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

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 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). 74 农业工程学报 2010 年

1.4 Vegetation recovery sites and Yan’an Meso-scale Site, categorized and The ecosystem’s restoration largely depends on comparative analysis was performed on the models of WSC vegetation recovery, because vegetation is the main part of and ecological restoration in the Loess Hilly Region. The the ecosystem. Natural recovery of vegetation is essentially origins of socioeconomic data for this analysis are from natural recruitment, which is subject to its succession law local yearbooks, available agricultural statistics and and can be fulfilled by self-organizing and self-regulating population census data for 7 models except for Zhifanggou properties of vegetation system. Natural rehabilitation, of small-scale model. In Yan’an Meso-scale Site of Experiment course, does not necessarily mean abandoning man-made and Demonstration, a participatory rural appraisal (PRA) restoration, but rather the process can be accelerated by study was carried out to quickly identify trends perceived by human intervention. Some natural recruitment practices of villagers and their benefits from these projects of SWC and vegetation, such as sealing mountain passes, natural reserves eco-restoration. One of the tasks was to stratify the and GGP started in 1999, have been implemented in all parts households into wealth categories: rich, average, and poor. of China, especially on the Loess Plateau where land cover On the basis of the PRA exercise, 30 farm households in has evidently increased in recent years. Only as China’s Zhifanggou catchment and 151 on Yan’an Meso-scale Site government successfully addresses the issue of farmers’ were selected and data was collected using questionnaires. subsistence in these areas where the GGP has been Furthermore, available agricultural statistics and population implemented would this become a successful model of census data were also analyzed. The ecological data were vegetation rehabilitation. However, the success of artificially obtained from every experimental station in selected study introduced propagules relies strongly on a sound areas. understanding of their recruitment and establishment 3 Results and analysis requirements. In other words, drought is a major constraint worldwide to the production of common vegetation types 3.1 The models of SWC and Ecological Restoration at such as forests[17]. In particular, re-vegetation of such Small catchment scale in Loess Hilly Region semi-arid and arid regions as the Loess Plateau is primarily The small scale models can be summarized into limited by water, and growth reductions caused by drought following categories: can significantly affect the success of afforestation programs. 3.1.1 Classical solutions concerned on effective use of The current expansion of afforestation in this region is often water and land resources and on food security in hilly occurring on sites where precipitation is near the minimum regions of the Chinese Loess Plateau limits for survival and growth of a species[18]. To avoid These models include Shanghuang model of Yuanzhou costly plantation failures, it is necessary to carefully select District, Hui Autonomous Region, Huangjiaercha the tree species used in afforestation so that the species do model of Xiji County, Ningxia Hui Autonomous Region, not use more water than the site can provide [19]. In the arid Gaoquangou model of Dingxi County, Province, and semiarid areas of China’sLoess Plateau, soil moisture is Gaoxigou model of , Northern Shaanxi generally deficient in planted forests as a result of low Province, and Hequ model of Hequ County, Shanxi annual precipitation, an unsuitable choice of tree species Province. (resulting in over-consumption of soil water reserves), and Yuanzhou District and Xiji County, city of overly high planting density [20-23]. Southern Ningxia Hui Autonomous Region and Dingxi Although so some literature documented achievements County of Gansu Province are classical rain-fed agricultural and advances on soil and water conservation and ecological areas and traditional agro-pastoral intersectant zones, where restoration in the Loess Hilly Regions, there were few works severe loss of soil and water, low land productivity and the that reviewed these above-mentioned models systematically poverty of the local population are imposing and concerned on the transition from small to larger scale. ecological-economic problems. According to the principle The purpose of this paper is systematically to review and for water use of “fully utilizing precipitation, capturing summarize researches and practices on SWC and ecological runoff as completely as possible and appropriately exploiting restoration in the Loess Hilly Region, and examine groundwater”, farmers have persisted in constructing ecological and socioeconomic impacts and differences subsistence farmlands on which they rely for their between the eight small scales models and Yan’an sustenance. The practice of dry land farming at these three Meso-scale Site of Experiment and Demonstration (707 km2) study sites is dedicated to obtaining high agriculture for the first time, and to make clear that, under improved productivity, high quality produce and efficiency of socioeconomic conditions, ecological reconstruction can be agricultural production. Cash forests and ecological forests made sustainable, leading to a reversal of the present (i.e. forests for environmental protection) have been ecological degradation. proportionally planted and herbivorous animal husbandry has been encouraged. This is of importance for vegetation 2 Material and methods recovery and consequently environmental improvement; Based on the observations of eight small-scale study on-farm protection of natural regeneration is not determined 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 75 by technological factors, but by the willingness and ability mechanisms and processes of interface between wind and of farmers to effectively protect the trees on their fields. water erosion, and on their controlling measures. Based on Planting cash trees and herbivorous animal husbandry results of these studies, researchers put forward the concept consequently increases farmers’income, further stimulating of interaction areas exposed to wind and water erosion, their initiative to protect vegetation. The major objective of while also recommending corresponding these development models is rehabilitation of the productive countermeasures[11]. capacity of the land through better control of rainfall and The models presented above are very different patterns runoff and improved soil fertility management and of environmental management, although the ultimate reforestation. These activities arguably have controlled the objectives of all are to control loss of soil and water and severe loss of soil and water and contributed to both the improve the natural environment, while simultaneously improvement of ecological conditions and economic increasing farmers’income and raise their standard of living. development of the targeted areas. The implementations of the models stated above are Since the 1950s, villagers of Gaoxigou in Mizhi County commonly characterized by 1) increasing on-site recharge of of Northern Shaanxi Province have undertaken initiatives to soil water from precipitation and enhancing precipitation use explore methods of rehabilitating degraded ecosystems efficiency with the objective of alleviating the acute damaged by a combination of severe loss of soil and water contradiction between severe loss of soil and water and soil and unreasonable land use. In the past several decades, this drought at each study site, 2) strengthening the village has gradually established ecologically sound patterns reestablishment of a dry farming system focused on of land use, i.e. building terraces on hillsides and dams capturing rainwater and water conservation, fertilizing fields alluvial of farmland in gullies, planting forest shelter belt on and conserving the “soil reservoir”(The conception of soil the top of mountains, cultivating orchards on sloping lands reservoir was introduced by Zhu Xianmo, an academician of near residential area, growing grass on abandoned fields and the Chinese Academy of Sciences), 3) attempts to growing Caragana shrub on steep lands. Evidence from the re-vegetate the site to prevent further soil erosion, and 4) performance in environmental and economic systems of this making great efforts to optimize the structure of rural village implies that such eco-reconstruction activities are industry and develop ecologically friendly industries that effectual. There were 71.33 hm2 terraces, 83.33 hm2 will contribute to constructing a concordant regime between woodlands, and 66.67 hm2 grasslands in Gaoxigou village economy and ecosystem. by 1978, that was known as the land use pattern the 3.1.2 Models for agricultural ecosystems focusing on dams “three-three ratio”. Specifically, the ratio of farmland to in silty farmland woodland to grassland was 3:3:3, and the area treated with Jiuyuangou and Wangjiagou models are two SWC techniques accounted for 69.1% of the whole area. representative of these models. Jiuyuangou Catchment This leaded to a reversal of the previous loss of soil and covers 70.7 km2 and is situated in the upstream Wudinghe water and ecological deterioration of the village. By the end River, which is a first level branch of the Huanghe River. of 1990s, Gaoxigou village had further adjusted land use According to statistics, the average annual precipitation is patterns to its improved ecological condition under the GGP, approximately 500 mm (minimum 109 mm, maximum 891 and developed livestock breeding by making use of mm), with an average annual temperature of 8.4℃ (the increased grassland for farmers’earning. The ratio of arable coldest－9.7℃ in January, the warmest 23.7℃ in July)[25]. land to grassland to woodland further reached 1:2:3. Under In this catchment, the soil erosion rate strikingly reaches 18 2 such circumstances, livestock holdings have increased over 120 t/(km ·a), exacerbating soil, water and nutrient losses time, while vegetation has not been damaged. Seven tenths and thus, soil drought and declining cereal yields; heavy of arable land around the village has been converted into rainfall in the summer is considered the main cause of soil woodland or grassland, while the population has increased erosion in this region. Wangjiagou Catchment in Lishi by 400 people; yearly food and income per capita has risen County lies in west Shanxi Province’shilly region of the to 500 kg and 2 000 RMB respectively; increases two to central Loess Plateau, the catchment’ssize is 9.1 km2, with three times larger than other similar villages. It is fact that the same problems as Jiuyuangou Catchment. Since the the conflict between ecological protection and economic 1950s, researchers have conducted several studies on soil development has been addressed successfully. By 2001, and water conservations in the two locations. To ensure food Gaoxigou village had already changed from an security in converting farmland on slopes greater than 15°, a impoverished village with severe soil erosion into a rich one dams system has been constructed to provide alluvium, with scenic beauty. locally called “Badi” with abundant soil moisture and Hequ experimental site is located at the southern edge of fertility. Maowusu Desert, which suffers from the double harm of This practice has proved successful for controlling soil wind and water erosion, leading to problems such as low erosion and simultaneously raising crop productivity thus land productivity and food shortage[24]. In order to address addressing the issue of food shortages. In the past decades, such issues, researchers conducted several studies on three lines of protection were built in Jiuyuangou Catchment, 76 农业工程学报 2010 年 i.e. terraces on sloping land, creating woodlands or grassland sustain agriculture as well as disappearing and impoverished on sloping sides of gullies, and dam systems in the gullies. vegetation So far 263 such dams have been built in Jiuyuangou A strong expansion of cultivation onto lands not suited Catchment to control and rehabilitate the gullies, whose total for agriculture contributed to a rapid destruction of holding capacity has reached 29.48 million cubic meters of vegetation and accelerated erosion processes. According to water, and 312 hm2 of alluvium has been formed. These traceable dates[15], vegetation coverage accounted for 85 activities not only control the loss of soil and water percent of available land in 1938. By 1958, however, there 2 successfully, but also increase crop yield by 1 500 kg/(hm ·a) were only 3.5 ha of orchards and shrubs, accounting for 1% on average. Since 1958, a study that is a part of the key of available land and leading to an incredibly high erosion 2 national research programs on WSC and agricultural rate (15 000 t/(km ·a)). On the other hand, expansion of development of the Loess Plateau has been conducted in cultivated land and pressure from firewood collection Wangjiagou Catchment. The objective of this study is to resulted in much reduction of adjacent bushland. The search for patterns of agricultural development that center on impoverished vegetation increased the burden of local the efficient use of water and land resources and on the villagers, who had to collect firewood to cover household construction of dam systems for alluvium in order to ensure energy needs. food production. During the past decades, terraces and 2) Drought as a result of soil and water loss and alluvium increased to 272 hm2, i.e. 0.136 hm2 per capita, declining rainfall crop yields rose to 2 021 kg/hm2, i.e. 451 kg per person and At the regional level, the northern part of Shaanxi earning per capita reached 2 266 RMB per annum. The Province experienced a 19% decrease (1.8 mm/a) in annual whole area treated with SWC measures reached 703 hm2, the rainfall from 1951 to 1999. In Ansai County the rainfall has ratio of vegetation coverage increased to 45.8% and soil decreased 14% (2.6 mm/a) from 1970 to 2 000, while the erosion decreased to zero[26-27]. temperature has increased almost 1 degree centigrade over 3.1.3 The Zhungeer model focusing on rehabilitation of the same period. desert steppe soft rock area 3) Low and declining cereal yields This study site was selected within the juncture of A series of statistics for cereal productivity from 1950 to Shanxi, Shaanxi Provinces and Inner Mongolia Autonomous 1970 (from Yearbooks of Ansai County, locally called Region; an area covered by soft rock that is known locally “Tongjinianjian”) indicate surprisingly low yields of as “skin cancer of the earth”. The combination of drought sorghum (Sorghum bicolor) and millet (Panicum sp.), which and quite harsh natural conditions leads to severe averaged 190 and 130 kg/hm2 respectively. Normally yields desertification. Given most plants’failure to survive under of these grains would be in the range of 400–600 kg/hm2. these soil conditions, survival experiments have been done These low and declining cereal yields explain why the for a long time in order to select species capable of living majority of farm households had structural food deficits under soft rock conditions. During long-term experiments, a between 1955 and 1975. momentous finding was made: Hippophae rhamnoides has 4) Population poverty high germination and survival rates under such sterile This region suffered from chronic poverty decades ago. conditions. Following this discovery, highly successful Due to low land productivity, scarcity of available resources research has tested the ability of Hippophae rhamnoides to and extremely adverse environmental conditions, the survive in the soft rock areas of this region. By the end of majority of farmers in this catchment area struggled for 1990s, the area of Hippophae rhamnoides plantation in this survival. Because many farming families could no longer region had reached 199 600 hm2, leading to a reversal of cope with bad living conditions and hunger, they moved to desertification and land degradation. At the same time, Yan’an city, or to areas in the middle of Shaanxi Province, because Hippophae rhamnoides oil possesses curatorial which were free of above-mentioned environmental issues. properties, it is a plant with cash-crop potential. Local Secondly, four reactions to practicing SWC-orientated industries relying on Hippophae rhamnoides are booming ecological-farming in combating these trends were made. following the increased planting area. Since 1986, key national science and technology programs, 3.1.4 Zhifanggou model of SWC-orientated ecological- including the ISWC, have funded several studies on SWC farming and rehabilitation of degraded ecosystems in the Zhifanggou Zhifanggou Catchment is located in Ansai County, region. Over the period of these examinations, the theory northern Shaanxi Province with an area of 8.2 km2 and is and techniques of SWC-orientated ecological farming were very representative in hilly areas of the Loess Plateau. Key introduced, the focus of which was summarized as its environmental issues of Zhifanggou Catchment over the emphasis on replenishing soil water from precipitation and period 1950s to 1970s were analyzed in the first place. From ecologically sound land use. Four reactions were made the late 1950s to the end of 1970s, the situation on the following this initial introduction of SWC principles and catchment was one of crisis and despair. The following these refinements were subsequently considered to be trends could be observed: critical in triggering a process of sustainable agriculture and 1) Expanding cultivation onto lands with little ability to environmental rehabilitation. These reactions include 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 77 following: ·Re-vegetation as a basic step to prevention of soil erosion and supply of rural firewood and fodder has been practiced nationwide on barren and highly degraded land or on land with a gradient above 25°. However, in such activities in the Loess Hilly Region, emphasis should not be placed on establishing timber forests. ·Terraces should be built on hill slopes in order to increase recharge of soil water and to alleviate soil drought, thus creating better conditions for crop production. In turn, this would allow implementing the conversion of steeper, less practicable farmland into woodland or grassland. Fig.2 Variation of main indicators in Zhifanggou catchment ·Some seasonal cash forests should be developed, aimed at promoting farmers’ enthusiasm in re-vegetation and applying these results to larger-scale ecological reconstruction environmental protection. activities. The results from ecological rehabilitation studies ·Following the local regeneration of vegetation and at small scales are usually restricted to the study catchments greater crop production, herbivorous animal husbandry can without affecting surrounding areas. Given the diversity and be strengthened. The Zhifanggou model indicates that complexity of regional ecological and socioeconomic farmers no longer need to move their herds, due to the conditions, encouraging results in improving localized abundance of crop residues and perennial grasses. Such ecologies does not necessarily imply similar success will be practices contribute not only to an increase in farmers’ achieved in the rest of the Loess Hilly Regions, let alone the rest of the Loess Plateau. Therefore more extensive earning, but also to eco-rehabilitation. insights and consideration are needed in determining Finally, the three phases in carrying out SWC-orientated schemes for rural economic development, land use pattern ecological-farming were introduced: and the goals for ecological reconstruction. The research on 1) The starting rehabilitation phase of ecosystems, which small-scale ecological rehabilitation, however, failed in needs 10 to 15 years, during which the loss of soil and water testing for programming of ecological farming and the decreases while vegetation coverage gradually increases. strategy for economic development in regional level. Thus 2) The stable evolution phase of ecosystems, during results gained in these case studies cannot be completely which ecological conditions are further improved, stresses extrapolated to regional scales because of the large on ecosystems are gradually eliminated and the relationships differences of biophysical and socioeconomic conditions between the ecosystem’scomponents become harmonious. from the case study area. 3) The sound development phase of ecosystems, a period 3.3 A meso-scale model: Yan’an meso-scale site of of 5 to 10 years, which is the highest level of model; at experiment and demonstration on SWC and sustainable which there is great harmony between the agricultural ecological restoration ecosystem and economic system in study site. Yan’an Meso-scale Site (36°22'40″–36°32'16″N; At present vegetation coverage is up to 60 percent, there 109°04'06″–109°34'25″E, see Fig.1 and 3) is located in has been no sediment removal from Zhifanggou Catchment Yan’an Municipality of northern Shaanxi Province of China after several recent storms, and the soil erosion rate has and involves nine townships within Ansai County and Baota 2 2 shrunk from 15 000 t/(km ·a) to 2 000 t/(km ·a), which District. Yan’an Region is representative of Loess Hilly indicates that the local environment has been improved Region and is a part of the large region of the Loess Plateau greatly. Population, food holdings and earnings per person locally known as the ‘sandy coarse-sandy area’,from which statistics all display rising trends over the period 1978 to approximately 90% of the sediment delivered to the Yellow 2005(Fig.2). Engel’scoefficient and Gini index were 0.45 River comes[3]. Over the past 20 years, the government of and 0.22 respectively in 2005, suggesting that such China has given special attention to the region due to erosion ecological-farming increased local farmers’living standards and its effects down stream on major rivers as well as the remarkably. A study suggests the preliminary stages of area’sagricultural importance[28]. To provide insights into rehabilitating the ecosystems of this catchment have been the issues of scaling small-scale research results up to accomplished and ecological-farming has entered its third regional levels in the Loess Hilly Regions, an area of phase[14]. 707 km2 was selected as a case study area to explore model 3.2 The emergence of limitations from small-scale for ecological reconstruction at larger level. This project, an eco-rehabilitation experiment and demonstration research on soil and water Although so many accomplishments have been made in conservation and sustainable eco-rehabilitation on the Loess above-mentioned studies on ecological rehabilitation at Plateau, was financed by the West Action Project of the small scales, there are limits to the potential success in Chinese Academy of Sciences and based on long-term 78 农业工程学报 2010 年 observations at Ansai Experimental Station, a part of China Ecosystems Research Net (CERN), as well as previous small-scale study results. Conceptual model 1 (Fig.4) shows the different ecological farming practices studied at the Yan’an Meso-scale site, along with their results. The components chain involved in the project is displayed in conceptual model-2 (Fig.5).

Fig.5 Conceptual model 2 for the ecological farming

In order to address the scientific objectives described above, five submodels for eco-rehabilitation were developed for use within the study area, following guidelines of SWC and eco-reconstruction. The models include the Hezhuangping model of establishing efficient farming; the Xiannangou model of compound crop farming and cash forests; the Feimahe model of compound crop farming and apple planting; the Gaoqiao model of compound crop farming and animal husbandry and the Yangou model of efficient use of water resources and “Badi” exploitation (Fig.3). On the basis of research into these five models, explorations of structures and functions of various models, necessary conditions, their environmental impacts and perspectives have been made. Fig.3 Sketch map of five submodels located in Yan’an meso-scale The characteristics of each model are presented in site of experiment and demonstration in SWC and sustainable Table 1.Fundamental information on the socioeconomic eco-restoration in Yan’an region situation of the study area in 2000 is presented in Table 2 and crop production over the period from 2001 to 2004 in Table 3 respectively. Tables 2 and 3 indicate these five models for SWC and eco-reconstruction have increased farmland productivity and farmers’income. The results from the PRA showed that Engel’scoefficients of each model were 46% for Feimahe, 45% for Xiannangou, 47% for Gaoqiao, 44% for Hezhuangping and 43% for Yangou in 2005. This compares to an average of 53% in 2005 and 55% in 2000 in rural areas of Yan’an region, indicating the improvement of farmers’living standards under the five models; similarly Gini indices of each model were 0.17, 0.17, 0.22, 0.26 and 0.28 in 2005 respectively, suggesting Fig.4 Conceptual model 1 for the ecological farming relatively equitable distribution of income.

Table 1 Characteristics for various models of ecological-farming Model Size and production value Applicable area Key technology

Establishing efficient Treated area accounts for more than 5 percent of Plains Greenhouses; soil and cultivation management farming whole area; production value above 40 percent

Compound crop farming Treated area accounts for more than 30 percent; Hilly areas with low Improved stock breeding; grain doubles as a and husbandry stockbreeding produce above 30 percent population density cash crop and as fodder; pasture management

Compound crop farming 0.13ha per capita of orchards; production value Gully areas with 500- Variety improvement; water and fertility and apple planting above 30 percent 700 mm precipitation management

Compound crop farming 0.13 hm2 per capita of cash forests; production Hilly areas with ＜500 mm Mixed fruits; horticultural management and cash forestry value above 30 percent precipitation Note: a) GGP –green for green program. 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 79

Table 2 Values of fundamental indicators for 5 submodels in Yan’an Meso-scale Site in 2000 Area/ Population Farmland/ Subsistence Woodland/ Cash forest/ Cultivated Crop land/ Productivity/ Food/ Income/ Area for the Model -2 km2 /person hm2 farmland/hm2 hm2 hm2 pasture/hm2 hm2 (kg·hm ) kg per capita Yuan per capita GGPa)/hm2

Xiannangou 59.0 2 729 533 267 759 130 83 427 2 415 477 1 368 360 Yangou 122.0 6 398 1 698 1 123 2 540 119 204 1 765 1 830 503 1 435 1 030 Gaoqiao 122.0 7 515 1 523 386 4 794 851 598 1 100 3 000 426 1 588 920 Feimahe 50.0 1 624 437 244 1 033 195 121 232 2 400 343 1 899 89 Hezhuangping 9.9 3 786 435 386 396 106 75 422 4 200 468 1 830 40 Summed 362.9 22 052 4 626 2 405 9 522 1 400 1 081 3 945 2 439

Table 3 Schedule for crop production of 5 models in Yan’an Meso-scale Site

-2 Model Year Cropland/hm2 Productivity/(kg·hm ) Gross crop output/t Growth amplitude/t Food/kg per capita Remark 2001 426.0 4200 1789.2 0 468.0 2002 422.0 5250 2215.5 426.3 488.0 Xiannangou 2003 352.7 5625 1983.9 194.6 378.0 2004 337.5 6000 2024.8 235.6 380.0 2001 373.3 3162 1180.4 0 486.2 2002 360.0 3242 1167.0 -13.5 501.6 Yangou 2003 338.2 3918 1325.1 144.6 512.8 2004 337.9 4070 1375.2 194.8 492.3 2001 223.3 2940 656.6 0 401.0 2002 220.9 3135 692.6 36.0 420.0 Gaoqiao 2003 208.5 3420 712.9 56.4 451.0 2004 213.3 4125 880.0 223.4 530.0 2001 379.4 2682 1017.6 0 377.0 2002 344.4 3452 1188.7 171.1 440.5 Feimahe 2003 305.6 3554 1085.9 683.7 398.8 2004 310.9 3690 1147.3 129.8 391.7 2001 1546.7 1862 2879.1 0 392.0 2002 1396.0 2171 3030.0 150.9 410.0 Hezhuangping hail 2003 1284.0 1559 2001.1 -878.0 270.0 2004 1208.0 2777 3354.0 474.9 450.0 2001 2948.7 7522.9 0 424.8 2002 2743.3 8293.8 770.9 452.0 Totals 2003 2489.0 7108.9 -414.2 402.1 2004 2407.6 8781.3 1258.4 448.8

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中国黄土丘陵区水土保持与生态恢复模式

党小虎 1,2，刘国彬 2※，薛 萐 2,3 （1．西安科技大学地质与环境学院，西安 710054； 2．中国科学院、水利部水土保持研究所，杨凌 712100； 3．西安理工大学水利与水电学院，西安 710048）

摘 要：以水土流失为主要特征的生态退化是黄土丘陵区最突出的生态经济问题，水土保持和生态恢复是解决这种问题的关键所在， 因而探索与当地的社会经济和环境条件相适应的水土保持和生态恢复模式是非常重要的。本文以 8 个小流域以及延安中尺度水土保 持与生态恢复试验示范区为基础，回顾了黄土丘陵区的水土保持与生态恢复研究和实践。为了评价这些试验示范模式的环境与社会 经济效应，采用了参与式评估方法研究了这些模式的有效性。结果显示不同尺度的水土保持和生态恢复在当地的经济发展和环境改 良中扮演了非常主要的角色，也为未来黄土高原生态可持续的经济发展模式提供了一个全新视角。同时，本文有助于增强这种共识， 即随着社会经济条件的改善，生态重建是能够扭转当前生态持续退化的现状而实现可持续性的。 关键词：模式，水土保持，生态恢复，水土保持型生态农业，中国黄土丘陵区