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Study on change in value of ecosystem service function of Tarim River
Acta Ecologica Sinica 30 (2010) 67–75
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Study on change in value of ecosystem service function of Tarim River Huang Xiang a,b, Chen Yaning a,b,*, Ma Jianxin a,b,c, Chen Yapeng a,b a
Xinjiang Institute of Ecology and Geography CAS, Uruqmi, Xinjiang 830011, China Key Laboratory for Oasis Ecology and Desert Environment, Uruqmi, Xinjiang 830011, China c Graduate University, Chinese Academy of Sciences, Beijing 100039, China b
a r t i c l e
i n f o
Keywords: Ecosystem service function Value Tarim River
a b s t r a c t The characteristic of change in value of Tarim River ecosystem service function and its causes are discussed by combining the remote-sensing images with social statistical data related to the change in land utilization of Tarim River Main stream area during 1973–2005 and applying correlation analysis, regressional analysis and principal component analysis methods. The results show a right ascension state in the value of Tarim River ecosystem service function over the past 30 years. Of which, the Cropland ecosystem service function is of the largest increment in the economic value, which is far in excess of other ecosystem systems; the capacity of forest, grassland and wetland in service supply and value attribution show a downward tendency relatively; the area of Cropland and unused land ecosystems increase while that of forest, grassland and wetland ecosystems decrease, which indicates that the integral capacity and balance of the ecosystem in the region investigated has been affected severely and the ecosystem deteriorated; the economic activity of human is the key factor to regulate the change in economic value of Tarim River ecosystem service function and its trend in development. Ó 2010 Ecological Society of China. Published by Elsevier B.V. All rights reserved.
1. Introduction Ecosystem is the foundation upon which human beings survive and their community civilization develops [1]. The products and service provided due to the ecosystem service function furnish the necessary environmental conditions and process in order to meet the requirements of human beings [2]. Therefore, the maintenance and protection of ecosystem service function is the essential for achieving the harmony and balance between human community and ecosystem. The study and evaluation on economic value of ecosystem service function and its change has become one of the hot spots in ecology and economics at present [3]. The current researches, however, rarely focus on the evaluation on arid-area ecosystem while mostly on those ecological types such as forest and wetland which render a service with a larger contribution capacity [4,5]. In view of ecosystem rehabilitation and sustainable development, the more we know about the economic value of various ecosystem service functions, the more we understand the importance of theirs. Therefore, it is necessary to accumulate the cases about study on arid-area ecosystem. Also, the evaluation on the value of arid-area ecosystem service function favors the judgment of ecosystem balance and its integrity, which ultimately promotes the harmonious development of community and ecosystem.
* Corresponding author. Address: Xinjiang Institute of Ecology and Geography CAS, Uruqmi, Xinjiang 830011, China. E-mail address: [email protected] (Y. Chen).
Tarim River Basin, being located in west arid area, is the biggest endorheic river valley in China and one of the most important bases of petroleum, cotton and grain in Xinjiang and China [6]. This region is abundant in resources with its fragile ecological environment and intensive conflict between economic development and ecological environment. Compare with other regions however, there is few researches on the development of the regional ecosystem under the impact of anthropic activities, in particular the researches on the ecosystem integrity and its balance state. In addition to the analysis and evaluation on land utilization and its change in the Main stream area of Tarim River by some researchers [7], no evaluation on the value of its ecosystem service function. The Main stream of Tarim River is taken as the subject investigated in this paper, the relation between ecosystem service function and anthropic activities is investigated systematically based on the dynamic change of ecosystem area and unit value, as well as the impact of the change in land utilization in this area on the value of ecosystem service function value; also, the mechanism of action between human beings and land is discussed from an ecosystem service function standpoint, which provides a theoretic foundation for the sustainable management of the river basin ecosystem. 2. General situation of region investigated Being located on the north edge and in west of Taklimakan Desert, the Main stream of Tarim River is 1320 km of full length. As a typical endorheic river in the arid area, the Main stream of
1872-2032/$ - see front matter Ó 2010 Ecological Society of China. Published by Elsevier B.V. All rights reserved. doi:10.1016/j.chnaes.2010.03.004
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Tarim River is mainly replenished by three sources at its upper reaches, i.e. Yerqiang River, Akesu River and Hotan River. The region is of typical continental climatic characteristics: arid with little precipitation and intensive evaporation; the annual precipitation is usually less than 50 mm and the evaporation is as high as 2300–3000 mm; being abundant in sunlight and the annual sunshine duration is 2800–3100 h; frost-free period 187–214 days, annual mean temperature 10–11 °C, accumulated temperature P10 °C is up to 4000–4350 °C [8]. There are 11 soil groups, 23 subgroups and 47 soil local types in the region of Tarim River Main stream; the main soil types cover floating aeolian sandy soil, semi-fixed aeolian sandy soil, salinized branchy tamarisk forest land, salinized diversifolious poplar forest land, diversifolious poplar forest land, salification meadow soil, meadow soil, meadow marsh soil, solonchak, residual solonchak, residual peat swamp soil and artificial oasis irrigation arable soil. The vegetation types cover warm-temperate-zone sparse shrub, subshrub desert area, Tarim Basin desert, spare shrub, subshrub desert area. According to administrative division, it covers Akesu city, Shaya County, Xinhe County and Kuche County under Akesu Prefecture, Luntai County, Korla City, Yuli County, Ruoqiang County under Bayinguoleng Mongolian Autonomous Prefecture, Xinjiang Uygur Autonomous Region, and 15 farms under Agricultural Division No. 1 (Farm Nos. 7, 8, 9, 10, 11, 12, 13, 14, 15 and 16) and Agricultural Division No. 2 (Farm Nos. 31, 32, 33, 34 and 35) of Xinjiang Production & Construction Corps. The section from Xiaojiake to Lopnur Lake is selected for this study, and the full length is 1320 km, reaching the lower edge of piedmont sloping plain at south foot of Tianshan Mountain in the north and the edge of Taklimakan Desert in the south; the geographic location is 39°200 0000 –41°300 0000 N, 80°300 0000 –88°300 0000 E, 1321 km 2 long, 20–75 km wide and the gross area 4:09 104 km (Fig. 1). 3. Materials and methods
processing modes are used for processing the data source of different periods. The topographic map of 1:100,000 is processed with projection processing and used as the master data source, a remote-sensing interpreting sign of corresponding land coverage type is established on GIS platform with combination of aerial remote-sensing land-use map of 1983 and TM (ETM) data of 2000 in register. The image data of 1973, 1990 and 2005 are rectified on the basis of TM image data of 2000, and the mean position error is controlled within two pixels. An interpretation of man-machine interaction is implemented based on land-use data of 1983 with the support of Arc/Info software, and the dynamic map spot of changes in various land-use types during two successive periods, therefore dynamic data of land use during different periods is obtained. At the same time, the data of ecosystem area in 1973, 1983, 1990, 2000 and 2005 are obtained, too. Due to the impact of Taklimakan Desert and Kuluk Desert, various land-use types in the region investigated are of regional characteristic along the river course, therefore, various ecosystems in this area are overlapped spatially. Based on the previous research results about land-use and ecosystem service function at home and abroad [10,11], and combining the hydrological and ecological characteristics with artificial intervening strength in this region, the ecosystem types of this region are classified as five types: Cropland, forest, grassland, wetland and unused land; of which, forest ecosystem consists of woodland, shrub land, open forest land and other woodland communities; grassland ecosystem consists of high-coverage grassland, medium-coverage grassland and lowcoverage grassland; wetland ecosystem consists of river and channel, lake, reservoir, bottomland and swampland; unused land ecosystem consists of desert, Gobi, alkaline land and bare land. Those five ecosystems interpreted with CBERS data of 2005 are rectified with large numbers of field spots which are selected at random, and ultimately the interpretation precision of all ecosystem areas is above 85%. Therefore, the requirement on analysis of large-area ecosystem area is satisfied.
3.1. Data acquisition 3.2. Equivalent determination The ecosystem area of the region investigated is represented by the data of land-use types based on the 1973 as MSS image, 1983 as the land-use map of 1:100,000 aerial remote-sensing [9], 1990 and 2000 as TM image and 2005 as CBERS image data; different
Equivalent Factor Table of Chinese Terrestrial Ecosystem Service Value (Table 1) is established by combining the classification of ecosystem types in this region and on the basis of ‘‘Equivalent Fac-
Fig. 1. Location of the main stream of Tarim.
X. Huang et al. / Acta Ecologica Sinica 30 (2010) 67–75
tor Table of Chinese Ecosystem Service Value” by Gaodi and coworkers [12]. The economic value of natural annual grain output 2 of 1 hm cropland with annual output nationwide is defined as 1 in this table; the equivalent factor of other ecosystem ecological service value refers to the ratio of contribution by the ecosystem’s ecological service to that by cropland’s grain-production service. 3.3. Parameter rectification
Ejr ¼ ej Ejc
ðj ¼ 1; 2; 3; 4; 5Þ;
ð1Þ
where, Ejr is the unit price of service of j ecosystem types in the region investigated, ej is the parameter of j ecosystem types and Ejr is the unit price of service of j ecosystem types nationwide.
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‘‘Equivalent Factor Table of Chinese Ecosystem Service Value” and the economic value of grain-production service per unit area of the cropland ecosystem in the region investigated, the unit price of other ecosystems or other ecological service functions in this region can be obtained.
Eij ¼ eij Ea
ði ¼ 1; 2 . . . ; 9; j ¼ 1; 2; . . . ; 5Þ;
ð4Þ
where Eij is the unit price of i ecological service functions of j ecosystem types, eij is the equivalent factor of i ecological service functions of j ecosystem types to the unit price of grain-production service provided by cropland ecosystem, i is the type of ecosystem service function, and j is ecosystem types including forest, grassland, cropland, wetland and unused land ecosystems. 3.7. Calculation of regional ecosystem’s service value
3.4. Method of calculating service function of Cropland ecosystem in grain production [12] To determine the service function of grain production per unit area of Cropland: n X mi pi qi Ea ¼ 1=7 M i¼1
ði ¼ 1; . . . ; nÞ;
ð2Þ
where Ea is the grain-production economic value per unit area of 2 Cropland ecosystem (yuan hm ), i is crop variety; the main crop varieties in the Tarim River Main stream area covers wheat, corn, sorghum, barley, beans and peas, oil crops and sugar beet, pi is 2 the average price of i crop nationwide (yuan hm ), qi is the yield 2 of per unit area of i crops (t hm ), mi is the area of i crop (hm2); 2 M is the gross area of i grain crop (hm ). 1/7 means that the economic value provided by the natural ecosystem without manpower investment is 1/7 of the grain-production economic value by current unit area of Cropland. 3.5. Conversion method of invariant economic value
Vn ¼ Vm
Um 100%; Un
ð3Þ
where Vn is the invariant economic value during the research period (calculating at constant price during the base period), Vm the present-year’s price of the economic value during the research period, U the inflation index of each year, m the research period, and n the base period. 3.6. Calculation of quantity of unit service value for the ecosystem of the river basin [12] Determination of economic value of ecological service per unit area for the ecosystem of the river basin ecosystem: based on Table 1 Equivalent Factor Table of Chinese Terrestrial Ecosystem Service Value. Content
Forest
Grassland
Cropland
Wetland
Useless land
A B C D E F G H I
3.5 2.7 3.2 3.9 1.31 3.26 0.1 2.6 1.28
0.8 0.9 0.8 1.95 1.31 1.09 0.3 0.05 0.04
0.5 0.89 0.6 1.46 1.64 0.71 1 0.1 0.01
0.9 8.78 17.94 0.86 18.18 2.495 0.2 0.04 4.945
0 0 0.03 0.02 0.01 0.34 0.01 0 0.01
A, gas regulation; B, climatic regulation; C, water-source conservation; D, formation and protection of soil; E, waste disposal; F, biodiversity protection; G, grain production; H, raw material; and I, amusement activities.
V¼
9 X 5 X i¼1
Aj Eij
ðI ¼ 1; 2; . . . ; 9; j ¼ 1; 2; . . . ; 5Þ;
ð5Þ
j¼1
where V is the total value of regional ecosystem service, Aj is the area of j ecosystem type, Eij is the unit price of I ecological service type of j ecosystem type, i is the type of ecosystem service function and j is ecosystem type. 4. Result and analysis 4.1. Calculation of unit price of ecosystem service function According to Xinjiang Statistical Yearbook and Statistical Yearbook of Xinjiang Production & Construction Corps the quantity of unit value of cropland ecosystem grain production during 1973–2005 is calculated. In order to increase the comparability of five-period data during 1973–2005, the annual unit price of grain-production value of cropland ecosystem is calculated based on the constant price of 1990 and the index of grain purchase with elimination of inflation factor, which, respectively are 217.39 yuan, 216.02 yuan, 289.18 yuan, 1042.63 yuan, and 1157.95 yuan (Table 2). In a similar way, the quantity of unit value is calculated regarding the service function of various ecosystem types within the Main stream area of Tarim River during 1973–2005 (Table 3). The quantity of unit value shows an increase trend as a whole in this area during 1973–1983, which increases from 0.19 109 yuan in 1973 to 1.05 109 yuan in 2005. In 1983, however, the grainproduction capacity of cropland ecosystem decrease slightly due to the implementation of policy of state monopoly for the purchase and marketing of grain and domestic political environments. 4.2. Economic value of ecosystem service function and its change 4.2.1. Change in area of ecosystem types During those 32 years from 1973 to 2005, a remarkable change in the areas of various ecosystem types is seen (Fig. 2) with an overall dynamic rate up to 272.76%. In terms of tendency, an increase trend shows in the areas of cropland and unused land by 186.15% and 85.56%, respectively in 2005 more than that in 1973 while a decrease trend in forest, grassland and wetland by 37.71%, 4.53% and 41.53%, respectively. The detailed analysis shows that the change in ecosystem types could be divided into three stages based on its rate and trend: the most remarkable change in ecosystem types took place during 1973–1983 and the dynamic degree of the change in each ecosystem type totals to 107.89%; the change during 2000–2005 comes next with total dynamic degree up to 68.29%; and the change during 1983–2000 is relatively mild with total dynamic degree of 56.31%; both the rate and trend of change are characteristic of a ‘‘U” shape.
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Table 2 Annual price of grain production of cropland ecosystem within main stream area of Tarim River during 1973–2005 and constant price in 1990 (yuan). Time
Index of grain consumption (100 in 1990)
Price of the same year
Deflation index
Constant price of 1990
1973 1983 1990 2000 2005
75.18 74.70 100.00 360.55 400.43
173.34 134.66 289.18 971.17 1363.55
79.73 62.34 100 93.15 117.76
217.39 216.02 289.18 1042.63 1157.95
Table 3 Unit price of service function of various ecosystems within Main stream area of Tarim River during 1973–2005 (constant price in 1990) (yuan). Forest 1973 A B C D E F G H I
Grassland
Cropland
Wetland
Useless land
760.88 586.97 695.66 847.84 284.79 708.71 21.74 565.23 278.27
173.92 195.66 173.92 423.92 284.79 236.96 65.22 10.87 8.70
108.70 193.48 130.44 317.40 356.53 154.35 217.39 21.74 2.17
195.66 1908.73 3900.06 186.96 3952.24 542.40 43.48 8.70 1075.02
0.00 0.00 6.52 4.35 2.17 73.91 2.17 0.00 2.17
756.08 583.26 691.27 842.49 282.99 704.24 21.60 561.66 276.51
172.82 194.42 172.82 421.25 282.99 235.47 64.81 10.80 8.64
108.01 192.26 129.61 315.39 354.28 153.38 216.02 21.60 2.16
194.42 1896.68 3875.46 185.78 3927.30 538.98 43.20 8.64 1068.24
0.00 0.00 6.48 4.32 2.16 73.45 2.16 0.00 2.16
1990 A B C D E F G H I
1012.13 780.78 925.37 1127.80 378.82 942.72 28.92 751.86 370.15
231.34 260.26 231.34 563.90 378.82 315.20 86.75 14.46 11.57
144.59 257.37 173.51 422.20 474.25 205.32 289.18 28.92 2.89
260.26 2538.99 5187.87 248.69 5257.27 721.50 57.84 11.57 1429.99
0.00 0.00 8.68 5.78 2.89 98.32 2.89 0.00 2.89
2000 A B C D E F G H I
3649.19 2815.09 3336.41 4066.24 1365.84 3398.96 104.26 2710.83 1334.56
834.10 938.36 834.10 2033.12 1365.84 1136.46 312.79 52.13 41.71
521.31 927.94 625.58 1522.24 1709.91 740.27 1042.63 104.26 10.43
938.36 9154.26 18704.73 896.66 18954.96 2601.35 208.53 41.71 5155.79
0.00 0.00 31.28 20.85 10.43 354.49 10.43 0.00 10.43
2005 A B C D E F G H I
4052.84 3126.47 3705.45 4516.02 1516.92 3774.93 115.80 3010.68 1482.18
926.36 1042.16 926.36 2258.01 1516.92 1262.17 347.39 57.90 46.32
578.98 1030.58 694.77 1690.61 1899.04 822.15 1157.95 115.80 11.58
1042.16 10166.83 20773.69 995.84 21051.60 2889.09 231.59 46.32 5726.08
0.00 0.00 34.74 23.16 11.58 393.70 11.58 0.00 11.58
1983 A B C D E F G H I
Note: A, gas regulation; B, climatic regulation; C, water-source conservation; D, formation and protection of soil; E, waste disposal; F, biodiversity protection; G, grain production; H, raw material; and I, amusement activities.
The analysis of change in the area of different type of ecosystem indicates that the said three stages of cropland ecosystem all are of increase trend with an increment more than 30%, of which, the increment during 2000–2005 is the most remarkable and up to 57.63%. The area of cropland increases 38.46% by during 1973–
1983 while that of forest and wetland decreases 28.42% and 21.65%, respectively; in the middle of 1990s, the ecological environment was deteriorating in the Main stream area of Tarim River. At the turn of this century, China started to implement the project of returning cultivated land to forestland or grassland, and the
Area (104hm2)
X. Huang et al. / Acta Ecologica Sinica 30 (2010) 67–75
Fig. 2. Area of each ecosystem in main stream area of Tarim River during 1973–2005.
Short-term Comprehensive Control Project of Tarim River Basin was carried out as a key point; thus the unused land decreased gradually from 1.3368 million hm2 in 1990 to 1.2405 million hm2 in 2005, the area of forest, grassland and wetland, however, is still of a trend of decrease. 4.2.2. Change in value of ecosystem service function According to the internal structural changes of service function value of various ecosystem types in the Main stream area of Tarim River, it is indicated that all the other types of service function value have a change trend the same as the general change trend with a U-curve in change rate except the continuous increase in the service function value of cropland ecosystem and unused land ecosystem. The area of each ecosystem type in the Main stream area of Tarim River during 1973–2005 and its corresponding unit price of service are analyzed, and the service function value of ecosystem in the Main stream area of Tarim River at each stage and its change is calculated (Fig. 3). It is shown in Fig. 3 that in the region investigated, the service function value of ecosystem increases as a whole, which increases from 9:44 109 yuan=year in 1973 to 40:69 109 yuan=year in 2005 by more than four times. A straight-line model can be used to describe the change trend of service function value of the ecosystem in this area along with time ðY ¼ 90844x 636320ðR2 ¼ 0:79ÞÞ. There is also, however, a period of decrease partially. The service function value of the ecosystem in the Main stream area of Tarim River decreased by 16.02% during 1973–1983, and the average decrease is 0.15 109 yuan per year. The service function value of the ecosystem in this area has been increasing continuously since 1983 with an average rate of annual increase 13.56%, in particular the maximum increment during 1990–2000 is up to 258.54%. The ecosystem service function value in the Main stream area of Tarim River is reflected with an integral increase on one hand, and on the other hand, also is manifested with the internal transfer of value. During 1973–1983, the service function values of forest, grassland and wetland ecosystems decrease, respectively by 1.06 109 yuan, 0.001 109 yuan and 0.54 109 yuan while that of cropland ecosystem and unused land ecosystem increases by 0.08 109 yuan and 0.02 109 yuan; during 1983–2005, the service function values of forest, grassland, cropland, wetland and unused land ecosystems increase, respectively by 9.61 109 yuan, 12.35 109 yuan, 2.87 109 yuan, 7.45 109 yuan and 0.49 109 yuan, of which, cropland ecosystem has the most remarkable increment up to 1007.8%, and the increments of service function value with respect to forest, grassland and wetland ecosystems are similar; and the service function value of unused land ecosystem increases also from 0.09 109 yuan in 1973 to 0.6 109 yuan in 2005 because the unused land ecosystem has a larger proportion and its area increases continuously during this period. The service function of forest, grassland and wetland ecosystems also shows an
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increase trend as a whole because the service function values provided by the unit area of those ecosystems are higher than that of other ecosystems, and the biomass produced by cropland ecosystem changes somewhat due to the improvement of economic development level, which causes that even the ecosystem area decreases as a whole, the service function value of those ecosystems increases still. The economic value of ecosystem service function, which is based on ‘‘Equivalent Factor Table of Nationwide Ecosystem Service”, reflects mostly people’s willingness to pay. Therefore, the increase of ecosystem service function value in this area reflects to some extent that the importance of the service function of the natural ecosystems such as forest, grassland and wetland etc. increases to the development of human community. The level of human community and economic development is reflected to some extent by the development of cropland ecosystem service function. In respect to agricultural ecosystem, the service function value of other ecosystems reflects the integral capacity of the ecosystem, which is opposite to the capacity of anthropic production and service. During 1973–2005, the ratios of the respective service function values of forest, grassland and wetland ecosystems to that of cropland ecosystem were decreasing, which reduced respectively from 17.8%, 14.6% and 11.7% in 1973 to 3.8%, 4.8% and 2.9% in 2005. It is indicated that the increase rate of the service function value of forest, grassland and wetland ecosystems is much less than that of cropland ecosystem. To the development of human community, the value of those ecosystems is in a state of decreasing continuously, and the capacity of providing service is also decreasing continuously, which brings a severe negative impact on the integral balance of the ecosystem. With the analysis of spatial variation in the ecosystem service function value of Tarim River at its upper reach, middle reach and lower reach, it can be seen that the ecosystem service function value at its upper reach and middle reach always accounts for more than 85% of the total value quantity of the region; the middle reach is bigger slightly than the upper reach, and the lower reach is the least, accounting only for about 14.57%. Since 1970, the runoff in this region has been affected by anthropic activities [13]. The change in ecosystem area becomes more evident towards the lower reach due to the decrease of surface runoff. For instance, the surface runoff at the middle reach and lower reach of the Main stream in 2005 is 25.5% and 20.9% less, respectively than that in 1973. During the same period, the areas of forest, grassland and wetland ecosystems at the middle and lower reaches of Tarim River decrease remarkably: decreasing by 14.43%, 21.63% and 21.47% at the middle reach, and 47.77%, 24.19% and 40.22% at the lower reach, respectively; whilst the areas of cropland and unused land ecosystems increase by 474.07% and 63.89%, respectively at the middle reach of Tarim River, and 170.76% and 86.09% at the lower reach of Tarim River. The overall equilibrium of ecosystem in service value is influenced directly by the structural adjustment and the increment of all the other ecosystems in service value is much less than that of cropland ecosystem. For instance, during 1973– 2005, the increment of cropland ecosystem at the lower reach in service function value is 13.42%, the increment of forest, grassland and wetland ecosystem in service function value, however, is only 2.34%; the increment of cropland ecosystem at the middle reach in service function value is 29.58%, the increment of forest, grassland and wetland ecosystem in service function value, however, is only 3.3%; the increment of cropland ecosystem at the upper reach in service function value is 11.27%, the increment of forest, grassland and wetland ecosystem in service function value, however, is only 2.88%. In this way, we can say that the trend and variation of the overall ecosystem in service value is influenced to a large extent by the cropland ecosystem at each reach, and the overall level of ecosystem structure and its service value is related closely to the increase of anthropic activities in strength.
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Fig. 3. Change in economic value of ecosystem service function in main stream area of Tarim River during 1973–2005.
4.3. Driving force analysis of change in ecosystem service function Due to the fact that the change of ecosystem is intricate with complicated contributing factors, the factors to be selected for the research on the driving force in the change of ecosystem service function value shall be comprehensive; however, too many indicators shall increase the difficulty and complexity of the issue to be analyzed. In order to further unveil the factors driving the change in economic value of the ecosystem service function in the Main stream area of Tarim River, the socioeconomic and demographic factors to be selected have a dependency relation not only with the change of ecosystem area, but with each other within themselves. Since it is difficult to quantify the factors such as social behaviors, behavior of the main ecosystem users, policy and system etc., here only three major driving factors are quantified for the purpose of research, which covers population development, economic development and technical progress; and nine indicators during 1973–2005 are used to reflect the change in social economy and population: economic factors (GDP, output value of the pri-
mary industry and output value of secondary industry), population factors (total population and agricultural population), science and technological factor (total power of agricultural machinery), and production factors of agriculture and animal husbandry (livestock inventories at end of year, acreage of grain and acreage of cotton). By taking the change in the economic value of ecosystem service function in this region as the subject investigated, we studied the extent of nine socioeconomic indicators’ impact on the subject investigated via principal component analysis (hereafter referred to as simply PCA). With PCA method and SPSS software, nine analysis factors are selected: X1 – gross domestic product (GDP) (100 million yuan); X2 – total output value of primary industry (100 million yuan); X3 – total output value of secondary industry (100 million yuan); X4 – total power of agricultural machinery (KW); X5 – gross population (10,000 persons); X6 – gross agricultural population (10,000 persons); X7 – livestock inventories at end of year (capita); X8 – acreage of cotton (hm2); X9 – acreage of grain (hm2). The data are processed with standardization first to eliminate the influence
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of various dimensions. It is discovered with statistical analysis that the service function value (F) of the ecosystems in the region investigated has a very significant correlation with the major socioeconomic factors. With a principal component analysis to the said factors, KMO test value is 0.711 and Bartlett spherical test value is 0.000. Therefore, the result is possibly acceptable with the said factors for principal component analysis. The result of principal component analysis indicates that the accumulative contribution rate of the first, secondary and third principal components is 89.3% (Table 4), which is more than 75%, the threshold value of accumulative contribution rate, thus it is in accordance with the analysis requirement: most variation shall be explained with three principal components collected. The accumulative contribution rate of the first principal component is far more than that of the secondary principal component, and the accumulative contribution rate of the secondary principal component is slightly more than that of the third principal component, those both are close to each other, and the first principal component has a contribution much bigger than the sum of the secondary and the third principal components. In order to make the complicated matrix concise, Rotated Factor Matrix and Factor Transformation Matrix are obtained with orthogonal rotation process (Tables 5 and 6). It is seen that the first principal component has an obvious positive correlation with the observation variables X2, X5, X6 and X7, and the correlation coefficient is over 0.67; the secondary principal component has an obvious positive correlation with the observation variables X4 and X8 but an obvious negative correlation with X9, and the correlation coefficient exceeds 0.81; the third principal component has an obvious positive correlation with the observation variables X1 and X3 with a correlation coefficient more than 0.72. Therefore, with reference to the meaning of each variable, it can be determined clearly that the active factor influencing the change in the economic value of the ecosystem service function in the Main stream area of Tarim River over the past thirty years shall be anthropic activities, which is reflected mainly in economic development and population growth. The first principal component consists of four factors and the impact of each factor is different. The sequence of their impact on the change in economic value of the ecosystem service function in this region is: total population > output value of primary industry > livestock inventories at end of year > agricultural population. This region is a typical oasis agricultural region distributing along Tarim River and the industrial structure always consists mainly of agriculture and animal husbandry. In the internal structure of agriculture, crop production is of absolute advantage all the time. Therefore, the growth of population in this region and the increase of the strength in agricultural and animal husbandry activities have a significant impact on the change in economic value of the ecosystem service function in this region. The secondary principal component consists of three factors and the sequence of their impact is grain acreage > cotton acreage > total power of agricultural
Table 4 Contribution rate of characteristic values and principal components. Component
Total
% of variance
Cumulative %
1 2 3 4 5 6 7 8 9
5.253 1.597 1.185 .634 .172 .077 .048 .026 .009
58.367 17.740 13.162 7.044 1.906 .852 .535 .292 .101
58.367 76.108 89.270 96.314 98.220 99.072 99.606 99.899 100.000
Table 5 Rotated factor (principal component) matrix. index X1 X2 X3 X4 X5 X6 X7 X8 X9
(GDP) (GDP of primary industry) (GDP of secondary industry) (total power of agricultural machinery) (gross population) (gross agricultural population) (livestock inventories at end of year) (acreage of cotton) (acreage of grain)
1
2
3
.513 .869 .179 .580 .939 .671 .779 .261 .193
.446 .333 .171 .805 .064 .272 .424 .926 .946
.716 .214 .962 .001 .269 .091 .053 .150 .124
Table 6 Factor transformation matrix. Component
1
2
3
1 2 3
.742 .130 .658
.667 .052 .743
.062 .990 .125
Extraction method: principal component analysis. Rotation method: varimax with Kaiser normalization.
machinery; the impact sequence of those factors of the third principal component is output value of secondary industry > GDP. Due to the influence of national development policy, the driving force of population growth and the development of agriculture and animal husbandry is characterized by its phases and developing nature: at the end of 1970s, the production level developed slowly in China because of the impact of macro-political environments, in particular the agricultural productivity is very low and the economic value of ecosystem service function per unit area was kept at a very low level; during 1973–1983, with the continuous growth of population in this region, the demand of grain increase sharply; due to the underdeveloped productivity, however, the demand of grain is met mainly by enlarging the cultivated area. In this way, the area of agricultural ecosystem and its service function economic value saw a large increment at this phase while the areas of forest, grassland and wetland ecosystem as well as their economic value per unit area are decline somewhat. During the medium-late 1980s, with the emphasis and encouragement of the country on the agricultural production and economic development of Xinjiang Production and Construction Corps, the land development in the Main stream area of Tarim River was expedited not only in agricultural size but also in intensive cultivation. Therefore, the unit biomass of cropland ecosystem increased greatly and promoted the improvement of the unit value quantity of other ecosystem service function while the expansion of cropland ecosystem area slowed. The downtrend of economic value of the whole ecosystem service function in this region was reversed and started to increase slowly. The advantage of cash crops market appeared gradually with the implementation of reform and opening policies and the development of market economy in China, in particular, the advantage of cotton price stimulated cotton planting. At the turn of the century, cash crops occupy not only part of grainplanted area, but a great amount of forest, grassland and unused saline-alkali land, which finally makes a remarkable increase in cropland ecosystem area and its quantity of unit value. At the same time, with the improvement substantially in agricultural productivity and industrial technological level, the economic values of other ecosystems also meet their peak value historically. Due to the implementation of various national preferential policies on agricultural production as well as the impact of market on grain and cotton prices, the enthusiasm for new land development and reclamation of abandoned field is still retained with the urge of
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economic interest so that the history see another rapid increase in the area and value of cropland ecosystem. It is thus evident that the growth of population and the development of agriculture and animal husbandry are the most direct and basic driving force for the change in economic value of the ecosystem service function in the Main stream area of Tarim River. During the period of a higher population growth rate, population growth is the most basic driving force for the change in various ecosystems’ area, and the economic growth provides a powerful support to this driving force. The pressure of population growth creates a potential demand of land, and the improvement of economic level transfer such a potential demand into an effective demand; they both promote the continuous change of ecosystem area; in a case of stable population, continuous improvement of population quality, continuous development of economy and continuous increase of productivity level, the driving force of technological progress is also an important factor influencing the economic value per unit area of ecosystem service function.
5. Conclusion and discussion Tarim River Main stream flows around the north edge and the west part of Taklimakan Desert, the ecosystem types along the river cover forest, grassland, wetland, cropland and unused land with typical characteristic of endorheic river ecosystem in arid area. This region features resources advantage and fragile environmental background, and the ecosystem is threatened by a synergistic impact of multiple environmental factors and intensive anthropic interference, which is the reason why it is selected for the research on the economic value of ecosystem service function and its change. On one hand, the research shall provide data for evaluating the scarcity of various ecosystems in arid area; on the other hand, with the research on the driving factors for the change in various ecosystems’ service value, the process and characteristics of change in ecosystem service function value of this region could be understood, which provides a theoretical foundation for exploring the control strategy of ecosystem service function value in this region, the ecological safety of arid-area endorheic river as well as the sustainable development of society and economy. (1) It is shown with the data analysis of gain procurement index in the Main stream area of Tarim River that the inflation coefficient of grain procurement price in the region investigated increases from 75.19% in 1973 to 400.43% in 2005 (calculating at 100 in 1990), excluding the impact of inflation factor, based on the grain production of cropland ecosystem, the quantity of unit value of the service function of each ecosystem is calculated. The result shows an increase trend of actual value regarding the quantity of unit value of service function of Tarim River Main stream ecosystem; of which, the quantity of unit value declines slightly by 0.63% during 1973–1983 and increases by 432.65% during 1973–2005. (2) It is shown with the analysis of change in the area of landuse type in the Main stream area of Tarim River during 1973–2005 that the areas of cropland and unused land in this region increase, respectively by 186.2% and 85.6%; the areas of forest, grassland and wetland drop relatively great as a whole by 37.71%, 4.53% and 41.53%, and the regional ecological environment is of a degradation trend as a whole. During 1973–1983, the annual decrease rate of forest and 2 wetland area is 2200 hm2 and 450 hm , and the annual 2 increase rate of unused land is up to 2010 hm ; the annual decrease rate of forest and wetland area has declined greatly 2 since 1983 to only 80 hm , but the annual increase rate of 2 unused land area is only 10 hm .
(3) It is shown with the analysis of change in the economic value of the ecosystem service function in the Main stream area of Tarim River during 1973–2005 that the economic value of the ecosystem service function in the region investigated is of an increase trend, and the economic value increases from 9:44 109 yuan=a in 1973 to 9 40.69 10 yuan/a in 2005 by more than four times, which reflects to some extent that the importance of ecosystem service function to the development of human community increases. On the other hand, the service function value of the ecosystem in this region transfers within the internal structure, namely, a great amount of economic value of the service function of forest, grassland and wetland ecosystems transfer into the cropland ecosystem. The increment per unit area of cropland ecosystem is superposed on the quantity of unit value that rises increasingly and leads to an increasing growth of the economic value of the cropland ecosystem service function during those 32 years. It is indicated with data that the value of cropland ecosystem service function increases by 2.95 109 yuan; the economic value of other ecosystems’ service function, however, increased far slower than that of cropland ecosystem did, in other words, the former is in a state of relative decrease, and the capacity and contribution provided by forest, grassland and wetland ecosystems decrease continuously in an integral ecosystem, thus the integrative capacity and integral equilibrium of the ecosystem is effected severely. (4) It is shown with the analysis of change in the spatial variation of the ecosystem service function in the Main stream area of Tarim River during 1973–2005 that the service value of upper-reach and middle-reach ecosystems accounts always for more than 85% of total value while that of the lower-reach ecosystem only 1/7. Due to the decrease of surface runoff and the increase of anthropic activities’ strength, the area of forest, grassland and wetland ecosystems at the middle- and lower-reach decreases remarkably but the area of cropland and unused land ecosystems increases evidently. The adjustment of ecosystem structure influences directly the integral equilibrium of the ecosystems’ service value, and the increment of other ecosystems’ service value is far less than that of cropland ecosystem: the increment of cropland ecosystem’s service function value at the upper-, middle- and lower-reach of Tarim River is 4.5, 9 and 6 times more than that of forest, grassland and wetland ecosystems, respectively. In this way, the cropland ecosystem at each reach of the river has an impact to a great extent on the trend and variation of the whole ecosystem’s service value. The ecosystem structure and its overall level of service value are related closely with the increment of anthropic activities’ strength. (5) According to the analysis of nine indicators (total population and agricultural population reflecting the change in population in the Main stream area of Tarim River Main stream, GDP reflecting the level of economic development, total output value of primary industry and secondary industry reflecting industrial structure and policy factor, grain yield and cotton output, livestock inventories at end of year, and total power of agricultural machinery reflecting technological innovation factor) and the analysis of change in the ecosystem service function value, it is discovered that there is a significant correlation among population, economic and social factors and the change in their economic values, which affects 89.3% of the change in the economic value of the ecosystem service function in this region and is a key factor promoting its change rate and adjusting its development trend.
X. Huang et al. / Acta Ecologica Sinica 30 (2010) 67–75
The economic value of ecosystem service function reflects to some extent the willingness to pay as well as the scarcity of various ecosystem types. The application of economic value in the importance explanation of ecosystem service function does not mean that all necessary resources and functions could be bought with money. The complexity to change the ecosystem shall be viewed from a standpoint of ecological integrity and then we can realize that what a huge loss would be caused due to the missing of some functions of the ecosystem, and then we shall understand that, comparing with the loss, how inappreciable the economic benefit we obtained is. It is indicated with this study that the more intensive the anthropic activities for satisfying humans’ interests are, the more important the functions of the natural ecosystem are. The equilibrium state of ecosystem can be secured only when the stable state between artificial and natural ecosystems is guaranteed. Acknowledgements Supported by the Natural Science Foundation of China (No. 40901105), Knowledge Innovation Project from the Chinese Academy of Sciences (No. XBBS200810) and National Natural Science Foundation of China (No. 2006BAC01A03). Project funded by Xinjiang Statistical Yearbook (1989, 1999, 2006); Statistical Yearbook of Xinjiang Production & Construction Corps (1989, 1999, 2006); 50 Years of Xinjiang (1955–2005); Alaer Statistical Yearbook of Agricultural Division No. 1 (1990–2006); Statistical Summary of Division No. 2 of Xinjiang Production & Construction Corps (2002– 2006; 1991–2000) and Statistical Historical Data Collection of Division No. 2 of Xinjiang Production & Construction Corps (1952– 2002).
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Acta Ecologica Sinica journal homepage: www.elsevier.com/locate/chnaes
Study on change in value of ecosystem service function of Tarim River Huang Xiang a,b, Chen Yaning a,b,*, Ma Jianxin a,b,c, Chen Yapeng a,b a
Xinjiang Institute of Ecology and Geography CAS, Uruqmi, Xinjiang 830011, China Key Laboratory for Oasis Ecology and Desert Environment, Uruqmi, Xinjiang 830011, China c Graduate University, Chinese Academy of Sciences, Beijing 100039, China b
a r t i c l e
i n f o
Keywords: Ecosystem service function Value Tarim River
a b s t r a c t The characteristic of change in value of Tarim River ecosystem service function and its causes are discussed by combining the remote-sensing images with social statistical data related to the change in land utilization of Tarim River Main stream area during 1973–2005 and applying correlation analysis, regressional analysis and principal component analysis methods. The results show a right ascension state in the value of Tarim River ecosystem service function over the past 30 years. Of which, the Cropland ecosystem service function is of the largest increment in the economic value, which is far in excess of other ecosystem systems; the capacity of forest, grassland and wetland in service supply and value attribution show a downward tendency relatively; the area of Cropland and unused land ecosystems increase while that of forest, grassland and wetland ecosystems decrease, which indicates that the integral capacity and balance of the ecosystem in the region investigated has been affected severely and the ecosystem deteriorated; the economic activity of human is the key factor to regulate the change in economic value of Tarim River ecosystem service function and its trend in development. Ó 2010 Ecological Society of China. Published by Elsevier B.V. All rights reserved.
1. Introduction Ecosystem is the foundation upon which human beings survive and their community civilization develops [1]. The products and service provided due to the ecosystem service function furnish the necessary environmental conditions and process in order to meet the requirements of human beings [2]. Therefore, the maintenance and protection of ecosystem service function is the essential for achieving the harmony and balance between human community and ecosystem. The study and evaluation on economic value of ecosystem service function and its change has become one of the hot spots in ecology and economics at present [3]. The current researches, however, rarely focus on the evaluation on arid-area ecosystem while mostly on those ecological types such as forest and wetland which render a service with a larger contribution capacity [4,5]. In view of ecosystem rehabilitation and sustainable development, the more we know about the economic value of various ecosystem service functions, the more we understand the importance of theirs. Therefore, it is necessary to accumulate the cases about study on arid-area ecosystem. Also, the evaluation on the value of arid-area ecosystem service function favors the judgment of ecosystem balance and its integrity, which ultimately promotes the harmonious development of community and ecosystem.
* Corresponding author. Address: Xinjiang Institute of Ecology and Geography CAS, Uruqmi, Xinjiang 830011, China. E-mail address: [email protected] (Y. Chen).
Tarim River Basin, being located in west arid area, is the biggest endorheic river valley in China and one of the most important bases of petroleum, cotton and grain in Xinjiang and China [6]. This region is abundant in resources with its fragile ecological environment and intensive conflict between economic development and ecological environment. Compare with other regions however, there is few researches on the development of the regional ecosystem under the impact of anthropic activities, in particular the researches on the ecosystem integrity and its balance state. In addition to the analysis and evaluation on land utilization and its change in the Main stream area of Tarim River by some researchers [7], no evaluation on the value of its ecosystem service function. The Main stream of Tarim River is taken as the subject investigated in this paper, the relation between ecosystem service function and anthropic activities is investigated systematically based on the dynamic change of ecosystem area and unit value, as well as the impact of the change in land utilization in this area on the value of ecosystem service function value; also, the mechanism of action between human beings and land is discussed from an ecosystem service function standpoint, which provides a theoretic foundation for the sustainable management of the river basin ecosystem. 2. General situation of region investigated Being located on the north edge and in west of Taklimakan Desert, the Main stream of Tarim River is 1320 km of full length. As a typical endorheic river in the arid area, the Main stream of
1872-2032/$ - see front matter Ó 2010 Ecological Society of China. Published by Elsevier B.V. All rights reserved. doi:10.1016/j.chnaes.2010.03.004
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Tarim River is mainly replenished by three sources at its upper reaches, i.e. Yerqiang River, Akesu River and Hotan River. The region is of typical continental climatic characteristics: arid with little precipitation and intensive evaporation; the annual precipitation is usually less than 50 mm and the evaporation is as high as 2300–3000 mm; being abundant in sunlight and the annual sunshine duration is 2800–3100 h; frost-free period 187–214 days, annual mean temperature 10–11 °C, accumulated temperature P10 °C is up to 4000–4350 °C [8]. There are 11 soil groups, 23 subgroups and 47 soil local types in the region of Tarim River Main stream; the main soil types cover floating aeolian sandy soil, semi-fixed aeolian sandy soil, salinized branchy tamarisk forest land, salinized diversifolious poplar forest land, diversifolious poplar forest land, salification meadow soil, meadow soil, meadow marsh soil, solonchak, residual solonchak, residual peat swamp soil and artificial oasis irrigation arable soil. The vegetation types cover warm-temperate-zone sparse shrub, subshrub desert area, Tarim Basin desert, spare shrub, subshrub desert area. According to administrative division, it covers Akesu city, Shaya County, Xinhe County and Kuche County under Akesu Prefecture, Luntai County, Korla City, Yuli County, Ruoqiang County under Bayinguoleng Mongolian Autonomous Prefecture, Xinjiang Uygur Autonomous Region, and 15 farms under Agricultural Division No. 1 (Farm Nos. 7, 8, 9, 10, 11, 12, 13, 14, 15 and 16) and Agricultural Division No. 2 (Farm Nos. 31, 32, 33, 34 and 35) of Xinjiang Production & Construction Corps. The section from Xiaojiake to Lopnur Lake is selected for this study, and the full length is 1320 km, reaching the lower edge of piedmont sloping plain at south foot of Tianshan Mountain in the north and the edge of Taklimakan Desert in the south; the geographic location is 39°200 0000 –41°300 0000 N, 80°300 0000 –88°300 0000 E, 1321 km 2 long, 20–75 km wide and the gross area 4:09 104 km (Fig. 1). 3. Materials and methods
processing modes are used for processing the data source of different periods. The topographic map of 1:100,000 is processed with projection processing and used as the master data source, a remote-sensing interpreting sign of corresponding land coverage type is established on GIS platform with combination of aerial remote-sensing land-use map of 1983 and TM (ETM) data of 2000 in register. The image data of 1973, 1990 and 2005 are rectified on the basis of TM image data of 2000, and the mean position error is controlled within two pixels. An interpretation of man-machine interaction is implemented based on land-use data of 1983 with the support of Arc/Info software, and the dynamic map spot of changes in various land-use types during two successive periods, therefore dynamic data of land use during different periods is obtained. At the same time, the data of ecosystem area in 1973, 1983, 1990, 2000 and 2005 are obtained, too. Due to the impact of Taklimakan Desert and Kuluk Desert, various land-use types in the region investigated are of regional characteristic along the river course, therefore, various ecosystems in this area are overlapped spatially. Based on the previous research results about land-use and ecosystem service function at home and abroad [10,11], and combining the hydrological and ecological characteristics with artificial intervening strength in this region, the ecosystem types of this region are classified as five types: Cropland, forest, grassland, wetland and unused land; of which, forest ecosystem consists of woodland, shrub land, open forest land and other woodland communities; grassland ecosystem consists of high-coverage grassland, medium-coverage grassland and lowcoverage grassland; wetland ecosystem consists of river and channel, lake, reservoir, bottomland and swampland; unused land ecosystem consists of desert, Gobi, alkaline land and bare land. Those five ecosystems interpreted with CBERS data of 2005 are rectified with large numbers of field spots which are selected at random, and ultimately the interpretation precision of all ecosystem areas is above 85%. Therefore, the requirement on analysis of large-area ecosystem area is satisfied.
3.1. Data acquisition 3.2. Equivalent determination The ecosystem area of the region investigated is represented by the data of land-use types based on the 1973 as MSS image, 1983 as the land-use map of 1:100,000 aerial remote-sensing [9], 1990 and 2000 as TM image and 2005 as CBERS image data; different
Equivalent Factor Table of Chinese Terrestrial Ecosystem Service Value (Table 1) is established by combining the classification of ecosystem types in this region and on the basis of ‘‘Equivalent Fac-
Fig. 1. Location of the main stream of Tarim.
X. Huang et al. / Acta Ecologica Sinica 30 (2010) 67–75
tor Table of Chinese Ecosystem Service Value” by Gaodi and coworkers [12]. The economic value of natural annual grain output 2 of 1 hm cropland with annual output nationwide is defined as 1 in this table; the equivalent factor of other ecosystem ecological service value refers to the ratio of contribution by the ecosystem’s ecological service to that by cropland’s grain-production service. 3.3. Parameter rectification
Ejr ¼ ej Ejc
ðj ¼ 1; 2; 3; 4; 5Þ;
ð1Þ
where, Ejr is the unit price of service of j ecosystem types in the region investigated, ej is the parameter of j ecosystem types and Ejr is the unit price of service of j ecosystem types nationwide.
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‘‘Equivalent Factor Table of Chinese Ecosystem Service Value” and the economic value of grain-production service per unit area of the cropland ecosystem in the region investigated, the unit price of other ecosystems or other ecological service functions in this region can be obtained.
Eij ¼ eij Ea
ði ¼ 1; 2 . . . ; 9; j ¼ 1; 2; . . . ; 5Þ;
ð4Þ
where Eij is the unit price of i ecological service functions of j ecosystem types, eij is the equivalent factor of i ecological service functions of j ecosystem types to the unit price of grain-production service provided by cropland ecosystem, i is the type of ecosystem service function, and j is ecosystem types including forest, grassland, cropland, wetland and unused land ecosystems. 3.7. Calculation of regional ecosystem’s service value
3.4. Method of calculating service function of Cropland ecosystem in grain production [12] To determine the service function of grain production per unit area of Cropland: n X mi pi qi Ea ¼ 1=7 M i¼1
ði ¼ 1; . . . ; nÞ;
ð2Þ
where Ea is the grain-production economic value per unit area of 2 Cropland ecosystem (yuan hm ), i is crop variety; the main crop varieties in the Tarim River Main stream area covers wheat, corn, sorghum, barley, beans and peas, oil crops and sugar beet, pi is 2 the average price of i crop nationwide (yuan hm ), qi is the yield 2 of per unit area of i crops (t hm ), mi is the area of i crop (hm2); 2 M is the gross area of i grain crop (hm ). 1/7 means that the economic value provided by the natural ecosystem without manpower investment is 1/7 of the grain-production economic value by current unit area of Cropland. 3.5. Conversion method of invariant economic value
Vn ¼ Vm
Um 100%; Un
ð3Þ
where Vn is the invariant economic value during the research period (calculating at constant price during the base period), Vm the present-year’s price of the economic value during the research period, U the inflation index of each year, m the research period, and n the base period. 3.6. Calculation of quantity of unit service value for the ecosystem of the river basin [12] Determination of economic value of ecological service per unit area for the ecosystem of the river basin ecosystem: based on Table 1 Equivalent Factor Table of Chinese Terrestrial Ecosystem Service Value. Content
Forest
Grassland
Cropland
Wetland
Useless land
A B C D E F G H I
3.5 2.7 3.2 3.9 1.31 3.26 0.1 2.6 1.28
0.8 0.9 0.8 1.95 1.31 1.09 0.3 0.05 0.04
0.5 0.89 0.6 1.46 1.64 0.71 1 0.1 0.01
0.9 8.78 17.94 0.86 18.18 2.495 0.2 0.04 4.945
0 0 0.03 0.02 0.01 0.34 0.01 0 0.01
A, gas regulation; B, climatic regulation; C, water-source conservation; D, formation and protection of soil; E, waste disposal; F, biodiversity protection; G, grain production; H, raw material; and I, amusement activities.
V¼
9 X 5 X i¼1
Aj Eij
ðI ¼ 1; 2; . . . ; 9; j ¼ 1; 2; . . . ; 5Þ;
ð5Þ
j¼1
where V is the total value of regional ecosystem service, Aj is the area of j ecosystem type, Eij is the unit price of I ecological service type of j ecosystem type, i is the type of ecosystem service function and j is ecosystem type. 4. Result and analysis 4.1. Calculation of unit price of ecosystem service function According to Xinjiang Statistical Yearbook and Statistical Yearbook of Xinjiang Production & Construction Corps the quantity of unit value of cropland ecosystem grain production during 1973–2005 is calculated. In order to increase the comparability of five-period data during 1973–2005, the annual unit price of grain-production value of cropland ecosystem is calculated based on the constant price of 1990 and the index of grain purchase with elimination of inflation factor, which, respectively are 217.39 yuan, 216.02 yuan, 289.18 yuan, 1042.63 yuan, and 1157.95 yuan (Table 2). In a similar way, the quantity of unit value is calculated regarding the service function of various ecosystem types within the Main stream area of Tarim River during 1973–2005 (Table 3). The quantity of unit value shows an increase trend as a whole in this area during 1973–1983, which increases from 0.19 109 yuan in 1973 to 1.05 109 yuan in 2005. In 1983, however, the grainproduction capacity of cropland ecosystem decrease slightly due to the implementation of policy of state monopoly for the purchase and marketing of grain and domestic political environments. 4.2. Economic value of ecosystem service function and its change 4.2.1. Change in area of ecosystem types During those 32 years from 1973 to 2005, a remarkable change in the areas of various ecosystem types is seen (Fig. 2) with an overall dynamic rate up to 272.76%. In terms of tendency, an increase trend shows in the areas of cropland and unused land by 186.15% and 85.56%, respectively in 2005 more than that in 1973 while a decrease trend in forest, grassland and wetland by 37.71%, 4.53% and 41.53%, respectively. The detailed analysis shows that the change in ecosystem types could be divided into three stages based on its rate and trend: the most remarkable change in ecosystem types took place during 1973–1983 and the dynamic degree of the change in each ecosystem type totals to 107.89%; the change during 2000–2005 comes next with total dynamic degree up to 68.29%; and the change during 1983–2000 is relatively mild with total dynamic degree of 56.31%; both the rate and trend of change are characteristic of a ‘‘U” shape.
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Table 2 Annual price of grain production of cropland ecosystem within main stream area of Tarim River during 1973–2005 and constant price in 1990 (yuan). Time
Index of grain consumption (100 in 1990)
Price of the same year
Deflation index
Constant price of 1990
1973 1983 1990 2000 2005
75.18 74.70 100.00 360.55 400.43
173.34 134.66 289.18 971.17 1363.55
79.73 62.34 100 93.15 117.76
217.39 216.02 289.18 1042.63 1157.95
Table 3 Unit price of service function of various ecosystems within Main stream area of Tarim River during 1973–2005 (constant price in 1990) (yuan). Forest 1973 A B C D E F G H I
Grassland
Cropland
Wetland
Useless land
760.88 586.97 695.66 847.84 284.79 708.71 21.74 565.23 278.27
173.92 195.66 173.92 423.92 284.79 236.96 65.22 10.87 8.70
108.70 193.48 130.44 317.40 356.53 154.35 217.39 21.74 2.17
195.66 1908.73 3900.06 186.96 3952.24 542.40 43.48 8.70 1075.02
0.00 0.00 6.52 4.35 2.17 73.91 2.17 0.00 2.17
756.08 583.26 691.27 842.49 282.99 704.24 21.60 561.66 276.51
172.82 194.42 172.82 421.25 282.99 235.47 64.81 10.80 8.64
108.01 192.26 129.61 315.39 354.28 153.38 216.02 21.60 2.16
194.42 1896.68 3875.46 185.78 3927.30 538.98 43.20 8.64 1068.24
0.00 0.00 6.48 4.32 2.16 73.45 2.16 0.00 2.16
1990 A B C D E F G H I
1012.13 780.78 925.37 1127.80 378.82 942.72 28.92 751.86 370.15
231.34 260.26 231.34 563.90 378.82 315.20 86.75 14.46 11.57
144.59 257.37 173.51 422.20 474.25 205.32 289.18 28.92 2.89
260.26 2538.99 5187.87 248.69 5257.27 721.50 57.84 11.57 1429.99
0.00 0.00 8.68 5.78 2.89 98.32 2.89 0.00 2.89
2000 A B C D E F G H I
3649.19 2815.09 3336.41 4066.24 1365.84 3398.96 104.26 2710.83 1334.56
834.10 938.36 834.10 2033.12 1365.84 1136.46 312.79 52.13 41.71
521.31 927.94 625.58 1522.24 1709.91 740.27 1042.63 104.26 10.43
938.36 9154.26 18704.73 896.66 18954.96 2601.35 208.53 41.71 5155.79
0.00 0.00 31.28 20.85 10.43 354.49 10.43 0.00 10.43
2005 A B C D E F G H I
4052.84 3126.47 3705.45 4516.02 1516.92 3774.93 115.80 3010.68 1482.18
926.36 1042.16 926.36 2258.01 1516.92 1262.17 347.39 57.90 46.32
578.98 1030.58 694.77 1690.61 1899.04 822.15 1157.95 115.80 11.58
1042.16 10166.83 20773.69 995.84 21051.60 2889.09 231.59 46.32 5726.08
0.00 0.00 34.74 23.16 11.58 393.70 11.58 0.00 11.58
1983 A B C D E F G H I
Note: A, gas regulation; B, climatic regulation; C, water-source conservation; D, formation and protection of soil; E, waste disposal; F, biodiversity protection; G, grain production; H, raw material; and I, amusement activities.
The analysis of change in the area of different type of ecosystem indicates that the said three stages of cropland ecosystem all are of increase trend with an increment more than 30%, of which, the increment during 2000–2005 is the most remarkable and up to 57.63%. The area of cropland increases 38.46% by during 1973–
1983 while that of forest and wetland decreases 28.42% and 21.65%, respectively; in the middle of 1990s, the ecological environment was deteriorating in the Main stream area of Tarim River. At the turn of this century, China started to implement the project of returning cultivated land to forestland or grassland, and the
Area (104hm2)
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Fig. 2. Area of each ecosystem in main stream area of Tarim River during 1973–2005.
Short-term Comprehensive Control Project of Tarim River Basin was carried out as a key point; thus the unused land decreased gradually from 1.3368 million hm2 in 1990 to 1.2405 million hm2 in 2005, the area of forest, grassland and wetland, however, is still of a trend of decrease. 4.2.2. Change in value of ecosystem service function According to the internal structural changes of service function value of various ecosystem types in the Main stream area of Tarim River, it is indicated that all the other types of service function value have a change trend the same as the general change trend with a U-curve in change rate except the continuous increase in the service function value of cropland ecosystem and unused land ecosystem. The area of each ecosystem type in the Main stream area of Tarim River during 1973–2005 and its corresponding unit price of service are analyzed, and the service function value of ecosystem in the Main stream area of Tarim River at each stage and its change is calculated (Fig. 3). It is shown in Fig. 3 that in the region investigated, the service function value of ecosystem increases as a whole, which increases from 9:44 109 yuan=year in 1973 to 40:69 109 yuan=year in 2005 by more than four times. A straight-line model can be used to describe the change trend of service function value of the ecosystem in this area along with time ðY ¼ 90844x 636320ðR2 ¼ 0:79ÞÞ. There is also, however, a period of decrease partially. The service function value of the ecosystem in the Main stream area of Tarim River decreased by 16.02% during 1973–1983, and the average decrease is 0.15 109 yuan per year. The service function value of the ecosystem in this area has been increasing continuously since 1983 with an average rate of annual increase 13.56%, in particular the maximum increment during 1990–2000 is up to 258.54%. The ecosystem service function value in the Main stream area of Tarim River is reflected with an integral increase on one hand, and on the other hand, also is manifested with the internal transfer of value. During 1973–1983, the service function values of forest, grassland and wetland ecosystems decrease, respectively by 1.06 109 yuan, 0.001 109 yuan and 0.54 109 yuan while that of cropland ecosystem and unused land ecosystem increases by 0.08 109 yuan and 0.02 109 yuan; during 1983–2005, the service function values of forest, grassland, cropland, wetland and unused land ecosystems increase, respectively by 9.61 109 yuan, 12.35 109 yuan, 2.87 109 yuan, 7.45 109 yuan and 0.49 109 yuan, of which, cropland ecosystem has the most remarkable increment up to 1007.8%, and the increments of service function value with respect to forest, grassland and wetland ecosystems are similar; and the service function value of unused land ecosystem increases also from 0.09 109 yuan in 1973 to 0.6 109 yuan in 2005 because the unused land ecosystem has a larger proportion and its area increases continuously during this period. The service function of forest, grassland and wetland ecosystems also shows an
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increase trend as a whole because the service function values provided by the unit area of those ecosystems are higher than that of other ecosystems, and the biomass produced by cropland ecosystem changes somewhat due to the improvement of economic development level, which causes that even the ecosystem area decreases as a whole, the service function value of those ecosystems increases still. The economic value of ecosystem service function, which is based on ‘‘Equivalent Factor Table of Nationwide Ecosystem Service”, reflects mostly people’s willingness to pay. Therefore, the increase of ecosystem service function value in this area reflects to some extent that the importance of the service function of the natural ecosystems such as forest, grassland and wetland etc. increases to the development of human community. The level of human community and economic development is reflected to some extent by the development of cropland ecosystem service function. In respect to agricultural ecosystem, the service function value of other ecosystems reflects the integral capacity of the ecosystem, which is opposite to the capacity of anthropic production and service. During 1973–2005, the ratios of the respective service function values of forest, grassland and wetland ecosystems to that of cropland ecosystem were decreasing, which reduced respectively from 17.8%, 14.6% and 11.7% in 1973 to 3.8%, 4.8% and 2.9% in 2005. It is indicated that the increase rate of the service function value of forest, grassland and wetland ecosystems is much less than that of cropland ecosystem. To the development of human community, the value of those ecosystems is in a state of decreasing continuously, and the capacity of providing service is also decreasing continuously, which brings a severe negative impact on the integral balance of the ecosystem. With the analysis of spatial variation in the ecosystem service function value of Tarim River at its upper reach, middle reach and lower reach, it can be seen that the ecosystem service function value at its upper reach and middle reach always accounts for more than 85% of the total value quantity of the region; the middle reach is bigger slightly than the upper reach, and the lower reach is the least, accounting only for about 14.57%. Since 1970, the runoff in this region has been affected by anthropic activities [13]. The change in ecosystem area becomes more evident towards the lower reach due to the decrease of surface runoff. For instance, the surface runoff at the middle reach and lower reach of the Main stream in 2005 is 25.5% and 20.9% less, respectively than that in 1973. During the same period, the areas of forest, grassland and wetland ecosystems at the middle and lower reaches of Tarim River decrease remarkably: decreasing by 14.43%, 21.63% and 21.47% at the middle reach, and 47.77%, 24.19% and 40.22% at the lower reach, respectively; whilst the areas of cropland and unused land ecosystems increase by 474.07% and 63.89%, respectively at the middle reach of Tarim River, and 170.76% and 86.09% at the lower reach of Tarim River. The overall equilibrium of ecosystem in service value is influenced directly by the structural adjustment and the increment of all the other ecosystems in service value is much less than that of cropland ecosystem. For instance, during 1973– 2005, the increment of cropland ecosystem at the lower reach in service function value is 13.42%, the increment of forest, grassland and wetland ecosystem in service function value, however, is only 2.34%; the increment of cropland ecosystem at the middle reach in service function value is 29.58%, the increment of forest, grassland and wetland ecosystem in service function value, however, is only 3.3%; the increment of cropland ecosystem at the upper reach in service function value is 11.27%, the increment of forest, grassland and wetland ecosystem in service function value, however, is only 2.88%. In this way, we can say that the trend and variation of the overall ecosystem in service value is influenced to a large extent by the cropland ecosystem at each reach, and the overall level of ecosystem structure and its service value is related closely to the increase of anthropic activities in strength.
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Fig. 3. Change in economic value of ecosystem service function in main stream area of Tarim River during 1973–2005.
4.3. Driving force analysis of change in ecosystem service function Due to the fact that the change of ecosystem is intricate with complicated contributing factors, the factors to be selected for the research on the driving force in the change of ecosystem service function value shall be comprehensive; however, too many indicators shall increase the difficulty and complexity of the issue to be analyzed. In order to further unveil the factors driving the change in economic value of the ecosystem service function in the Main stream area of Tarim River, the socioeconomic and demographic factors to be selected have a dependency relation not only with the change of ecosystem area, but with each other within themselves. Since it is difficult to quantify the factors such as social behaviors, behavior of the main ecosystem users, policy and system etc., here only three major driving factors are quantified for the purpose of research, which covers population development, economic development and technical progress; and nine indicators during 1973–2005 are used to reflect the change in social economy and population: economic factors (GDP, output value of the pri-
mary industry and output value of secondary industry), population factors (total population and agricultural population), science and technological factor (total power of agricultural machinery), and production factors of agriculture and animal husbandry (livestock inventories at end of year, acreage of grain and acreage of cotton). By taking the change in the economic value of ecosystem service function in this region as the subject investigated, we studied the extent of nine socioeconomic indicators’ impact on the subject investigated via principal component analysis (hereafter referred to as simply PCA). With PCA method and SPSS software, nine analysis factors are selected: X1 – gross domestic product (GDP) (100 million yuan); X2 – total output value of primary industry (100 million yuan); X3 – total output value of secondary industry (100 million yuan); X4 – total power of agricultural machinery (KW); X5 – gross population (10,000 persons); X6 – gross agricultural population (10,000 persons); X7 – livestock inventories at end of year (capita); X8 – acreage of cotton (hm2); X9 – acreage of grain (hm2). The data are processed with standardization first to eliminate the influence
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of various dimensions. It is discovered with statistical analysis that the service function value (F) of the ecosystems in the region investigated has a very significant correlation with the major socioeconomic factors. With a principal component analysis to the said factors, KMO test value is 0.711 and Bartlett spherical test value is 0.000. Therefore, the result is possibly acceptable with the said factors for principal component analysis. The result of principal component analysis indicates that the accumulative contribution rate of the first, secondary and third principal components is 89.3% (Table 4), which is more than 75%, the threshold value of accumulative contribution rate, thus it is in accordance with the analysis requirement: most variation shall be explained with three principal components collected. The accumulative contribution rate of the first principal component is far more than that of the secondary principal component, and the accumulative contribution rate of the secondary principal component is slightly more than that of the third principal component, those both are close to each other, and the first principal component has a contribution much bigger than the sum of the secondary and the third principal components. In order to make the complicated matrix concise, Rotated Factor Matrix and Factor Transformation Matrix are obtained with orthogonal rotation process (Tables 5 and 6). It is seen that the first principal component has an obvious positive correlation with the observation variables X2, X5, X6 and X7, and the correlation coefficient is over 0.67; the secondary principal component has an obvious positive correlation with the observation variables X4 and X8 but an obvious negative correlation with X9, and the correlation coefficient exceeds 0.81; the third principal component has an obvious positive correlation with the observation variables X1 and X3 with a correlation coefficient more than 0.72. Therefore, with reference to the meaning of each variable, it can be determined clearly that the active factor influencing the change in the economic value of the ecosystem service function in the Main stream area of Tarim River over the past thirty years shall be anthropic activities, which is reflected mainly in economic development and population growth. The first principal component consists of four factors and the impact of each factor is different. The sequence of their impact on the change in economic value of the ecosystem service function in this region is: total population > output value of primary industry > livestock inventories at end of year > agricultural population. This region is a typical oasis agricultural region distributing along Tarim River and the industrial structure always consists mainly of agriculture and animal husbandry. In the internal structure of agriculture, crop production is of absolute advantage all the time. Therefore, the growth of population in this region and the increase of the strength in agricultural and animal husbandry activities have a significant impact on the change in economic value of the ecosystem service function in this region. The secondary principal component consists of three factors and the sequence of their impact is grain acreage > cotton acreage > total power of agricultural
Table 4 Contribution rate of characteristic values and principal components. Component
Total
% of variance
Cumulative %
1 2 3 4 5 6 7 8 9
5.253 1.597 1.185 .634 .172 .077 .048 .026 .009
58.367 17.740 13.162 7.044 1.906 .852 .535 .292 .101
58.367 76.108 89.270 96.314 98.220 99.072 99.606 99.899 100.000
Table 5 Rotated factor (principal component) matrix. index X1 X2 X3 X4 X5 X6 X7 X8 X9
(GDP) (GDP of primary industry) (GDP of secondary industry) (total power of agricultural machinery) (gross population) (gross agricultural population) (livestock inventories at end of year) (acreage of cotton) (acreage of grain)
1
2
3
.513 .869 .179 .580 .939 .671 .779 .261 .193
.446 .333 .171 .805 .064 .272 .424 .926 .946
.716 .214 .962 .001 .269 .091 .053 .150 .124
Table 6 Factor transformation matrix. Component
1
2
3
1 2 3
.742 .130 .658
.667 .052 .743
.062 .990 .125
Extraction method: principal component analysis. Rotation method: varimax with Kaiser normalization.
machinery; the impact sequence of those factors of the third principal component is output value of secondary industry > GDP. Due to the influence of national development policy, the driving force of population growth and the development of agriculture and animal husbandry is characterized by its phases and developing nature: at the end of 1970s, the production level developed slowly in China because of the impact of macro-political environments, in particular the agricultural productivity is very low and the economic value of ecosystem service function per unit area was kept at a very low level; during 1973–1983, with the continuous growth of population in this region, the demand of grain increase sharply; due to the underdeveloped productivity, however, the demand of grain is met mainly by enlarging the cultivated area. In this way, the area of agricultural ecosystem and its service function economic value saw a large increment at this phase while the areas of forest, grassland and wetland ecosystem as well as their economic value per unit area are decline somewhat. During the medium-late 1980s, with the emphasis and encouragement of the country on the agricultural production and economic development of Xinjiang Production and Construction Corps, the land development in the Main stream area of Tarim River was expedited not only in agricultural size but also in intensive cultivation. Therefore, the unit biomass of cropland ecosystem increased greatly and promoted the improvement of the unit value quantity of other ecosystem service function while the expansion of cropland ecosystem area slowed. The downtrend of economic value of the whole ecosystem service function in this region was reversed and started to increase slowly. The advantage of cash crops market appeared gradually with the implementation of reform and opening policies and the development of market economy in China, in particular, the advantage of cotton price stimulated cotton planting. At the turn of the century, cash crops occupy not only part of grainplanted area, but a great amount of forest, grassland and unused saline-alkali land, which finally makes a remarkable increase in cropland ecosystem area and its quantity of unit value. At the same time, with the improvement substantially in agricultural productivity and industrial technological level, the economic values of other ecosystems also meet their peak value historically. Due to the implementation of various national preferential policies on agricultural production as well as the impact of market on grain and cotton prices, the enthusiasm for new land development and reclamation of abandoned field is still retained with the urge of
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economic interest so that the history see another rapid increase in the area and value of cropland ecosystem. It is thus evident that the growth of population and the development of agriculture and animal husbandry are the most direct and basic driving force for the change in economic value of the ecosystem service function in the Main stream area of Tarim River. During the period of a higher population growth rate, population growth is the most basic driving force for the change in various ecosystems’ area, and the economic growth provides a powerful support to this driving force. The pressure of population growth creates a potential demand of land, and the improvement of economic level transfer such a potential demand into an effective demand; they both promote the continuous change of ecosystem area; in a case of stable population, continuous improvement of population quality, continuous development of economy and continuous increase of productivity level, the driving force of technological progress is also an important factor influencing the economic value per unit area of ecosystem service function.
5. Conclusion and discussion Tarim River Main stream flows around the north edge and the west part of Taklimakan Desert, the ecosystem types along the river cover forest, grassland, wetland, cropland and unused land with typical characteristic of endorheic river ecosystem in arid area. This region features resources advantage and fragile environmental background, and the ecosystem is threatened by a synergistic impact of multiple environmental factors and intensive anthropic interference, which is the reason why it is selected for the research on the economic value of ecosystem service function and its change. On one hand, the research shall provide data for evaluating the scarcity of various ecosystems in arid area; on the other hand, with the research on the driving factors for the change in various ecosystems’ service value, the process and characteristics of change in ecosystem service function value of this region could be understood, which provides a theoretical foundation for exploring the control strategy of ecosystem service function value in this region, the ecological safety of arid-area endorheic river as well as the sustainable development of society and economy. (1) It is shown with the data analysis of gain procurement index in the Main stream area of Tarim River that the inflation coefficient of grain procurement price in the region investigated increases from 75.19% in 1973 to 400.43% in 2005 (calculating at 100 in 1990), excluding the impact of inflation factor, based on the grain production of cropland ecosystem, the quantity of unit value of the service function of each ecosystem is calculated. The result shows an increase trend of actual value regarding the quantity of unit value of service function of Tarim River Main stream ecosystem; of which, the quantity of unit value declines slightly by 0.63% during 1973–1983 and increases by 432.65% during 1973–2005. (2) It is shown with the analysis of change in the area of landuse type in the Main stream area of Tarim River during 1973–2005 that the areas of cropland and unused land in this region increase, respectively by 186.2% and 85.6%; the areas of forest, grassland and wetland drop relatively great as a whole by 37.71%, 4.53% and 41.53%, and the regional ecological environment is of a degradation trend as a whole. During 1973–1983, the annual decrease rate of forest and 2 wetland area is 2200 hm2 and 450 hm , and the annual 2 increase rate of unused land is up to 2010 hm ; the annual decrease rate of forest and wetland area has declined greatly 2 since 1983 to only 80 hm , but the annual increase rate of 2 unused land area is only 10 hm .
(3) It is shown with the analysis of change in the economic value of the ecosystem service function in the Main stream area of Tarim River during 1973–2005 that the economic value of the ecosystem service function in the region investigated is of an increase trend, and the economic value increases from 9:44 109 yuan=a in 1973 to 9 40.69 10 yuan/a in 2005 by more than four times, which reflects to some extent that the importance of ecosystem service function to the development of human community increases. On the other hand, the service function value of the ecosystem in this region transfers within the internal structure, namely, a great amount of economic value of the service function of forest, grassland and wetland ecosystems transfer into the cropland ecosystem. The increment per unit area of cropland ecosystem is superposed on the quantity of unit value that rises increasingly and leads to an increasing growth of the economic value of the cropland ecosystem service function during those 32 years. It is indicated with data that the value of cropland ecosystem service function increases by 2.95 109 yuan; the economic value of other ecosystems’ service function, however, increased far slower than that of cropland ecosystem did, in other words, the former is in a state of relative decrease, and the capacity and contribution provided by forest, grassland and wetland ecosystems decrease continuously in an integral ecosystem, thus the integrative capacity and integral equilibrium of the ecosystem is effected severely. (4) It is shown with the analysis of change in the spatial variation of the ecosystem service function in the Main stream area of Tarim River during 1973–2005 that the service value of upper-reach and middle-reach ecosystems accounts always for more than 85% of total value while that of the lower-reach ecosystem only 1/7. Due to the decrease of surface runoff and the increase of anthropic activities’ strength, the area of forest, grassland and wetland ecosystems at the middle- and lower-reach decreases remarkably but the area of cropland and unused land ecosystems increases evidently. The adjustment of ecosystem structure influences directly the integral equilibrium of the ecosystems’ service value, and the increment of other ecosystems’ service value is far less than that of cropland ecosystem: the increment of cropland ecosystem’s service function value at the upper-, middle- and lower-reach of Tarim River is 4.5, 9 and 6 times more than that of forest, grassland and wetland ecosystems, respectively. In this way, the cropland ecosystem at each reach of the river has an impact to a great extent on the trend and variation of the whole ecosystem’s service value. The ecosystem structure and its overall level of service value are related closely with the increment of anthropic activities’ strength. (5) According to the analysis of nine indicators (total population and agricultural population reflecting the change in population in the Main stream area of Tarim River Main stream, GDP reflecting the level of economic development, total output value of primary industry and secondary industry reflecting industrial structure and policy factor, grain yield and cotton output, livestock inventories at end of year, and total power of agricultural machinery reflecting technological innovation factor) and the analysis of change in the ecosystem service function value, it is discovered that there is a significant correlation among population, economic and social factors and the change in their economic values, which affects 89.3% of the change in the economic value of the ecosystem service function in this region and is a key factor promoting its change rate and adjusting its development trend.
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The economic value of ecosystem service function reflects to some extent the willingness to pay as well as the scarcity of various ecosystem types. The application of economic value in the importance explanation of ecosystem service function does not mean that all necessary resources and functions could be bought with money. The complexity to change the ecosystem shall be viewed from a standpoint of ecological integrity and then we can realize that what a huge loss would be caused due to the missing of some functions of the ecosystem, and then we shall understand that, comparing with the loss, how inappreciable the economic benefit we obtained is. It is indicated with this study that the more intensive the anthropic activities for satisfying humans’ interests are, the more important the functions of the natural ecosystem are. The equilibrium state of ecosystem can be secured only when the stable state between artificial and natural ecosystems is guaranteed. Acknowledgements Supported by the Natural Science Foundation of China (No. 40901105), Knowledge Innovation Project from the Chinese Academy of Sciences (No. XBBS200810) and National Natural Science Foundation of China (No. 2006BAC01A03). Project funded by Xinjiang Statistical Yearbook (1989, 1999, 2006); Statistical Yearbook of Xinjiang Production & Construction Corps (1989, 1999, 2006); 50 Years of Xinjiang (1955–2005); Alaer Statistical Yearbook of Agricultural Division No. 1 (1990–2006); Statistical Summary of Division No. 2 of Xinjiang Production & Construction Corps (2002– 2006; 1991–2000) and Statistical Historical Data Collection of Division No. 2 of Xinjiang Production & Construction Corps (1952– 2002).
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