Chen and Cai, 2006) and in the granitic red clay soils area of southern China (Zhang, 2010), which stretches from 21°01′N to 32°05′N and from 106°49′E to 120°27′E. The flooding, debris flows, and other disasters that result from this form of erosion jeopardize sustainable development in regions of China that have steep slopes and degraded land combined with low vegetation cover (Chen and Cai, 2006 and Zhang, 2010). From 1950 to 2005, erosion and gulley collapse affected 1220 km2 in the granitic red clay soils region, leading to the loss of more than 60 Mt of soil; this, in turn, caused the loss of 380,000 ha of farmland, 554,000 houses, 37,000 km of road, 11,000 bridges, 9000 reservoirs, and 73,000 ponds, as well as 0.38 billion RMB in economic losses that affected 11.62 million residents (Zhang, 2010). Unfortunately, there is currently no effective approach to prevent such disasters, and tens of millions of Chinese citizens live in areas vulnerable to this kind of erosion (Cao et al., 2010). Monitoring data reveals that collapsing gullies are widespread in China's granitic red clay soils area, which includes Hubei, Hunan, Jiangxi, Anhui, Fujian, Guangdong, and Guangxi provinces. Since 2000, the Monitoring Center of Soil and Water Conservation of China (Zhang, 2010) has reported more than 239,000 collapsing gullies, affecting an area of 122,000 ha (Table 1). It is clearly essential to find an approach capable of restoring this degraded land that can also improve the livelihoods of the local population to avoid the need for relocation or emigration of these people. To accomplish this, a new strategy named “An Ecological Economics Approach for the Restoration of Collapsing Gullies” was tested in Changting County, in Fujian Province of southern China. Changting County established one of the earliest soil and water conservation monitoring stations in China, in 1940 (Yang et al., 2005). However, a half-century of unsustainable cutting of forests, combined with a rainy climate and mountainous topography, have led to active development of a system of collapsing gullies, leading to severe land degradation. These conditions have contributed to the inability of the degraded sites to recover naturally (Gao et al., 2011). The combination of degraded land, a lack of vegetation cover, and high inputs of rain have increased the frequency and scale of water erosion of the soil and the severity of flooding, leading to further degradation of the county's forests and landscape. In 2005, monitoring revealed 3585 collapsing gullies in the county, covering 6304 ha (Zhang, 2010). The flooding, debris flows, and other disasters caused by the collapse of these gullies due to erosion have seriously jeopardized sustainable development in the county (Yang et al., 2005). For example, flooding on 8 August 1996 caused the loss of an astounding 93,367 ha of farmland, as well as 1.2 billion RMB in economic losses that affected 296,000 residents, with 398 residents hurt and 96 residents killed (Yang et al., 2005). The severity of this damage led to the launch of an aggressive erosion-control program in the county. Since 1996, the conventional method of erosion control has involved the installation of diversion channels that direct runoff away from steep slopes, and this approach has been widely used since 1996 (Yang et al., 2005). However, although the conventional approach can mitigate the problem, it has not eliminated the problem and it provides no economic benefits to local residents. To alleviate the damage caused by the land degradation that leads to this erosion and to improve the livelihoods of local residents, an old Chinese strategy has been reinvented: terrace engineering (Fig. 1, middle), followed by revegetation with trees and crops (Fig. 1, bottom). This approach, which combines environmental engineering with economic development, has been tested in Changting County since 2001. The strategy is designed to collect precipitation in the terraced farmland, retaining water so that the water cannot form the large quantities of surface runoff that would create erosion. As a result, the terraces retain both the soil and its nutrients, and protect the farmland's soil properties (Cao et al., 2007). In accordance with the principle of working with rather than against nature, appropriate vegetation is planted in the terraced land to retain the soils. This represents an improvement over the conventional method because it provides socioeconomic benefits and improves the livelihoods of local residents. To accomplish this, crops are planted in the terraces nearest to residential areas, fruit trees are planted 1 km or more from the residential areas, and timber trees are planted 2 km and farther from these areas. To understand the benefits of this new approach based on ecological economics, we undertook a monitoring study to explore the potential for revegetation of steep slopes by planting appropriate vegetation. We compared the new methods with the existing (conventional) method on steep slopes with the goals of sustaining the functional characteristics of the landscape, protecting the slopes, and improving the visual and other characteristics of the study area, while also increasing the income of local residents. Our results showed that the new techniques can improve the protection of ecosystems in steep terrain while dramatically improving vegetation restoration, soil conservation, and sustainable socioeconomic development. Two important goals of this paper are to introduce the new techniques to readers outside of China and thereby help improve environmental protection in mountainous terrain around the world, while also drawing attention to the need for conservation of similar ecosystems.

Balancing the need for environmental protection with the need for local citizens to earn a livelihood is difficult because huge populations live in environmentally fragile areas and desperately need to earn a living and improve their lives, even at the expense of the environment (Tallis et al., 2008 and Cao et al., 2009). This makes environmental conservation a complex systems problem rather than a “simple” matter of environmental engineering, because conservation and poverty reduction are dynamically linked to each area's unique combination of socioeconomic and environmental conditions (Berkes, 2007, Tallis et al., 2008 and Wang et al., 2011). Environmental goals cannot be achieved without some type of economic development that provides a livelihood to the people who will be affected by the program (Berkes, 2007, Cao et al., 2007 and Cao et al., 2009). Therefore, conservation and development must be achieved simultaneously (Berkes, 2007 and Tallis et al., 2008). There is no inherent reason why projects cannot meet both conservation and development objectives (Lewis et al., 2011). The case study in this paper confirms that this is possible in a part of China facing a difficult combination of poverty and a fragile environment. Our new approach to environmental conservation combines an appropriate ecological restoration technique with a sustainable socioeconomic development component that provides sufficient income to encourage local residents to maintain the approach in the long term. This is an important point, because a survey of farmers who were compensated under China's Grain for Green plan to adopt more environmentally sustainable activities (Cao, 2011) found that 37% of the project participants in Shaanxi Province, 34% in Guizhou Province, and 29% in Ningxia Province planned to return to their old farming methods as soon as funding expired because they had no alternative way to earn a living. The new approach in the present study accounts for the unique combination of local human and environmental constraints and therefore provides residents with an ongoing source of income, thereby avoiding this problem. Collapsing gullies are a serious and typical form of land degradation in the study area, but this problem is common around the world (Avni, 2005 and Zhang, 2010). Despite the difficult topography and soil conditions in such areas, some species have suitable characteristics to grow well and provide a good economic yield (Table 3). This example also illustrates how a situation formerly seen as a serious problem (severe soil erosion on steep, collapsing slopes in severely degraded land) can become an opportunity (protecting the regional environment while increasing the income of local residents). Although there is risk in any such opportunity, our results demonstrate that innovative thinking can sometimes find solutions that both prevent disasters and improve the living conditions of an area's residents. In China, most land is owned by the state and is managed collectively, thus collapsing gullies do not directly affect any individual's property rights or ability to earn a living. However, the statistics we have presented demonstrate that the indirect effects can be severe because erosion and flooding damage land near the gullies that is being actively managed and reduce the area of land that remains suitable for essential activities such as agriculture. China's government understands the seriousness of the problem, and has invested 10 billion RMB since 2005 to combat collapsing gullies and the associated land degradation (Zhang, 2010). This heavy initial investment was required by the need to fundamentally change land-use practices, which is very costly. To reduce the cost and improve the environmental restoration, local governments have encouraged the transfer of land ownership to individual residents and enterprises who were willing to take responsibility for the land (e.g., by planting trees) since 2000. Governments have encouraged a “green vocation”, in which residents and enterprises engage in soil- and water-conservation projects and participate in the development of environmentally sustainable development projects such as the planting of fruit orchards. This approach increased employment in the Changting project area by 8012 workers (an increase of 12.4% in the total workforce) and increased net farmer income by RMB 407 per year, which represents an 11.2% increase over the mean net income before the new project (Cao et al., 2009). Although this increase does not solve the poverty problem in Changting County, it greatly ameliorates living conditions, and there has been no large-scale emigration from the county during the study period. Ecological restoration plays a crucial role in rebuilding the equilibrium of degraded ecosystems and reversing their degradation. Our results demonstrate that despite the study area's challenging topography and soil conditions, it is possible to greatly mitigate the problem created by collapsing gullies by judicious choice of vegetation that is both well suited to the growing conditions and capable of generating a significant economic yield. However, restoration of the degraded land has complex and poorly understood consequences for the structure and composition of future ecosystems. For example, the topographic change may lead to microclimatic and vegetation changes. The potential impact of the land use policy must therefore be monitored to detect adverse consequences before they become difficult to solve. Underestimating the complexity of ecological restoration may result in failures if managers only consider the early phases of an apparently successful project. For example, previous research on China's massive afforestation programs in arid northern areas (Cao et al., 2011) has revealed that despite promising initial results, many of the areas were planted with inappropriate species, and high levels of tree mortality began to develop within 20 years after the initial surveys suggested successful afforestation. Researchers must therefore perform long-term monitoring of the restored sites to confirm that the ecological restoration will remain successful and that it will not create any new problems.