درایورهای عملکرد مدیریت عرضه سبز: مدارک و شواهد از آلمان

Five potential drivers of green supply management performance were identified in the literature review: green supply management capabilities, the strategic level of the purchasing department, the level of environmental commitment, the degree of green supplier assessment, and the degree of green collaboration with suppliers. These constructs were used to form a structural model explaining the environmental performance and the purchasing performance. The model was analysed with SmartPLS 2.0 using data collected among German purchasers. The results suggest that the degree of green supplier assessment and the level of green collaboration exert direct influence on environmental performance. These two practices are driven by the strategic level of the purchasing department and the level of environmental commitment of the firm. Whereas commitment influences green assessment directly, the impact of commitment on green collaboration is mediated by the capabilities of the purchasing department. Furthermore, the results show that environmental performance has a positive impact on purchasing performance.

Protecting the environment is an ethical value in itself. Ethics establishes moral norms in consideration of the natural environment. Individuals should feel obliged to protect and maintain the sources of human life. They “should have a sense of responsibility for their actions and the consequences that these actions provoke” (Oliveira de Paula and Negrão Cavalcanti, 2000, p. 110). These moral requirements are not only relevant for private individuals but also for managers acting as representatives of their companies. Managers have the duty to take into account the attitudes, values and beliefs of the public regarding environmental protection. Nevertheless, environmental responsibility is not only an encumbrance to managers. Environmental commitment could be a source of competitive advantage and sustainable development of a firm. In summary, environmental performance is a concern for managers due to reasons ranging from regulatory and contractual compliance, to public perception and competitive advantage (Theyel, 2001). Many firms have realised that customers and other stakeholders do not always distinguish between a single company and its partners in the supply chain. Also, the lead company in a particular supply chain is often held responsible for the adverse environmental impacts of all organisations within its supply chain (Rao and Holt, 2005 and Kovács, 2008). Managers of a focal firm select and govern business partners throughout the supply network. Therefore, they are responsible for the environmental performance of the entire supply chain (Seuring and Müller, 2008). For this reason, Green Supply Chain Management (GSCM) is a concept that is gaining popularity. Green Supply Chain Management is defined as a buying firm's plans and activities that integrate environmental issues into SCM in order to improve the environmental performance of suppliers and customers (Bowen et al., 2001). Greening the supply chain is one of the three major issues of sustainable SCM besides the economic and social dimensions (Seuring and Müller, 2008). Although the literature on GSCM has been growing during the last decade, there are still some areas that need further research. Intra- and inter-firm diffusion of best practices and the transfer of environmental technologies were identified as critical areas needing research (Angell and Klassen, 1999). Theyel (2001) pointed out that “the literature offers insight on potential patterns in supply-chain relations for improving environmental performance. However, more understanding is needed on the ways firms work with their customers and suppliers for environmental purposes and whether supply-chain interaction helps firms improve their environmental performance”. More recently, Vachon and Klassen (2006) stated that little research has focused on the management of the interactions with immediate customers and suppliers and their potential impact on an organisation's environmental management. This paper tries to cover these gaps and focuses on how to extend green practices to immediate suppliers. The emphasis of this research is on the greening of supplier–customer relationships (Green Supply Management), as buying firms are normally in the strategic position to exert significant influence on the environmental behaviour of their suppliers. Green Supply Management (GSM) is being adopted by industry, but the extent and mode of implementation vary significantly (Rao, 2002). In some instances, it takes the form of questionnaires or suppliers' visits to assess suppliers' environmental performance (Noci, 1997). In other cases, companies go for a partnering and mentoring approach, such as site visits, exchange of personnel, technical assistance, and various other tactics (Lamming and Hampson, 1996, Handfield et al., 1997, Geffen and Rothenberg, 2000 and Zsidisin and Sifert, 2001). Although companies can follow both approaches simultaneously, few papers have considered the joint effect of these two different approaches on environmental performance improvement (see Theyel, 2001, Klassen and Vachon, 2003 and Lee and Klassen, 2008). Furthermore, only few papers have considered the development process of the preconditions needed to adopt these approaches of supplier environmental improvement. Bowen et al. (2001) identified the following potential drivers of green supply: a more strategic purchasing approach and the supply capabilities developed by a proactive firm's environmental management. There is also a gap in the literature concerning the impact of environmental performance improvements on purchasing performance. Carter et al. (2000) found evidence for a positive influence of environmental purchasing activities on firms' financial performance. However, from a supply perspective the performance outcome of a purchasing department (Sanchez-Rodriguez et al., 2005) is more relevant to evaluate the appropriateness of the assessment and the collaboration approach than the general financial performance of the firm. Therefore, the purpose of this paper is to analyse the effectiveness of different approaches used to extend sustainable practices to suppliers. More specifically, the research objectives of this paper are (1) to study the impact of different approaches (green assessment and green collaboration) on environmental performance improvement; (2) to analyse the factors that drive or contribute to the implementation of such efforts; and (3) to investigate the impact of environmental performance improvement on the performance outcome of a purchasing department. The structure of the paper is as follows: first, we provide a literature review and the conceptual model and related hypo-theses. Next, we explain the methodology employed. Then, we present the results and discuss them. Finally, we highlight the main conclusions and managerial implications and provide some directions for future research.

As a result of this study we have a better understanding of how green collaboration with suppliers and green supplier assessment can impact firms' environmental performance. The results suggest that the degree of green supplier assessment and the level of green collaboration exert direct influence on environmental performance. These two practices are jointly driven by the strategic level of the purchasing department and the level of environmental commitment of the firm. Whereas commitment influences assessment directly, the impact of commitment on collaboration is mediated by the capabilities of the purchasing department. This indirect influence moderated by environmental capabilities is plausible, because collaboration is based on human interactions between individuals whereas assessment is rather a technocratic approach. The main contribution of this paper is the complex interaction of these single effects. No previous study had considered enablers, practices (green assessment and green collaboration) and performance (environmental and purchasing performance) together. The study is also important to management because it provides managers with some understanding of the impact of different purchasing practices. Our model has shown that green supplier assessment and green collaboration with suppliers have a positive impact on environmental performance. Our results also show that these two practices are driven by the strategic level of the purchasing department and the level of environmental commitment of the firm. Whereas commitment influences assessment directly, the impact of commitment on green collaboration is mediated by the capabilities of the purchasing department. The managerial implications of this paper can be summarised as follows: • In order to improve environmental performance, companies should pursue both types of approaches: green supplier assessment and green collaboration with suppliers. • To implement these approaches companies should have an environmental commitment. This means that they should have the protection of the environment as a central corporate value and a clear policy statement urging environmental awareness in every area of the business. This commitment should result in (1) the implementation of green supplier assessment practices, such as the implementation of formal evaluation systems; and (2) the development of supply capabilities needed to implement a collaborative approach. • The purchasing department should also have a strategic level. This means that the purchasing department should (1) have a formal long-term plan to develop and support business strategy and (2) participate directly in the business' strategic planning process. This would contribute to the successful implementation of the collaborative and assessment approaches. Although this study has an important contribution to research and some key managerial implications, it has some limitations that should be pointed out: the fact that green collaboration with suppliers, green supplier assessment and environmental performance have been measured in general terms and not for specific buyer–supplier relationships is also an important limitation. Another limitation is that performance has been measured only from the perspective of the buying firm; suppliers' environmental performance has not been considered. Finally, the data of this research was collected in Germany whereas previous studies used data from other countries. A bias caused by different cultures and national institutions should be excluded. Further research should try to overcome the aforementioned limitations. Future research should also consider if different approaches or environmental practices are more appropriate for different types of environmental performance (pollution reduction, pollution control, etc.).