Studies On Services From Artificial Ecosystems

The demand of human beings for ecosystem services (e.g., food, fiber, fuel, wastewater treatment and aesthetic cultural value) is increasing and may continue to do so for decades, propelled by a2.3billion person increase in global population and greater per capita incomes anticipated through midcentury. Natural ecosystem cannot meet the increasing demand. Sufficient service supply must rely on artificial ecosystem, which could intensively provide services with a high efficiency. At the same time, the pressure of ecological protection demand limiting the environmental impacts of artificial ecosystems. Such dilemma requires artificial ecosystem to simultaneously supply targeted services and other services. Although ecosystem service has already been a main stream analyzing tool to study ecological-economic-social system,a systematic research about services from artificial ecosystem are still lacking. In this study, we established an exclusive evaluating frame work for artificial ecosystem, encompassing targeted services and accompanying services, based on the characteristics of artificial ecosystems. We evaluated and analyzed services of three different systems, namely, production, decomposition and residential supporting systemswith different targeted services. We took tea plantations and plastic greenhouse vegetable cultivation (PGVC), constructed wetland (CW) and urban green space as cases for the three categories of systems, respectively. Considering the dilemma between human demand and environmental impacts arising from modifying nature to meet demand is far more serious in developing countries, we took Chinaas an example to study. The main results are as follows:1) A service evaluating framework for artificial ecosystems was established. We analyzed the characteristics of artificial ecosystems and the reasons why main stream evaluating systems in current were not applicative to artificial ecosystems. We established a framework exclusively for artificial systems, encompassing targeted service and accompanying service based on some characteristics, such as target-focus establishing and regulable, of artificial systems. This framework could embody not only the establishing purpose of artificial ecosystem but also the services other than purpose; and could integrate various artificial ecosystems to a single framework, excluding the possibility that targets to be multiple categories of services, and can embody not only the nature, but also the marketablilityof different service, so as to analyze from welfare economics perspective.2) Services of the selected artificial ecosystems were evaluated. We established service frameworks for the four selected systems and evaluated the service values. We found that other than targeted servicewith significant value, all of the four selected systems could provide accompanying service, including positive or negative service with certain value. Based on current framework, negative service could only offset a portion of positive service value and the net accompanying services were calculated as positive. Based on evaluation, the value of targeted services from tea plantation and PGVC were5653yuan hm-1yr-1and44000yuan hm-1yr-1, respectively. While the net accompanying services from the two systems were6054yuan ha-1yr-1and7894yuan hm-1yr-1, respectively. Constructed wetland, which is a decomposition system, provided a targeted service valued at1,436,809yuan hm-1yr-1and net accompanying service valued at10,576yuan hm-1yr-1. In contrast, the water treatment plant, another kind of decomposition system, has a more than three folds value of targeted service of CW, however, its net accompanying services are negative, and the value are as high as-2,838,860yuan hm1-yr-1.Urban green space, a typical residential supporting system, provided targeted and net accompanying service valued at21050yuan hm-1yr-1and5186yuan hm-1yr-1, respectively.3) We propose the conception of tradeoff intensity and calculating method of tradeoff intensity coefficient (TI). Tradeoff intensity refers to the extent of tradeoff between targeted service and accompanying service resulted from land use change. TI is the quantitative parameter to indicate the tradeoff intensity. We measured TI as the ratio of the changed percentage of accompanying service to the changed percentage of targeted service. The sign of TI represent whether a land use change result in synergy (a same direction of change in targeted and accompanying service, sign is positive) or trade off (a negative direction of change in targeted and accompanying service, sign is negative), and the value of TI indicate the extent of trade off or synergy. Based on calculation of TI, we found that different land use change with different tradeoff intensity. We calculated the TI of four land use changes (i.e., changes from forest to tea plantations, from forests to croplands, from croplands to tea plantations and from tea plantations to croplands) in Zhejiang province. Results indicated that there were big differences of land use changes. Both conversions from cropland to tea plantations and from tea plantations to croplands leaded to synergy. However, the former change was positive synergy and the latter one was negative. While conversions from forests to croplands and to tea plantations leaded to trade-off. However, the former trade-off with a five times TI of that of the latter. Secondly, we found that even one conversion could have different TI in different regions: TIs of conversion from cultivated vegetable cultivation (CVC) to PGVC in nine regions in China indicated that such conversion resulted in positive synergy in North I-IV region and Southern Ⅱ and Ⅴ region and the biggest TI was42times of the smallest one. In contrast, change from CVC to PGVC resulted in trade-off and biggest differences in TI was18times. TI considered both the targeted and accompanying service and was calculated on scientific data of ecosystem services. Our data suggested that TI had a good ability to differentiate various land use changes and one single change in different regions, suggesting that TI could used be a scientific parameter when land use decision making.4) The trade-off or synergy modes between targeted or accompanying services from one ecosystem spreading over a large area were explored. A service evaluation of targeted and accompanying service of tea plantations in918tea cultivation counties indicated that the value changed a lot across tea plantations in different counties. The targeted service values were from109to63904yuan hm-1yr-1, the max value was57.6times of the minimum value. The net accompanying values were from-237to5410yuan hm-1yr-1. There is no spatial congruence between targeted value and net accompanying value.58.2%(n=534) counties with synergetic tea plantations of high targeted/high accompanying value;2.0%(n=18) counties with synergetic tea plantations of low targeted/low accompanying value;38.1%(n=350) counties with tradeoff tea plantations of low targeted/high accompanying service value, and1.7%(n=16) counties with tradeoff tea plantations of high targeted/low accompanying service value. In China, most of win-win tea plantations are in southern and eastern tea cultivation area and lose-lose tea plantations are in western and northern tea cultivation area.5) The spatial heterogeneity of artificial ecosystemservice was explored. We found that the service of artificial system was affected by social-economic factors and natural climatic factors. Furthermore, different kinds of services would be affected by different kinds of factors. Results showed that the target service value of tea plantations was not related to natural climatic factors (annual mean precipitation and temperature), but significantly positively related to social-economic factor (GDP per capita). As for the four accompanying services (i.e., carbon sequestration, soil conservation, soil fertility protection and water conservation), only carbon sequestration and water conservation were found to be significantly related with annual mean precipitation and temperature, but had no relationship to GDP per capita. While three negative accompanying services (i.e., CO2emission, N2O emission and non-point source pollution) all had no relationship to either annual mean precipitation and temperature or GDP per capita. Interestingly, the targeted service of PGVC were found to be significantly negatively related to natural climatic factors, annual mean precipitation and temperature, but has no relationship to social economic factor, GDP per capita. The four positive accompanying service (i.e., carbon sequestration, soil conservation, soil fertility protection and water saving), only water saving was significantly negatively related to annual mean temperature and precipitation and did not related to GDP per capita. As for the three negative accompanying service (i.e., CO2emission, N2O emission and soil salination), CO2emission was negatively related to temperature and precipitation and N2O was positively related to the two factors.6) The relationship of service value of artificial system and the extent of land scarcity and population density is explored. Studies on value of urban green space in Hangzhou city indicated that, along with the center to the edge of urban area (representing a decreasing land scarcity and population density), targeted service (aesthetic cultural service) had a decreasing tendency. Among the seven accompanying service (i.e., carbon sequestration, noise reduction, soil conservation, water conservation, SO2absorption, micro-climate regulation and dust reduction), five services was decreasing from the city center to edge expect for carbon sequestration and noise reduction. VOC emission, the negative accompanying service of urban green space, was also decreasing. The cost, the benefit and the net benefit were also decreasing from city center to edge.7) The conception of emergent service was proposed. Artificial system would generate new services when several requirements were satisfied. Taking tea plantations as a case, we analyzed the requirement for tea plantations to generate tourism service, finding that the value of targeted service, the location of the system and adjacent city core is the critical conditions. The process also revealed the positive feedback of targeted service, accompanying service and emergent service. Taking constructed wetland and urban green space as cases, we analyzed the requirement for them to generate biofuel service and revealed that net energy benefit balance, greenhouse gas emission, economic feasibility and technological feasibility were critical factors.In sum, this study focus on the characteristics of artificial systems, proposed a evaluating and analyzing framework encompassing targeted service and accompanying service and evaluated and analyzed the values of three important kinds artificial systems in urbanization areas. They were production, decomposition and residential supporting system. We analyzed the tradeoff across different systems and space. Furthermore, we deepen the service analyzing framework by case study of emergent service. This study was expected to improve the principle of scientific foundation for a win-win sustainable development and to provide basis for planning.