Sustainable Development of an Agricultural System Under Ecological Restoration Based on Emergy Analysis: A Case Study in Northeastern China

By Wei, Jian-bing Xiao, Du-ning; Zeng, Hui

Key words: Regional ecological restoration and rehabilitation, eco-economic system, agricultural effect, Emergy analysis SUMMARY

Using China’s advanced eco-agricultural model for Baiquan County, Heilongjiang Province, extensive statistical data and original information were collected. Based on dynamic analyses of economic features of the agricultural system and ecological restoration and rehabilitation, the Emergy theory was used to study production efficiency and sustainable developmental dynamics of the agricultural eco-economic system in an ecological rehabilitation time series (1980-2000). The objectives were to explore the research concept on quantification of agricultural effects of regional ecological restoration and rehabilitation, and to provide a scientific basis for planning of harmonious socio-economic development in this and similar regions. The results show great achievements in economic development and ecological reconstruction of the county. The production and living environments have also been significantly improved, but there is still environmental pressure on the agricultural system itself: production efficiency of the county’s agriculture and farmers’ living standards are still low. However, large-scale ecological restoration and rehabilitation has yielded some agricultural improvements, and the Emergy of the system is now better in terms of sustainable development.

INTRODUCTION

A regional eco-economic system is a complex megasystem. It links a region’s natural resources with the socio-economy through material circulation, energy flow and information transfer, and thereby constitutes an organic eco-economic entity. Because of the influences of internal and external factors, the system is moving, developing and changing all the time (Liang 2002; Cao and Dawson 2005; Chen et al. 2006). Developing the economy and protecting the environment have long been irresolvable contradictions. Harmonious coexistence between man and nature and sustainable development of the society and economy have become primary tenets for human existence and development. Avoiding deterioration to the ecology and environment in economic development processes has become an important dilemma facing humans. Because dimensions of ecological and socio-economic indices are difficult to unify, quantitative evaluation of harmonious ecoeconomic development in a region is difficult. In 1983, Odum established the theoretical system of Emergy analysis, based on the study of energy systems (Odum 1983; Lan et al. 2002), which provides objective evaluation criteria for industrial capital, characterised by market price, and production capital, characterized by ecological services (Li et al. 2005). This theory uses solar Emergy as a common scale for evaluation of assets with different properties, and links the socio-economic system with natural ecosystems using the same standards; hence, this may be a useful way to solve and evaluate harmonious development of the ecology and economy.

Numerous examples of energy and Emergy analyses of agricultural eco-economic systems have been reported (Wen and Pimentel 1984; Giampietro et al. 1992; An et al. 1998; Chen and Xu 2002; Karkacier and Gokalp Goktolga 2005; Martin et al. 2006). However, the significance of this paper lies in the uniqueness of the system to be analysed. Baiquan County in Heilongjiang Province is one of China’s more advanced counties in terms of ecological restoration and rehabilitation. In the initial land reclamation stage, the county had a good environment and fertile land; in the late 1970s, soil erosion became severe and the ecology and environment deteriorated; however, through large-scale ecological restoration and rehabilitation since the 1980s, the county’s environment is now much improved (Wei and Xiao 2005). At the same time, the county’s economy was also successfully improved through the readjustment of industrial structures, rapidly developing animal husbandry and eco- agriculture, control of soil erosion, and establishment of eco- economic districts in small basins. However, the county is still poor, farmers lead a hard life, and environmental protection and economic development are not in harmony. Systematic and quantitative studies of socio-economic development, ecological rehabilitation and their interrelationships are still lacking in the region.

Baiquan is a typical big agricultural county in northeastern China. Crop planting, livestock breeding and poultry raising are the main economic activities. The functional advantages and disadvantages of agricultural production and eco-economic systems can be manifested in the harmony between ecology and economy, as well as visible sustainable development of the ecoeconomic system (Zhang 2000; Zhou et al. 2005). Taking Baiquan County as an example, based on studies of economic features of the county’s agricultural system and ecological reconstruction, this paper uses Emergy analysis to evaluate energy use of the county’s agricultural eco- economic system and sustainable development dynamics before and after large-scale ecological reconstruction, so as to explore this concept for quantifying the region’s ecological rehabilitation and agriculture, and to provide a scientific basis for ecological and environmental rehabilitation and harmonious socio-economic development in this and other regions.

STUDY AREA AND METHODS

Study area

Baiquan County is in midwest Heilongjiang Province, in the transition zone between the Xiaoxing’an Mountains and the Song-Neng Plain, with a total area of 3599 km^sup 2^. Much of the county consists of low hills and an undulating high plain, with black silty clay loam Mollisols and Phacozems. Before reclamation, most of the land was grassland and forest. The region has a temperate continental monsoon climate, with a mean annual temperature of 1.2[degrees]C, and annual precipitation of 488.2 mm. Seventy per cent of the land is cultivated, and 85% of the population is involved in agriculture. As a typical agricultural county in the black soil region, it is an important commercial grain base for China.

In the initial land reclamation stage, the county’s environment was good and the land was fertile, After several decades of reclamation and overgrazing, soil nutrients were depleted, environmental quality deteriorated, land productivity was reduced, and population grew rapidly. Unreasonable land use after the founding of the new China largely accelerated the depletion of natural resources. By the end of the 1970s (Guo 2001; Lu et al. 2002), the region’s forest cover was reduced to 3.7%, the soil thickness decreased from 0.8 m to 0.3 m, soil organic matter in topsoil decreased from 6-8% to 3%, the soil erosion area reached 2.15 x 10^sup 5^ ha, and the wind-eroded area was 4.8 x 10^sup 4^ ha. Natural disasters frequently occurred, grain yield per hectare was less than 750 kg, farmer annual income was less than 100 yuan, and agricultural production and socio-economic development faced severe challenges. In the early 1980s, the county started a pilot eco-agricultural reconstruction project, and in 1986 a strategy at whole county scale was implemented. After 20 years of large-scale afforestation, slope and gully erosion control and comprehensive rehabilitation of the small basins, the ecology and environment has markedly improved.

Methods

Using a comparison method for statistical data from different time series, a dynamic analysis of the county’s economic system, including gross domestic product (GDP), per capita GDP, total agricultural output, per capita agricultural output, and ecological reconstruction (including water and soil conservation of farmland), flood and water-logging control measures and irrigation systems were implemented.

Analysis of Emergy includes three main steps (Lan et al. 2002): 1. establishment of a conceptual eco-economic system; 2. estimate of the Emergy; and 3. calculation of Emergy indices. In this study, material and energy input and output items of the county’s agricultural system were first established, then the energy values were converted into unified solar Emergy, according to their respective conversion ratios. Finally, production efficiency of the eco-economic system, people’s living standards, renewable energy consumption and sustainable development degree were evaluated using the Emergy yield ratio, Emergy per person, environmental load ratio and Emergy sustainable indices, respectively. The original data include the 1980-2002 yearbooks of socio-economic statistical data for Baiquan County, the Annals of Baiquan County, the Annals of Water Resources, land resources, and agricultural planning and investigations on land use in 2004 and 2005. The conversion parameters of energy were calculated using the methods described in Niu and Liu (1984), Wen and Pimentel (1984) and Luo (2001). The conversion ratios of Emergy were introduced from Ulgiati et al. (1994) and Lan et al. (2002). The calculation methods for Emergy indices and their significances are presented in Table 1. RESULTS

General features of the eco-economic system

Economic development dynamics of agricultural systems for different time series

Like most regions of China, since the policy of reform and opening to the outside world, the economy of Baiquan County has developed rapidly. The GDP, per capita GDP, total agricultural output value and per capita agricultural output value exhibited a rapid increase (output values in different years were calculated according to the invariant price in 2000), and increased more quickly in the 1990s than the 1980s (Figure 1). The above four figures increased from 350 million yuan, 601 yuan, 230 million yuan and 453 yuan in 1982 to 2.18 billion yuan, 3852 yuan, 900 million yuan and 1863 yuan in 2002, respectively. Their mean annual increase rates were 10.6%, 11.1%, 8.89% and 8.97%, respectively. However, the agricultural economy had a relatively low rate of increase although its development potential is large.

Both GDP and total agricultural output tended to continuously increase (Figure 1), but there were several low values in previous and subsequent years (1984, 1985,1988, 1989 and 2000) that all exactly corresponded to GDP and total agricultural output value. In terms of natural disasters in these years, the county still has low disaster resistance, and agricultural production significantly influenced the county’s economic increase, showing that agriculture is the leading industry in the county.

Ecological reconstruction dynamics of agricultural systems

Undulating hills, widespread gully-ridge terrain and severe soil erosion are important factors hindering agricultural production and economic development in Baiquan County. The county has adopted measures such as terracing fields, contour tillage and planting an anti-scour plant belt (shrub strips) to control slope erosion. Building terraced fields and transforming ridge direction peaked in the 1980s, and planting of anti-scour plant belts was mainly done in the late 1980s. By 2003, the county had 36267 hm^sup 2^ of terraced fields, had transformed 53533 hm^sup 2^ of ridge fields, and had planted 90200 hm^sup 2^ of anti-scour belts.

Baiquan County has always treated farmland shelterbelts as a basic skeleton for eco-agricultural reconstruction and conducted multi-layered and large-scale greening and afforestation projects, particularly in the periods 1981-1985, 1986, 1991-1995 and after 1999. Over the past 20 years, some 10000 hm^sup 2^ of farmland shelterbelts have been established, forming about 9000 shelterbelt meshes. A perfect and continuous protective forest system has been established and most of the county’s farmlands have been effectively protected.

About 20% of farmland in Baiquan County frequently suffers waterlogging. Over the years, dykes, drainage culverts, ditches and runoff-intercepting ditches have been built to control waterlogging and open up rice fields in suitable areas. As a result, land productivity in the waterlogging-prone areas has continuously improved. By 2002 the improved waterlogged land area reached 18230 hm^sup 2^, 43.6% of the county’s waterlogging-prone land area.

Baiquan County is in the dry farming zone, and water shortage has always been a limiting factor for agricultural production. Since the 1980s, the county has built 115 new reservoirs and 1302 ponds to supply irrigation water to arid lands and rice fields, especially for sowing in the arid spring season. The area of irrigated fields increased from about 1000 ha in the early 1980s to 10,000 ha in 2000.

Emergy dynamics of agricultural systems

The results of input and output Emergy in agricultural systems of Baiquan County in 1980, 1985, 1990, 1995 and 2002 are shown in Tables 2 and 3, respectively.

Analysis of Emergy input structure

The input of Emergy in the agricultural system for 1980-2002 showed a continuous increase (Figure 2), and input of Emergy in 2002 was 5.9-times that in 1980. The input of renewable environmental resources for 1980-1990 decreased but then increased from 1990 onwards (Figure 2). This may be related to a decrease in rainwater potential energy and rainwater chemical energy because of a decrease in rainfall. In addition, solar energy received by the system also decreased because of a decrease in cultivated land area. The input of non-renewable environmental resources is mainly due to soil loss; in 20 years of soil conservation, soil erosion intensity of farmland has decreased, therefore the input of non-renewable environmental resources also decreased (Figure 2). In a sense, modern agriculture is petroleum-based agriculture, and Baiquan County is no exception. Since the 1980s, agricultural machinery, application of fertiliser, mulching film and agricultural chemicals have continuously increased; hence, nonrenewable industrial auxiliary energy constituted a higher percentage or even continuous increased (Figure 2). Renewable organic energy slightly decreased from 1980-1985, possibly because of an increase in ploughing machinery and a decrease in use of manpower and animal power; in the same period, the application rate of organic manure was little changed. Since 1986, eco-agriculture has been practiced on a large scale, and the sown area of green manure crops has increased year on year. After the 1990s, rapidly developing animal husbandry produced huge amounts of manure and, hence, led to increased use of organic manure in fields. Since 1985, the sown area of commercial crops also increased, and seeds of new commercial crops have a higher energy value than those of grain crops.

Analysis of Emergy output structure

Emergy output of the agricultural system in Baiquan County for 1980-2000 continuously increased, especially after 1995 (Figure 3). The total Emergy output in 2000 was 7.4-times that of 1980. The output of agricultural systems mainly consisted of plant and animal products. The changes in output structure over the years were mainly manifested in the percentage of commercial crops and the scale of animal husbandry. From the mid-1980s, the sown area of commercial crops with high Emergy gradually increased, and Emergy output also increased (Figure 3). The output Emergy of commercial crops in 1985, 1990, 1995 and 2002 was 1.01-, 1.09-, 1.10- and 1.16-times those of 1980, respectively. Emergy of animal husbandry accounted for over 50% of total Emergy of agricultural products, and also continuously increased (Figure 3), reaching 62% in 2002. This shows that the increase in commercial crops and large-scale development of animal husbandry have led to the increased Emergy output of the system.

Evaluation indices of Emergy

Emergy yield ratio

The Emergy yield ratio (EYR) tended to decrease from 1980 to 1990, but slightly increased in the 1990s (Figure 4). This reveals that: production efficiency was higher in the 1980s than in the 1990s; and the 1990s had lower production efficiency but with an increasing trend. Although the Emergy yield had a higher increase in the 1990s than in the 1980s, this resulted from the input of large amounts of industrial auxiliary energy: the increase in the 1990s is attributed to the increased input of renewable organic Emergy due to eco-agriculture and increased animal products with higher Emergy yields. The 1980s had lower outputs and inputs, but from the 1990s onwards, output increased but input was relatively higher.

Emergy per person

Because the total Emergy input continuously increased, while population increase was limited after 1980, and some of the rural population moved to cities, the agricultural population decreased from 509,337 in 1980 to 483,449 in 2002; therefore, per capita Emergy consumption increased (Figure 4) and living standards of farmers steadily improved. However, the per capita Emergy consumption was still low, e.g. 1.79 E + 15 in 1980 and 3.33 E + 15 in 2002, while in Guangzhou city in southern China in 1995 it was 13.39 E + 15 (Sui and Lan 2003), and the county value was still lower than the China mean of 4.38 E + 15 (Lan et al 2002) and that of the USA, at 29.25 E + 15 in 1983 (Lan et al. 2002).

Environmental load ratio

The environmental load ratios for the agricultural system in Baiquan County in 1980, 1985, 1990, 1995 and 2002 were 2.5,2.7,6.8,6.2 and 9.2, respectively, showing an increase (Figure 4). This suggests that the scientific and technological level of agricultural production was improving, but environmental pressure was also increasing. However, the county’s agricultural environmental pressure was lower than that in developed countries such as Japan (14.49 in 1990) and Italy (10.43 in 1989) and also lower than that for corn and rice planting systems (10.06 and 13.66) in Gongzhuling city in Jilin Province in northeast China (Zhang 2000), but higher than the world mean of 1.15 (Ulgiati and Odum 1994).

Energy sustainability index (ESI)

Ulgiati and Brown (1998) suggested the energy-based sustainability index (ESI) to describe the relation between Emergy yield ratio and environmental load ratio of a system. If a country or a region’s eco-economic system has a high net energy yield but a relatively low environmental load, the system is sustainable. From 1980 to 1990, ESI was high but exhibited a lowering trend and, after 1990, it gradually rose (Figure 4). In the early 1980s, use of manpower and animal power increased but application rates of fertilisers and agricultural chemicals decreased; hence, the system had high sustainability. However, with increased input of industrial auxiliary energy, sustainability rapidly reduced. This was alleviated after 1990 and showed a slight rise, possibly related to effective soil and water conservation over 10 years and eco- agriculture since the mid-1980s. Large-scale water and soil conservation brought the depletion of non-renewable resources (soil) under control, and the input of organic manure and growing commercial crops and seeds of new varieties increased the percentage of renewable resources. An ESI < 1 means that the system is of the consumption type, with an undeveloped economy (Ulgiati and Brown 1998). The normal operation of the system relies heavily on external auxiliary energy supply, and consumption rate of local nonrenewable resources in the county is large and, hence, there is a need to develop local renewable resources. DISCUSSION

Based on economic features of the agricultural system and ecological rehabilitation of Baiquan County, Emergy analysis was used to study the production efficiency and sustainable developmental dynamics of the system over 20 years. The county’s economy and ecological reconstruction have been largely successful, but the agricultural system still faces environmental pressure, despite improvements in the county’s living and production environment. Production efficiency of the agricultural system and farmers’ living standards are low, but large-scale ecological rehabilitation has yielded preliminary agricultural effects and the system now shows better Emergy sustainable development. To improve production efficiency of the agricultural system, it is necessary to decrease inputs of non-renewable industrial auxiliary energy sources, and to continuously increase the input of renewable new energy sources, and the output, quality and quantity of agricultural secondary products. Therefore, efforts should be made to conserve water and soil in farmlands, reduce soil loss, control fertiliser and chemical application rates, increase application of organic manure and biological pesticides and degradable mulching film, increase the area of commercial crops with high Emergy, increase animal and aquatic products, and enhance output value through processing of agricultural products.

The living standards of farmers in Baiquan County are low, however, the county has great agricultural production potential and requires increases in Emergy inputs to tap such latent potential. At the same time, attention should be paid to reducing environmental pressures. After many years of ecological rehabilitation the county’s production and environmental conditions have been gready improved and the disaster resistance of farmland has been enhanced, but the application rates of non-renewable resources, machines, fertiliser and agricultural chemicals has continuously increased, and the environmental pressure on agricultural systems has not been reduced. Therefore, future research is needed to reduce environmental pressure on agricultural systems and develop the economy under the already improved environmental conditions. Eco- agricultural reconstruction has had some effect on the sustainable development of agricultural systems in Baiquan County, but remains limited. Continuous efforts should be made to develop eco- agriculture and explore new techniques and new methods to enhance the Emergy output efficiency of the system while reducing environmental pressure on the system.

Emergy provides a new method to judge sustainability of an economic system. The method integrates environmental elements into the calculation, and can reflect the contribution of the environment and its service functions to economic development by converting various elements into solar energy units to calculate and compare indices used for the sustainable development analysis. In this case study, it provides a bridge for exploring the promotion effect of ecological rehabilitation on agricultural production. Of course, the regional economic complex is a complicated system, many factors need to be taken into account, and the quantitative relationship between environment and production needs to be calculated and tested using several methods.

The improved environment created by many years of ecological rehabilitation and low-economic development are a prominent contradiction of the region. Soil has high natural productivity and can best be improved by control of soil erosion, which is a priority for future ecological reconstruction. In addition, realising ecological industrialisation and extending the industrial chain of ecological reconstruction in Baiquan County are effective ways to promote agricultural economic development and enhance economic returns of the agricultural eco-economic system.

This study was confined to Emergy input and output changes of the agricultural system itself, not quantitative analysis of the Emergy of artificial ecological engineering used to protect the agricultural system, or the feedback mechanism between ecological engineering and the agricultural ecoeconomic system, which remain unclear. In addition, the theory of Emergy is still at an early stage in China and basic study on Emergy conversion ratios is still lacking. Therefore, there is a need to seek more eco-economic methods in addition to analysis of Emergy to study the agricultural effects of ecological reconstruction, and to make comparative analyses of the methods and results.

ACKNOWLEDGEMENT

This paper is sponsored by the National Natural Science Foundation of China (No. 40571161).

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Jian-bing Wei1,2,3, Du-ning Xiao2 and,Hui Zeng1,3

1 Key Laboratory of Environmental and Urban Sciences, Shenzhen Graduate School of Peking

University, Shenzhen, China

2 Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang, China

3 College of Environmental and Urban Sciences of Peking University, Beijing, China

Correspondence: Jian-bing Wei, 405, E building, Shenzhen Graduate School of Peking University, Shenzhen University Town, Xili, Shenzhen 518055, China. Email: weijb@szpku.edu.cn

Copyright Sapiens Publishing Apr 2008

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