第 26 卷 第 9 期 农 业 工 程 学 报 Vol.26 No.9 72 2010 年 9 月 Transactions of the CSAE Sep. 2010 Models of soil and water conservation and ecological restoration in the loess hilly region of China Dang Xiaohu1,2,Liu Guobin2※,Xue Sha2,3 (1. School of Geology and Environment, Xi’an University of Science and Technology, Xi’an 710054, China; 2. Institute of Soil and Water Conservation, CAS and MWR, Yangling 712100, China; 3. Institute of Water Resources and Hydro-electric, Xi’an University of Technology, Xi’an 710048, China) Abstract: Ecological degradation characterized by severe soil erosion and water loss is the most imposing ecological-economic issue in the Loess Hilly Region; the soil and water conservation (SWC) and ecological restoration are crucial solutions to this issue. It is of importance to explore SWC models for ecological reconstruction compatible with local socioeconomic and environmental conditions. The paper reviewed on SWC and ecological rehabilitation researches and practices and mainly concerned on eight small-scale (small catchments) models and Yan’an Meso-scale model in the Loess Hilly Region. To evaluate the environmental and socioeconomic impacts of these models, their validities were examined using the participatory rural appraisal. The results indicated that SWC and ecological restoration at different scales have played important roles both in local economic development and environmental improvement and provided an insight into sustainable economic development on the Loess plateau in the future. Furthermore, this paper strengthens our belief that, under improved socioeconomic conditions, SWC and ecological reconstruction can be made sustainable, leading to a reversal of the present ecological degradation. Key words: models, soil and water conservation, ecological restoration, SWC-oriented ecological farming, the Loess Hilly Region of China doi：10.3969/j.issn.1002-6819.2010.09.012 CLC number: S157.2 Document code: A Article ID: 1002-6819(2010)-09-0072-09 Dang Xiaohu, Liu Guobin, Xue Sha. Models of soil and water conservation and ecological restoration in the loess hilly region of China[J]. Transactions of the CSAE, 2010, 26(9): 72－80. (in English with Chinese abstract) of the river bed is on average 3 to 10 m above the 0 Introduction surrounding land surface. Severe soil erosion also shortens Ecological degradation of the Loess Plateau (33°43'– the life expectancy of reservoirs in this region, deteriorates 41°16'N, 100°54'–114°33'E), characterized by severe soil water quality and seriously interferes with the region’s erosion and water loss and the overuse of land resources, has economic development. As such, this ‘hot-spot’ of been the most imposing ecological-economic issue. The environmental degradation is a tremendous challenge to the erosion rates ranging from 20 000 to 30 000 t/(km2·a) are social and economic development of this relatively commonly reported[1] with extremely high rates (59 700 impoverished region, which not only endangers the t/(km2 · a)) also being documented[2]. The build-up of development of the region itself, but also tampers seriously sediment in lower reaches (32°02'–40°28'N, 95°58'– with development of it-rim regions, even of the whole 116°45'E) of the Yellow River leads to rising riverbed. nation. About 25% of the sediment load is deposited on the riverbed Loess Hilly Region, as the main body of the Loess resulting in an annual riverbed rise of 8 to 10 cm[2-3], Plateau, is characterized by the cause and effect chain although annual rates of 10 to 20 cm were reported between linking population poverty and ecological degradation. The the 1950s and 1970s[4]. The high erosion rates combined reestablishment of ecological-economic harmony in this with continuous presence of levees and dykes along the region is crucial to the ecological restoration and economic trunk channel means that in these lower reaches, the bottom development of the Loess plateau, even of the whole of China. The sensitive natural environment together with unreasonable human activities, hive heavily contributed to Received date: 2008-07-27 Revised date: 2008-11-27 Foundation Item: West Action Project of Chinese Academy of Sciences (No. great tension between economic development and the KZCX2-XB2-05); National Program for Science and Technology Support (No. maintenance of ecological processes on the Loess plateau. 2006BAD09B10-2) Over the past 20 years, the government of China has paid Biography: Dang Xiaohu, Ph.D, associate professor, School of Geology and special attention to this region due to its agricultural Environment, Xi’an University of Science and Technology, Xi’an710054, China. importance, population poverty, erosion and the effects of Email: [email protected] ※Corresponding author: Liu Guobin, Ph.D, professor, Institute of Soil and erosion downstream on major rivers. Since the early 1950s, Water Conservation, CAS and MWR, Yangling 712100. China’s government has dedicated to ecological Email: [email protected] reconstruction such as the SWC, re-vegetation programs and, 第 9 期 党小虎等：中国黄土丘陵区水土保持与生态恢复模式 73 more recently (from 1999 on), the Grain for Green Program the environment and increase in farmers’income on the (GGP) at the national level (also called the Cropland Loess Plateau[9,14-15]. Conversion Program). The GGP aims to minimize the cultivation of crops in slope areas by encouraging farmers to plant trees and grasses instead, hence decreasing arable land. The central government originally provided compensation in terms of money and food grains for a period of eight years (1999 to 2007), with a second eight-year period of funding scheduled to begin in 2008. Given shortage of water resources, especially of soil moisture and appalling ecological conditions, there are some arguments in academe against ecological-economic development on the Loess Plateau. These arguments can be summarized into three categories: first, the Loess Plateau should be constructed as a forestry base; second, animal husbandry should be actively developed; finally, the direction of economic development should be oriented subsistence agriculture, commerce-orientated animal Fig.1 Sketch map of 11 small catchment scale and Yan’an husbandry and protection-orientated forestry[5-6]. Such Meso-scale experiment and demonstration sites in SWC and debate may continue in the future. However, more careful sustainable eco-restoration on the Loess Plateau and comprehensive strategies for management of land and water, as well as an improved understanding of human 1.2 Study on ecological rehabilitation at meso-scale in effects, are required to reverse the environment degradation the Hilly Region on the Loess Plateau, and to construct a concordant regime As it enters a new millennium, China is putting more between economic growth and the local ecosystem. emphasis on SWC-orientated ecological restoration at larger scales. Research support is also generally increasing in this 1 The overview of the demonstration areas field on the Loess Plateau. However, some scientific Since the 1980s, China has successively conducted experiences of ecological restoration at small catchments several experiments on SWC and ecological reconstruction scale are not sufficient to address the more complex issues in models at 11 small catchment levels [7-11]. Eight of these are regional levels. To meet the theory and practice demands for in the Loess Hilly Region (Figure 1). Based on these ecological reconstruction at larger scales, a study on small-scale studies, a meso-scale site with an area of 707 ecological rehabilitation has been conducted at a meso-scale 2 km2 in Yan’an Prefectures, northern Shaanxi Province site (707 km ) in Yan’an Prefecture. Meso-scale is a regional (known as the Yan’an Meso-scale Site of Experiment and conception relative to small catchment (small-scale), an 2 Demonstration-Figure 1) was selected for examining models extent quantitatively ranging from 50 to 1 000 km in the of ecological-economic reconstruction at larger scale and Loess Hilly Region. provide insights into the scaled-up issues [12-13]. Recently in As the diversity and complexity in environmental the hilly region of the Loess Plateau, scientists from the conditions at the meso-scale site are more similar to a region Institute of Soil and Water Conservation (ISWC), Chinese than small catchment, the theories and experiences elicited Academy of Sciences (CAS), Ministry of Water Resources for ecological reconstruction not only can be spread more (MWR) and other academies started a study program on easily at high levels, but also provide scientific foundation SWC and ecological reconstruction at mega-scale (around for national and regional macro decision-making on [12] an area of 80 000 km2, including parts of Yulin City and ecological reconstruction . Yan’an City, northern Shaanxi Province), aiming to further 1.3 The system of SWC orientated ecological farming explore models of SWC and ecological restoration at To fulfill the self-sufficiency in food on the Loess region scale (mega-scale) in semi-arid and arid areas. plateau, the SWC-orientated eco-farming was introduced by 1.1 Small catchment management researchers from ISWC. Its core is to recharge soil moisture In 1980 China’sscientists and corresponding agencies from precipitation on-site, to prevent the loss of soil and introduced the concept of the ‘small catchment’, which is a water, to construct terraces on sloping farmlands, revegetate close drainage area ranging from 3 km2 to 50 km2. From on wasteland and sloping farmland over 15°, and to increase then on the small catchment integrated management (SCIM) farmers’earning by cash forests growth and herbivorous has been practiced nationwide; the above-mentioned 11 animal husbandry thus insuring that farmers no longer models and other demonstrational sites on SWC were expand cultivation onto lands marginal for farming”[14,16]. developed on the Loess Plateau at this time. SCIM is a basal At the same time 3 phases of implementing SWC-orientated experience drawn from long-term practice of SWC in China, ecological-farming were introduced (enlarged upon in which arguably is the essential approach to improvement of section 3).