Abstract: Firms′ survival and development depend on key resources from the external environment, and firms can obtain external resources by establishing resource dependence with the external environment. Therefore, it is critical for organizations to reduce resource dependence through adopting response strategies. Previous studies have identified two response strategies: buffering and bridging, and viewed external resource dependence as antecedents of buffering and bridging, but the effects of buffering and bridging has not yet been verified. Although past studies theoretically inferred that buffering and bridging can reduce external resource dependence, their main focus is on how firms choose between buffering and bridging, and lack empirical evidence to support combined effects of buffering and bridging to reduce resource dependence. There are still several gaps needed to be explored: First, extant research focus on a single response strategy (i.e. buffering or bridging) to reduce resource dependence, lack the understandings of multiple response strategies, that is, when firms adopt multiple strategies, whether they have a complementary or substitutive effect among them, and what is the complementary or substitutive effect on resource dependence? There is still a lack of empirical evidence. Second, when a firm adopts multiple response strategies, will it implement these strategies sequentially? How does the use of different response strategies change over time? How does adopting a response strategy affect other response strategies? And how does a firm trade-off these strategies? Although firms can adopt initial buffering-later bridging, they are not examined by using firm-level data. An organizational ambidexterity perspective provides new insights into the use of multiple response strategies. Third, when the external environment changes, what are the effects of the use of response strategies and their combination? Empirical testing is also required. This study introduces an organizational ambidexterity perspective, selects the sample data of 946 Chinese listed firms during 2011-2013, examines the impact of buffering, bridging and its combined strategies on external resource dependence, and the moderating effects of environmental munificence. The results suggest that buffering and bridging are effective strategies to respond to external resource dependence, and their impacts depend on environmental munificence, i.e. bridging is more effective, when firms face a more munificent environment; while buffering is more effective, when the environment becomes less munificent. Firms can reduce resource dependence by sequential ambidexterity strategy (i.e. initial buffering-later bridging). However, firms can reduce external resource dependence by simultaneous ambidexterity strategy (i.e. simultaneous buffering-bridging), only when their external environment becomes less munificent. The theoretical contributions of this study are as follows: First, this study promotes a comprehensive understanding of response strategies to external resource dependence. Extant research focuses more on the impact of buffering or bridging strategies alone, as well as the factors that enable or constrain buffering and bridging. Hillman et al. pointed out that the future direction should focus on the interaction between different types of response strategies, such as whether sequential response strategies exist or not. This study introduces an organizational ambidexterity perspective, examines the effects of simultaneous ambidexterity strategy and sequential ambidexterity strategy, and shows that sequential ambidexterity strategy can reduce resource dependence more than simultaneous ambidexterity strategy, which provides empirical evidence for Van den Bosch and Van Riel′s study. Second, this study contributes to the understanding of the contingent conditions of responding to resource dependence. This study introduces environmental condition as a contingent factor, which shows that response strategies and its combined strategies depend on specific environmental characteristics. These studies enrich the implementation conditions of enterprise response resource dependence strategy, and show that under certain environmental conditions, firms can not only use response strategy alone, but also use different types of ambidexterity strategies. Third, this study enriches the strategies responding to resource dependence from ambidexterity perspective, and promotes the understanding of the relationship between ambidexterity and resource dependence, and their contingent conditions. The effects of ambidexterity on performance depend on specific contextual factors, but extant research still lacks the understanding of the effects of contextual factors. This study shows that ambidexterity strategy depend on the degree of environmental munificence, low munificent environment is more able to make simultaneous ambidexterity strategy to reduce external resource dependence.

Key words: buffering, bridging, resource dependence, ambidexterity, environmental munificence