1 Introduction

It has been argued that economic development should balance the ecosystem when large quantities of resources are needed during the period of industrial products emerged into the market. However, in the history of economic development worldwide, circumventing this balance leads to serious environmental damage, which is called resources consumption oriented development. In this development, all substantial resources such as fossil fuels, ore and water are depleted during the existence of industries and consumption, producing polluted water and air. They are recycled into the environment, and eventually these hazardous elements will negatively impact people. Thus, conscientious leaders worldwide have acknowledged the need for a harmonious relationship between people and the ecosystem, which helps to maintain a constant economic development. At present, much attention has been placed on ecosystem functions other than resources, such as city ecological services in urbanization and implicit benefits of biodiversity. Thus, to formulate a valuable list of ecosystem services, scientists have produced several methods and principals, such as services of functions classification, valuation and ethics(Costanza, 1998; Costanza et al., 1998; Costanza and Farber, 2002; Chee, 2004; Boyd and Banzhaf, 2007; Costanza and Kubiszewski, 2012).

Valuation is defined as the process of expressing a value for a particular action or object. Beyond the single requirement of Gross Domestic Product(GDP), ecosystem valuation(VES)represents the process of expressing a value for ecosystem goods or services, thereby providing the opportunity for scientific observation and measurement(Farber et al., 2002; Kubiszewski et al., 2013). Ecosystem services consist of flows of materials, energy, and information from natural capital stocks. Costanza et al.(1997) categorized ecosystem services into 17 items, from natural resources to cultural services, such as gas, water, soil, climate regulation and recreation. They placed a monetary value on these functions based on worldwide l and use and cover change and personal habits while ignoring man-made capital such as urban construction, residence and other related infrastructure. They also treated natural l and scapes such as desert and Gobi as no monetary value. Bockstael et al.(1995) valued the ecosystem with an economic model of a Washington state watershed. Unfortunately the model is specific to this l and scape, and their opinion has been debated since the model's inception. Serafy(1998), rather than depicting a supply function c urve as rising continuously, illustrated an initial flat line running along the horizontal axis until the point at which the function was threatened by excessive use or properties change, and then gradually rising with dem and until it hits a vertical straight line representing saturation or exhaustion. Afterwards, the cost of restoring the function increases at the same rate with dem and pressure. Therefore, it is solved by add a curve of the individual dem and with a family needs rather than the sole goal of protection the functions. Björklund et al.(1999) conducted a case study according to Swedish statistics and l and scape mosaic changes after WWII, showing that different qualities of assessing and comparing resources must be identified as a result of large disparities between items valued in ecosystem services. Norberg(1999) noted that natural services should focus on three main categories: services internal to the ecosystem, abiotic or biotic origin and level of ecological hierarchy. Firstly, there are always natural services associated with other species as other kinds of biological resources, which enhance or reduce the values for people. Secondly, biotic or abiotic goods may consist of services that regulate some exogenous chemical or physical input. Thirdly, organization of biotic entitles like food chains have a close relationship with the valuation of ecosystem services. Díaz and Cabido(2001). contended that ecosystem functioning is strongly determined by value and range of species traits rather than species numbers, and the nature and strength of the links between diversity and ecosystem functioning vary strongly across spatial scales, from local plots to regional gradients. In contrast, discussion still exists on whet her biodiversity really influences the value of ecosystem services, or that biodiversity consideration is relevant to economic valuation. Nunes and Van den Bergh(2001) stated that multilevel diversity and types of biodiversity play different roles in ecosystem values. Howarth and Farber(2002) argued that the Values of Ecosystem Service(VES)must be linked to the concepts of willingness to pay for nonmarket benefits or willingness to accept compensation for nonmarket costs. Thus, economists introduce various methods of marginal effect calculation to define the willing to pay(WTP) and willing to accept(WTA)for local residents especially in nonmarket valuation(Whittington, 1998). In a case study from Costa Rica, Barton(2002) surveyed coastal water prices, which tracked the transferability of benefit. Because, within the water pricing, there are several sections respectively depending on its intrinsic value, cost of management and surcharge for shortage of resources, which form a cycle accompanying the water use distribution and protection. The fundamental point is that l and use and cover change of local areas can influence the function and valuation of ecosystems, while ecological, socio-cultural and economic values of the l and scape will negatively influence l and use planning and decision-making(De Groot, 2006).

The aforementioned studies focused attention on a single ecosystem within a complex set of ecosystems, which are simultaneously influenced by natural and human factors. Therefore, a critical first step in analyzing any type of ecosystem is to identify components and flows, and equally important, boundary delineation because it is the explicit analysis ends(Limburg et al., 2002). In sustainable research, Critical Natural Capital(CNC)is commonly defined as part of the natural environment which performs important and irreplaceable functions, but could be a socio-cultural-involved system(Chiesura and De Groot, 2003). Furthermore, De Groot et al.(2003)addressed a set of natural capital to over six ecosystem types, considered crucial to all natural resources, including unique, semi-natural and modified, sustainable cultivated, and intensive cultivated systems, plus urban green space and constructed environments. Figure 1 illustrates multifaceted natural capital from the dimensions of ecological, social-cultural, and economic, and items derived from their interaction.

Figure 1 Natural capital division seen from three dimensions

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The category of methods used in the aforementioned studies focused on a core idea that natural capital-oriented evaluation is based on l and scape changes(called stable VES), penalty-oriented valuation based on the loss of ecosystem, and market-oriented valuation based on stakeholders' willing to award or payment. Therefore, fundamental means employed in most of the studies in the area of ecosystem valuation assessment corresponding to the categories in three orientations are classified as below.

The l and use and cover change of a study area is a basic item of identifying the functions of ecosystems, because all ecosystem valuation changes are triggered by l and use changes dependent upon natural and artificial factors(Metzger et al., 2006). Especially, in case study of various scales area of land scape, correspondingly, with data from remote sensing. For example, for urban regions with a mid-level population, Land sat data are applied in the ecosystem value assessment(Zhaoet al., 2004; Wang and Chen, 2010; Liang and Xu, 2012). Additionally, l and use and cover change determines ecosystem valuation, with Costanza ecosystem service coefficient per capita, with the total value of ecosystem services represented by each l and -cover category. Nevertheless, problems may exist in remote sensing data within GIS platform(Troy and Wilson, 2006), because seasonal city construction does not correspond well with remote sensing data.

The Ecological Footprint concept provides an intuitive framework for underst and ing the ecological bottom-line of sustainability(Van den Bergh and Verbruggen, 1999). The basic idea is that every individual, process, activity, and region has an impact on the earth, via resource use, generation of waste and the use of services provided by nature. These impacts can be converted to biologically productive areas, which is account for the capacity of natural capital to underpin the bio-vitality.(Wackernagel and Rees, 1997). Reports of footprint is continually and refresh every a time regularly, population, urbanization, and climate change are the main factors which largely direct ecological footprint(Xie et al., 2013). In the modern world, dense populations have limited recourses, and the ecosystem footprint is virtually non-existent. In details, population richness, size and distribution would finally affect t he litters, carbon emission, and distribution of ecological footprint(Luck et al., 2003).

At present, the assessment is that for public goods, society should allocate resources to those willing to pay the most for them in order to maximize aggregate social well-being(Sagoff, 1998). With embedding effects, contingent pricing are key prices based on those that can afford to pay, especially for quasi-public goods such as the environmental effects of l and scape improvement and interests after the ecological recovery(Carson et al., 1996; Venkatachalam, 2004). In developed countries like the USA, contingent valuation methodology(CVM)is used to measuring ecosystem services especially in an impaired river to price the water for different users(Bateman and Willis, 1999; Loomis et al., 2000). In developing countries like China, questionnaires and interviews are employed to analyze non-market pricing after implementation of grazing policies or desertification conversion(Xu et al., 2003; Zhao X et al., 2010; Zhao H et al., 2011; Zuo et al., 2013).

In current studies of function and valuation of ecosystem services, there are several main points that should be addressed. Firstly, the principles of ecosystem services are fairness and justice, such that people have the right to enjoy the ecosystem with reasonable pricing. Secondly, process flows in the ecosystem are very complex, and increasingly human activities are becoming an impediment to natural resources. Afterwards, feedback will be hold by human beings correspondingly. Thirdly, the ecosystem consist of a large number of components such as water, forest, wetl and ecosystems, all of which function in different ways, thus revealing disparities in ecosystem services valuation(Zhang et al., 2007; Costanza, 2008; Fisher and Kerry Turner, 2008).

VES seems to be an objective concept for researchers without considering the stakeholders, and for the employment of each kind of resources, payment is necessary.

In past studies, whether how to divide stakeholders of ecosystem, it always ignored that authorities like government are not just policy makers but also the participators so as to build a win-win game instead of a zero-sum game. Take for example the Payment for Ecosystem Services(PES)for a river basin in Costa Rica, in order to mitigate the harms resulting from carbon dioxide emission, the governmental officials create a policy system mainly in three respects. First is payment for resources usage such as water, soil and biological products; next is carbon dioxide emission tax; and the last is amercement for pollution. Each of policies would be an authority-oriented implement; otherwise, it may become a policy black hole which makes the policy unavailable consistently. Initially, different parties may veer in different directions without considering the condition of the previous policy, which in part may be due to the ineffectiveness of an official's short term of office. Therefore, discontinuous policy implementation will result in profit loss rather than acquisition. In addition, profit loss will instill a lack of confidence from the perspective of both authorities and residents, leading to eventual policy dismissal. However, unless the policy makers have considered their term of office and the policies' implementation, payment for ecosystem services is a zero-sum game in every situation. In contrast, if policy makers are participators, overcoming the obstacles between parties, states and nations, a market-oriented policy system can be established, irrespective of peoples enthusiasm because their profits are under protection. Further, ecosystem's valuation will be changed as a feedback due to the incorrect policy implementation.

Therefore, policy makers for Ecosystem Services should consider the policy over the long term, and that stakeholders should balance profits for each participant, ignoring pressures from the society, community, and residents.

VES research focuses on the natural capital valuation of each type of ecosystem, in relation to ecosystem change as a result of l and scape changed in disparate districts worldwide. Valuation for the potential ecosystem is not considered due to the rapid development of society and economies.

According to the strategy of rebuilding Silk Pathway in northwestern China, increased functions of ecosystem valuation are being addressed, such as urbanization and city ecosystem services in relation to the residents' daily activities especially in the western part of China. In addition, cultural products as well as historical mining will benefit and to a large extent enrich the ecosystem services. VES methods rely on traditional and developing economies as they advance at the same time.