پایداری در روابط ارائه دهنده خدمات لجستیک-محموله کشتی : طبقه بندی آزمایشی بر اساس نظریه نمایندگی و تجزیه و تحلیل محرک-پاسخ

The paper contributes to research on sustainability in dyadic buyer–supplier relationships of logistics services. It presents deeper knowledge on why and how suppliers choose to behave sustainably. The research analyzes how shippers stimulate their LSPs and how LSPs respond by conducting sustainability activities. Agency theory and the stimulus–organism–response model are applied as the theoretical foundations for an explorative case study analysis of three large and five small and medium-sized European logistics service providers (LSPs) active in road transport services. Significant differences are found between the sustainability efforts of SMEs and large LSPs and a tentative taxonomy of the sustainability response types of LSPs is derived. The taxonomy contributes to theory-guided research in sustainable supply chain management and procurement. Thereby, mismatches of stimuli and responses are identified and related agency problems in dyadic relationships in terms of sustainability are discussed. From a managerial point of view, the findings may serve as a starting point for purchasers of logistics services to develop adequate sustainability selection criteria and incentives.

Contemporary academic and practitioner journals reflect the increasing relevance of sustainability in purchasing and supply chain management. Publications on topics like corporate social responsibility, environmental responsibility, philanthropy and business ethics (interchangeable names for sustainability) (Bansal and Roth, 2000, Lockett et al., 2006 and McWilliams et al., 2006) have increased significantly within the past decade (Carter and Easton, 2011 and Seuring and Müller, 2008b). However, in times of global value creation networks and growing outsourcing, sustainability management clearly surpasses corporate borders and demands linkages with supply chain management (SCM) (Carter and Rogers, 2008, Pagell and Wu, 2009 and Svensson, 2007). The evolving interorganizational supply chain perspective of sustainability brings up the questions of if and how suppliers' sustainable behavior is required and actuated by buyers (Seuring and Müller, 2008a), as well as how suppliers react to the new sustainability demands of their customers. These questions play a prominent role in research on sustainable procurement. Articles in the field deal with drivers and mediators for the integration of supplier levels (Min and Galle, 1997, Pagell et al., 2010, Simpson et al., 2007 and Walton et al., 1998) and their impact on firm performance (Foerstl et al., 2010 and Reuter et al., 2010), the development of sustainability selection criteria and methodologies (Bai and Sarkis, 2010 and Lu et al., 2007), and the organizational changes required to implement sustainable supplier management practices (Koplin et al., 2007). A closer look at relevant articles outlines four major research gaps and elucidates the relevancy and objectives of this paper. First, current research predominantly deals with conceptual frameworks on the constituents and mediators of sustainable purchasing principles from a buyer perspective (Amaeshi et al., 2008, Carter, 2004, Carter, 2005, Carter and Jennings, 2004 and Salam, 2009). Although the supplier's view from a dyadic perspective may give deeper insights regarding the implementation of interorganizational sustainability management, this perspective has rarely been contemplated (Simpson et al., 2007 and Wolf and Seuring, 2010). Second, the majority of current publications neglect the tripartition of the sustainability concept by focusing on the environmental dimension only (Carter and Dresner, 2001, Kogg, 2003, Lu et al., 2007, Min and Galle, 1997, Vachon, 2007 and Walton et al., 1998). Third, from the viewpoint of organization theory, institutional and stakeholder approaches are identified as being predominant in the field (Amaeshi et al., 2008 and Simpson et al., 2007). According to Sarkis et al. (2011), research into incentive mechanisms and their impact on the adoption of sustainable practices could especially benefit from the consideration of agency theory (Kogg, 2003) and the behavioral sciences. Finally, it was found that the available research on sustainable procurement intensively focuses on international product suppliers and less on service suppliers such as logistics services providers (Wolf and Seuring, 2010). However, in addition to their well-known economic role, logistics processes have a strong impact on the environment (e.g. transportation-induced greenhouse gas emissions, noise and land consumption) and social issues (e.g. transport safety and physically draining occupations). Moreover, the derivative character of logistics services (i.e. the dependency of the demand for logistics services on the production and sales volumes of shipping industries) promotes the importance for focal companies to integrate related services into their interorganizational sustainability management. Against this background, this research aims to fill the identified gaps regarding interorganizational sustainability management in shipper–LSP relationships using the following research question: RQ: How is sustainability stimulated by shippers and how do LSPs respond? The study contributes to research on the procurement of sustainable logistics services through the application of a combined theory approach that encompasses the agency theory of economics and the stimulus–organism–response model (S–O–R) of behavioral science. This combined approach provides a deeper conceptual understanding of the contractual relationship between shippers and LSPs in terms of sustainability and rational behavior. For empirical evidence, an exploratory case study analysis of eight European LSPs is applied from a dyadic but supplier-focused perspective. Based on the theoretical and empirical implications, a taxonomy of sustainability response types of LSPs is developed. In a first step, relevant literature is analyzed with respect to findings and identified research gaps. Frameworks on the motivation for sustainability and sustainable supply chain management (SSCM) are considered, as well as sustainable logistics. Second, the underlying research framework and the combined theory approach are introduced. Third, the methodological steps of the case study analysis and taxonomy development are presented. Within the first part of the results section, the current status of stimuli or incentives in interorganizational sustainability management in the context of logistics services is analyzed. The second part deals with the responding sustainability activities. Finally, the results are contrasted and a tentative taxonomy of the response types of LSPs is developed. Thus, a categorization for sustainable logistics services is presented and the findings are discussed from an agency theory point of view.

This study analyzed sustainability in dyadic shipper–LSP relationships. It applied a combined theory approach based on agency theory and the S-O-R model to observe shippers' stimuli, as well as LSP response activities, and develop a tentative taxonomy of response types. It therefore contributes to theory building and research in sustainability procurement and supply chain management and indicates various future research topics. First, it is found that shippers' stimuli for sustainability (i.e. selection criteria and incentives) are at an early stage and demand research into their design, effects and implementation. Against this background, agency theory may support research into the traditional problem types (adverse selection and moral hazard problems) of sustainability in dyadic relationships. However, the findings on the stimulus side also raise the question: why have even proactive buyers barely yet integrated logistics services within their sustainability management? Second, it is found that the sustainability activities of LSPs hold a strong environmental focus. Therefore, further research is proposed into the reasons for the operationalization imbalance of the tripartite sustainability concept. Third, further research effort into the methodologies and standards used to evaluate and assess the sustainability performance of logistics companies is suggested. Fourth, the case sample presented significant differences regarding the proactiveness of SMEs and large companies. Hence, deeper analysis into the drivers and impacts of separate institutional pressures for the sustainable behavior of SMEs is encouraged. Fifth, research into sustainability in dyadic or supply chain relationships demands different point of views and datasets, such as from the focal firm or from a network perspective. Finally, quantitative research is suggested to validate and extend the presented taxonomy and research on sustainability strategies. From a managerial point of view, this study makes recommendations for purchasing shippers, LSPs and policymakers. Purchasers of logistics services may find the presented taxonomy useful to categorize their LSPs with respect to their sustainable behavior and the resulting agency problems in order to establish suitable contractual arrangements. Furthermore, the extended relevance of the presented ideas to the design of selection criteria and incentive mechanisms is underlined. LSPs may find the detailed presentation of activities helpful to enhance their concepts and prepare them for future sustainability demands. In addition, the conjoint action of shippers and LSPs with respect to incentive design is recommended. Finally, policymakers can support the development of sustainability incentives in dyadic relationships by assisting cooperation, shippers and LSPs and by creating end-consumer sustainability awareness.